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Bio 111 > Chapter 12 > Flashcards

Chapter 12 Flashcards

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Biology 101 flashcards
1
Q

list 6 reasons why Mendel used pea plants in his experiments

A
  1. easy to work with
  2. complete life cycle in one season
  3. pea plants self-pollenate
  4. female and male repro parts in one flower
  5. all truebreeding pea offspring look exactly like the parents
  6. there are many varieties of pea plants with many different flower colors
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2
Q

how did Mendel get the true-breeding parents for his experiment? (P generation)

A
  1. let purple flowering pea plants self-pollenate, so all offspring will be purple
  2. let white flowering plants self-pollenate so all offspring will be white
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3
Q

what was the first non-truebreeding cross that Mendel did and what were the results?

A

crossed pollen from purple flowering plants to female repro parts of white flowering plants
purple x white = offspring all purple

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4
Q

what is the genotype for the F1 generation of a monohybrid cross?

A

PP x pp = all Pp (heterozygous)

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5
Q

what is the phenotype of the offspring from a F1 monohybrid cross?

A

all dominant trait expressed

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6
Q

what does F1 mean?

A

1st filial generation

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7
Q

what is the genotype for the F2 generation of a monohybrid cross?

A

Pp x Pp = 1 (PP): 2 (Pp): 1 (pp)

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8
Q

what is the phenotype for the F2 generation of a monohybrid cross?

A

3 (dominant trait): 1 (recessive trait) expressed

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9
Q

what is a genotype?

A

tells what the members of a homologous pair carry

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10
Q

where do the allele of a genotype come from?

A

1 maternal, 1 paternal

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11
Q

what are the results of a monohybrid cross?

A

1 true-breeding dominant plant
2 not-true-breeding dominant plants
1 true-breeding recessive plant

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12
Q

what is a gene?

A

DNA coding for a trait, passed from parent to offspring

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13
Q

what are alleles?

A

alternate forms of a gene

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14
Q

what are the alleles for a heterozygous genotype?

A

2 different alleles

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15
Q

what are the alleles for a homozygous genotype?

A

2 same alleles

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16
Q

what is the phenotype?

A

the outward appearance of an individual

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17
Q

what is the principle of segregation?

A

2 alleles for a gene separate during gamete formation (meiosis) and are rejoined at random, one from each parent, during fertilization

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18
Q

what type of cross does the principle of segregation apply to?

A

monohybrid cross

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19
Q

how could you determine the genotype of an individual with the dominant phenotype?

A

test cross with a homozygous recessive individual to determine if it’s PP or Pp

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20
Q

what will the result of the test cross between a homozygous recessive individual and an individual with a homozygous dominant genotype be?

A

all offspring heterozygous, dominant trait always shown

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21
Q

what will the result of the test cross between a homozygous recessive individual and an individual with a heterozygous genotype be?

A

50/50 heterozygous/homozygous recessive offspring

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22
Q

what kind of inheritance is shown in monohybrid crosses?

A

simple gene inheritance, where some exhibit dominant inheritance and some exhibit recessive inheritance

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23
Q

what is pedigree analysis?

A

used to track inheritance patterns in families

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24
Q

what is a dihybrid cross?

A

an examination of 2 SEPARATE traits in a single cross

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25
Q

give an example of a genotype of a dihybrid cross

A

RR YY x rr yy

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26
Q

what is the genotype of the F1 generation of a dihybrid cross?

A

RrYy, heterozygous

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27
Q

what is the phenotypic ratio of the F2 generation of a dihybrid cross?

A

9:3:3:1

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28
Q

what is the principle of independent assortment?

A

in a dihybrid cross, the alleles of each gene assort independently, they don’t influence each other

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29
Q

what is the rule of addition?

A

the probability of 2 mutually exclusive events occurring simultaneously is the sum of their individual probabilities

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30
Q

when crossing Pp x Pp, the probability of producing Pp offspring is?

A

the probability of obtaining Pp (1/4) PLUS the probability of obtaining pP (1/4)
1/4 + 1/4 = 1/2
ALWAYS VERIFY WITH A PUNNET SQUARE

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31
Q

what is the rule of multiplication?

A

the probability of 2 independent events occurring SIMULTANEOUSLY is the PRODUCT of their individual probabilities

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32
Q

when crossing RrYy x RrYy, the probability of obtaining rryy offspring is?

A

probability of rr = 1/4
probability of yy = 1/4
probability of rryy = 1/4 x 1/4 = 1/16

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33
Q

what 3 things does the simple Mendelian model of genetic inheritance assume?

A
  1. each trait is controlled by a single gene
  2. each gene has only 2 alleles
  3. there is a clear dominant-recessive relationship between the alleles
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34
Q

do most genes meet the criteria of simple Mendelian genetics?

A

no

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35
Q

what is incomplete dominance?

A

when heterozygotes are intermediate in phenotype between the 2 homozygotes, alleles are equal, so phenotype is a combo of both

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36
Q

give an example of incomplete dominance

A

red flowers x white flowers = pink flowers

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37
Q

what is used to denote alleles in incomplete dominance?

A

superscripts

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38
Q

draw a punnet square for incomplete dominance

A

i’m serious, get out a piece of paper and a pen and DRAW IT :)

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39
Q

what is codominance?

A

the heterozygote shows the phenotypes of both homozygotes

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40
Q

give an example of codominance

A

roan horse coat color, chestnut and white both displayed

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41
Q

what 2 inheritance patterns does the human ABO blood group system demonstrate and how?

A
  1. multiple alleles: there are 3 alleles for the I gene (Ia, Ib, and i)
  2. codominance: Ia and Ib are dominant to i, but codominant to each other
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42
Q

list the allele combinations for each blood type

A

Type A: Ia Ia, Ia i
Type B: Ib Ib, Ib, i
Type AB: Ia Ib
Type O: ii

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43
Q

what is polygenic inheritance?

A

when multiple genes are involved in controlling the phenotype of a trait, is an accumulation of contributions by multiple genes

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44
Q

what kind of traits come from polygenic inheritance and what do they show?

A

quantitative traits with continuous variation

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45
Q

give an example of a trait controlled by polygenic inheritance

A

human height

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46
Q

list 4 factors that control the polygenic trait of human height

A
  1. growth hormones
  2. calcium metabolism
  3. muscle flexibility
  4. environmental factors: nutrition, activity, stress
47
Q

what does polio do to human height?

A

depresses growth

48
Q

what is pleiotropy?

A

when an allele has more than one effect on the phenotype

49
Q

give an example of pleiotropy

A

human diseases like cystic fibrosis or sickle cell anemia, where multiple symptoms can be traced back to one defective allele

50
Q

is sickle cell anemia strictly a homozygous recessive trait?

A

no, you can be heterozygous or homozygous recessive for sickle cell anemia

51
Q

what is the advantage of heterozygous sickle cell anemia?

A

malaria resistance; malaria is a protozoa that attacks healthy red blood cells, so if your RBC’s are already fuckity, malaria doesn’t bother with your trash cells

52
Q

which type of sickle cell anemia is worse to have and why?

A

homozygous, the decreased ability to carry oxygen throughout the body can cause learning disabilities and organ failure

53
Q

what else can influence gene expression other than inheritance?

A

the environment

54
Q

give an example of genes expression that is influenced by the environment, and how it happens

A

coat color in Himalayam rabbits and Siamese cats, an allele produces an enzyme that allows pigment production only at temperatures below 30 degrees celsius (room temp is about 20 degrees celsius)

55
Q

what part of the Himalayan rabbits and Siamese cats are colored and why?

A

the extremities; they are further away from the core of the body and colder because blood flow diversion to keep them warm

56
Q

what can happen sometimes when genes interact with each other?

A

the phenotype is influenced

57
Q

what is epistasis?

A

one gene can interfere with the expression of another gene

58
Q

give an example of epistasis

A

coat color in labrador retreivers
“brown” allele- eumelanin pigment color (B or b)
“eumelanin” allele- pigment present (E or e)

59
Q

if a black lab has to have at least on dominant allele at each loci (for each gene) what are the possible genotypes (4)?

A
  1. EEBB
  2. EeBb
  3. EEBb
  4. EeBB
60
Q

if a chocolate lab has to have at least one dominany eumelanin allele (E), what are the possible genotypes (2)?

A
  1. EEbb
  2. Eebb
    homozygous recessive for fur color because lighter brown
61
Q

if a yellow lab with dark skin has to have at least one brown allele, and both eumelanin alleles recessive, what are the 2 possible genotypes?

A
  1. eeBb

2. eeBB

62
Q

if a yellow lab with light skin has to have both alleles recessive, what is the only possible genotype?

A

eebb

63
Q

what chromosome pair number are the sex chromosomes?

A

23

64
Q

what is every other chromosome pair other than the sex chromosomes called?

A

autosomes

65
Q

what sex chromosomes do human females have?

A

XX

66
Q

what sex chromosomes do human males have?

A

XY

67
Q

what does the y chromosome do?

A

controls male sex characteristics

68
Q

how did we find out about x-linked traits?

A

fruits fly experiments

69
Q

what were the wild type and mutant traits in fruit fly eye colors?

A

wild type: trait normally found, red eyes

mutant: white eyes, rare

70
Q

when scientists crossed a red-eyed female with a white-eyed male fruit fly, what was the expected phenotype?

A

red eyes

71
Q

when scientists crossed F1 females and F1 male fruit flies, what were the F2 results?

A

3 red-eyed, 1 white-eyed

72
Q

after 2 crosses, what gender of fruit fly had white eyes and what did this suggest?

A

only males, suggested that eye color is on the X, not the Y chromosome

73
Q

what test cross was done with fruit flies to determine if you could get white-eyed females and what was the result and what did the result prove?

A

white-eyed male x heterozygous female = white eyed females are viable, eye color is linked to X, and absent from Y chromosome

74
Q

what is sex determination in fruit flies based on?

A

number of X chromosomes, XX is female, XY is male

75
Q

do all organisms have X and Y chromosomes?

A

no

76
Q

how is sex determined in birds?

A

Z and W chromosomes

ZZ= males (ZZ top), ZW= females

77
Q

how is sex determined in grasshoppers?

A

number of X chromosomes, but no Y chromosome, so

XX= female, X0= male

78
Q

how is sex determined in bees?

A

diploid= female, haploid= male

79
Q

for males, from which parent does the Y chromosome come?

A

paternal

80
Q

what parent do X chromosomes come from in humans?

A

male: from mom
female: from mom and dad

81
Q

what is a characteristic of the X chromosome?

A

carries a LOT of genes

82
Q

what is a characteristic of the Y chromosome?

A

male secondary sex characteristics

83
Q

what are sex-linked traits?

A

controlled by genes present on the X chromosome

84
Q

do sex-linked traits show the same inheritance patterns as autosomes?

A

no, so different pedigree patterns

85
Q

who do sons inherit sex-linked traits from?

A

mother

86
Q

who do daughters inherit sex-linked traits from?

A

both parents

87
Q

who are carriers of sex-linked traits?

A

heterozygous females

88
Q

what is dosage compensation?

A

equal expression of genes from sex chromosomes, double dose

89
Q

why is dosage compensation a problem?

A

too much of same gene/genetic info

90
Q

what happens in female cells with dosage compensation?

A

1 X chromosome is inactivated and highly condensed into a BARR BODY, to look more like a Y chromosome

91
Q

what are females heterozygous for genes on the X chromosome called and why?

A

genetic mosaics, because which chromosome is activated it deactivated is totally random, and determines phenotype

92
Q

what gender are most calico cats?

A

female

93
Q

why are calico cats different patchy colors?

A

from activation and inactivation of fur color alleles

94
Q

what is genetic mapping?

A

the distance between genes on a chromosome can yield information

95
Q

what is genetic mapping based on?

A

genetic recombination (crossing over) between genes

96
Q

what is true about distance between genes on a chromosome and their likelihood of crossing over TOGETHER?

A

genes that are closer together tend to cross over TOGETHER while genes that are father apart are less likely to cross over TOGETHER

97
Q

what can cause human genetic disorders?

A

mutated DNA sequences leading to altered proteins

98
Q

what protein is mutated in sickle cell anemia?

A

hemoglobin

99
Q

give an example of a protein being altered at only one single amino acid causing a genetic mutation

A

sickle cell anemia, hemoglobin

100
Q

what gene associated with sickle cell anemia that alters one amino acid to cause the disorder?

A

HBB gene

101
Q

what is nondisjunction?

A

failure to separate either members of a homologous pair (meiosis I) or sister chromatids (meiosis II)

102
Q

what is 2n?

A

diploid

103
Q

what is n?

A

haploid

104
Q

what causes miscarriage, genetically?

A

nondisjunction mutations that do not allow for continued development

105
Q

what happens if nondisjunction occurs during meiosis I?

A

there are no viable cells

106
Q

what does fertilization of gametes with non-normal chromosome numbers create?

A

trisomic or monosomic individuals

107
Q

what, gentically, is down syndrome?

A

trisomy of chromosome 21

108
Q

list 5 human genetic disorders, other than down syndrome, that can occur from nondisjunction and their genotypes

A
  1. triple-X females (XXX)
  2. Klinefelter syndrome (XXY)
  3. Turner syndrome (X0)
  4. 0Y nonviable zygote
  5. Jacob syndrome (XYY)
109
Q

describe what happens to the chromosomes in triple XXX females

A

2 of the X chromosomes for Barr bodies

110
Q

list an example of Klinefelter syndrome?

A

male calico cats, one X will form a Barr body

111
Q

describe a physical characteristic of Turner syndrome

A

webbing in toes, fingers, and neck

112
Q

what is Jacob syndrome known for?

A

producing extra male characteristics

113
Q

what do Barr bodies do?

A

contribute to formation of sex organs

114
Q

if there are no physical characteristics of some nondisjunction genetic disorders, how do most people find out they have them?

A

they are usually infertile/sterile

Bio 111 (17 decks)

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