Lecture I Cell Cycle

Question 1

Which cell divide more skin cell or liver cell and how many times each

Answer 1

Skin cell divide more
Skin cell frequently
Liver cell once in one year or two

Question 2

Do Nerve and muscle cell divide after maturation

Answer 2

Not at all

Question 3

What are the phases of cell cycle

Answer 3

Interphase , mitoses or meiosis and G0 phase

Question 4

Cell spend 90% of their life on which phase

Answer 4

Interphase

Question 5

Does cell divide all the time ? Why ?

Answer 5

No , because most of the time they are in interphase

Question 6

What are the stages of interphase

Answer 6

G1 , G2 , S phases

Question 7

What happen for the cell in interphase

Answer 7

Growth and DNA replication

Question 8

Cell cycle length differ due to

Answer 8

The time in G1 or G0 phases

Question 9

What is the special of embryonic stem cells

Answer 9

They have the capacity of unlimited proliferation and short G1 phase and high cell proportion In S phase

Question 10

What happen in G1 phase

Answer 10

G1 : synthesis of RNA and proteins , growth recovery after previous division

Question 11

What happen in S phase

Answer 11

DNA , RNA , proteins synthesis, DNA replication and the chromosome enters with one chromatid and leave with two

Question 12

What happen in G2 phase

Answer 12

DNA , protein synthesis , growth

Question 13

What is mitosis ?

Answer 13

Cell division that gives two identical diploid cells

Question 14

What are the stages of mitosis

Answer 14

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

Question 15

What happen in prophase

Answer 15

Disappearance of nuclei , condensation of chromosome, formation of mitosis spindle , centrosomes move apart

Question 16

What happen in prometaphase

Answer 16

Nuclear membrane disappears, formation of kinetichorses at centromere

Question 17

What happen at metaphase

Answer 17

Chromosome lined at metaphase plate and the centrosomes at the opposite poles

Question 18

What happen at telophase

Answer 18

Formation of nuclear membrane around chromosome, reappear of nucleus and decondinsation of chromosomes

Question 19

What happen at cytokinesis

Answer 19

Division of organelles and cytoplasm , contractile ring of actin and myosin divid the cell

Question 20

What happen at interphase before meiosis ?

Answer 20

Replication of chromosome which result in two identical sister chromatid

Question 21

Meioses result in How many cells ?

Answer 21

4 haploid not identical cells

Question 22

What is the longest phase of meiosis

Answer 22

Prophase l

Question 23

What happen at prophase l

Answer 23

Condensation of chromosome
Synapsis
Crossing over

Question 24

What is synapsis of chromosome

Answer 24

When two chromosomes come together to form tetrad

Question 25

What happen in crossing over

Answer 25

Breaks of no sister chromatid segments and rejoin in other chromstid

Question 26

What is the site of crossing over called

Answer 26

Chiasmata

Question 27

Why do siblings have different traits

Answer 27

Due to crossing overs

Question 28

Non-disjunction definition

Answer 28

Failure of homologous chromosome or sister chromatid to separate

Question 29

Non-disjunction result in what

Answer 29

Zygote whit abnormal number of chromosomes

Question 30

Why cell division is important? Important for what

Answer 30

Growth Maintenance of Tissue and organ function Repair tissue damage Immune cell proliferation

Question 31

What is check points

Answer 31

Check if the cell cycle processed or stop , check If the cell is ready to keep going by checking growth , replication and division

Question 32

What are the check point in cell cycle

Answer 32

G1/S , G2/M , Mitosis ( metaphase )

Question 33

G1/S checks what ?

Answer 33

Size and environment

Question 34

Platelet-derived growth factors needed for what

Answer 34

Needed for fibroblast division in wound healing

Question 35

Which protein is important for G1/S check point

Answer 35

Retinoblastoma protein ( Rb)

Question 36

When does cyclin-CDK complies phosphorylate RB protein

Answer 36

S phase

Question 37

What each cyclin bind to CD , CE , CB ( cyclin = C )

Answer 37

CD to CDK4 or 6 CE to CDK2 CB to CDK1

Question 38

How to activate Rb

Answer 38

When cyclinD-CDK4/6 phosphorylate it

Question 39

What happen when Rb phosphorylated

Answer 39

E2F will bind to DNA and regulate gene transcription which is needed to enter S phase

Question 40

CyclinE-CDK2 who activate them and what happen when they are activated ?

Answer 40

Activated by E2F Phosphorylate Rb to activate it and phosphorylate p21/27 that deactivate CD-CDK4/6

Question 41

G2/M check point for what

Answer 41

If the cell have damaged genom will not pass

Question 42

What does mitosis promoting factor composed of

Answer 42

CyclinB-CDK1 complex

Question 43

What are the site of activation and inhibition of MPF

Answer 43

threonine 161 when phosphorylate MPF will be activated Threonine 14 and tyrosine 15 when phosphorylate MPF will be deactivated

Question 44

What does cdc25 do

Answer 44

Dephosphorylation of thr14 and tyr15 to activate MPF

Question 45

What is the different between oocyte and spermocyte meiosis

Answer 45

Soermocyte happrn without interruption but oocyte has arrest

Question 46

When does oocyte arrest

Answer 46

Prophase l and metaphase ll

Question 47

MPF induce what for oocyte

Answer 47

Exit from prophase l arrest

Question 48

Cytostatic factor mediates what ? How

Answer 48

Metaphase ll arrest by inhibiting anaphase promoting factor

Question 49

When does the inhibition of anaphase promoting factor ended

Answer 49

When the sperm derived ca+2 signal arrive