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BIOL 107 > Chapter 7: The Cellular Basis of Inheritance > Flashcards

Chapter 7: The Cellular Basis of Inheritance Flashcards

1
Q

define asexual reproduction

A
  • produces genetically identical offspring
  • binary fission, mitosis, budding, cloning, etc
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2
Q

define sexual reproduction

A
  • produces genetically different offspring
  • meiosis and fertilization: production and fusion of haploid cells into single diploid cell
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3
Q

define diploid life cycle

A
  • haploid gametes undergo fertilization to create diploid zygote
  • zygote undergoes mitosis to grow
  • meiosis creates haploid gametes from diploid cells
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4
Q

advantages of asexual reproduction

A
  • faster
  • no mate needed
  • population size increases rapidly
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5
Q

how does asexual reproduction introduce genetic variation

A

mutations

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6
Q

disadvantages of asexual reproduction

A
  • no genetic variation
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7
Q

why do most eukaryotes reproduce sexually

A
  • evolutionary success
  • advantage of genetic variation outweighs all disadvantages
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8
Q

advantages of sexual reproduction

A
  • genetic variation
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9
Q

how does sexual reproduction introduce genetic variation

A
  • mutations
  • meiosis: shuffling of genetic information
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10
Q

disadvantages of sexual reproduction

A
  • requires mate
  • energy spent in the process
  • only 1/2 of the population is capable of producing offspring
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11
Q

what are the 4 main differences between mitosis and meiosis

A
  • number of divisions: mitosis=1, meiosis=2
  • number of cells and their ploidy: mitosis=2 diploid, meiosis=4 haploid
  • genetics: mitosis=genetically identical, meiosis=genetically unique
  • type of cell: mitosis=somatic, meiosis=sex
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12
Q

describe the level of organization of a genome

A
  • DNA makes genes
  • genes make chromosomes
  • chromosomes make a genome
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13
Q

define autosomes

A
  • all except sex chromosomes
  • homologous pairs: one similar chromosome from each parent
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14
Q

define sex chromosomes

A
  • determines biological sex of individual
  • heterologous chromosomes: differ in shape and organization
  • X and Y in humans
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15
Q

define allele

A
  • different variations of the same gene
  • more than 2 alleles often exist for 1 gene
  • creates genetic variation
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16
Q

do X and Y chromosomes share any similar regions

A
  • yes
  • pseudo autosomal regions
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17
Q

define ploidy

A
  • measure of number of sets of chromosomes
  • diploid: 2 sets (somatic cells)
  • haploid: 1 set (gametes)
  • polyploid: more than 2 sets (common in plants)
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18
Q

describe the ploidy of human somatic cells and gametes

A
  • somatic cells: diploid, 2 sets of chromosomes (one from each parent), 46 chromosomes
  • gametes: haploid, 1 set of chromosomes, 23 chromosomes
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19
Q

what ploidy do most animal cells have

A

diploid

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20
Q

what animals are haploid

A
  • very rare
  • male bees
  • wasps
  • ants
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21
Q

what animals are polyploid

A
  • 2 species of birds
  • 1 species of rat
  • most common in insects, crustaceans, fish, reptiles, and amphibians
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22
Q

is there a correlation between genome number and organism complexity

A

no

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23
Q

do all animals have the same number of chromosomes

A
  • no
  • chromosome number is characteristic of a particular species
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24
Q

can species with different diploid numbers interbreed

A
  • unlikely
  • if they can the offspring are usually infertile due to uneven chromosome numbers
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25
Q

example of interbreeding species

A
  • horse and donkey breed and produce a mule
  • mule is infertile
  • horse: 2n=64
  • donkey: 2n=62
  • mule: 2n=63 –> cannot form functional gametes
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26
Q

describe interphase in meiosis

A
  • same as mitosis
  • has G1, S, and G2 phase
  • S phase replicates chromosomes and creates identical sister chromatids
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27
Q

what does meiosis result in

A
  • reduction of chromosome number
  • produces 4 haploid gametes: have single set of chromosomes
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28
Q

which part of meiosis do homologous chromosomes separate

A

meiosis 1

29
Q

which part of meiosis do sister chromatids separate

A

meiosis 2

30
Q

which part of meiosis reduces the cell from diploid to haploid

A

meiosis 1

31
Q

explain prophase 1

A
  • chromosomes condense and pair up
  • synapsis: each chromosome aligns with its homologous partner so corresponding positions along chromosome are matching
  • crossing over: homologues exchange part of their DNA
32
Q

explain the process of crossing over in prophase 1

A
  • homologous chromosomes pair up
  • synaptonemal complex holds them together in synapsis: physical connection of chromosomes
  • segments are exchanged through crossing over
33
Q

what does the process of crossing over result in

A
  • exchange of genetic information
  • recombinant chromosomes: carry genes from two parents
34
Q

what is the physical point where homologues are connected during crossing over in prophase 1 called

A

chiasmata

35
Q

during which step in meiosis does crossing over occur

A

prophase 1

36
Q

what is the group of 2 homologous pairs of chromosomes during meiosis 1 called

A

tetrad

37
Q

explain prometaphase 1

A
  • spindle fiber microtubules attach to the kinetochore proteins at the centromeres
  • homologs still held together at chiasmata
  • nuclear membrane completely broken down
38
Q

explain metaphase 1

A
  • spindles attached to chromosomes
  • chromosomes line up in the center of the cell along the metaphase plate
  • independent assortment of chromosomes along metaphase plate
39
Q

define independent assortment in meiosis

A
  • sister chromatids separate without influence from another chromosome
  • random assortment of chromosomes (maternal and paternal) along metaphase plate during metaphase 1
40
Q

during which phase of meiosis does independent assortment take place

A

metaphase 1

41
Q

explain anaphase 1

A
  • microtubules pull tetrads apart
  • homologous pairs move toward opposite poles of the cell
  • tetrads separate as chiasmata is broken but sister chromatids remain attached at the centromeres
42
Q

define telophase 1

A
  • separated chromosomes arrive at opposite poles
  • nuclear membrane sometimes reforms and chromosomes decondense (depends on organism)
43
Q

what is the result of meiosis 1

A

two haploid cells

44
Q

explain meiosis 2

A
  • division of sister chromatids
  • very similar to mitotic division except sister chromatids are not genetically identical and resulting cells are haploid
45
Q

what are the products of meiosis 2

A
  • 4 haploid cells
  • genetically unique
46
Q

what are the two types of chromosome abnormalities

A
  • disorders in chromosome number
  • structural rearrangement of chromosomes
47
Q

are chromosomes abnormalities typically severe or mild

A
  • severe
  • fatal
  • result in miscarriages
48
Q

define karyotype

A
  • number and appearance of chromosomes
  • length, banding pattern, centromere position
49
Q

define nondisjunction

A
  • occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis
  • results in duplication or loss of chromosome
50
Q

if there is nondisjunction during meiosis 1, how will the final cells be affected

A
  • all will be affected
  • 2 will have extra chromosome
  • 2 will have one less chromosome
51
Q

if there is nondisjunction during meiosis 2, how will the final cells be affected

A
  • 2 cells will be affected
  • 1 will have extra chromosome
  • 1 will have one less chromosome
  • 2 will be unaffected
52
Q

define euploid

A

individuals with the appropriate number of chromosomes

53
Q

define aneuploid

A
  • individual with an error in chromosome number
  • includes monosomy and trisomy
54
Q

define monosomy

A
  • loss of one chromosome
  • lethal for all autosomes
55
Q

define trisomy

A
  • gain of extra chromosome
  • most are lethal, some are not
56
Q

describe x inactivation

A
  • in each cell only one x chromosome is activated (only traits on that chromosome are expressed)
  • tortoiseshell cats fur color
  • allows nondisjunction with extra x chromosome to be less fatal
57
Q

describe triple x syndrome

A
  • XXX
  • females with three x chromosomes
  • 1 in 1000 births
  • 90% undiagnosed due to x silencing/inactivation
58
Q

symptoms of triple x syndrome

A
  • taller than average
  • increased risk of learning disabilities
  • weak muscle tone
  • behavioral and emotional difficulties
  • cardiovascular and reproductive issues
59
Q

describe turner’s syndrome

A
  • X0
  • females with only 1 x chromosome
  • 1 in 2500 births
  • more severe than triple x syndrome (95% don’t survive to birth)
60
Q

symptoms of turner’s syndrome

A
  • heart and kidney issues
  • short stature
  • webbing of neck
  • infertility
61
Q

describe kleinfelter syndrome

A
  • XXY
  • male with extra x chromosome
  • 75% undiagnosed
  • usually diagnosed when seeking medical advice for infertility issues
  • can be treated with testosterone therapy
62
Q

symptoms of kleinfelter syndrome

A
  • infertility
  • sparse facial hair
  • enlarged breasts
  • small testicles
  • narrow shoulders
63
Q

describe jacob’s syndrome

A
  • XYY
  • male with extra y chromosome
  • 1 in 1000 males affected
  • often diagnosed along with autism
64
Q

symptoms of jacob’s syndrome

A
  • attention difficulties
  • delayed motor skills
  • involuntary muscle movement
  • emotional or behavioral issues
  • taller than average
  • prone to acne and skin irritation
65
Q

what are the 4 types of chromosome structural rearrangements

A
  • duplications
  • deletions
  • inversions
  • translocations
66
Q

explain chromosome duplications

A
  • extra copy of a small piece of a chromosome
  • ex: potocki-lupski syndrome
67
Q

explain chromosome deletions

A
  • deletion of segment of a chromosome
  • ex: cri-du-chat
68
Q

explain chromosome inversions

A
  • detachment, 180-degree rotation, and reinsertion of part of a chromosome
  • changes orientation of gene
  • usually mild unless gene sequence is interrupted during detachment
69
Q

explain chromosome translocations

A
  • segment of chromosome breaks off and reattaches to different chromosome
  • can be benign or devastating
  • can be reciprocal: two non-homologous chromosomes exchange genetic information, no loss or gain of genetic information

BIOL 107 (18 decks)

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