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338 Cards in this Set
- Front
- Back
chrom's are made up of many ______
|
genes
|
|
what is the haploid # of chrom's in humans?
|
23
|
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________ genes are distributed among human chrom's
|
35,000
|
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_______ megabases (over 3 billion nucleotides) in human chrom's
|
3300
|
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what is mendels 4th postulate?
|
during gamete formation, segregating pairs of unit factors assort independently of eachother
|
|
in 1903 _________ discovered that there must be more unit factors than chromosomes
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Sutton and Boreri
|
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t/f Certain genes are transmitted according to the law of independent assortment-
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F- certain genes are NOT transmitted according to the law of independent assortment
|
|
describe independent assortment-
|
2 genes on 2 different homologous pairs of chromosomes form 4 genetically distinct gametes
|
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when 2 nonallelic genes are on the same chrom, that tend to be inherited together
|
linked
|
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when 2 genes are so close to one another that no crossover occurs and parental gametes are produced
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complete linkage
|
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this type of crossover takes place during prophase I
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crossover of 2 linked genes
|
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________ are 2 new allele combinations generated by crossover b/t 2 linked genes
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recombinant/ crossover gametes
|
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t/f it's more likely that crosses involving genes on the same chrom will result in a percentage of offspring from recombinant gametes
|
T
|
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the % of offspring from recombinant gametes is variable, depends on the _______ b/t 2 genes
|
distance
|
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these 2 men first explained crossover events-
|
Morgan and Sturtervant
|
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Morgan discovered ______ in __________ (where the inheritance pattern of genes is located on the X-chromosome)
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X-linkage, Drosophila
|
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during meisosi, these are the pts of genetic exchange-
|
chiasmata- synapsed homologous chrom's
|
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these are synapsed homologous chrom's and the pts of genetic exchange during meiosis
|
chiasmata
|
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t/f if 2 genes are located relatively close to eachother along a chromosome they are MORE likely to have a chiasma form b/t them and undergo genetic exchange-
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FALSE, the closer 2 genes are located to eachother the LESS likely they are to form a chiasma and undergo genetic exchange, the FARTHER apart they are, the more likely to undergo genetic exchange
|
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physical exchange of chromosomal material during meiosis
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cross over
|
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t/f in drosophila, crossover occurs in females, in humans it occurs in BOTH sexes
|
TRUE
|
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who came up w/ the idea of chrom mapping?
|
sturtevant
|
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who came up with the idea of x-linkage
|
thomas morgan, by study of the drosophila
|
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this involves the data based on recombination events b/t genes that could be used to map a sequence of genes on the chrom
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chromosomal mapping
|
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the frequency of exchange can be taken as an estimate of _________ b/t 2 genes or loci along a chrom
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relative distance
|
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if you have 24 map units you have how many centimorgans (cM's)
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24
|
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__________ represent points of genetic exchange
|
chiasmata
|
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the physical exchange leading to recombination
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crossing over
|
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the % of recombinants can be used to determine-
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relative distance of genes to one another
|
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t/f in flies crossover only occurs in females
|
T
|
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t/f crossover events occur on autosomal and sex chromosomes
|
T (however in flies, crossover only occurs in females)
|
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Sturtevant and Morgans data strongly supports the idea that chrom's contain genes organized in a __________, and that genes are equivalent to Mendel's 'unit factors'
|
linear order
|
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who discovered that genes are equivalent to Mendel's theorized unit factors
|
Sturtevant and Morgan
|
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t/f crossing over can go undetected
|
T, if the linkage b/t 2 the alleles is unchanged after cross-over
|
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this type of crossover involves 3 gene pair's in the exchange
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double crossover
|
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what are the 3 requirements of mapping 3 or more genes-
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1)the genotype of the organism producing the gametes must be heterozygous for the genes of interest
2)genotypes can be accurately determined by observing phenotype 3)a sufficient # of offspring must be produced |
|
this is the crossover event in one region of the chrom that inhibits a second event in nearby regions-
|
interference
|
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what is the coefficient of coincidence (c)?
|
c= observed DCO/expected DCO
|
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what is the equation for interference-
|
I= 1.0- c
|
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t/f interference decreases as the genes in question are located farther apart-
|
TRUE
|
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as the ______ b/t 2 genes increases, mapping experiments become more inaccurate
|
distance
|
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_______ can be obscured when studying genes of interest on the same chrom
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pedigrees
|
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a statistical method used to determine if 2 genes are linked or unlinked
|
LOD score method
|
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this method was important for assigning genes to chrom's and in constructing human chrom. maps-
|
LOD score method
|
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describe somatic cell hybridization as a way to assign human genes to a chrom-
|
1) 2 cells in a culture can be induced to fuse, producing a heterokaryon
2) the cell contains 2 nuclei in a single cytoplasm 3) the nuclei fuse, creating a synkaryon 4)as cells are cultured, the human chrom's are gradually lost |
|
human deletion syndrom, in which it gets its name from the 'crying like a cat' symptom of the genetic disease-
|
cru du chat
identified in 1963 |
|
this chromosomal abberation involves 2n + or - a number, X
|
Aneuploidy
|
|
2n-1
|
monosomy
|
|
2n+1
|
trisomy
|
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chromosomal abberations involving multiples of n-
|
euploidy; polyploidy
|
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3n
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triploidy
|
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chromosomal abberation in which multiples of the same genome are present-
|
autopolyploidy
|
|
chromosomal abberation in which multiples of different genomes are present
|
alloplyploidy
|
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the loss of one chromosome (2n-1)
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monosomy
|
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in humans this is the name of the disease caused by the loss of one chrom (monosomy)-
|
turner syndrome (45, X)
-monosomy of autosomes, will die during development |
|
this syndrome involves the monosomy of autosomes, and death during development occurs
|
turner syndrome
|
|
in Drosophila this is the syndrom caused by the loss of 1 chrom (2n-1)
|
Haplo IV, where a loss of Chrom IV occurs and results in reduced body size and low viability
|
|
this is the syndrome in Drosophila caused bye the loss of 1 chrom (monosomy, 2n-1) in which the loss of chrom IV occurs and results in reduced body size and low viability
|
Haplo IV
|
|
t/f plants can tolerate the loss of one chrom-
|
TRUE
|
|
_________ is the partial loss of 1 chrom
|
segmental deletion
|
|
this syndrome is an example of segmental deletion (loss of 1 part of a chrom as opposed to the whole chrom)
|
cru du chat (crying like a cat)
|
|
what is the designation for cru du chat syndrome?
|
46, -5p (where -5p indicates the loss of part of the small arm of chrom 5)
|
|
what chrom is missing in cru du chat syndrome?
|
the p arm of chrom 5
(-5p) |
|
__________ births result in cru du chat syndrome (____% die during the 1st year of life)
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1 in 50,000 and 90% die during the 1st year of life
|
|
list the problems accompanying the cru du chat syndrome-
|
1) anatomic malformation
2) gastrointestinal and cardiac complications 3) mental retardation 4) abnormal development of larynx |
|
t/f in cru du chat the deleted portion of chrom 5 is paternal in origin in most of the cases
|
TRUE, 80% of the cases of cru du chat the deleted portion of chrom 5 is paternal in origin
|
|
the addition of a chrom to a diploid genome (2n+1)
|
trisomy
|
|
what syndrome is commonly associate with trisomy in which the designation is 47, XXY
|
Kleinfilder syndrome
|
|
t/f the addition of an autosome is usually lethal during development
|
TRUE
|
|
the only human autosomal trisomy in which a significant # of individuals survive longer than a year past birth
|
down syndrome
|
|
what is the designation for down syndrome?
|
trisomy 21
47, 21+ an extra chrom, called chromosome 21 |
|
how many births result in down syndrome
|
approximately 1 in 800 live births (6,000 children a year)
|
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what are some phenotypical results of down syndrome (trisomy 21)
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1)fold in corner of each eye
2)flat face 3)round head 4)short 5)protruding tongues 6)short hands 7)physical psychomotor and mental retardation 8)short life expectancy 9)prone to respiratory disease 10)heart malformations 11)leukemia |
|
___% of people affected by down syndrome are expected to live to the age of 50
|
50%, over 50 they teend to develop many problems
|
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what would be the designation of a BOY with down syndrome?
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(47, XY, 21+)
|
|
what would be the designation of a girl with down syndrome?
|
(47, XX, +21)
|
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the _______ is the source of the extra chromosome in 95% of down syndrome cases
|
ovum
|
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t/f the female is more than likely responsible for the extra chromosome present in down syndrome children
|
TRUE
|
|
t/f the female is more than likely responsible for the deleted portion of chrom 5 in the cru du chat syndrome-
|
FALSE, 80% of the cases, the deleted chrom 5 portion is paternal in origin
|
|
at the age of 30 how many births would likely be affected by down syndrome?
|
1 in 1,000
|
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at the age of 40 how many births would likely be affected by down syndrome?
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1 in 100
|
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why are older women more likely to have a child w/ DS?
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the primary oocytes that undergo complete meiosis I and enter into meiosis II in a 40 yr old woman are older than the oocyte that went through the same process 10 years ago
|
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what is the mean maternal age for those giving birth to down syndrome children
|
32
|
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t/f maternal nondisjunction during the 2nd meiotic division is the cause of trisomy 21
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F, nondisjunction during the 1st meiotic division is the most common cause of DS
|
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what is the most common cause of DS?
|
maternal nondisjunction of the 1st meiotic division
|
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what is the designation of Patau Syndrome?
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(47, +13)
|
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___ in _______ live births result in Patau Syndrome
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1 in 19,000
|
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what is the avg survival rate of someone w/ Patau syndrome
|
3 months (1 in 20 will live longer than 6 months)
|
|
this syndrome is addition of a chromosome to the 13th genome, results in death due to cardiopulmonary arres, congenital heart disease and pneumonia
|
Patau Syndrome
|
|
this syndrome is related to partial monosomy
|
Cru du chat
|
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this syndrome is trisomy 13
|
Patau syndrome
|
|
this syndrome is trisomy 18
|
Edwards Syndrome
|
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this syndrome is trisomy 21
|
Downs Syndrome
|
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this is a test used to detect partial monosomy
|
fluorescent in situ hybridization (FISH)
|
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it is estimated that ______% of all conceptions are terminated by spontaneous abortion
|
15-20%
|
|
t/f a significant number of spontaneous abortuses are trisomic
|
TRUE
|
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t/f trisomies for every chromosome have been detected
|
TRUE
|
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_________ aberrations for every chromosome have been detected
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trisomic
|
|
_____ abberations are rarely found
|
monosomic
|
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what 3 organisms have been commonly used to study modes of sexual differentiation by studying the lifecycle
|
1)Clamaydomonas (green algae)
2) Zea Mays (corn) 3) C. elegans (nematodes) |
|
C elegans have ___ autosomal chrom's
|
5
|
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what are the genotypes of female and male nematodes?
|
female XX
male XO (they lack the Y chromosome) |
|
how do you determine the sex of a nematode?
|
the ratio of X chromosomes to the number of autosomal chromosomes
|
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a ratio of ____ in nematodes results in hermaphrodites, and a ratio of ____ results in males-
|
1, 0.5
|
|
who used the hermipteran insect Lugaeus turicus to study XX/XY mode of sex determination
|
Edmund Wilson
|
|
females produce similar gametes and are referred to as being the ________ sex
|
homogametic
|
|
t/f females are the heterogametic sex
|
F, homogametic (XX)
|
|
t/f males are the heterogametic sex
|
T, (XY)
|
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Edmund Wilson used _______ to begin to understand how sex is determined
|
Protenor
|
|
in 1920 ______ discovered the Y chromosome
|
Painter discovered the Y chromosome
|
|
what did Painter discover?
|
Y chromosome
|
|
when was it determined that the diploid number is 46
|
1956
|
|
this syndrome involves abnormal sexual development such as male genitalia and internal ducts, but testes fail to produce sperm, enlargment of breasts and rounded hips, below normal intelligence
|
Klinefelter syndrome
|
|
what are some symptoms of Klinefelter syndrome?
|
1) male genitalia and internal ducts, but failure to produce sperm
2) enlargement of breasts and rounded hips 3) below avg intelligence 4) long arms, legs, large feet and hands |
|
what is the designation for Klinefelter syndrome?
|
(47, XXY) 44 autosomes and the XXY chromosomes
can also be 48,XXXY; 48,XXYY; 49,XXXXY; 49,XXXYY |
|
how many males will have the klinefelter syndrome?
|
2 in every 1,000
|
|
what are treatment options for klinefelter syndrome?
|
1) testosterone replacement for correction of the androgen deficiency
2) tailoring school curricula to address learning difficulties |
|
syndrome involving female external genitalia and internal ducts, but the ovaries are rudimentary
|
turner syndrome
|
|
this phenotype would indicate what genetic disorder?
short stature, skin flaps on the back of neck, underdeveloped breasts, but normal intelligence- |
turner syndrome
|
|
t/f someone with turners syndrome would be LESS susceptible to disorders such as osteoperosis, hypothyroidism, and diabetes
|
FALSE, they would be MORE susceptible
|
|
what is a viable treatment for turners syndrome?
|
hormone treatment (estrogen)
|
|
what is the designation of turners syndrome?
|
(45, X) 44 autosomes and one X chromosome
|
|
how many females will develop turner syndrome?
|
1 in 2,000 (most 45,X embryos die in utero)
|
|
when a mitotic error during development occurs such as (45,X)/(46,XY) and (45,X)/(46,XX)
|
mosaic
|
|
t/f turner syndrome is an example of a mosaic genetic disorder
|
T, mosaic is a mitotic error during early development
|
|
which syndrome is a good example of a mosaic disorder?
|
Turner Syndrome
|
|
term for an error during cell division in which the homologous chrom's fail to seperate and migrate to opposite poles
|
nondisjunction
|
|
this syndrome is a result of nondisjunction that results in monosomic gametes
|
Turner syndrome
|
|
this syndrome is a result of nondisjunction where trisomic gametes form
|
Kleinfelder
|
|
this designation occurs 1 in 1200 births, can appear normal or can have underdeveloped secondary sex characteristics, sterility and mental retardation
|
47,XXX
|
|
this sex linked disorder will result in above avg height and subnormal intelligence
|
47,XXY
no consistent correlation b/t the extra Y chrom and the predisposition of males to behavioral problems |
|
region of the human Y chrom that contains genes
|
euchromatin
|
|
region of the human Y chrom that lacks genes
|
heterochromatin
|
|
region of the Y chrom that has some genes that are homologous to the X and some that aren't
|
NRY-non recombining region
|
|
region of the human Y chrom that shares homology w/ the X chrom
|
PAR (psuedoautosomal region)
|
|
region of the human Y chrom that encodes a gene product that signals undifferentiated gonadal tissue of the embryo to form testes (the testis determining factor)
|
SRY region (sex determining region Y)
|
|
this region of the Y chromosome is NOT in female chromosomes
|
SRY (sex determining region Y) region
|
|
t/f the SRY region is present in ALL male mammals
|
TRUE
|
|
how can a human male have the sexual genotype XX?
|
if the SRY region is present on one of the X chrom's
|
|
how can human females have the sexual genotype XY?
|
if the SRY region is missing from the Y chromsome
|
|
explain the transgenic mice experiment-
|
eggs that are XX are injected with SRY DNA and the offspring develop into males thus proving that SRY gene is the primary signal for male development
|
|
t/f because females have 2 X chromosomes more genes are expressed in females
|
F, only a SINLGE active X chromosome exists in each cell, no more genes are expressed in females than males
|
|
this is a term to describe a mechanism that regulates the level of gene products at a certain loci on the X chrom such that the males nad females have equal amnts of gene product
|
dosage compensation
|
|
the dark staining body in interphase cells of females is referred to as-
|
barr bodies
|
|
t/f the study of sex chromosome syndromes have shown that regardless of how many X chromosomes exist, all but one is inactivated
|
TRUE, no matter how many X chromosomes exist, all but one is inactivated
|
|
if all but one X chrom is inactivated why aren't individuals w/ Turner or Kleinfelder syndrome 'normal'?
|
-perhaps inactivation doesn't occur during early stages of development
-maybe not ALL of the genes are inactive |
|
this is the idea that inactivation of the X chrom occurs randomly-
|
Lyon Hypothesis (Mary Lyon and Liane Russell)
|
|
the mosaic pattern of orange or black in Calico cats is an example of -
|
the Lyon Hypothesis
-in rare cases there are male calicos (1 in 3,000) |
|
Pigmentation gene on the ______ chromosome allows calico cats to have one allele that will give rise to black color and another allele that gives rise to the orange color
|
X chromosome
|
|
the allelic forms of Glucose-6-Phosphate dehydrogenase in which fibroblasts taken from females and G6PD isoforms were analyzed is evidence for -
|
Lyon Hypothesis
|
|
give an example of a phenotype of an X-linked disorder in females-
|
the retinas of female carriers are composed of mosaic patches of colorblind and normal areas
|
|
how are almost all genes on an entire X chrom inactivated?
|
there is a region on the X chrom, called the X Inactivation Center (XiC) 1Mb or 10^6 base prs
|
|
this is the region of the X chromosome that is responsible for the inactivation of almost all genes on an entire X chrom
|
X Inactivation Center (XiC)
|
|
in the X inactivation center what gene is transcribed (RNA made) that is involved in inactivating the X chrom
|
Xist gene
|
|
what experiment proved that the XIC region inactivated the genes on the extra X chromosome
|
an experiment that deleted that region resulted in the X chromosome no longer being inactivated thus proving that the XIC region was responsible for inactivating the genes on the extra X chrom
|
|
who first showed in 1916 that in flies the Y chrom doesn't determine maleness?
|
Calvin Bridges
|
|
what did Calvin bridges propose about the drosophila sex determination?
|
he proposed that both the X chrom's and the autosomes play a role in sex determination
|
|
t/f if a fly displays the sex genotype XXY it will be male-
|
F, XXY flies were normal females, thus proving that Y chromosomes did not cause maleness
|
|
what is the genotype of sterile drosophila males?
|
XO
|
|
what is the role of the Y chromosome in flies-
|
the Y chromosome in flies lacks male determining factors, but Y does contain some genes important for male fertility
|
|
what determines sex in flies?
|
the ratio of X chroms to the number of haploid sets of autosomes
|
|
what characteristics would indicate a triploid female drosophila?
|
heavy set bodies, course bristles, course eyes, and they may be fertile
|
|
how do triploid drosophila females originate?
|
from diploid eggs fertilized by normal haploid sperm
|
|
what kind of gametes are produced by triploid drosophila females?
|
gametes that display a wide range of chrom complements, thus giving rise to offspring w/ a variety of abnormal chromosomal constituents
|
|
this involves the sex-determining system of flies in which sexual phenotype is controlled by a balance b/t genes on the X chrom and genes on the autosomes
|
Genic Balance Theory
|
|
this sex determining factor of flies involves the X:A ratio at 1:2, where the presence of an additional X chrom alters the balance and results in female differentiation
|
threshold for maleness
|
|
t/f mutants have been identified that are involved w/ sex determination in flies
|
TRUE
|
|
this is the autosomal gene causing maleness even if the sex genotype is XX
|
transomer (tra) tra/tra
XX tra/tra are male |
|
this X linked gene is known as the 'master switch' in which if females of XX have it they will die, but if XY males with the gene have it, they are fine-
|
Sex lethal (sxl)
XX sxl/sxl-females die XY sxl males- are fine |
|
t/f in both mammals and flies x-linked genes are transcribed at twice the level of the genes in females
|
FALSE, only in drosophila (flies)
|
|
term that describes the expression of a recessive allele on one homolog as caused by the deletion of the dominant allele on the other homolog
|
psuedodominance
|
|
describe psuedodominance
|
expression of a recessive allele on one homolog as caused by the deletion of the dominant allele on the other homolog
|
|
what is the inheritance pattern of chrom duplication?
|
semidominance
|
|
how do new genes arise?
|
duplications of an essential genes and an extra copy of the gene can get mutations and thus give rise to a new gene
|
|
t/f in general an essential gene doesn't accumulate mutations
|
TRUE, duplications of essential genes, and extra copies can get mutations
|
|
this describes a segment of the chrom that is turned around 180 degrees
|
inversion
|
|
t/f the inverted sequence may or may not include the centromere
|
TRUE, doesn't necessarily involve the centromere
|
|
in this type of inversion the arm ratio remains unchanged
|
paracentric inversion
|
|
in this type of inverstion the arm ratio is changed
|
pericentric inversion
|
|
what are the consequences of inversions during gamete formation?
|
normal linear synapsis during meiosis is not possible
an inversion loop will form and crossing over doesn't occur |
|
in this type of inversion the centromere is not part of the rearranged chromosome segment
|
paracentric inversion
|
|
what happens when a single crossover occurs w/i an inversion loop?
|
the inversion loop can produce abnormal chromatids
|
|
when a single crossover occurs, this type of inversion doesn't involve centromere's as part of the rearranged chrom segment
|
paracentric
|
|
when a single crossover occurs, this type of inversion involves the centromere as part of the rearranged chrom segment
|
pericentric inversion
|
|
this is the movement of a chromosomal segment to a new location in the genome
|
translocation
|
|
the exchange that occurs in translocation occurs b/t 2 ___________ chromosomes
|
nonhomologous
|
|
breaks occur w/i the ___________ region on 2 nonhomologous chromosomes
|
centromeric
|
|
this syndrome involves sensitive sites along chrom X, results in mental retardation
|
Fragile X syndrome
|
|
fragile X syndrome affects ___________ males and ___________ females
|
1 in 4000 males and 1 in 8000 females
|
|
what gene on the X chromosome accounts for the Fragile X syndrome?
|
FMR1 gene encodes an RNA binding protein, and thus a trinucleotide repeat of CGG occurs
|
|
what reasons are bacteria good research organisms?
|
1) short reproductive cycles
2) grow fast 3) haploid 4) spontaneous mutations |
|
this is considered the primary source of genetic variation
|
spontaneous mutation
|
|
why is it advantageous for bacteria to be haploid-
|
b/c all mutations will be expressed DIRECTLY in the descendants of mutant cells
|
|
type of medium where the nutrient components of the growth medium are very simple and consist only of an organic carbon source-
|
minimal medium
|
|
wild type bacteria for all growth reuqirements and can grow on minimal medium
|
prototroph
|
|
a bacterium that is unable to synthesize one or more organic compounds-
|
auxotroph
|
|
an auxotroph that loses its ability to make histidine would be disignated as-
|
his-
|
|
what 2 bacteriologists were involved in conjugation studies
|
lederburg, tatum
|
|
process where the genetic info from one bacterium is transferred and recombined w/ that another bacterium
|
conjugation
|
|
genetic info is transferred from one chrom to another, resulting in an altered genotype
|
genetic recombination
|
|
describe tatum and lederburgs experiment that implied genetic recombination-
|
they plate 2 auxotrophic strains (A and B) on minimal medium and discovered NO GROWTH, but after mixing the 2 (both containing components the other didn't have) they found that plating would produce prototrophs, and growth occurred on the minimal medium through genetic recombination
|
|
cells that serve as donors of parts of their chrom's
|
F+ cells (f for fertility)
|
|
recipient bacteria that receive the donor chrom material (DNA) and recombine it w/ part of their own chrom
|
F- cells
|
|
who designed the U tube in which to grow F+ and F- cells
|
Davis
|
|
physcial interaction is the initial stage of the process of conjugation and is mediated through a conjugation tubed called the ______
|
F or sex pilus
|
|
F+ cells contain a __________ that confers the ability to donate part of their chrom during conjugation
|
F factor (fertility factor)
|
|
following conjugation and genetic recombination- recipient cells always become ___
|
F+
|
|
a gene of the F factor that is involved in the transfer of genetic info
|
tra genes
|
|
t/f the F factor has been shown to consist of a circular dbl stranded DNA mx, making up about 2% of the bacterial chrom
|
TRUE
|
|
t/f the F factor is AKA a plasmid
|
T
|
|
process in which a separation of 2 strands of the dbl helix of DNA occurs, one moving by way of a sex pilus into a recipient cell (F-) and the other remaining in the donor cell (F+), both replicating which results in both cells becoming F+
|
conjugation
|
|
cells that behave as chrom donors, a special calls of F+ cells that demonstrate an elevated frequency of recombination
|
Hfr (high frequency recombination)
|
|
t/f when Hfr comes into contact with F- cells, the F-cells become Hfr
|
FALSE, they remain F- cells
|
|
t/f when F+ cells come into contact w/ F- cells, the recipient becomes F+
|
TRUE
|
|
technique in which Hfr and F- cells come into contact but are put in a blender to separate conjugation, then grown on medium containing the antibiotic to ensure recovery of only recipient F- cells
|
interrupted mating technique
|
|
what experiment proved that Hfr bacterium was transferred linearly and gene order and distance between genes, as measure in minutes could be predicted
|
interrupted mating technique- by interrupting the conjugation of Hfr and F- cells at different pts in time, one could see which genes were transferred at a faster rate and before others
|
|
t/f minutes are equivalent in bacterium to mu's in eukaryotes
|
TRUE
|
|
t/f E.coli chrom is circular (no free ends) w/ a point of origin (O) that varies from strain to strain
|
T
|
|
What determines the O site of E.coli Chrom-
|
the F factor intergrates into the chrom at different pts and its position determies the O site
|
|
the use of _________________ w/ different Hfr strains allowed researchers to map the entire E. coli chrom
|
interrupted mating technique
|
|
Hfr underwent a comination at a rate of ______ times more frequently than F+ strain
|
1,000
|
|
Alderberg discovered that the F factor could lose its integrated status, causing the cell to revert to the F+ state known as
|
F'-> Hfr
|
|
F' cells initiate conjugation w/ F- cells, much like F+ cells do; the f factor is transferred to the F- cell, and then duplicate w/i the recipient cell, b/c the recipient still has a complete chrom- this creates a partially diploid calle called a
|
merozygote
|
|
t/f the transfer of DNA b/t bacteria is unidirectional
|
T
|
|
this is an enzyme consisting of polypeptide subunits encoded by 3 rec genes (recb, recc, and recd)
|
RecBCD protein
|
|
extrachromosomal, circular piece of dsDNA that replicates independent of the chromosome
|
plasmid
|
|
what are the 2 components of R plasmids
|
1)RTF-resistance transfer factor
2) r-determinants |
|
this component of the R plasmid encodes genetic info essential to transfer the plasmid b/t bacteria
|
RTF factor
|
|
this component of the R plasmid are genes conferring resistance to antibiotics
|
r-determinants
|
|
what would happen if a bacteria contained r-determinant plasmids but not RTF plasmids?
|
the bacterial cell would still be resistant however it would not be able to transfer the genetic material for resistance to recipient cells
|
|
_______ derived from E.coli, encodes for one or more proteins that are highly toxic to bacterial strains that don't harbor the same plasmid
|
Col plasmid- not usually transmissable to other cells, whereas the R plasmid is easily trasmissable
|
|
proteins, called ______, encoded for by the Col plasmid kill neighboring bacteria
|
colicins
|
|
process in which small peices of extracellular DNA are taken up by a living bacterium, leading to a stable genetic change in the recipient cell
|
transformation
|
|
what are the 2 main categories of transformation
|
1)entry of DNA into a recipient cell
2)recombination of the donor DNA w/ its homologous region in the recipient chrom |
|
t/f only competent bacterial cells will take up DNA in transformation
|
T
|
|
the recombinant region in transformation that contains one host strand and one mutant strand
|
heteroduplex
|
|
after the first round of cell division following transformation what is produced-
|
1 cell containing the original nontransformed chrom and the other containing the transformed chrom.
|
|
these are referred to as bacterial viruses
|
bacteriophages
|
|
these are viruses that have bacteria as their host
|
bacteriophages/phages
|
|
bacteriophage that includes an icosahedral head filled w/ DNA, a tail consisting of a collar, tube, sheath, base plate and tail fibers-
|
bacteriophage T4
|
|
what are the 3 processes in assembly of a mature virus structure-
|
1)DNA packaging as viral heads are assembled
2)tail assembly 3)tail fiber assembly |
|
a cleared area where bacteria is absent
|
plaque
|
|
______ occur wherever a single virus has intially infected one bacterium in the lawn that as grown up during incubation
|
plaques
|
|
virally mediated gene transfer from one bacterium to another
|
transduction
|
|
when approximately _____ viruses are constructed w/i a bacteria, the cell lyses and the mature phages are released to infect other bacterial cells
|
~200 viruses
|
|
process in which viral DNA enters a bacterial cell and instead of replicating in the bacterial cytoplasm, its integrated into the bacterial chrom
|
lysogeny
|
|
t/f in lysogeny- no new viruses are produced and no lysis of the bacterial cell will occur
|
TRUE, unless introduced to certain stimuli that would induce viral DNA to lose its integrated status and initiate replication, phage reproduction, and lysis of the bacterium
|
|
viral DNA integrated into the bacterial chromosome
|
prophage
|
|
ciruses that can either lyse the cell or behave as a prophage
|
temperate
|
|
viruses that can only lyse the call are referred to as-
|
virulent
|
|
bacterium harboring a prophage has been ___________ and is said to be ________
|
lysogneized, lysogenic
|
|
bacterium that is capable of being lysed as a result of induced viral reproduction
|
lysogenic
|
|
viral DNA, that can replicate either in the bacterial cytoplasm or as part of the bacterial chrom is classified as an-
|
episome
|
|
virus mediate bacterial DNA transfer
|
transduction
|
|
who discovered transduction
|
Zinder and Lederberg
|
|
describe the Zinder-Lederberg experiment using Salmonella-
|
using the Davis U tube, they placed 2 auxotrophic strains of Salmonell LA-2 and LA 22 on either side of the filter, when plated independently the LA 22 side produced prototrophs
|
|
this type of inheritance is exhibites when intermeidate phenoypic expression fo a trait occurs in an organism that is heterozygours for 2 alleles
|
incomplete dominance
|
|
inheritance where 2 distinctive effects of 2 alleles occur simultaneously in a heterozygous organism
|
codominance
|
|
chromosomes consist of very lg numbers of genes that are part of the same chrom and are said to be __________
|
linked
|
|
the _________ is the unit of transmission during meiosis
|
chromosome (NOT THE GENE)
|
|
-the reshuffling or recombination of the alleles b/t homologs
-a physical breaking and rejoining process that occurs during meiosis |
crossing over
|
|
the degree of crossing over b/t any 2 loci on a single chrom is proportional to the distance b/t them known as-
|
interlocus distance
|
|
these indicate the relative locations of genes on the chrom
|
chromosome maps
|
|
type of linkage resulting in only parental or noncrossover gametes
|
complete linkage (seldom occurs)
|
|
t/f the frequency w/ which crossing over occurs b/t any 2 linked genes is proportional to the distance seperating the respecitve loci along the chrom-
|
TRUE
|
|
as the distance b/t 2 genes increases the proportion of _______ gametes increases and that of __________ gametes decreases
|
recombinant, parental
|
|
t/f the number of recombinant gametes approaches but will not exceed 50%
|
TRUE
|
|
what ratio is characteristic of complete linkage?
|
1:2:1
|
|
_________ is observed only when 2 genes are located very close together and the # of progeny is relativiely small
|
complete linkage
|
|
who was the first to discover X-linkage
|
Morgan
|
|
these are known as points of genetic exchange
|
chiasmata
|
|
t/f if linked genes exist in a linear order along the chrom, then a variable amount of exchange occurs b/t any 2 genes
|
TRUE
|
|
the physical exchange of genetic info leading to recombination
|
crossing over
|
|
t/f linkage and crossing over are restricted to X-linked genes
|
F, thy could also be demonstrated w/ autosomal genes
|
|
in flies crossing over only occurs in-
|
females
|
|
what is the chromosomal theory of inheritance-
|
chromosomes contain genes in a linear order and these genes are equivalent to Mendel's unit factors
|
|
the closer 2 loci reside on the axis of the chrom, the less likely that any ____________ event will occur b/t them
|
single crossover
|
|
when 2 loci are far apart, crossover will occur in an area of the chrom b/t them, this seperates them, yielding-
|
recombinant gametes
|
|
the chromatids that are not involved in the exchange of material during cross over
|
non cross over gametes
|
|
in a single crossover-the %age of tetrads involved in an exchange b/t 2 genes is twice as great as the percentage of __________
|
recombinant gametes produced
|
|
what is the theoretical limit of recombination due to crossing over?
|
50%
|
|
double exchanges of genetic material result from -
|
DCOs (double cross overs)
|
|
in the case of a ____________, 2 seperate and independant events or exchanges must occur simultaneously
|
double crossover
|
|
if 3 genes are relatively close together along one chrom, the expected frequency of dbl crossover gametes is
a)extremely high b)extremely low |
extremely LOW
|
|
the 3 criteria for a successful mapping cross-
|
1) genotype of the organism producing the crossoer games must be heterozygoes at all loci under consideration
2)crross must be constructed so that genotypes of all gametes can be accurately determined by observing the phenotypes of offspring 3)a sufficient # of offspring must be produced in the mapping experiment to recover a representative sample of all crossover classes |
|
phenotypes that complement one another (i.e. one wild, other mutant)
|
reciprocal classes
|
|
these phenotypes generally occur in the greateast proportion of offspring
|
noncrossover phenotype
|
|
phenotype, because of their probability of occurence, must be present in the least numbers
|
double crossover phenotype
|
|
when a crossover event in one region of the chrom inhibits a 2nd event in nearby regions
|
interference
|
|
_________ decreases as the genes in question are located father apart
|
interference
|
|
this type of exchange of genetic material takes place in Drosophila as well as certain Fungi
|
mitotic recombination
|
|
a statistical method used to determine if 2 genes are linked or unlinked
|
LOD score method
|
|
technique that aids in assigning human genes to their respective chrom's that relies on the fact that 2 cells in culture can be induced to fuse into a single hybrid cell
|
somatic cell hybridization
|
|
when 2 cells from different organisms are induced to fuse together they produce a__________, containing 2 nuclei in a common cytoplasm-
|
heterokaryon
|
|
when the 2 nuclei of a heterokaryon eventually fuse together they form a-
|
synkaryon
|
|
result of fragments of a particular chrom become transferred to another chrom
|
translocation
|
|
_______ ensures genetic constancy within members of the same species
|
meiosis
|
|
chromosomes such as XY, often characterize one sex or the other
|
heteromorphic chrom's/ sex chrom's
|
|
_______ rather than _________ ultimately serve as the underlying basis of sex determination
|
genes rather than chrom's
|
|
differentiation involving the gonads where gametes are produced
|
primary sexual differentiation
|
|
differention that involves the overall appearance of the organism, IE differences in such organs as mammary glands, external genetalia
|
secondary sexual differentiation
|
|
an individual containing ONLY male or ONLY female reproductive organs-
|
unisexual, dioecious, gonochoric
|
|
individuals containing both male AND female reproductive organs
|
bisexual, monoecious, hermaphroditic
|
|
individuals of intermediate sexual differentiation, who are most often sterile
|
intersex
|
|
green alga Chalmydomonas spend most of their lives in the _______ phase, asexually producing daughter cells by mitotic division
|
haploid
|
|
this organism spends most of its life in the haploid phase, reproducing asexually
|
Chlamydomonas
|
|
this organism has an alternating life cycle b/t the diploid sporophyte stage and the haploid gametophyte stage, that are linked by the processes of meiosis and fertilization
|
Zea mays
|
|
what are the 2 sexual phenotypes of C. elegans-
|
hermaphroditic-both testes and ovaries and males with only testes
|
|
approximately how many male C. elegans would be produced after self fertilization?
|
less than 1%, the rest hermaphrodite
|
|
what percentage of male vs hermaphrodite would result in the cross fertilization of a male and a hermaphrodite C. elegans
|
50% male, 50% hermaphrodite
|
|
t/f C. elegans lacks a Y chromosome completely
|
T, maleness is determined by genes located on both the X chrom and autosomes
|
|
what determines the sex of C. elegans?
|
the ratio of X chromosomes to the number of sets of autosomes
|
|
who demonstrated that females have 2 X chromosomes whereas males only have 1, by examining Protenor (with 14 chrom's)
|
Wilson
|
|
fertilization by X bearing sperm resultes in ______ offspring, and fertilization by X deficient sperm results in ________ offspring
|
female, male
|
|
ratio of offspring depending on the random distribution of the X chrom into 1/2 male gamets during segregation
|
XX/XO sex determination or Protenor mode of sex determination
|
|
what 2 organisms did Wilson study to better understand sex determining chromosomes
|
Protenor and Lygaeus turicus
|
|
Wilson discovered that males of the Lygaeus turicus species have a single X and a smaller heterochromosome called a
|
Y chrom
|
|
mode of sex determination following random fertilization, equal numbers of male and female progeny will be produced w/ distinct chrom complements-
|
XX/XY sex determination
|
|
In Protenor and Lygaeus insects, males produce unlike gametes and are thus described as-
|
heterogametic sex
|
|
females who have 'like' sex chroms are the________ producing uniform gametes w/ regard to chrom numbers and types
|
homogametic sex
|
|
t/f the male is always the heterogametic sex
|
FALSE
|
|
who discovered the Y chrom in human males
|
Painter
|
|
when was the diploid number of human chromosomes finally clarified?
|
1956
|
|
t/f the Y chrom determines maleness in humans
|
TRUE
|
|
syndrome where genetalia and internal ducts are usually male, but testes are rudimentary and fail to produce sperm
|
Klinefelter syndrom
|
|
syndrome where affected individ'l has female external genetalia and internal ducts, but ovaries are rudimentary
|
Turner syndrome
|
|
t/f in Klinefelter syndrome intelligence is not affected
|
FALSE, its usually below normal
|
|
t/f in Turner syndrome intelligence is not affected
|
TRUE
|
|
what is the designation of Klinefelter syndrome?
|
(47, XXY)
|
|
what is the designation of Turner syndrome?
|
(45,X)
|
|
both turner and klinefelter syndrome result from __________, the failure of the X chrom to segregate properly during meiosis
|
nondisjunction
|
|
individuals called _____ whose somatic cells display 2 different genetic cell lines, each exhibiting a different karyoype
|
mosaics
(IE 45,X/46,XY or 45,X/46,XX) |
|
t/f most 45,X fetuses die in utero and are aborted spontaneously
|
TRUE, making Klinefelters more frequent than Turner syndrome
|
|
syndrome that occurs every 1 in 1200 births, varies highly in expression, some women are normal and other are underdeveloped secondary sex charactersitcs, sterility, retardation
|
47, XXX syndrome
|
|
present on both ends of the Y chrom are ______ that share homology w/ the X chrom and synampse and recombine during meiosis
|
PARS
|
|
gene that controls male sexual development, encodes a gene product that triggers the undifferentiated gonadal tissue of an embryo to form testes-
|
SRY (sex determining region Y)
|
|
t/f the SRY gene on the Y chrom provides the primary signal for male development
|
TRUE
|
|
the critical factor in determining sex of drosophila is the ratio of X chrom's to the number of haploid sets of _________
|
autosomes
|