Chapter 2

Question 1

Eukaryotic DNA packaging

Answer 1

DNA associates closely with a special class of proteins called histones.

Histones help regulate accessibility of DNA to enzymes and enable DNA to fit into nucleus.

Question 2

Chromatin

Answer 2

Complex of DNA and histones

Question 3

Viruses

Answer 3

Not prokaryotic or eukaryotic, no cell structure.

Outer protein coast surrounding nucleic acid

Question 4

Describe Prokaryotic Binary Fission

Answer 4

Single circular chromosome of DNA, the ORIGINS OF REPLICATION separate to opposite sides, which are then anchored to the cell. The new cell then divides.

Question 5

Diploid has

a. two chromosomes
b. two sets of chromosomes
c. one set of chromosomes
d. two pairs of homologous chromosomes

Answer 5

B.

2 sets of genetic info.

Question 6

If an organism has more than 2 sets of genetic info

Answer 6

polyploid

Question 7

Functional Chromosomes have what 3 elements?

Answer 7

Centromere
Pair of Telomeres
Origin of replication

Question 8

Where do kinochores attach?

Answer 8

Centromere

Question 9

What protects/stabilizes chromosome ends?

Answer 9

Telomeres

Question 10

DNA synthesis begins at

Answer 10

origin of replication

Question 11

G0 phase

Answer 11

No dividing, stable

Question 12

During what phase does the cell grow and proteins needed for cell division are synthesized?

Answer 12

G1

Question 13

G1/S Checkpoint

Answer 13

holds cell in G1 until the cell has all of the enzymes and proteins needed for replication of DNA

Question 14

G2

Answer 14

Several biochemical events needed for cell division

Question 15

G2/M

Answer 15

Checkpoint reached near the end of G2. Passed only if the cell’s DNA is completely replicated and undamaged.

Question 16

Prophase

Answer 16

Chromosomes more compact

Condensins bind to chromosomes and bring about condensation.

mitotic spindle forms

Question 17

Mitotic Spindle

Answer 17

organized array of microtubules that move the chromosomes in mitosis

Question 18

Prometaphase

Answer 18

Spindle microtubules enter nuclear region (nucleus). Spindle microtubules are composed tubulin. tubulin molecules add/removed in cycle from microtubules until they get to kinochore.

Question 19

Metaphase

Answer 19

Spindle-assembly checkpoint: each chromosome aligned on metaphase plate and attached to spindle microtubules from opposite poles. Tension is required to move past this checkpoint. the purpose is to Detect even a single pair of chromosomes that are not attached to microtubules.

Question 20

Anaphase

Answer 20

Chromosome movement is cause by dissemble of tubulin molecules at both kinetochore (+ end) and spindle pole end (- end).

Special proteins called molecular motors disassemble tubulin molecules and generate forces that pull the chromosomes toward the spindle pole.

Question 21

Telophase

Answer 21

Arrival of chromosomes at spindle poles. Nuclear envelope reforms, condensed chromosomes relax.

Cytokinesis: division o cytoplasm

Question 22

Meiosis 1 (1 cell –> 2 cells)

Answer 22

Reduction Division

Question 23

Meiosis 2 (2 cell –> 4 cells)

Answer 23

Equational Division

Question 24

Prophase 1 Stages Part 1

Leptotene
Zygotene
Pachytene

Answer 24

Leptotene- chromosomes condense.
Zygotene- chromosomes continue to condense homologous chromosomes pair up and being SYNAPSIS (very close pairing association)
Pachytene- chromosomes are shorter and thicker, synaptonemal complex develops

Question 25

Each homologous pair of synapses chromosomes called ___ or ____ consists of 4 chromatids

Answer 25

Bivalent

Tetrad

Question 26

When does crossing over occur?

Answer 26

Prophase 1

Question 27

Prophase 1 stages Part 2

Diplotene
Diakinesis

Answer 27

Diplotene- centromeres of paired chromosomes move apart, but the two homologs remain attached at each chiasma.

Diakinesis- the last one?

Question 28

Metaphase 1

Answer 28

pull homologous pairs apart

Question 29

Anaphase 1

Answer 29

Separate homologous chromosomes. However, sister chromatids travel together.

Question 30

Telophase 1

Answer 30

chromosomes arrives at the spindle poles and the cytoplasm divides

Question 31

Interkinesis

Answer 31

between meiosis 1 and 2

nuclear membrane re-forms around chromosomes at each pole, spindles break down, and chromosomes relax.

Question 32

Prophase 2

Answer 32

Reverses interkinesis. So what was the point?

Question 33

Metaphase 2

Answer 33

Individual chromosomes line up

Question 34

Anaphase 2

Answer 34

Chromatids separate

Question 35

Telophase 2

Answer 35

Chromosomes arrive at spindle poles, a nuclear envelope re-forms around the chromosomes, and they cytoplasm divides. Chromosomes relax and are no longer visible.

Question 36

______ is the basis for intrachromosomal recombination, the creation of new combinations of alleles on a chromatid.

Answer 36

Crossing Over

Question 37

When does random separation occur?

Random alignment?

Answer 37

Anaphase 1

Metaphase 1

Question 38

Number of chromosome combinations is

Answer 38

2^n

n= number of homologous pairs

Question 39

Protein developed during S phase holds chromatids

Answer 39

Cohesin

Question 40

In mitosis when is cohesion broken down?

Answer 40

in anaphase by an enzyme called separase.

Question 41

Cohesin during Meiosis

Answer 41

Metaphase 1 –> Anaphase 1, the cohesion on arms breaks down. Centromere cohesion is protected by shugoshin

Anaphase 2, the centromeric cohesion breaks down.