Lecture 2/10

Question 1

why does elongation eventually stop in PCR?

Answer 1

because the polymerase is only good for a certain number of nucleotides

Question 2

what is special about round 3 of PCR amplification?

Answer 2

you start ending up with more fragments the exact size of your target gene, and these smaller pieces amplify faster

Question 3

At what temperature does denaturation happen?

Answer 3

94 degrees

Question 4

What is taq polymerase good at?

Answer 4

extension

Question 5

what is taq polymerase bad at?

Answer 5

proofreading, it is missing critical residues for 3’ to 5; exonuclease alpha activity

Question 6

how do we get around taw polymerases bad proofreading?

Answer 6

taq is usually used along with another thermal stable polymerase that is good at proofreading

Question 7

when can you see chromosomes?

Answer 7

during mitosis

Question 8

what does condensin ii do and at what stage?

Answer 8

acts during prophase to make large loops to condense, makes the chromosomes visible

Question 9

what does condensin i do and when?

Answer 9

acts during metaphase to make smaller loops within the larger loops

Question 10

when does the nuclear envelope break down?

Answer 10

starts during prophase and finishes in metaphase

Question 11

what happens in prophase?

Answer 11

centrosomes move to opposite poles and nucleoli begin to disappear

Question 12

what are centrosomes?

Answer 12

specialized microtubule organizing center (a pair of centrioles, perpendicular to each other)

Question 13

what is MTOC responsible for?

Answer 13

nucleating more microtubules – there are tubulin subunits that are polymerized into microtubules

Question 14

what happens in prometaphase?

Answer 14

nuclear envelope breaks down and microtubules from MTOC invade the nuclear region

Question 15

once the nuclear envelope breaks down, what does condensin i do?

Answer 15

it further condenses the chromosomes

Question 16

what 2 things happen when the microtubules from MTOC invade the nuclear region?

Answer 16

1. mitotic spindles form from 3 types of microtubules
2. sister chromatids must attach to microtubules from different poles

Question 17

what are the 3 kinds of microtubules?

Answer 17

astral (stay at the poles), kinetochore, polar

Question 18

do microtubules go all the way across the cell?

Answer 18

no, they interdigitate

Question 19

which side (+ or -) of mitotic spindles can have subunits removed?

Answer 19

both

Question 20

which side of the mitotic spindle sees faster growth?

Answer 20

the + side

Question 21

what happens in metaphase?

Answer 21

sister chromatids attach to spindle fibers from opposite poles and align on metaphase plate

Question 22

why do chromosomes move to the metaphase plate?

Answer 22

because they’re being pulled in both directions

Question 23

do chromosomes bind directly to microtubules?

Answer 23

no

Question 24

why does metaphase take a long time?

Answer 24

chromatids must attach correctly, and nothing will divide until everything is correct

Question 25

what is a centromere?

Answer 25

constricted region of chromosome with specialized, repeated, satellite DNA sequences (CENP-B box

Question 26

when are the complexes like CENP box created?

Answer 26

G2

Question 27

What are CENP-B boxes

Answer 27

a specific DNA sequence that centromere protein B binds to, playing a role in centromere form and function

Question 28

what happens during anaphase?

Answer 28

centromeric proteins divide and chromosomes move to the separate poles

Question 29

in what order do centromeric proteins divide?

Answer 29

they divide nearly simultaneously

Question 30

do all chromosomes move to the poles at the same time?

Answer 30

no, they move at slightly different rates, which helps them set up chromosome territories within the cell

Question 31

how do chromosomes travel to the poles?

Answer 31

along microtubules -- as the chromosome moves to the poles, the middle microtubule starts to depolymerize because they have to be gone for cell division

Question 32

when does cytokinesis occur?

Answer 32

it begins during anaphase but isn't completed until the end of telophase

Question 33

what 3 things happen in cytokinesis?

Answer 33

1. the parent cell splits into 2 daughter cells with identical DNA content 2. the nuclear envelope starts to form again 3. DNA starts to de-condense

Question 34

once cytokinesis occurs, are the 2 daughter cells exactly the same?

Answer 34

the DNA content is the same, but the cytoplasmic content might not be equally distributed, which can give the cells different cellular fates

Question 35

what protein complex helps keep the chromatids together after replication?

Answer 35

cohesin

Question 36

when is cohesin lost?

Answer 36

when polo comes in to phosphorylate sonorin

Question 37

which parts of the cell cycle is cohesin around for?

Answer 37

all of them

Question 38

how do chromatids attach to spindle fibers?

Answer 38

via kinetochores

Question 39

what are kinetochores?

Answer 39

complexes of proteins associated with the centromere, it's where the microtubules of the spindle fibers attach

Question 40

at what point must cohesin molecules be cleaved?

Answer 40

during anaphase, as the motors in kinetochores move chromosomes along microtubules to different poles in the cell

Question 41

what is ploidy?

Answer 41

the number of sets of chromosomes in the nucleus

Question 42

what is a genome?

Answer 42

sum of genetic information in a cell

Question 43

what does n represent?

Answer 43

one full set of chromosomes of an organism

Question 44

how many chromosomes are around in metaphase? and what is n?

Answer 44

the amount of the somatic cell, 4n

Question 45

how many sister chromatids are around during metaphase?

Answer 45

double the number of chromosomes that are around (for 4n)

Question 46

how many chromosomes are around during anaphase? what is n?

Answer 46

double the amount from metaphase, 4n

Question 47

how many sister chromatids are around during anaphase?

Answer 47

none

Question 48

how many sister chromatids are around after telophase?

Answer 48

none

Question 49

how many chromosomes are around after telophase? and what is n?

Answer 49

whatever the diploid number of chromosomes is, 2n

Question 50

what is the goal of meiosis?

Answer 50

take a diploid germ cell and make it haploid (half the DNA content)

Question 51

Does sperm have an X or Y chromosome?

Answer 51

it can carry either

Question 52

how is genetic diversity generated in meiosis?

Answer 52

recombination -- independent assortment

Question 53

what is gametogenesis?

Answer 53

formation of gametes

Question 54

what is the germ line?

Answer 54

specialized diploid cells set aside during embryogenesis that undergo mitosis to generate more germline cells and then mitosis to generate gametes

Question 55

do all cells in the germ line go through meiosis?

Answer 55

they go through mitosis to make more germ line cells and once they make the switch to meiosis, they can generate gametes

Question 56

what is the result of meiosis ii in women? men?

Answer 56

1 egg or 4 sperm

Question 57

when does recombination occur and what is it between?

Answer 57

in meiosis i, between sister chromatids of homologous chromosomes

Question 58

after chromosomes have duplicated and are going to go through meiosis, how do the chromosomes organize?

Answer 58

the homologous chromosomes align

Question 59

what holds the homologous chromosomes together?

Answer 59

synaptonemal complex that forms between the sister chromatids of homologous chromosomes