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BIO 375 - Genetics > Exam 1 Review (Bio 375- Genetics) > Flashcards

Exam 1 Review (Bio 375- Genetics) Flashcards

1
Q

Prokaryotic cell

A

no nucleus; no paired chromosomes (haploid); typically single circular chromosome consisting of a single origin of replication; single chromosome is replicated with each copy moving to opposite sides of the cell; no histone proteins complexed to DNA

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2
Q

Eukaryotic Cell

A

nucleus present; paired chromosomes common (diploid); typically multiple linear chromosomes consisting of centromeres, telomeres, and multiple origins of replication; chromosomes are replicated but require mitosis or meiosis to ensure that chromosome migrates to the proper location; histone proteins are complexed to DNA

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3
Q

three predominant stages of interphase of cells active in the cell cycle

A

G1 -> S Phase -> G2

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4
Q

G1 (Gap 1)

A

cell grows and synthesizes proteins necessary for cell division; once the cell passes the G1/S checkpoint then the cell is committed to divide

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5
Q

S phase

A

DNA replication takes place

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6
Q

G2 (Gap 2)

A

additional biochemical reactions take place that prepare the cell for mitosis; once the cell passes the major G2/M checkpoint it enters into mitosis

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7
Q

G0

A

nondividing stage; found in cells prior to G1/S checkpoint; cells may exit active cell cycle to enter this nondivision stage

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8
Q

checkpoints

A

function to ensure that all cellular components (such as important proteins and chromosomes) are present and functioning before the cell moves to the next stage of the cell cycle; if components are missing or not functioning, then these will prevent the cell from moving to the next stage; these prevent defective cells from replicating and malfunctioning

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9
Q

checkpoints of cell cycle

A

G1/S checkpoint (occurring during G1 prior to S phase); G2/M checkpoint (occurring during G2 prior to mitosis); and spindle-assembly checkpoint (occurring during mitosis)

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10
Q

meiosis processes responsible for genetic variation

A

crossing over, random distribution

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11
Q

point during meiosis at which crossing over takes place

A

begins during the zygotene stage of prophase I and is completed near the end of prophase I

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12
Q

point during meiosis at which random distribution of chromosomes to daughter cells takes place

A

anaphase I of meiosis

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13
Q

spermatogenesis

A

primordial diploid germ cells divide mitotically to produce diploid spermatogonia that can either divide repeatedly by mitosis or enter meiosis. spermatogonium that entered prophase I of meiosis is called a primary spermatocyte and is diploid. upon completion of meiosis I, two haploid cell called secondary spermatocytes are produced. upon completing meiosis II, the secondary spermatocytes produce a total of four haploid spermatids. the spermatids then mature to yield sperm.

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14
Q

oogenesis

A

primordial diploid cells divide mitotically to produce diploid oogonia that can divide repeatedly by mitosis or enter meiosis. oognonium that entered prophase I of meiosis is called a primary oocyte and is diploid. upon completion of meiosis I, the cell divides but unequally. one of the newly produced haploid cells receives most of the cytoplasm and is called the secondary oocyte. the other haploid cell receives only a small portion of the cytoplasm and is called the first polar body. ultimately, the secondary oocyte will complete meiosis II and produce two haploid cells. one cell, the ovum, will receive most of the cytoplasm from the secondary oocyte. the smaller haploid cell is called the second polar body. typically, the polar bodies disintegrate and only the ovum is capable of being fertilized

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15
Q

acrocentric chromosome

A

a chromosome with the centromere located very close to one end

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16
Q

metacentric chromosome

A

Chromosome in which the two chromosome arms are approximately the same length

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17
Q

submetacentric chromosome

A

A chromosome in which the centromere establishes a long arm and a short arm– in which the centromere is halfway between the top and the middle of the chromosome

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18
Q

telocentric chromosome

A

Chromosome in which the centromere is at or very near one end.

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19
Q

chromosome alignment in metaphase of mitosis

A

lined up with centromeres on the metaphase plate

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20
Q

(mitosis) G2

A

4n number of DNA and 2n number of chromosomes - DNA molecules were replicated in S phase

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21
Q

(meiosis) metaphase I

A

4n number of DNA and 2n number of chromosomes - neither homologous chromosomes nor sister chromatids have separated

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22
Q

(mitosis) prophase

A

4n number of DNA and 2n number of chromosomes

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23
Q

(meiosis) anaphase I

A

4n number of DNA and 2n number of chromosomes - homologous chromosomes separate and begin moving to opposite ends of cell, but sister chromatids do not separate

24
Q

(meiosis) anaphase II

A

2n number of DNA and 2n number of chromosomes - sister chromatids separate, resulting in temporary doubling of chromosome number in haploid daughter cell

25
Q

(meiosis) Prophase II

A

2n number of DNA and n number of chromosomes - daughter cells are haploid

26
Q

(mitosis) after cytokinesis (during telophase)

A

2n number of DNA and number of chromosomes - daughter cells enter G1 after mitosis

27
Q

(meiosis) after cytokinesis (during telophase II)

A

n number of DNA and number of chromosomes

28
Q

determining diploid number

A

determine number of centromeres present within a cell that contains homologous pairs of chromosomes, recalling that each chromosome possesses a single centromere

29
Q

location/presence of a centromere

A

determined by attachment of spindle fibers to chromosome

30
Q

anaphase of meiosis I

A

separation of homologous pairs of chromosomes

31
Q

anaphase of mitosis

A

cell contains diploid chromosome number for species, but sister chromatids have separated to result in a doubling of chromosome number within cell

32
Q

anaphase II of meiosis

A

sister chromatids are being separated, but there are no homologous chromosomes present within the cell

33
Q

independent assortment

A

occurs during anaphase I of meiosis

34
Q

separation of chromatids

A

occurs during anaphase of mitosis and anaphase II of meiosis

35
Q

crossing over

A

occurs during prophase I of meiosis

36
Q

bivalent pairs line up on metaphase plate

A

occurs during metaphase I of meiosis

37
Q

spermatogonium

A

2n number of DNA and number of chromosomes (assuming that it is in G1 prior to S phase)

38
Q

first polar body

A

2n number of DNA and n number of chromosomes (it is a product of meiosis I so it will be haploid, but sister chromatids have not separated so each chromosome consists of two sister chromatids)

39
Q

primary oocyte

A

4n number of DNA and 2n number of chromosomes (it is stopped in prophase I of meiosis, so homologues have not yet separated and each chromosome consists of two sister chromatids)

40
Q

secondary spermatocyte

A

2n number of DNA and n number of chromosomes (it is the product of meiosis I and has yet to enter meiosis II, so it will be haploid because the homologous pairs were separated in meiosis I but each chromosome is still composed of two sister chromatids)

41
Q

principle of segregation (mendel’s first law)

A

states that an organism possesses two alleles for any one particular trait and that these alleles separate during the formation of gametes; ie one allele goes into each gamete; explains that homologous chromosomes segregate during anaphase I of meiosis

42
Q

concept of dominance

A

when two different alleles are present in a genotype, only the dominant allele is expressed in the phenotype

43
Q

incomplete dominance

A

when different alleles are expressed in a heterozygous individual, the resulting phenotype is intermediate to the phenotypes of the two homozygotes

44
Q

principle of independent assortment

A

genes for different characteristics and at different loci segregate independently of one another; an extension of the principle of segregation

45
Q

principle of segregation vs principle of independent assortment

A

principle of segregation indicates that the two alleles at a locus separate; principle of independent assortment indicates that the separation of alleles at one locus is independent of the separation of other pairs at other loci

46
Q

principle of independent assortment relation to meiosis

A

in anaphase I of meiosis, each pair of homologous chromosomes separates independently of all other pairs of homologous chromosomes. assortment of homologues explains how genes located on different pairs of chromosomes will separate independently of one another

47
Q

testcross

A

cross between an organism with an unknown genotype and an organism with a recessive phenotype

48
Q

binomial equation

A

(n!/s!t!)p^sq^t

49
Q

chi square test

A

sum of (observed-expected)^2/expected

50
Q

XX-XO system of sex determination

A

females have two copies of sex-determining chromosome, whereas males have only one copy. males must be considered heterogametic because they produce two different types of gametes with respect to the sex chromosome: either containing an X or not containing an X

51
Q

XX-XY system vs ZZ-ZW system of sex determination

A

in XX-XY system, males are heterogametic and produce gametes with either an X chromosome or a Y chromosome; in ZZ-ZW system, females are heterogametic and produce gametes with either a Z or a W chromosome

52
Q

pseudoautosomal region

A

region of similarity between X and Y chromosomes that is responsible for pairing the X and Y chromosomes during meiotic prophase I

53
Q

inheritance of genes in pseudoautosomal region vs inheritance of other Y-linked characteristics

A

genes in this region are present in two copies in males and females and thus are inherited like autosomal genes; whereas other Y-linked genes are passed on only from father to son

54
Q

tortoiseshell cats

A

have two different alleles of an X-linked gene: X+ (non-orange / black) and X° (orange)… patchy distribution results from X-inactivation during early embryo development. each cell of early embryo randomly inactivates one of the two X chromosomes, and the inactivation is maintained in all of the daughter cells. so each patch of black fur arises from a single embryonic cell that inactivated X° and each patch of orange fur arises from an embryonic cell that inactivated X+

55
Q

Barr body

A

darkly staining bodies in nuclei of female mammalian cells; Mary Lyon hypothesized that they are inactivated (condensed) X chromosomes. by inactivating all X chromosomes beyond one, female cells achieve dosage compensation for X-linked genes

BIO 375 - Genetics (8 decks)

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