cell cycle/division

Question 1

The location of DNA in eukaryotic and prokaryotic cells

Answer 1

in prokaryotic it is found in the nucleoid.

in eukaryotic it is found in the nucleus.

Question 2

The phases and main characteristics of the cell cycle for prokaryotic cells

Answer 2

undergoes binary fission.

b period: daughter cell grows.
c period: DNA synthesis; chromosomes replicated and separated to opposite ends.
d period: membrane pinches together b/w to form 2 daughter cells.

Question 3

The phases and main characteristics of the cell cycle for eukaryotic cells

Answer 3

mitosis, g1, s, g2

G1: cell functions and grows
S: DNA replications and chromosomes duplicate
G2: cell grows and prepares for mitosis

Question 4

The stages and main characteristics of mitosis

Answer 4

prophase: chromosomes condense (2 sister chromatids with identical genetic info); chromosomes pair up; nucleus membrane dissolves.
metaphase: chromosomes line up at middle; miotic spindle fibres from centrioles attach to sister chromatids.
anaphase: sister chromatids pulled apart. one chromatid to each pole.
telophase: chromosomes decondense; membrane forms round it (nuclei); pinches in the middle to form 2 daughter cells. (CYTOKINESIS)

Question 5

The stages and main characteristics of meiosis

Answer 5

P1: chromosomes condense and nuclear membrane dissolves. homo chromos form bivalents… crossing over may occur causing genetic distinction.
M1: spindle fibers connect to bivalents at centromere and align homochromos along middle.
A1: spindle fibers split bivalents; homochromos split move to opposite end.
T1: chromosomes decondense; nuclear membrane may reform; cells divide to form 2 haploids (daughter cells).
P2: chromosomes condense and nuclear membrane dissolves
M2: spindle fibers attach to chromosomes at centromere & align them along middle
A2: spindle fibers split sister chromatids (now called chromosomes); chromosomes move to opposite ends
T2: chromosomes decondense and nuclear membrane reforms; cell divides forming 4 haploids

Question 6

STUDY THIS: The stage of cell division if given a micrograph or diagram of a dividing cell

Answer 6

11324

Question 7

The basic mechanism of DNA recombination in prophase of meiosis.

Answer 7

crossing over. homo chromos line up and exchange strands (DNA).

Question 8

The role of cohesin and synaptonemal complex

Answer 8

in meiosis, disappears after prophase 1; protein framework holding together homochromos as they pair and form new allele combos

Question 9

The relationship between the distance separating genes and the likelihood of recombination occurring between them: what are linked genes? what is a chiasma?

Answer 9

the chance of crossing over b/w two genes is related to distance (recombination frequency)

if diff types of genes are inherited together - they are linked genes. more likely to occur if closer.

chiasma forms b/w homo chromos by crossover recombination & physically links them during meiosis.

Question 10

The importance of distinct stages of the cell cycle

Answer 10

G1: to produce protein & grow. cell responds to stimulus that tells cell what type of cell they must become or how they must function (determine what genes they will off - cell differentiation)
G0: where cells go to mature & differentiate - leave cell cycle and MAY receive stimulus to reenter
G2: prevents cells with dmg’d DNA from undergoing mitosis
S: it is where DNA duplicate/replicate

Question 11

The difference between positive and negative regulation at cell cycle checkpoints

Answer 11

positive regulation drives cell cycle. negative regulation halts it.

Question 12

What proteins are involved in positive/negative regulation pathways and how these proteins operate

Answer 12

positive: cyclins & CDKs (cyclin dependent kinases). cyclin binds to CDK. cyclin-CDK is phosphorylated. activated cyclin-CDK complex phosphorylates target. changes conformation to active form and cell moves to next stage.
negative: mainly involves p53, p21, and retinablastoma protein. these mainly act during G1-S since this is when it makes biggest commitment to divide.

Question 13

What is the risk of any protein involved at the cell cycle checkpoints not functioning properly (be specific)?

Answer 13

cancer cells mutate these proteins.

Question 14

Why p53 is considered the guardian of the genome

Answer 14

a tumor/cancer suppressing protein.

Question 15

Example of situation in which cells would be programmed to die by apoptosis.

Answer 15

p53 triggers apoptosis if DNA dmg cant be repaired.

Question 16

STUDY THIS!! Stage of mitosis or meiosis based on a micrograph or diagram of a dividing cell

Answer 16

Q

Question 17

The reason why meiosis I is “reductional” and meiosis II is “equational”

Answer 17

reductional meiosis 1: #of chromosomes reduced in each daughter cell

equational meiosis 2: sister chromatids separated into “chromosomes”

Question 18

Other mechanisms giving rise to variation in meiosis

Answer 18

independent assortment: occurs during metaphase 1 &2. after meiosis each haploid cell contains mix of genes from parents - all random.

random fertilization: zygotes bring DNA from 2 diff parents into same cell.

Question 19

why cell division is so important

Answer 19

if cell grows in size it will not be able to function. its cell membrane (surface area) is not able to provide all the req nutrients for its large volume. cell will receive signal for it to divide when it is large enough.

Question 20

Mechanisms giving rise to aneuploid products of meiosis

Answer 20

due to non-disjunction events in meiosis 1&2 where chromosomes dont separate properly. can even occur in sex chromosomes.

Question 21

Relationship between age of an oocyte and the risk of offspring having Down Syndrome

Answer 21

after age of 35, a woman’s offspring has an increased chance of having down syndrome.

oocytes are arrested in prophase 1 & after released they undergo complete meiosis. they sit in the womb, accumulating mutations.

Question 22

Life cycles of different organisms: What are the products of mitosis and meiosis in animals?

Answer 22

gametes arise by meiosis & zygotes divide by mitosis.

Question 23

Life cycles of different organisms: What are the products of mitosis and meiosis in plants, fungi and algae?

Answer 23

gametes arise by mitosis & spores formed by meiosis.

Question 24

when is a karyotype taken?

Answer 24

during metaphase so it shows 2N and 4C

Question 25

what is kinetochore?

Answer 25

protein found at centromeres, attaches spindles to chromosomes

Question 26

when are the cell cycle checkpoints?

Answer 26

G1 (can it replicate?), G2 (can it divide?), and metaphase (can chromosomes separate?)

Question 27

ploidy in plant life cycle?

Answer 27

n after meiosis and 2n after mitosis

Question 28

do values of n and c change during meiosis/mitosis?

Answer 28

NEVER!!!

Question 29

what is the difference between nondisjunction and misdivison?

Answer 29

nondisjunction occurs in meiosis 1 misdivision occurs in meiosis 2.

Question 30

what is the difference between synamptomel complex and cohesion?

Answer 30

synaptomel complex holds homologous chromosomes together and cohesion holds sister chromatids together