3. Cellular reproduction: the cell cycle Flashcards Preview

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Flashcards in 3. Cellular reproduction: the cell cycle Deck (52)
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1

in single celled organisms, cellular reproductions ensures ___________ of species.

propagation

2

multicellular organisms

-1 cell (zygote) divides to become highly organized complex of many of cells
-cell division continues through life
-adult humans have millions dividing at any moment
-replaces old, damaged cells

3

cell cycle

the time from one division to the next division

4

cell cycle is divided into 2 visible phases:

interphase and Mitotic phase (M phase)

5

Interphase

G1, S, G2
-cell growth and metabolism
-length of interphase can vary depending on cell type
*

6

M phase

-includes mitosis (nuclear division) and cytokinesis (cell division)
-occurs after interphase
MITOSIS (prophase, prometaphase, metaphase, anaphase, telephase)
CYTOKINESIS

7

G1

cell grows and carries out normal metabolism; organelles duplicate

8

S

DNA replication and chromosome duplication

9

G2

cell grows and prepares for mitosis

10

Cells can be grouped into 3 broad categories with respect to cell cycle

1. cells that do no cycle, but enter a permanent arrest stage (G0)
(ex. neurons, muscles cells, RBCs- once differentiated, they remain in that state until they die)
2. Cells that normally do not divide, but can be induced
(eg. liver cells, lymphocytes- liver cells reproduce with infection or too much alcohol. the damaged liver cells need to be replaced)
3. Cells that divide regularly
(eg. epithelial cells that line body cavities and surfaces)

11

How is cell cycle controlled?

Cytoplasmic factors control cell division

12

Who did and experiment where they fused mitotic and interphase cells?

Rao and Johnson (1970)

13

What did Rao and Johnson found?

if interphase cells were in G1, they observed "premature chromosomes" (slightly condensed)
I.e the non-mitotic cell tried to enter M phase

14

What did Rao and Johnson conclude?

a "factor" present in the mitotic cell directs cells to undergo mitosis

15

Entry into mitosis requires a protein complex called _____________.

Maturation promoting factor or MPF
(Rao and Johnson's factor)

16

MPF is a complex of two proteins:

1. Cyclin b
2. Cdk1 (cyclin dependent kinase)

17

Cyclin b

-regulates Cdk1 activity
-levels rise and fall throughout cell cycle

18

Cdkl1

(cyclin dependent kinase )
-a kinase is a protein that adds a phosphate to other proteins; the activity of the target protein is modified.

19

In what phase does cyclin b increase its concentration?

G2 phase
decreases in M phase

20

In what phase does MPF increase its concentration?

end of G2 and beginning of M.

21

MPF phosphorylates and activates _______ of _______.

protein, mitosis

22

In the ______ phase, cyclin creases enough to bind to _______.

G2, Cdk1

23

Some MPF functions (3)

1. activates lamin proteins- causes nuclear envelope to break up
2. alters DNA-bound proteins (histones)- causes DNA to condense
3. activates proteins of mitotic spindle

24

phosphorylate

introduce a phosphate group into a molecule or compound

25

third tenet of cell theory

new cells originate only from other living cells

26

wild type

not a mutant
M forms two daughter cells

27

- sign indicates a _______

mutant

28

Wee1 and Wee1-

Wee1 protein is an inhibitor of MPF (prevents mitosis)
Wee1- mutant lacks inhibitor- results in early division ( the cell divides prematurely, prematurely creat daughter cells, forming small cells )

29

Cdc25 and Cdc25-

Cdc25 protein activates MPF
Cdc25- mutant lacks activator, division fails to occur; the cell does not divide but continues to grow resulting in an overly large cell

30

in the g2 phase cyclin increases enough to bind to cdkl however MPF is not ______ yet because it does not work alone

active