Abg: Module 2 Basic Genetics And Biochemistry Of Inheritance

Branch of genetics that deals with chromosomes

English chemist, X-ray crystallographer – instrumental in the discovery of DNA like Crick and Watson

o used X-ray diffraction to determine the structure of DNA molecules

o Her Photo 51 helped scientists learn more about the three-dimensional structure of DNA and enabled scientists to understand DNA´s role in heredity

physicist, molecular biologist

o X-ray crystallography equipment 1954 o Assisted the Watson-Crick discovery/establishment of the chemical structure of DNA

• Linear end-to-end arrangement of genes and other DNA, sometimes with associated proteins and ribonucleic acid

tip/end of the chromosomes

o made of repetitive sequences of non-coding DNA that protect the chromosome from damage. Each time a cell divides, the ______ become shorter. Eventually, they become so short that the cell can no longer divide

o specific DNA–protein structures found at both ends of each chromosome, protect genome from nucleolytic degradation, unnecessary recombination, repair, and interchromosomal fusion. It therefore play a vital role in preserving the information in our genome.

specialized region DNA on each eukaryotic chromosome that acts as a site for the binding of kinetochore proteins

less-condensed chromosomal region, thought to contain most of the normally functioning genes

o defined as the area of the chromosome which is rich in gene concentration and actively participates in the transcription process

o the genetically active region of the chromosome. It contains structural genes that are replicated during G1 and S phase of interphase by allowing polymerases to access the genes

cytologically dense material that is typically found at centromeres and telomeres. It mostly consists of repetitive DNA sequences and is relatively gene poor. Its most notable property is its ability to silence euchromatic gene expression.

Types of chromosomes based on the position of the centromere

same length p and q arms

shorter p arm

very short p arm

no p arm

Forms of chromosomes

• Complete set of chromosomes that are arranged in order size • Each species and sex have different karyotype characteristic (e.g., shape, size, number)

CHROMOSOMES OF DOMESTIC ANIMALS

cells contain half of the chromosomes (e.g., reproductive cells)

– cells with 2 members of each chromosome pair - (2n, where n=number of chromosome pair in a species)

Adult female

Adult male

Equine up to 1 yr old

Equine after 1 year old

Swine species as a whole, or any member of it

unweaned young pig, or any immature pig

a pig between birth and weaning.

a young pig recently separated from the sow

an unusually small and weak piglet, often one in a litter

male pig of breeding age

male pig castrated before puberty

male pig castrated later in life (an older boar after castration)

young female not yet mated, or not yet farrowed, or after only one litter (depending on local usage)

breeding female, or female after first or second litter

Sheep (_______) and lambs (_______)

fiber that most sheep grow is called _______. The wool from one sheep is called a ________.

female lamb

young female sheep

Process giving birth in sheeps

birthing

pregnancy

male sheep

is the slang term ram lamb (young male)

In parts of the United Kingdom, a ram is called a _____ and the mating season is called _______

Shaving of wool in sheep

castrated male sheep, less aggressive than rams

between 1 and 2 years of age that may or may not have produced offspring.

In other countries, a yearling ewe is called a

In goat; ________ (adult male), ________ (young)

In goats: __________ (adult female), ______ (young)

Young goats

Newly Hatched Chicken

Male chicken that is under a year old

Female that is under a year old

A young male or female bird

Male that is a year or older

Female that is a year or older

A male chicken (includes cock and cockerel)

Refers to small breeds of chicken (AKA Miniature Chicken)

Breed of chicken that is raised primarily for egg collection

Breed of chicken that is raised for both eggs and meat

Breed of chicken that is raised primarily for show or exhibition

Breed of chicken that is raised for high egg production or meat production

Two essential processes in the survival of organisms (especially those reproducing sexually)

True or false: In humans, a somatic cell normally contains 23 pairs of chromosomes (total=46 chromosomes). Twenty-two (22) pairs are autosomes, one pair of sex chromosomes (the X and Y)

Nuclear division resulting in _________

mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

True or false: Gametes are diploid

point of contact, the physical link, between two chromatids belonging to homologous chromosomes

exchange of genetic material can occur between both chromatids, what is called a chromosomal _________ in _________ in Meiosis

• for growth and development of an organism

• happens in somatic cells

Part of cell cycle of mitosis

same type (e.g., chromosome 1 from father and mother and so on)

Is the presence of the Y chromosome enough for the development of a male in mammals?

Sex inheritance is investigated in early 1900s by __________

• Sex chromosome in: X and Y

➢ Females:

➢ Males:

• After meiosis

➢ Females:

➢ Males:

is important in the expression of doublesex and mab-3 related transcription factor 1 (DMRT 1) gene (present in chromosomes/autosomes) important in the expression of male

Sex chromosomes in avian

carries the genes that are essential for the development of female in avian species

Female expressed transcript

Avian sex-specific W-linked

In avian species the sex chromosomes for

• Females:

• Males:

Involves a large portion of or multiple genes in the genome

Techniques to assess mutations

Why study chromosome mutations?

Forms of chromosome mutations

Change in number results in extra or lacking DNA molecules

Types of aberration in number

changes in whole chromosome set

- 1 set of chromosomes

- characteristically sterile, gametes are produced by mitosis

changes in parts of chromosome set

normal number of chromosomes

– with more than two sets of chromosomes

– Common in plants and rare in animals

– Increase in the number of chromosomes=origin of new plant species

– Often larger and have larger component parts of their diploid relatives

– individual species that have more than 2 chromosome sets( 3n, 4n, 5n, 6n )

Is the containment of multiple sets of chromosomes that are derived from the same species

is the containment of multiple sets of chromosomes that are derived from different species.

• with multiple chromosome sets within one species

• triploids-characteristically sterile

• can arise from nature or can be constructed by a geneticist

➢ crossing a 4n and 2n (2n+n=3n)

• chromosome set made up of two or more chromosome sets from more or less complete from different species; same genus diff species

Forms of aneuploidy

only 1 chromosome has 1 extra

1chromosome is missing

1 chromosome pair is missing

1 c pair has 2 extra chromosomes

Also termed as rearrangement

Two types of aberration in structure

Subtypes of unbalanced aberration of structure

Subtypes in balanced aberration of structure

Type of aberration in structure in which there is a change in chromosome’s gene dose

Type of aberration in structure in which there is a change in gene order

— Loss of segment in one chromosome

— Assembly of the two segments

Only 1 gene is deleted

many deletion

Under unbalanced aberration in structure wherein it involves duplication of a segment

— Two breakages in one chromosome segment

— Segment is flipped 180 and rejoined

Types of inversions

A type of inversion in which there is an involvement of centromere

A type of inversion in which there is no involvement of centromere

Two nonhomologous chromosomes are broken once and segments (acentric) trade places

Type of reciprocal translocation in which the arm is breaking off from one chromosome attaches to another chromosome

Type of reciprocal translocation in which two acrocentric chromosomes fuse forming a metacentric chromosome and karyotype appears to be monosomic but genome is intact

metacentric chromosome is split into two acrocentrics

Centromere of a metacentric chromosome splits transversely (perpendicular to the chromatids) during mitosis or meiosis

It is different from a gene mutation, as this involves a large portion of or multiple genes in the genome. Moreover, the use of a microscope, genetic or molecular analysis or a combination of several techniques helps assess chromosome variation.

Chromosome mutation can be in two forms: namely?

It does not affect the structure of the DNA but the number. A change in the number of DNA molecules results in extra or lacking DNA molecules needed for normal genetic function.

Aberration in number. Two basic types of chromosome mutation in number includes?

Type of chromosome mutation in number wherein there is changes (more or fewer) in whole chromosome set

Type of chromosome mutations in number wherein it involves changes in parts of chromosome set.

possess the normal chromosome set

normal euploidy in certain organisms

organisms with more than two chromosome sets

Can be triploid (3n), tetraploid (4n), pentaploid (5n), hexaploid (6n), and others

refers to the chromosome set number, thus, triploidy, tetraploidy, pentaploidy and so on

A diploid organism with only one chromosome set is called a _________.

True or false: Male bees, wasps and ants are naturally tetraploids

This are common in plants but rare in animals

Polyploidy is present in flatworms, leeches and brine shrimps, and these species reproduce by ____________?

"the production of offspring by a female with no genetic contribution from a male"

These are organisms that possess abnormal chromosome numbers in which it is smaller or greater in number than the normal chromosome number

- It is the most common cause of aneuploidy.

- Happens when the homologous chromosomes failed to segregate normally to opposite poles during meiosis or mitosis

True or false: Meiotic nondisjunction is more common than mitotic nondisjunction and may happen either during meiosis I or meiosis II.

In Rearrangements or aberration in structure. There are two types of rearrangements, namely?

True or false: When DNA breakage happens within genes, there will be a resulting abnormality in gene functions or the formation of a hybrid gene (apposing of two broken sequences)