Ch 2 Chromosomes and Cellular Reproduction Flashcards

1
Q

Describe the differences between a eukaryote and prokaryote.

A

Prokaryote:
- absent nucleus
- small cell diameter
- usually consists of one circular DNA molecule
- no membrane-bound organelles
Eukaryote:
- nucleus
- large cell diameter
- multiple linear DNA molecules with large amounts of DNA
- histones associate with DNA to form tightly packed chromosomes
- membrane-bound organelles

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2
Q

unicellular organism with relatively simple cell structure; bacteria and archaea

A

prokaryote

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3
Q

unicellular or multicellular organisms that have a compartmentalized cell structure

A

eukaryote

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4
Q

what are the purpose of histones?

A

histones associate with DNA to form tightly packed chromosomes; help regulate DNA accessibility to enzymes and proteins

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5
Q

complex of DNA and histone proteins

A

chromatin

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6
Q

describe the differences between bacteria and archaea?

A

both are prokaryotes, however some genetic processes in archaea are more similar to those in eukaryotes

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7
Q

simple structures composed of an outer protein coat surrounding a nucleic acid

A

viruses

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8
Q

are viruses prokaryotic or eukaryotic?

A

viruses are neither

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9
Q

where can viruses reproduce?

A

viruses can only reproduce within host cells

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10
Q

what is binary fission, and describe it

A

binary fission is prokaryotic cell division
1) replication begins at a single origin of replication
2) after replication, the two origins move away from each other to the opposite ends of the cell
3) a new cell wall forms between the two chromosomes and divides them, producing two cells

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11
Q

how is eukaryotic genetic information organized in a cell?

A
  • ## chromosomes are located in the nucleus
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12
Q

what is a homologous pair

A

one set of a chromosomes has a corresponding chromosome in the other set

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13
Q

what does the ploidy of a cell indicate?

A

how many sets of genetic info it has

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14
Q

two sets of genetic information

A

diploid

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15
Q

one set of genetic information

A

haploid

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16
Q

more than two sets of genetic information

A

polyploid

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17
Q

what are the three elements of a chromosome

A
  • centromere
  • telomeres
  • origins of replication
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18
Q

attachment point on a chromosome for spindle microtubules

A

centromere

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19
Q

how do spindle microtubules attach to centromeres of chromosomes?

A

a kinetochore assembles on the centromere, allowing the spindle microtubules to attach to the kinetochore

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20
Q

how are chromosomes classified?

A

they are classified based on location of the centromere

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21
Q

what are the four types of chromosomes

A
  • submetacentric
  • metacentric
  • telocentric
  • acrocentric
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22
Q

regions of specific DNA sequences and proteins at the ends of chromosomes that protect and stabilize chromosome ends

A

telomeres

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23
Q

what are sister chromatids and when are they present?

A

two identical copies of a chromosome, held together at the centromere; they are present only after replication occurs

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24
Q

series of steps where one cell passes from one division to the next

A

cell cycle

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25
Q

key points throughout the cell cycle that allow or prohibit a cell from continuing to the next stage

A

checkpoints

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26
Q

what are the two major phases of the cell cycle

A

interphase
mitotic phase

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27
Q

phase where cell grows, develops, and functions

A

interphase

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28
Q

phase of active cell division

A

mitotic phase

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29
Q

process of nuclear division

A

mitosis

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30
Q

cytoplasmic division

A

cytokinesis

31
Q

stage where the cell grows and synthesizes necessary proteins for cell division

A

G1 stage

32
Q

describe the G1/S checkpoint

A

holds the cell in G1 until all necessary cell components for replication are made

33
Q

what is G0 phase?

A

a stable state during which cells are nondividing

34
Q

stage where DNA replication/synthesis occurs

A

S phase

35
Q

what stage would sister chromatids appear?

A

sister chromatids appear in S phase, after DNA is replicated

36
Q

stage where additional biochemistry events occur to prepare the cell for division

A

G2 phase

37
Q

describe the G2/M checkpoint

A

ensures DNA is replicated and undamaged, and if there is some damage or missing DNA, it will prevent the cell from proceeding further

38
Q

what state are the chromosomes in throughout interphase?

A

the chromosomes are relaxed and uncoiled

39
Q

describe prophase

A
  • chromosomes condense
  • mitotic spindle forms
40
Q

group of proteins that bind to DNA and help condensation of chromosomes

A

condensins

41
Q

describe prometaphase

A
  • nuclear envelop disintegrates
  • spindle microtubules enter nuclear regions and attach to sister chromatids
42
Q

describe metaphase

A
  • chromosomes line up on the metaphase plate
43
Q

describe the importance of the spindle-assembly checkpoint

A

it verifies chromosomes are aligned and attached during metaphase

44
Q

describe anaphase

A
  • sister chromatids separate and move toward opposite poles
45
Q

describe telophase

A
  • chromosomes arrive at spindle poles
  • sister chromatids now considered separate chromosomes
  • nuclear membrane reforms around each set of chromosomes
  • chromosomes decondense and relax
46
Q

what are the five steps of mitosis?

A

prophase
prometaphase
metaphase
anaphase
telophase

47
Q

describe cytokinesis

A
  • cytoplasm divides
  • in plants, a cell wall forms
48
Q

what are the products of mitosis?

A

genetically identical daughter cells

49
Q

what are the two processes of sexual reproduction?

A

meiosis and fertilization

50
Q

what are the two parts of meiosis

A

meiosis I
meiosis II

51
Q

describe prophase I

A
  • chromosomes condense
  • homologous chromosomes pair up
  • crossing over occurs
  • nuclear membrane breaks down
  • spindle forms
52
Q

describe metaphase I

A
  • homologous pairs align along metaphase plate
  • microtubules attach to each chromosome of homolog pair
53
Q

describe anaphase I

A
  • homologous chromosomes separate
  • sister chromatids stay attached
54
Q

describe telophase I

A
  • chromosomes arrive at spindle poles and cytoplasm divides
55
Q

process in which homologous chromosomes exchange genetic information

A

crossing over

56
Q

location where two chromosomes cross

A

chiasma

57
Q

period between meiosis I and meiosis II

A

interkinesis

58
Q

describe what occurs in interkinesis

A
  • nuclear membranes reform around chromosomes
  • spindle breaks down
  • chromosomes relax
59
Q

describe prophase II

A
  • chromosomes recondense
  • spindle reforms
  • nuclear membrane breaks down
60
Q

describe metaphase II

A
  • replicated chromosomes line up on metaphase plate and sister chromatids face opposite poles
61
Q

describe anaphase II

A
  • sister chromatids separate
  • chromatids pulled to opposite poles and now considered distinct chromosomes
62
Q

describe telophase II

A
  • chromosomes arrive at opposite poles
  • nuclear membrane reforms
  • chromosomes decondense
  • cytoplasm divides
63
Q

what kind of division is the result of meiosis I?

A

reductional division

64
Q

what kind of division is the result of meiosis II?

A

equational division

65
Q

how many and what kind of cells are produced from meiosis?

A

four genetically different daughter cells

66
Q

what two processes allow for genetic variation in meiosis?

A
  • crossing over
  • random separation of homologous chromosomes
67
Q

creation of new combinations of alleles on a chromatid

A

recombination

68
Q

when does crossing over occur?

A

prophase I

69
Q

describe how random separation of homologous chromosomes leads to genetic variation?

A

homologous chromosomes randomly align in metaphase I, where the orientation may cause different variations in whether a cell gets a maternal or paternal chromosome. this produces different combinations of chromosomes in the resulting cells

70
Q

how do you determine the number of possible combinations of cells?

A

2^n, where n = # of homologous pairs

71
Q

protein that holds chromatids together

A

cohesin

72
Q

what allows sister chromatids to separate in mitosis?

A

cohesin along the length of chromosomes is broken down by separase

73
Q

what allows homologs to separate in anaphase I, but not sister chromatids?

A

cohesin breaks along the chromosome arms, so the homologs can separate, but shogushin prevents the sister chromatids from separating

74
Q

protein that protects cohesin at centromere to prevent sister chromatids from separating

A

shugoshin