Mitosis and Meiosis

Question 1

What drives the cell cycle

Answer 1

Cyclin-dependent kinase

Question 2

How does Cdk do its job

Answer 2

Phosphorylating specific substrates

Question 3

What happens during mitosis prophase

Answer 3

Chromosomes condense
Centromeres migrate to poles
Spindle starts to form

Question 4

What happens during mitosis pro-metaphase

Answer 4

Nuclear envelope breaks down
Chromosomes attach to spindle

Question 5

Mitosis metaphase

Answer 5

Sister chromatids linked to opposite spindle poles
Chromosomes align along equatorial plane

Question 6

Mitosis anaphase

Answer 6

Sister chromatids separate
Daughter chromatids pulled to opposite ends of cell

Question 7

Mitosis - telophase

Answer 7

Chromosomes arrive at poles
Nuclear membrane reforms
Chromosomes decondense

Question 8

Centrosome:

Answer 8

Microtubule organizing center, contains a pair of centrioles

Question 9

What holds sister chromosomes together

Answer 9

Cohesin

Question 10

What helps DNA coil

Answer 10

Condensin

Question 11

What triggers nuclear envelope breakdown

Answer 11

It goes to vet school
JK. Cdk phosphorylation of lamins, which provide the structural integrity

Question 12

How do microtubules attach to the chromosomes

Answer 12

Attach to the kinetochore which is bound to the DNA

Question 13

What are the names of improper spindle alignment

Answer 13

Syntelic
Merotelic
Monotelic

Question 14

What is proper spindle attachment/orientation called

Answer 14

Amphitelic

Question 15

Syntelic attachement:

Answer 15

Both kinetochores attached to the same pole

Question 16

Merotelic attachments

Answer 16

Uneven number of microtubules between poles (more attached to one pole than the other pole)

Question 17

Monotelic attachments

Answer 17

Microtubules only attach to one kinetochore

Question 18

Astral microtubules:

Answer 18

orient spindles, pull centrosomes apart

Question 19

Kinetochore microtubules

Answer 19

Pull chromatids apart

Question 20

Polar microtubules

Answer 20

Extend the entire length of the spindle

Question 21

Is tension between centromeres good or bad

Answer 21

Good. It means there’s a stable attachment

Question 22

How do microtubules pull chromosomes apart

Answer 22

Fast subunit subtraction at kinetochore –> MT shortened –> kinetochore pulled toward pole

Question 23

What is APC

Answer 23

Anaphase promoting complex

Question 24

What activates APC

Answer 24

Cdk

Question 25

What is APC's job

Answer 25

To activate separase by cleaving securin

Question 26

Why does separase need to be activated

Answer 26

Separase degrades cohesin which holds the sister chromatids together. Anaphase cannot happen until cohesin has been degraded

Question 27

What happens if the chromosomes aren;t correctly aligned going into anaphase

Answer 27

APC is never activated --> separase never activated --> cohesin keeps sister chromatids together --> no anaphase

Question 28

What is cytokinesis

Answer 28

Cytoplasmic division

Question 29

When does cytokinesis occur

Answer 29

Anaphase-telophase

Question 30

What is the contractile ring

Answer 30

Actin and myosin filaments that form inside the plasma membrane at the metaphase plate

Question 31

What is the goal of meiosis

Answer 31

To produce haploid gametes from diploid parent cells

Question 32

What aspects of meiosis contribute to genetic diversity

Answer 32

-Independent assortment of maternal & paternal homologs during meiotic division I -Crossing over during prophase I

Question 33

What is the primary driver of proper chromosome segregation in meiosis

Answer 33

Crossing over

Question 34

Sparknotes of meiosis I

Answer 34

Duplicated homologs pair up At least one cross-over occurs per pair Homologs align on spindle Homologs segregate to opposite poles

Question 35

Sparknotes of meiosis II

Answer 35

Spindle reforms Chromosomes align Chromatids segregate to opposite poles

Question 36

Prophase I:

Answer 36

Homologous chromosomes pair up Protein elements established between homologs Recombination (crossing over)

Question 37

Where on the chromosomes does recombination occur

Answer 37

At recombination nodules--large protein complexes containing recombination proteins

Question 38

Steps of recombination:

Answer 38

Double-stranded DNA break Resected so that 3' end overhangs Overhanging 3' end invades homologous chromatid Double Holliday junction forms Resolvase cuts joined molecules to produce recombined chromosomes

Question 39

What is the site of completed cross-over called?

Answer 39

Chiasma

Question 40

Two pairs of homologous chromosomes are called a...

Answer 40

bivalent

Question 41

Non-disjunction:

Answer 41

Failure of chromosomes to separate and segregate properly at anaphase I or II

Question 42

What holds pairs of homologs together

Answer 42

Chiasma(s/e)? is it Latin? who knows cohesins at arms

Question 43

What holds sister chromatids together

Answer 43

Cohesins at the centromere

Question 44

Where do oocytes arrest during meiosis

Answer 44

Prohpase I

Question 45

What is special about oogenesis in terms of divisions

Answer 45

They are asymmetric--one set is discarded (1st and 2nd polar bodies)

Question 46

When does meiosis initiate in the male

Answer 46

After puberty

Question 47

Why are there so many more sperms than oocytes?

Answer 47

Because it takes more energy and resources to create an oocyte and sperm exploit maternal investment. Classic.

Question 48

Mitosis vs meiosis: where does it happen

Answer 48

Mi: somatic cells Me: germ cells

Question 49

Mitosis vs meiosis: what is the result

Answer 49

Mi: 2 diploid cells Me: 4 haploid cells

Question 50

Mitosis vs meiosis: what happens to the # chromosomes/cell

Answer 50

Mi: maintained Me: halved