L3 Cell Cycle, Meiosis and Mitosis

Question 1

what cells are found in the cell cycle?

Answer 1

eukaryotic somatic cells that have the capacity to divide

Question 2

what is the cell cycle?

Answer 2

the time from birth of a new cell until it is capable of cell division to form 2 new daughter cells

Question 3

what are the 2 stages of the cell cycle?

Answer 3

interphase - period between cell division

mitosis - period of actual cell division

Question 4

which phase is most variable?

Answer 4

interphase

Question 5

in what stage does the cell spend most time?

Answer 5

interphase - variable from one cell type to the next

Question 6

what happens to the cell during interphase?

Answer 6

the cell grows - ready for mitosis at the end of interphase

Question 7

what happens to the cell during mitosis?

Answer 7

the cell actually divides to form 2 new daughter cells

time spent in mitosis is 2-4 hours and is usually constant

Question 8

what are labile cells?

Answer 8

multiply throughout life
cells of skin, GIT, epithelial cells
they have short interphases

Question 9

what are stable cells?

Answer 9

quiescent (G0 phase)
can divide if stimulated by growth factors
liver cells

Question 10

what are permanent cells?

Answer 10

lost the capacity to divide
permanently in G0 phase
neurons, cardiac muscles cells etc.

Question 11

what is the most significant checkpoint?

Answer 11

G1 checkpoint - checks for cell size, nutrients, growth factors and DNA DAMAGE

Question 12

what happens during G1 phase?

Answer 12

cell size increase
protein synthesis active
cell differentiation and performs functions
at the end, cell checks whether it is ready for division

Question 13

what is the G0 phase?

Answer 13

(quiescent)
permanent and stable cells in here
stable cells can re-enter with GFs

Question 14

what happens during S phase?

Answer 14

DNA synthesis/DNA replication
enzymes of replication are active
chromosome number x2
chromatid number x2
1 chromosome = 2 sister chromatids

Question 15

what happens during the G2 phase?

Answer 15

chromatid number x2
cell size increases (help form new daughter cells)
genome is scanned for mistakes
DNA repair mech. active

Question 16

what proteins are important at the G1–>S checkpoint?

Answer 16

p53 and Rb (tumor suppressor genes)

Question 17

what are cyclins?

Answer 17

regulate the entry of cells into the various phases of the cell cycle

Question 18

what are the functions of p53?

Answer 18

1. cell cycle arrest
2. DNA repair
3. apoptosis - if DNA is damaged badly

Question 19

what do growth factors do?

Answer 19

stimulate cell division

serve as signals that tell the cell to move though the cell cycle in order to divide

Question 20

cells have a ___ lifespan

Answer 20

finite - some point no longer able to divide

Question 21

what is cancer in terms of the cell cycle?

Answer 21

defect in the regulation of the cell cycle - rapidly dividing cells that are no longer controlled!

Question 22

in non-stressed cells, what is the concentration of p53?

Answer 22

low - visa versa

Question 23

what is a chromatid?

Answer 23

copy of a duplicated chromosome which is joined by a centromere

Question 24

what happens during mitosis?

Answer 24

sister chromatids are divided and cytoplasmic division forms 2 daughter cells

Question 25

the genetic composition of the daughter and parent cell are?

Answer 25

identical

Question 26

what is meiosis?

Answer 26

takes place only in gamete forming cells of ovary and testies - final stage of gametogenesis

Question 27

are the gametes formed haploid or diploid?

Answer 27

haploid

Question 28

each gamete is____

Answer 28

genetically unique

Question 29

what is homologous recombination?

Answer 29

homologous chromosomes undergo exchange of short fragments of their genetic material
responsible for genetic variation between gametes

Question 30

what are the 2 stages of meiosis?

Answer 30

Meiosis 1 - homologous chromosome separate (aka reduction division because you get 1/2 # of chromosomes at end)

meiosis II - sister chromatids of a chromosome separate
similar to mitosis - except begin with 23 chromosomes instead of 46

Question 31

what is the crucial role of meiosis?

Answer 31

• formation of haploid gamete

- allows for genetic recombination and genetic diversity

Question 32

what is nondisjunction

Answer 32

when homologous chromosomes (meiosis I) or sister chromatids (meiosis II) do not separate

Question 33

how many sperm does male meiosis make?

Answer 33

4 per round

Question 34

how many eggs and polar bodies does female meiosis make?

Answer 34

1 egg, 3 polar bodies

Question 35

when do males gametes undergo mitotic division?

Answer 35

puberty

Question 36

when do female gametes undergo mitotic division?

Answer 36

birth - oocyte are arrested in prophase I of meiosis until ovulation)

Question 37

what are the defects if maternal or paternal age increase?

Answer 37

FEMALE high risk of non-disjunction in the meiotic divisions - higher risk of trisomy

MALE - greater risk of development of new dominate single gene mutations (errors during replication)