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47 Cards in this Set
- Front
- Back
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Who is Gregor Mendel? |
1. discovers basic principles of heredity 2. breed garden pea plants- foundation of genetics |
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Why did Mendel work with pea plants? |
1. easy to cultivate 2. could self pollinate/ cross pollinate 3. had many varieties 4. had true-breeding varietes (gene. pure) |
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As a result of Mendel’s experiments, what basic principles did he discover? |
He discovered: 1,law of segregation 2. law of independent assortment |
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What is the law of segregation? |
1.Each organism contains two alleles for each inherited character 2. the alleles segregate (separate) during the formation of gametes 3. each gamete contains only one allele for each character |
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What is the law of independent assortment? |
1. Members of one pair of alleles (characters) separate independently of members of another pair of alleles (characters). 2. Therefore all possible combination of alleles (characters) can occur in the gametes. |
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Define character. |
one pair of alleles |
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Define trait. |
Characteristics or attributes of an organism that are expressed by genes |
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Define true-breeding. |
- producing offspring with the same traits (phenotypes) as the parent - self pollination - must be homozygous (RR or rr) |
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Define hybridization. |
producing hybrids when mating two varieties |
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Define monohybrid-cross. |
a cross that tracks the inheritance of a single character ex: flower color |
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Define P-generation. |
True breeding parents |
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Define F1 generation. |
The hybrid offspring of the P gen. |
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Define F2 generation. |
the offspring that is produced when F1 gen. self-pollinates |
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Define dominant trait. |
An inherited trait that results from the expression of the dominant allele over the recessive allele.
ex. RR or Rr |
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Define recessive trait. |
A genetic trait that results from the expression of the two recessive alleles. ex. rr |
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Define alleles. |
alternative versions of a gene found on homologous chromosomes |
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Define somatic cells. |
all body cells of an organism |
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Define Punnett square. |
1. A tool that helps to show all possible allele combinations of gametes in a cross of parents with known genotypes 2. in order to predict the probability of their offspring possessing certain sets of alleles. |
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Define homozygous. |
when an organism has 2 identical alleles. ex: RR or rr |
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Define heterozygous. |
When an organism has 2 different alleles ex: Rr |
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Define phenotype. |
description of an organism Ex: Tall, purple flower |
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Define genotype. |
the letters that show the genetic makeup Ex: Tall (hom-dom), Purple (het) flower =TTPp |
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Conduct a simple monohybrid-cross using letters to represent alleles. |
P gen: TT (T) - tall * tt (t) - short : Tt - tall * Tt - tall F2 gen: 1TT, 2 Tt, 1tt = 3 tall & 1 short |
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Conduct a test cross. |
P gen: Tt (T) - tall * tt (t) - short F1 gen: : 2 Tt and 2tt = 2 tall & 2 short F2 gen: offspring- tt |
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Why would someone use a test cross? |
If there is an organism with a dominant allele and the other allele is not known. |
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7. Conduct a dihybrid cross. |
P gen: TTGG - tall/green * ttgg - short/yellow P gen gamete: TG * tg F1 gen: TtGg F1 gametes: (Tt)(Gg) and (Tt)(Gg) -tall/green F2 gen: 9 tall/green, 3 tall/yellow, 3 short/green, and 1 short/yellow |
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What is incomplete dominance? example. |
When F1 hybrids are inbetween the the parent phenotypes; F1 hybrids have a hetero. condition ex. P1: red (RR) * P2: white (rr) = F1: pink (Rr) 100% |
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What is complete dominance? |
When phenotypes of hetero. and homo. are indistinguishable |
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What is codominance? example. |
When neither allele is dom. over the other. -both are expressed in hetero. Ex. AB blood: IaIb unlike A blood: IaIa |
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Define multiple alleles. |
When genes exist within a population in more than 2 allele forms ABO blood group: 3 forms A-Ia B-Ib O-i |
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Define pleiotropy. example. |
When on gene can affect the whole body (characteristics) ex. sickle cell allele |
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Define epistasis. example. |
I gene that affects another gene in a different location, determintes whether that second gene gets expressed. Ex. Fur color in mice B-black b-brown, C-pigment, or c- no pigment; affects whether the mouse will be brown, black, or white (cc) |
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Define polygenic inheritance. example. |
An additive effect of 2+ genes on a single phenotype characteristic ex. skin pigment: three genes A, B,C- dark pigments and a,b,c- light pigments = AABBCC (darkest), aabbcc (lightest), AaBbCc (midtone) |
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What is the chromosomal theory of inheritance? |
The chromosomal theory of inheritance holds that the separation of maternal and paternal chromosomes during gamete formation is the physical basis of Mendelian (Henry Mendel) inheritance. |
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What are X-linked genes? |
sex-linked genes that are located in sex chromosomes |
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What are linked genes? |
A gene that is co-transcribed with another, due to proximity on the same chromosome. |
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What is a gene locus? |
location of a gene on a chromosome |
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What are the sex chromosomes for humans? |
XX- female XY- male |
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Give some examples of sex-linked genes. |
When all female flies have red eyes. When male flies can have red or white eyes. |
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What are the Barr Bodies in female mammals? |
inactive X chromosome (only 1 X is active, but it will be random) |
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Define nondisjunction. |
members of a pair of homologous chromosomes do not move apart properly during meiosis I or II - 1 gamete can receive two of the same chromosomes while another receives zero. |
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Define euploidy. |
normal number of chromosomes (46) |
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Define aneuploidy. |
abnormal number of chromosomes |
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Define trisomy. |
3 copies of the chromosome (47) ex. down syndrome |
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Define monosomy. |
1 copy of the chromosomes ex. Turner syndrome |
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Define polyploidy. |
more than two complete sets of chromosomes |
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What is a karyotype? |
a size-ordered chart of the chromosomes in a cell |
