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BIO 111 > ch. 12 patterns of inheritance > Flashcards

ch. 12 patterns of inheritance Flashcards

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Biology 101 flashcards
1
Q

what are the two basic early ideas of inheritance?

A
  1. heredity occurs within species
  2. traits are transmitted directly from both parents to offspring
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2
Q

what contradicted the idea that inherited traits are always a blending of parental traits in the early ideas of heredity?

A

when plant hybrids were crossed, some offspring resembled the original strains rather than the hybrid parents

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3
Q

What are hybrids in plants?

A

crosses between two true-breeding plants

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4
Q

what did mendel study and when?

A

pea plants in the mid 1800s

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5
Q

why did mendel study pea plants?

A
  1. Hybrids could be produced
  2. Many “varieties” were available
  3. They were small and easy to grow
  4. They can self-fertilize or be cross-fertilized
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6
Q

what were mendel’s methods?

A
  1. produce true-breeding strains for many traits
  2. cross true-breeding strains having alternate forms of a trait to produce hybrids
  3. perform reciprocal crosses (each plant serves alternatively as a “mother” and a “father”)
  4. allow the hybrids to self-fertilize and count the number of offspring showing each form of the trait
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7
Q

what is a monohybrid cross?

A

a cross that studies only 2 forms of a single trait at a time

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8
Q

What is the f1 generation?

A

“Hybrid” offspring produced by crossing 2 true breeding strains

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9
Q

What did Mendel do with the true-breeding pea strains that he produced?

A

He hybridized the 2 true-breeding strains for each trait

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10
Q

why when mendel studied traits, the F1 generation would resemble only one parent?

A

because the trait of the parent whom the F1 generation resembled is homozygous dominant while the other variation is homozygous recessive

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11
Q

what is the F2 generation?

A

offspring resulting from the self-fertilization of F1 plants

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12
Q

what is a gene?

A

the section of a chromosome that codes for a particular trait

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13
Q

what are alleles?

A

alternate forms of genes that occur on homologous chromosomes

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14
Q

what does homozygous mean?

A

having all of the same allele

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15
Q

what does heterozygous mean?

A

having different alleles

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16
Q

what is a genotype?

A

the alleles carried by an individual

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17
Q

what is phenotype?

A

the outward appearance of a cross

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18
Q

what is the principle of segregation?

A
  1. Alleles separate (segregate) during gamete formation (meiosis).
  2. If an individual is homozygous, all of its gametes will have the same form of the allele.
  3. If an individual is heterozygous, half of its gametes will have the dominant allele and half the recessive allele.
  4. Alleles are joined at random during fertilization to produce the genotypes of the offspring. One allele from father, one allele from mother.
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19
Q

In a monohybrid cross, one parent is homozygous dominant and the other homozygous recessive.

what would be the ratio of genotypes in the F2 generation?

A

25% homozygous dominant
50% heterozygous
25% homozygous recessive

20
Q

what does a dihybrid cross examine?

A

2 separate traits in a single cross

21
Q

what are the F2 generation results from RrYy x RrYy cross?

A

9 dominant, dominant
3 recessive, dominant
3 dominant, recessive
1 recessive, recessive

22
Q

what is the rule of addition?

A

The probability of an event that can occur in two or more independent ways is the sum of the separate probabilities of the different ways.

23
Q

what is the rule of multiplication?

A

the probability that independent events will occur simultaneously is the product of their individual probabilities

24
Q

what is a testcross?

A

used to determine the genotype of an individual with the dominant phenotype (is it homozygous dominant or heterozygous?)

25
Q

what assumptions came from mendel’s model of inheritance?

A

-each trait is controlled by a single gene
-each gene has only 2 alleles
-there is a clear dominant-recessive relationship between the alleles

26
Q

what is pleiotropy?

A

when one allele has more than one effect on the phenotype

27
Q

Cystic fibrosis or sickle cell anemia. In these diseases, multiple symptoms can be traced back to one defective allele.

what is this an example of?

A

pleiotropy

28
Q

what is incomplete dominance?

A

The heterozygote is intermediate in phenotype between the 2 homozygotes

29
Q

what is a heterozygote?

A

an individual having two different alleles of a particular gene or genes, and so giving rise to varying offspring.

30
Q

what is codominance?

A

when the heterozygote shows some aspect of both homozygous phenotypes

31
Q

what can influence the expression of some genes?

A

the environment

32
Q

coat color in Himalayan rabbits and Siamese cats; an allele produces an enzyme that allows pigment production only at temperatures below 30oC

what is this an example of?

A

the expression of genes being influenced by the environment

33
Q

what is polygenic inheritance?

A

when multiple genes control phenotype

34
Q

what is epistasis?

A

a form of a gene interaction in which one pair of alleles masks the phenotypic expression of another

35
Q

what can epistasis result in?

A

albinism

36
Q

what is sex determination in humans based on?

A

the presence of a Y chromosome

37
Q

what is the sex determination in Drosphila based on?

A

the number of X chromosomes

38
Q

how many chromosomes do humans have?

A

46

39
Q

what is an autosome?

A

any chromosome that is not a sex chromosome

40
Q

how many pairs of autosomes do humans have?

A

22

41
Q

what is the “default” sex for humans?

A

female

42
Q

what kind of trait is hemophilia?

A

sex-linked

43
Q

what is dosage compensation?

A

Ensures an equal expression of genes from the sex chromosomes even though females have 2 X chromosomes and males have only 1

44
Q

what are females heterozygous for genes on the X chromosome?

A

genetic mosaics

45
Q

what is the principle of independent assortment?

A

Genes for different traits assort independently, as long as they are on different chromosomes

46
Q

an RrYy individual can produce all combinations of gamete genotypes: RY, rY, Ry, and ry

what is this an example of?

A

principle of independent assortment

47
Q

what information does genetic mapping give us?

A

relative distance between genes on a chromosome based on the frequency of recombination between genes

BIO 111 (18 decks)

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