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BIO112 > Unit 3 Chapter 13: Mendellian Genetics > Flashcards

Unit 3 Chapter 13: Mendellian Genetics Flashcards

1
Q

What is heredity

A

inheritance or the transmission of traits from parents to off spring

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2
Q

What is a trait

A

any characteristic of an individual

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3
Q

What is blending inheritance

A

one of the hypotheses to answer “what are basic patterns of transmission of traits from parents to offspring”

  • claimed that the traits observed in a mother and father blend together to form the traits observed in their offspring.
  • offspring traits are intermediate between mothers and fathers
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4
Q

What is inheritance of acquired traits

A

mendel’s second hypohesis

  • claimed that traits present in parents are modified through use and passed on to their offspring in modified form
  • kinda like natural selection in a way
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5
Q

Aside from practical reasons what are the 2 features of the pea that made it possible for Mendel to design his experiment were

A
  1. he could control which parents were involved in mating

2. he could arrange matings between individuals that differed in easily recognizable traits

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6
Q

How did Mendel control matings

A

cross fertilization (removed male reproductive organ from a flower before pollen formed, then transferred pollen from another pea plant to that flower’s female reproductive organ with a brush)

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7
Q

What is a pheneotype

A

what you see

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8
Q

What is a pure line

A

consists of individuals that produce offspring identical o themselves when they are self pollinated or crossed with another pure line member

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9
Q

What are hybrids

A

off spring from matings between true breeding parents that differ in one or more traits

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10
Q

What is continuous variation

A

here are a seemingly infinite number of traits for a given character. These traits fall along a continuous spectrum (i.e. height, skin color). “Blended inheritance”

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11
Q

What is discrete variation

A

there are only 2 or a few traits for a given character

ie. fur colour in mice

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12
Q

Does seed shape depend on whether or not the genetic determinant is in a male or female gamete

A

no, proven by mendel’s cross fertilization

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13
Q

What was Mendel’s first experiment

A

single trait crossed 2 individuals from round seed and wrinkled seed pure lines by taking pollen from round seed plants and putting it on the female reproductive organs of round seed plants

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14
Q

What were the results of Mendel’s first monohybrid cross

A
  • produced all round peas

- proved that traits did not blend together to form an intermediate

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15
Q

What is a monohybrid cross

A

a mating between parents that each carry 2 different genetic determinants for the same traits

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16
Q

What are recessive traits

A

traits that become temporarily hidden and are only shown if an individual has 2 recessive alleles

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17
Q

What are dominant traits

A

traits that dominate over the other traits they are competing with
-always shown

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18
Q

What was Mendel’s second experiment

A

he planted the F1 generation from his monohybrid cross and allowed them to self fertilization and produce the F2 generation

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19
Q

What were the results of his second experiment

A
  • 5474 round peas and 1850 wrinkled ones
  • wrinkled trait reappeared
  • lead to the terms dominant and recessive
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20
Q

What was Mendel’s third experiment

A
  • wanted to test whether or not the sex of the parent influenced the inheritance of seed shape
  • did a second set of crossed between 2 pure breeding lines but this time with pollen taken from wrinkled peas and brushed onto round organs
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21
Q

What is a reciprocal cross

A
  • a set of matings where the mother’s phenotype in the initial cross is the father’s phenotype in a subsequent cross and the father’s in the initial cross is the mothers in the subsequent one
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22
Q

What were the results of his third experiment

A
  • identical to his first

- proved seed shape has no dependence on sex of parents

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23
Q

What is particulate inheritance

A
  • mendel’s revised hypthothesis
  • hereditary determinants of traits do not blend together or acquire new modified traits through use, but they do maintain their integrity from generation to generation
  • they act like discrete entities or particles
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24
Q

What are genes (in genetics)

A

hereditary determinants/units of heredity

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25
Q

What are alleles

A

different versions of the same gene

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26
Q

What is a genotype

A

alleles that are found in a particular individual, affects phenotype

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27
Q

What is the principle of segregation

A

2 members of each gene pair must segregate (separate into different gamete cells during the formation of sperm and egg in the parent)
-as a result, each gamete contains one allele for each gene

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28
Q

What does homozygous mean

A

2 copies of the same allele

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29
Q

What does heterozygous mean

A

2 different alleles for the same gene

30
Q

What is the probability theory

A

the probability of 2 independent events is the product of the probability of each event

31
Q

What was mendel’s extension of his research

A
  • dihybrid cross
  • crossed round yellow peas with green wrinkled ones (pure lines)
  • hypothesis 1-law of independent assortment
  • hypothesis2-dependent assortment
  • predicted that F1 would be heterozygous for both genes
32
Q

What is a dihybrid cross

A

-mating between 2 individuals that are both heterozygous for 2 traits

33
Q

What is the law of independent assortment

A

-alleles of different genes present in each parent will separate from each other and be transmitted to offspring independently

34
Q

What is dependent assortment

A

alleles of different genes stick together and are transmitted together

35
Q

What were the results of Mendel’s dihybrid cross

A
  • all of F1 had round yellow seeds, therefore they were heterozygous for both traits as predicted
  • F2 generation made a 9:3:3:1 phenotype ratio
  • concluded that the law of independent assortment holds true
36
Q

What is a test cross

A

-uses a parent that contributes only recessive alleles to its offspring to help determine the unknown genotype of the second parent

37
Q

In general, what were Mendel’s 4 accomplishments

A
  1. heredity exists as discrete units (alleles)
  2. units do not blend
  3. segregation of discrete paired genes into separate gametes
  4. law of independent assortment of alleles of different genes
38
Q

What is a genetic locus

A

the physical location of a gene

39
Q

Which stage of meiosis is responsible for Mendel’s principle of segregation

A

the separation of chromosomes/alleles in anaphase 1

40
Q

What is the chromosome law of independent assortment

A

if the alleles for different genes are located on different non-homologous chromosomes, they assort independently in meiosis 1

41
Q

What is the chromosome theory of inheritance

A

states that Mendel’s rules can be explained by the independent alignment and separation of homologous chromosomes during meiosis 1

42
Q

What is a wild type

A

most common phenotype for each trait

43
Q

What is a mutation

A

change in gene, individuals with mutations are called mutants

44
Q

What is X-linked inheritance

A

-when a gene is only on the X-chromosome

45
Q

What is Y-linked inheritance

A

when a gene is only on the Y-chromosome

46
Q

What are X and Y linked inheritance both an example of

A

sex linked inheritance

47
Q

What kind of inheritance do regular genes show

A

autosomal inheritance

48
Q

What is linkage

A

the physical association among genes on the same chromosome

  • linkage and sex linkage are NOT the same
  • if 2 genes are linked they are on the same chromosome
  • if a gene is sex linked it is on a sex chromosome
49
Q

Is red-green colour blindess x or y linked

A
  • x linked
  • mostly in males
  • affected females of affected fathers
  • only males of unaffected parents are colour blind
50
Q

What is a polymorphic allele

A

an allele that is present in more than 1% of the pop

51
Q

Do linked (not sex linked) genes follow the law of independent assortment

A

no the law only applies to genes on different chromosomes

-unless crossing over occurs

52
Q

Linked genes can be linked in cis or trans what do these mean

A

cis: dominant allele on one homolog and recessive on another ie. AB and ab : 50% AB gametes and 50%ab

trans; one dominant is linked to one recessive on one homolog and the other 2 on the other ie. Ab and aB; 50%Ae and 50%aB gametes

53
Q

What does recombinant mean

A

individuals whose combination of alleles on their X chromosome is different from the combinations of alleles present in the parental generation

54
Q

Why does no crossing over occur in male fruit flies

A

the chromosomes are not as closely associated

55
Q

What is genetic recombination

A
  • occurs when crossing over occurs
  • occurs at random points on the chromsome
  • the production of offspring with combinations of traits that differ from those found in either parent
  • depends on how far apart the genes are on the chromsome
56
Q

What is recombination rate

A

a measure of physical distance along the chromosome

  • the more recombination the further apart the genes are
  • distance (in centi morgans)= # of recombinants/divided by total # of progeny
57
Q

What is a linkage group

A

all of the genes linked together on the same chromosome

58
Q

What is incomplete dominance

A

when heterozygotes have an intermediate phenotype (ie. neither pure line dominates)

59
Q

What is codominance

A

heterozygotes have the phenotype associated with each individual allele
-ie. AB blood type (both type A and B glycoproteins are present)

60
Q

What is multiallelism

A

when more than 2 alleles are on the same gene

61
Q

What are polymorphic traits

A

when more than 2 distinct phenotypes are present in a population due to multiple allelism

62
Q

What is a pleiotropic gene

A

a gene that affects more than one trait (many)

63
Q

What is gene-by-environment interaction

A

an individual’s phenotype is often as much a product of the physical environment as it is of the genotype

64
Q

What is penetrance

A

% of individuals of a given genotype that show the phenotype at all

65
Q

What is expressivity

A

the degree to which a phenotype is expressed

66
Q

What are discrete traits

A

characteristics that are qualitatively different from eachother
-ie. colour, peas could be either yellow or green

67
Q

What are qualitative traits

A

traits that exhibit quantitative variation like height or weight

68
Q

What is polygenic inheritance

A

when each gene adds a small amount of value to the phenotype

69
Q

What is gene by gene interaction

A

in discrete traits, the phenotype associated with an allele depends on which alleles are present at another gene

70
Q

What is epistasis

A

the interaction of genes that are not alleles, in particular the suppression of the effect of one such gene by another

71
Q

What is an allelic series

A

Different mutant alleles of a gene cause a range of phenotypes; each one carries a single point mutation within different regions of the same gene

72
Q

What does tyrosinase do

A

converts tyrosine to melanin (pigment) in coat colours

BIO112 (19 decks)

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