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37 Cards in this Set
- Front
- Back
The blending vs the particulate hypothesis |
Blending: 1800, genetic material contributed by the two parents mixes in a manner analogous to the way blue and yellow pains blend to make green. Predicts over many generations that a freely mating pop will give rise to a uniform population
Particulate: analogous to a deck of cards. genes are shuffled and passed along. parents pass on discrete heritable units - genes - that retain their separate identities in offspring. This hypothesis helps to explain reappearance of traits after several generations |
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Holes in the blending hypothesis |
-predicts we will give rise to a uniform population however: -everyday observations contradict -results of breeding experiments contradict -fails to explain other phenomena of inheritance such as traits reappearing after skipping a generation |
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Through his experiment with pea plants, what theory, and through what mechanism did Mendel documents? |
Inheritance theory, through a Particulate mechanism. |
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Character vs Trait |
Character is a heritable feature that varies among individuals ex: flower colour
Trait is each variant for a character ex: purple or white flower colour |
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Advantages of using pea plants |
-short generation time -large number of offspring -strictly control mating -able to self fertilize, each had a sperm producing organ (stamen) and an egg producing organ (carpal) -available in many varieties (many traits in a character ex: flower colour) |
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Mendel is known as the _______ |
father of genetics |
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genetics vs heredity |
heredity: transmission of trait from one generation to the next
genetics: the study of heredity and heredity variation |
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How did Mendel cross-pollanate |
-all were self-pollenating with an egg and a sperm producing organ -was able to cross-pollinate (fert between diff plants) -involved dusting one plant with another plants pollen -used two contrasting true-breeding pea varieties |
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True breeding |
varieties that over many generations of self-pollination produce only the same variety as the parent plant -purple flowers only giving rise to purple flowers |
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Hybirdization |
The mating, or crossing, of two true-breeding varieties. |
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True breeding parents are called______ Hybrid offspring of true breeding parents are called _______ When offspring self-pollinate or cross-pollinate, their offspring are called _______ |
P gen (parent) F1 gen (filial) F2 gen |
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What would have happened if Mendel had stopped his experiments after the F1 generation? |
he would have missed the basic patterns of inheritance |
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What are the two fundamental principles of heredity developed by Mendal as a result of his pea plant experiments and analysis |
1. The law of independent assortment 2. The law of segregation |
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We now call Mendel's "heritable factor" a _______ |
gene |
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The law of segregation |
Two alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes. Thus: an egg and sperm get only one of the two alleles that are present in the somatic cells of the organism making the gamate. -crossing F1 hybrids results in a 3:1 ratio in F2 -dominant and recessive traits -factor for recessive was not diluted because if |
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when Mendel crossed F1 hybrids the results were: |
Most F2 were purple but some were white, a 3:1 ratio |
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when Mendel crossed true-breeding White and Purple, the results were _______ |
F1 were all purple |
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Mendel's Model (4) |
1. Alleles: Alternative versions of genes accounts for variations in inherited characters (example, different alleles as a result of diff genetic nucleotide sequence on the same locus, on same chromosome). 2. 2 alleles (can be Het or homo) For each character, an organism inherits two copies of a gene - one from each parent 3. D&R: If two alleles at a locus differ, then one, the dominant allele, determines the organism's appearance. The other,recessive, has no noticeable effect 4. The law of segregation |
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Alleles |
Alternative version of a gene ex: the gene for the flower colour of pea plants |
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locus |
a specific location - on a specific chromosome that holds the specific sequence of nucleotides for a gene |
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Which concept of Mendel's model corresponds to the ditribution of the two members of a pair of homologous chromosomes to different gamates? |
The law of segregation: Two alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes. Thus: an egg and sperm get only one of the two alleles that are present in the somatic cells of the organism making the gamate. |
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Heterozygous vs Homozygous |
Homo: organism with two identical alleles Hetero: organism with two diff alleles |
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Phenotype vs Geneotype |
Phenotype: observable trait Genotype: genetic makeup (alleles) |
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How can we tell the genotype of an individual with a dominant phenotype? |
Testcross: breeding an organism of an unknown genotype with a recessive homozygote -if any offspring display the recessive phenotype, the mystery parent must be heterozygous |
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The law of independent assortment |
Each pair of alleles segregates independently of each other pair of alleles during gamete formation Medel followed only a single character (such as colour) |
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Monohybrid Cross |
A test cross between heterozygotes |
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Monohybrid |
-F1 progeny (of true-breeding) -Heterozygous for one particular character being followed in a test cross |
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The law of independent assortment |
each pair of alleles segregates independently of each other pair of alleles during gamate formation |
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Mendel identified The law of independent assortment by following _____ characters at the same time, such as seed _______ and seed ______ shape |
Two, colour, shape |
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Dihybrids |
individuals that are heterozygous for the two characters being followed in the cross (YyRr) |
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Are two characters being transmitted from parents to offspring, get transmitted as a package? |
No, hybrids do not have to transmit their alleles in the same combinations in which the alleles were inherited from the P generation. If this were the case, they would only create two classes of gamates (YR and yr). This would be called dependent assortment. -genes are packaged in gamates in all possible allelic combinations -only true for alleles that are on DIFFERENT chroms or far from each other |
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What law was the outcome of Mendal's dihybrid experiment? |
The law of independent assortment |
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An experiment that can determine whether two characters are transmitted to offspring as a package (dependently) or independently is called a: |
dihybrid cross |
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_________ govern Mendel's 2 laws |
the laws of probability |
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What are the two basic rules of probability that can help predict the outcome of the fusion of gametes in both simple monohybrid crosses and more complicated crosses |
1. The multiplication and addition rules 2. solving complex genetics |
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Multiplication rule |
to determine this probability, we multiply the probability of one event by the probability of the other event -used in F1 monohybrid cross |
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Addition rule |
the probability that any one of two or more mutually exclusive events will occur is calculated by adding their individual probabilities -used the probability of a F2 heterozygote |