Ch. 7: Cell Division

Question 1

2 phases of cell division

Answer 1

nuclear division (mitosis/ meiosis) and cytokinesis

Question 2

First step in mitosis/ meiosis

Answer 2

condensation of chromatin into chromosomes

Question 3

Chromosome

Answer 3

2 identical sister chromatids joined at centromere

each chromatid consists of single tightly coiled DNA

Question 4

Diploid vs. Haploid cell

Answer 4

diploid: 2 copies of every chromosome (2n)
haploid: 1 copy of every chromosome (n)

Question 5

M phase

Answer 5

mitosis and cytokinesis

Question 6

Prophase (mitosis)

Answer 6

first stage of mitosis
nucleoli disappear and chromatin condenses into chromosomes
nuclear envelope breaks down
mitotic spindle forms: microtubules develop from MTOCs and connect to centromeres at kinetochore

Question 7

Metaphase (mitosis)

Answer 7

second stage of mitosis
chromosomes align at metaphase plate
ends when microtubules at kinetochores pull chromosome apart into two chromatids (chromosomes)

Question 8

Anaphase (mitosis)

Answer 8

third stage of mitosis
sister chromatids pulled apart to opposite poles
microtubules not attached to chromosomes push poles farther apart to elongate cell

Question 9

Telophase (mitosis)

Answer 9

fourth (final) stage of mitosis

nuclear envelope is restored around each pole, nuclei form and chromosomes disperse into chromatin

Question 10

Mitotic spindle

Answer 10

fibers of microtubule proteins that form during prophase
consist of: spindle microtubules, centrosome, asters
attach to chromosomes at kinetochore to assist in their movement

Question 11

Kinetochore

Answer 11

structure of proteins on centromere of DNA chromosome
attachment site for microtubules and move chromosome to pole from which the microtubules extend, opposite pole attaches and starts tug-of-war

Question 12

Cell plate

Answer 12

cytokinesis in plants
vesicles originating from Golgi bodies migrate to plane between the two newly forming nuclei, membranes of vesicles fuse to form two new plasma membranes and the contents form cell plate, which develops into the new cell wall

Question 13

Cleavage furrow

Answer 13

actin filaments between two newly forming nuclei shorten and act like purse strings to pull plasma membrane to center, forming a groove = cleavage furrow to split the two cells

Question 14

Interphase

Answer 14

3 stage growth: G1, S, G2
G1: cell growth
S: DNA synthesis (make 2 chromatids)
G2: all materials for next mitosis prepared, cell growth

Question 15

Meiosis

Answer 15

meiosis I (homologous chromosome pairs) and meiosis II (chromosomes/ chromatids)

Question 16

Prophase I (meiosis)

Answer 16

begins like prophase in mitosis: nucleolus disappears, chromatin condenses to chromosomes, nuclear envelope breaks down and spindle forms
homologous chromosomes pair with each other in synopsis, during which crossing over can happen at region called chiasmata

Question 17

Metaphase I (meiosis)

Answer 17

homologous chromosome pairs align at metaphase plate, microtubules from each pole attach to kinetochore and pull homologous pairs apart

Question 18

Anaphase I (meiosis)

Answer 18

homologues uncouple as they’re pulled to opposite poles

Question 19

Telophase I (meiosis)

Answer 19

new nuclei form and new cells form and all that jazz

daughter cells haploid

Question 20

Mitosis is similar to which process in meiosis

Answer 20

meiosis II

its literally the same thing except no replication so result are haploid (1 chromosomes in each)

Question 21

Types of genetic recombination (3)

Answer 21

crossing over, independent assortment of chromosomes, joining of gametes

Question 22

Crossing over

Answer 22

only in meiosis I

during prophase I, nonsister chromatids of homologous chromosomes exchange pieces of genetic material

Question 23

Independent assortment of homologues

Answer 23

during metaphase I, homologues of each pair of homologous chromosomes go to opposite poles, the separation is random for each homologous pair

Question 24

Joining of gametes

Answer 24

bc sexual reproduction requires gametes of two individuals, new combos are created
which sperm fertilizes the egg is random (faster swimmer)

Question 25

Surface-to-volume ratio (cell limit)

Answer 25

want large S:V ratio
as cell grows, volume increases faster than surface area so it limits how much the cell can grow to efficiently be able to support diffusion of oxygen in and waste out

Question 26

Genome-to-volume ratio (cell limit)

Answer 26

chromosomes in nucleus (genome) control cell by producing substances that make enzymes and molecules to regulate cell… when cell grows, volume increases but genome stays same size so limits how much cell can grow

Question 27

Regulation of cell cycle

Answer 27

at specific points of cell cycle, cell evaluates internal and external conditions to determine whether to go through
think border control/ airport security

Question 28

G1 checkpoint

Answer 28

at end of G1 phase
quality of DNA evaluated, if can’t be repaired then cell performs apoptosis (death), if nutrients missing G1 phase might be extended to get proper conditions

Question 29

G2 checkpoint

Answer 29

at end of G2 phase

evaluates accuracy of DNA replication and signals whether or not to start mitosis

Question 30

M checkpoint

Answer 30

during metaphase
ensures that microtubules are properly attached to all kinetochores at metaphase plate before division c continues w/ anaphase (and non-disjunction occurs)

Question 31

Cyclin-dependent kinases (CDKs) (internal cell cycle regulation)

Answer 31

proteins responsible for advancing cell past checkpoints and through cell cycle

• CDKs are kinases: phosphorylate other proteins to activate
• CDKs activated by cyclins: cyclins attach to create conformational change

Question 32

Mitosis-promoting factor (or maturation-promoting factor) (MPF)

Answer 32

cyclin-CDK complex that advances the cell through G2 checkpoint
each checkpoint has its specific CDK that advances it through

Question 33

Growth factors (external cell cycle) regulation

Answer 33

plasma membranes have receptors for growth factors that stimulate cell to divide
Ex: platelet-derived growth factor (PDGF)

Question 34

Density-dependent inhibition (external cell cycle regulation)

Answer 34

cells stop dividing when surrounding cell density reaches certain max
Ex. petri dish

Question 35

Anchorage dependence (external cell cycle regulation)

Answer 35

most cells only divide when they are attached to external surface, like flat surface of neighbor cell or petri dish

Question 36

Cancer (cells)

Answer 36

uncontrolled cell growth and division: disease of cell cycle
transformed cells go on w/out checkpoints, density-dependent inhibition, anchorage dependence or any regulatory mechanisms