Ch 2 Chromosomes and Cellular Reproduction

Question 1

Describe the differences between a eukaryote and prokaryote.

Answer 1

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

Question 2

unicellular organism with relatively simple cell structure; bacteria and archaea

Answer 2

prokaryote

Question 3

unicellular or multicellular organisms that have a compartmentalized cell structure

Answer 3

eukaryote

Question 4

what are the purpose of histones?

Answer 4

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

Question 5

complex of DNA and histone proteins

Answer 5

chromatin

Question 6

describe the differences between bacteria and archaea?

Answer 6

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

Question 7

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

Answer 7

viruses

Question 8

are viruses prokaryotic or eukaryotic?

Answer 8

viruses are neither

Question 9

where can viruses reproduce?

Answer 9

viruses can only reproduce within host cells

Question 10

what is binary fission, and describe it

Answer 10

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

Question 11

how is eukaryotic genetic information organized in a cell?

Answer 11

• ## chromosomes are located in the nucleus

Question 12

what is a homologous pair

Answer 12

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

Question 13

what does the ploidy of a cell indicate?

Answer 13

how many sets of genetic info it has

Question 14

two sets of genetic information

Answer 14

diploid

Question 15

one set of genetic information

Answer 15

haploid

Question 16

more than two sets of genetic information

Answer 16

polyploid

Question 17

what are the three elements of a chromosome

Answer 17

• centromere
• telomeres
• origins of replication

Question 18

attachment point on a chromosome for spindle microtubules

Answer 18

centromere

Question 19

how do spindle microtubules attach to centromeres of chromosomes?

Answer 19

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

Question 20

how are chromosomes classified?

Answer 20

they are classified based on location of the centromere

Question 21

what are the four types of chromosomes

Answer 21

• submetacentric
• metacentric
• telocentric
• acrocentric

Question 22

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

Answer 22

telomeres

Question 23

what are sister chromatids and when are they present?

Answer 23

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

Question 24

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

Answer 24

cell cycle

Question 25

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

Answer 25

checkpoints

Question 26

what are the two major phases of the cell cycle

Answer 26

interphase mitotic phase

Question 27

phase where cell grows, develops, and functions

Answer 27

interphase

Question 28

phase of active cell division

Answer 28

mitotic phase

Question 29

process of nuclear division

Answer 29

mitosis

Question 30

cytoplasmic division

Answer 30

cytokinesis

Question 31

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

Answer 31

G1 stage

Question 32

describe the G1/S checkpoint

Answer 32

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

Question 33

what is G0 phase?

Answer 33

a stable state during which cells are nondividing

Question 34

stage where DNA replication/synthesis occurs

Answer 34

S phase

Question 35

what stage would sister chromatids appear?

Answer 35

sister chromatids appear in S phase, after DNA is replicated

Question 36

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

Answer 36

G2 phase

Question 37

describe the G2/M checkpoint

Answer 37

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

Question 38

what state are the chromosomes in throughout interphase?

Answer 38

the chromosomes are relaxed and uncoiled

Question 39

describe prophase

Answer 39

- chromosomes condense - mitotic spindle forms

Question 40

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

Answer 40

condensins

Question 41

describe prometaphase

Answer 41

- nuclear envelop disintegrates - spindle microtubules enter nuclear regions and attach to sister chromatids

Question 42

describe metaphase

Answer 42

- chromosomes line up on the metaphase plate

Question 43

describe the importance of the spindle-assembly checkpoint

Answer 43

it verifies chromosomes are aligned and attached during metaphase

Question 44

describe anaphase

Answer 44

- sister chromatids separate and move toward opposite poles

Question 45

describe telophase

Answer 45

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

Question 46

what are the five steps of mitosis?

Answer 46

prophase prometaphase metaphase anaphase telophase

Question 47

describe cytokinesis

Answer 47

- cytoplasm divides - in plants, a cell wall forms

Question 48

what are the products of mitosis?

Answer 48

genetically identical daughter cells

Question 49

what are the two processes of sexual reproduction?

Answer 49

meiosis and fertilization

Question 50

what are the two parts of meiosis

Answer 50

meiosis I meiosis II

Question 51

describe prophase I

Answer 51

- chromosomes condense - homologous chromosomes pair up - crossing over occurs - nuclear membrane breaks down - spindle forms

Question 52

describe metaphase I

Answer 52

- homologous pairs align along metaphase plate - microtubules attach to each chromosome of homolog pair

Question 53

describe anaphase I

Answer 53

- homologous chromosomes separate - sister chromatids stay attached

Question 54

describe telophase I

Answer 54

- chromosomes arrive at spindle poles and cytoplasm divides

Question 55

process in which homologous chromosomes exchange genetic information

Answer 55

crossing over

Question 56

location where two chromosomes cross

Answer 56

chiasma

Question 57

period between meiosis I and meiosis II

Answer 57

interkinesis

Question 58

describe what occurs in interkinesis

Answer 58

- nuclear membranes reform around chromosomes - spindle breaks down - chromosomes relax

Question 59

describe prophase II

Answer 59

- chromosomes recondense - spindle reforms - nuclear membrane breaks down

Question 60

describe metaphase II

Answer 60

- replicated chromosomes line up on metaphase plate and sister chromatids face opposite poles

Question 61

describe anaphase II

Answer 61

- sister chromatids separate - chromatids pulled to opposite poles and now considered distinct chromosomes

Question 62

describe telophase II

Answer 62

- chromosomes arrive at opposite poles - nuclear membrane reforms - chromosomes decondense - cytoplasm divides

Question 63

what kind of division is the result of meiosis I?

Answer 63

reductional division

Question 64

what kind of division is the result of meiosis II?

Answer 64

equational division

Question 65

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

Answer 65

four genetically different daughter cells

Question 66

what two processes allow for genetic variation in meiosis?

Answer 66

- crossing over - random separation of homologous chromosomes

Question 67

creation of new combinations of alleles on a chromatid

Answer 67

recombination

Question 68

when does crossing over occur?

Answer 68

prophase I

Question 69

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

Answer 69

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

Question 70

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

Answer 70

2^n, where n = # of homologous pairs

Question 71

protein that holds chromatids together

Answer 71

cohesin

Question 72

what allows sister chromatids to separate in mitosis?

Answer 72

cohesin along the length of chromosomes is broken down by separase

Question 73

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

Answer 73

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

Question 74

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

Answer 74

shugoshin