Mitosis

Question 1

List the 3 reasons why cells can’t get too large

Answer 1

1. Diffusion
2. DNA
3. Surface area-to-volume ratio

Question 2

Why is diffusion a factor of cell size?

Answer 2

If organelles are too far from the cell membrane, they would have to wait a long time to get molecules that are diffusing through

Question 3

Why is DNA a factor of cell size?

Answer 3

The nucleus cannot provide DNA fast enough to act as the blue print for the high amounts of proteins and enzymes that a large cell would need

Question 4

Why is surface area-to-volume ratio a factor of cell size?

Answer 4

The volume of the cell increases a lot faster than the surface area. Therefore if the cell gets too big, the cell membrane will not have enough surface area to diffuse the amount of nutrients the cell needs or get rid of the waste the cell produces

Question 5

Describe interphase

Answer 5

period where the cell is preparing to divide through growth and maintenance

Question 6

What is the G1 phase?

Answer 6

(“first gap”) growth

Question 7

What is the S phase?

Answer 7

(“synthesis”) DNA duplication

Question 8

What is the G2 phase?

Answer 8

(“second gap”) Maintenance

Question 9

Describe synthesis

Answer 9

portion of interphase where cells duplicate their DNA

Question 10

DNA is packaged into sets of what?

Answer 10

chromosomes

Question 11

Humans have __ chromosomes ( __ from each parent)

Answer 11

46; 23

Question 12

Body cells are considered _______ _____

Answer 12

Somatic cells

Question 13

Are somatic cells diploid or haploid?

Answer 13

diploid

Question 14

Reproductive cells are considered ________

Answer 14

Gametes

Question 15

Are gametes diploid or haploid?

Answer 15

haploid

Question 16

What are sister chromatids

Answer 16

identical copies of a chromosome

Question 17

Describe centromere

Answer 17

holds sister chromatids together

Question 18

How is DNA duplicated in synthesis?

Answer 18

each chromosome gets copied and is attached to its copy

Question 19

Define mitosis

Answer 19

Cell division where 1 diploid parent cell makes 2 identical diploid daughter cells

Question 20

Describe prophase

Answer 20

the chromosomes coil up and become visible while the nuclear envelope disappears. Sister chromatids are present

Question 21

A _______ forms at each pole and ________ ______ made of microtubules grow out

Answer 21

centriole; spindle fibers

Question 22

Short microtubules stick out from the centriole in a star shape known as an ____

Answer 22

aster

Question 23

Describe prometaphase

Answer 23

spindle fibers attach to each of the chromatids at a sight called the kinetochore

Question 24

Describe metaphase

Answer 24

the spindle fibers line the chromatids up at the equator of the cell called the metaphase plate

Question 25

Describe anaphase

Answer 25

the kinetochores “reel in the spindle fibers to pull the sister chromatids apart by splitting their centromere. The split chromatids are pulled towards opposite poles of the cell

Question 26

Describe telophase

Answer 26

Once the chromatids have reached the opposite sides the spindle fibers disappear, the chromosomes unravel, and the nuclear envelope reappears on the two new nuclei.

Question 27

Describe cytokinesis

Answer 27

the cytoplasm forms a cleavage furrow at the equator to split the cytoplasm

Question 28

Describe binary fission

Answer 28

the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart

Question 29

The cell cycle is controlled by chemical signals in the __________

Answer 29

cytoplasm

Question 30

What is the cell cycle control system

Answer 30

a set of events that occurs in a sequence to regulate the cell cycle

Question 31

The cell cycle control system has specific _________ where the cell cycle stops until a go-ahead signal is received

Answer 31

checkpoints

Question 32

the __ checkpoint is the most important

Answer 32

G1

Question 33

If the cell does not receive the go-ahead signal what happens?

Answer 33

it will go into a non-dividing state called the G0 phase

Question 34

What is cyclin

Answer 34

a regulatory protein that builds up in the G2 phase

Question 35

What are Cyclin dependent kinases (Cdks)

Answer 35

a regulatory protein that is always present waiting for the arrival of cyclin

Question 36

What is MPF (maturation-promoting factor)

Answer 36

cyclin and Cdks combined to trigger a passage through G2 and Mitosis

Question 37

What are growth factors

Answer 37

proteins released by certain cells that stimulate other cells to divide

Question 38

What does the platelet-derived growth factor (PDGF) do

Answer 38

stimulates the division of human fibroblast cells (connective tissue). This is released when cut from blood platelets so healing can begin.

Question 39

What is density-dependent inhibition

Answer 39

crowded cells stop dividing

Question 40

What is anchorage dependence

Answer 40

cells must be attached to something in order to divide

Question 41

Why are cancer cells formed

Answer 41

Cancer cells do not respond normally to the cells cycle check points or external signals

Question 42

How do cancer cells' growth factor work?

Answer 42

They may make their own growth factor They may convey a growth factor’s signal without the presence of the growth factor They may have an abnormal cell cycle control system

Question 43

Define transformation

Answer 43

A normal cell is converted to a cancerous cell

Question 44

What is a benign tumor

Answer 44

The lump that is formed if the cancer stays at the original site

Question 45

________ tumors spread to surrounding tissues through _______ through _______ ________

Answer 45

Malignant; metastasis; blood vessels

Question 46

Describe the organization eukaryotic genome

Answer 46

Eukaryotic genomes are packaged into chromosomes, it is a double helix

Question 47

Compare and contrast cytokinesis in animals and plants

Answer 47

Animal cells undergo true cytokinesis- plants do not. In plants a cell plate forms to become the new cell wall separating the two daughter cells. Animal cells form a cleavage furrow. This occurs during telophase of mitosis and ends when the two daughter cells resolve.

Question 48

Describe the S phase checkpoint

Answer 48

ensure DNA is fully replicated before mitosis

Question 49

What do the G1 and G2 checkpoints check?

Answer 49

if DNA is damaged before moving to the next step

Question 50

What is the checkpoint in mitosis for?

Answer 50

to ensure chromosomes are lined up correctly in metaphase before continuing to anaphase