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mcat bio textbook > ch. 7 > Flashcards

ch. 7 Flashcards

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1
Q

what is genetics

A

the science that describes the inheritance of traits from one generation to another

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2
Q

what is the chromosome theory of inheritance

A

genes are located on chromosomes

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3
Q

dipoid organisms have

A

2 copies of the genome in each cell

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4
Q

haploid organisms have

A

1 copy of the genome

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5
Q

gene

A

a length of coding of dna for a particular gene product, it is the fundamental unit of inheritance

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6
Q

two non identical chromosomes are

A

homologous chromosomes

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7
Q

different versions of a gene is called

A

an allele

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8
Q

genotype

A

dna sequence of the alleles a person carriers

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9
Q

heterozygous vs homozygous

A

hetero: a person carrying 2 different alleles homo: a person carrying 2 of the same alleles

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10
Q

phenotype

A

the physical expression of a genotype

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11
Q

what is a dominant trait

A

a trait that will always be expressed in phenotype regardless of genotype

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12
Q

what is a recessive trait

A

an allele not expressed in the heterozygous state

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13
Q

meiosis is

A

a method of cell division that produces haploid cells (gametes) from a diploid cell that ends up reducing the number of copies of each chromosome to one

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14
Q

meiosis occurs where in males? females? what are each special cells name?

A

males: testes and spermatogonia females: ovaries and oogenia

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15
Q

what do mitosis and meiosis have in common

A

they both go through one round of replication of the genome (s phase) leaving a diploid cell with four copies of the genome

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16
Q

mitosis gives rise to what while meiosis give rise to

A

mitosis: two diploid cells meiosis: 4 haploid cells

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17
Q

when does recombination occur

A

it occurs when homologous chromosomes exchange genetic material with each other during prophase 1

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18
Q

what occurs in prophase 1? what is similar/different compared to mitosis?

A

like mitosis, the chromosomes condense and envelope breaks down. unlike mitosis, homologous chromosomes pair with each other and this is called crossing over/recombination

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19
Q

a paired homologous chromosome is called

A

a tetrad or bivalent

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20
Q

the formation of the tetrad is regulated by the

A

synaptonemal complex

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21
Q

what occurs in metaphase 1? what is similar/different compared to mitosis?

A

like mitosis: alignment along the metaphase plate occurs but unlike mitosis: the tetrads are getting in line not sister chromatids

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22
Q

what occurs in anaphase 1?

A

homologous chromosomes separate and sister chromatids stay together

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23
Q

what occurs in telophase 1?

A

the cell divides into two cells that are diploid

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24
Q

what occurs in meiosis part 2?

A

the same thing occurs but it separates the sister chromatids so each cell has a single set of Unreplicated chromosomes (SAME AS MITOSIS)

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25
Q

what is nondisjunction? example?

A

failure of chromosomes to separate correctly during meiosis where a cell has 2 copies instead of one or no copies of a given chromosome. ex. trisomy down syndrome

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26
Q

what is mendels first law

A

law of segregation: 2 alleles of a person are separated and passed onto the next generation

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27
Q

when does the law of segregation occur?

A

Anaphase 1 & 2

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28
Q

what is mendels second law

A

the law of independent assortment: the alleles of one gene will separate into gametes independent of alleles for another gene

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29
Q

what is a pure breeding strain

A

any strain that consistently yields progeny with the same characteristics if bred within the same strain

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30
Q

what is a test cross? what do you call the progeny of a test cross?

A

a test cross is when one organism is crossed with another that has homozygous (or pure breeding) recessive genotype. the offspring is called f1 generation

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31
Q

what is the rule of multiplication

A

the probability of 2 independent events happening can be found by multiplying the odds of either event alone

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32
Q

what is the rule of addition

A

the chance of either A or B happening is equal to the probability of A added to the probability of B minus the probability of AB occurring together

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33
Q

what is incomplete dominance

A

phenotype is a blended mix of both alleles like red and white make pink baby

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34
Q

what is codominance

A

when 2 alleles are both expressed but not blended

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35
Q

pleiotropism

A

if a genes expression alters many different seemingly unrelated aspects of a persons total phenotype (ex. Sickle cell anemia as it affects eyes, heart, and liver)

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36
Q

polygenism

A

complex traits that are influenced by many genes

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37
Q

penetrance

A

the likelihood that a person with a given phenotype will express that expected phenotype

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38
Q

epistasis

A

expression of alleles for one gene is dependent on a different gene

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39
Q

recessive lethal alleles

A

mutant alleles that can cause death when present homozygously

40
Q

women have what sex chromosomes? men? the absence of a – will cause what

A

women: xx man: xy, the lack of a y will cause female development

41
Q

sex linked traits

A

traits that are determined by x or y chromosomes

42
Q

linkage

A

failure of independent assortment because a gene is too close to another gene that it causes it to assort together

43
Q

the frequency of recombination

A

the # of recombinant phenotypes resulting from a cross divided by total # of offspring

44
Q

autosomal traits

A

traits caused by genetic variation on the autosomes

45
Q

autosomal dominant

A

where a single copy will cause the trait automatically

46
Q

autosomal recessive

A

where 2 copies of the alleles must be present to cause trait

47
Q

can autosomal dominant skip generations? autosome recessive?

A

autosomal recessive can skip generations while dominant cannot

48
Q

mitochondrial traits can cause what

A

hemizygosity where you can have only one copy in diploid organism because only one genome exists from mitochondrial genome

49
Q

x linked traits can be what? why?

A

dominant or recessive because women have two x’s

50
Q

what is important to note about x linked traits in men

A

they will alway show because men only have one x

51
Q

x linked dominance will cause what three things?

A
  1. they dont skip generations
  2. affected fathers will have affected daughters
  3. affected mothers can have both affected or not affected kids
52
Q

population genetics

A

the inheritance of traits in populations over time

53
Q

population is

A

a group of species that can reproduce with each other

54
Q

gene pool

A

sum of genetic info in population

55
Q

hardy-weinburg law

A

the frequency of alleles in the gene pool of a population will not change overtime

56
Q

what conditions are needed for HW law

A
  1. no mutations, 2. no migration 3. no natural selection, 4. random mating 5. population big enough to stop random drift
57
Q

what is HW equation? what does it mean?

A

p+q=1 where p^2+2pq+q^2=1. p is dom q is res and pq is hetero

58
Q

what will happen after one generation in a population in Hardy-W

A

it will reach HW equilibrium where allele frequencies will not change

59
Q

why cant HW law actually occur

A

we will always have natural selection, cannot control migration, mutations are inevitable etc

60
Q

evolution is? natural selection?

A

evolution is the changes in life. natural selection is an interaction between organisms and their environment that causes differential reproduction of diff. phenotypes and alters gene pool

61
Q

when does evolution occur

A

when natural selection acts on genetic variation to drive changes in genetic composition of a population

62
Q

natural selection is based on what? define it

A

fitness: how successful it is to pass its genes (its survived long enough to reproduce)

63
Q

does natural selection create new alleles

A

no it does not, it only affects the frequency of existing alleles

64
Q

what can cause genetic diversity

A

new alleles from mutation and new combinations from independent assortment, recombination, and segregation

65
Q

what is directional selection

A

polygenic traits follow a bell curve, those at ONE end die while the middle and other end survive. ex. giraffe gets taller as short giraffes die

66
Q

what is divergent selection

A

the middle or average of the bell curve die ex. big deer fight small deer hide while middle deer die

67
Q

what is stabilizing selection

A

those at the ends at BOTH extremes will die while middle survive,

68
Q

what is artificial selection

A

humans interfering with mating like dog breeding

69
Q

sexual selection

A

animals dont randomly mate, they have evolved to create rituals or bright displays to attract partners

70
Q

kin selection

A

animals that live socially often share alleles with other individuals and will sacrifice to save them for the sake of the shared allele

71
Q

species

A

a group of organisms that can reproduce sexually and make kids

72
Q

prezygotic

A

barriers of hybridization that prevent development of offspring.

73
Q

example of prezygotic: hybrid inviability

A

offspring doesnt develop normally

74
Q

example of prezygotic:: hydrid sterility

A

offspring develops well but cant mate

75
Q

example of prezygotic: hybrid breakdown

A

offspring can make but F2 cannot

76
Q

what creation is a new species is called

A

speciation

77
Q

cladogenesis

A

one branch of species branches to make 2 or more species

78
Q

anagenesis

A

when one animal chnages so much that it couldn’t mate with past animals, SPECIATION WITHOUT SPLITING

79
Q

homologous structure

A

physical features shared by 2 diff. species because they have same common ancestor

80
Q

analogous structure

A

physical features have the same function but not because of common ancestors

81
Q

convergent evolution

A

2 diff species come to posses many analogous structure because of similar pressures

82
Q

divergent evolution

A

when a subgroup of a species evolves traits different from its ancestors.

83
Q

parallel evolution

A

where 2 species go through similar evolutionary changes due to selective pressures, ex. animals in ice age survived cold temps

84
Q

taxonomy and what kind of classification? what are the two names

A

biological classification through binomial classification with genus and species

85
Q

what are the 8 principal taxonomic categoriees

A

domain, kingdom, phylum, class, order, family, genus, and species

86
Q

what are the two axes

A

dorsal ventral and anterior posterior

87
Q

anterior is ? posterior?

A

anterior: front posterior: back

88
Q

dorsal? ventral?

A

dorsal: on top ventral: on bottom

89
Q

superior? inferior?

A

superior : toward head inferior: toward feet

90
Q

earth’s early days had water, co2, co, no2 meaning it was a

A

reducing environment where e- donors were prevalent

91
Q

with o2 coming in the picture it became a what? and caused what

A

it was an e- acceptor and caused spontaneous monomers to form

92
Q

abiotic synthesis and what were the products of them

A

metal ions on rock surfaces are thought to have acted as catalysis and its products were proteinoids

93
Q

proteinoids in water would spontaneously make ? when we added lipids, it became ?

A

proteinoids would like microspheres and with lipids, liposomes

94
Q

more complex particles were called

A

coacervate

95
Q

microsomes, liposomes, polysaccharides are all called

A

protobionts

96
Q

When does the law of independent assortment occur in meiosis?

A

Metaphase 1

97
Q

Two heterozygous parents with independent assortment will give what genotype to their kids? In ratio and percentage format.

A

Ratio: 9:3:3:1 and 25% homo recessive 25% homo dominant and 50% heterozygous

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