Histo Sem 4

Front 1

What occurs in G1(gap) phase?

Back 1

• Cell prepares for DNA replication;
Intensive synthesis of proteins and RNA, including proteins engaged in the regulation of the cell cycle;

This leads to increased cell volume.
The nucleoli are reestablished.

Front 2

What occurs in s (synthetic) phase?

Back 2

Synthesis of histones and DNA (replication) by polimerases (α i δ); Alfa + delta

Front 3

What occurs in G2 phase?

Back 3

Preparation for mitosis,
more RNA and proteins are synthesized,
energy is stored, tubulin in synthesized,
DNA is analyzed for errors.

there are four copies of each chromosome in the cell (2n4C - 46 chromosomes but 92 chromatids

Front 4

Cyclin D is synthesized when?

Back 4

Early G1 phase

Front 5

Cyclin E is synthesized when?

Back 5

Late G1 phase

Front 6

Cyclin D binds to?

Back 6

CDK4 and CDK6

Front 7

Cyclin E binds to?

Back 7

CDK2

Front 8

cyclinD/CDK4
cyclinD/CDK6
cyclinE/CDK2 complexes do what when?

Back 8

In G1 phase,
Permits the cell to enter and progress through S phase.

Front 9

Cyclin A binds to?

Back 9

CDK2 and CDK1

Front 10

cyclinA/CDK2
cyclinA/CDK1 complexes do what when?

Back 10

S phase,
Permits the cell to leave S phase and enter G2 phase and induce the formation of Cyclin B

Front 11

Cyclin B bind to?

Back 11

CDK1

Front 12

Once the cyclins have done its take they enter the?

Back 12

Ubiqutin-proteasome pathway where they are degraded

Front 13

Karyokinesis is?

Back 13

the actual division of the cell nucleus into two daughter nuclei during mitosis.

Front 14

5 examples that can induce apoptosis?

Back 14

Acute injury,
accidents,
lack of vascular supply,
destruction of pathogens or immune system,
genetic programming

Front 15

G2/M checkpoint checks for?

Back 15

proper cell size, DNA replication is completed

Front 16

M checkpoint checks for?

Back 16

proper alignment of chromosomes on mitotic spindle

Front 17

Completion of M checkpoint leads to?

Back 17

completion of karyokinesis and triggering of cytokinesis

Front 18

Restriction point R is where?

Back 18

Late G1 phase

Front 19

Restriction point R checks for?

Back 19

proper cell size
proper external environment
presence of growth factors

Front 20

Three characteristics of Cyclins?

Back 20

no enzymatic activity,
regulatory subunit,
cyclical changes in the cyclin protein level

Front 21

Three characteristics of Cdk (cyclin-dependent kinases)?

Back 21

activated by cyclins,
catalytic subunit – protein kinase activity,
level of cdk protein is constant,
activity is regulated by cyclins

Front 22

cyclinB/CDK1 complex is also called?

Back 22

MPF (Mitosis Promoting Factor, M-phase Promoting Factor)

Front 23

cyclinB/CDK1 complex do what when?

Back 23

G2 phase,
allow the cell to leave the G2 phase and enter the M phase

Front 24

increase of concentration of MPF leads to?

Back 24

cell enters the prophase,
condensation of chromosomes,
damage of the nuclear envelope,
mitotic spindle formation

Front 25

decrease of concentration of MPF leads to(in mitosis)?

Back 25

cell enters the anaphase

Front 26

decrease of concentration of MPF leads to(in cell cycle)?

Back 26

segregation of chromosomes,
decondensation of chromosomes,
repair of nuclear envelope,
DNA replication,
duplication of centrosome

Front 27

Anaphase Promoting Complex(APC) triggers what and how?

Back 27

Transition from metaphase to anaphase by tagging specific proteins for degradation (ubiquitination)
(Lower MPF levels)

Front 28

How can MPF start the break down of the nuclear envelope?

Back 28

phosphorylates serine residues of lamins ->
lamin filaments depolimerize ->
nuclear envelope breaks up into bubbles

Front 29

Activity of cyclin-Cdk complex is regulated by?

Back 29

degradation of cyclins.

Front 30

cyclinD/CDK4
cyclinD/CDK6 Complexes acivates?

Back 30

Rb protein, which stimulates synthesis of cyclin E (Enter S phase)

Front 31

cyclins D production is induced by?

Back 31

Growth factors

Front 32

Detection of damaged DNA results in phosphorylation of?

Back 32

p53 protein

Front 33

p53 protein stimulates the synthesis of?

Back 33

p21, which is an inhibitor of cyclin-dependent kinases (CDKs)

Front 34

Major inhibitors of CDKs?

Back 34

Ink3 family(P15,p16,p18,p19) and
CIP/WAF family(p21, p27, p57)

Front 35

Cell cycle is arrested in G1/S (due to p53->p21 ) until?

Back 35

damaged DNA is repaired

Front 36

The characteristics of tumor cells:

Back 36

Self-sufficiency in growth signals,
Insensitivity to growth-inhibitory signals,
Evasion of apoptosis,
Limitless replicative potential,
Angiogenesis,
Ability to invade and metastasize,
Defects in DNA repair

Front 37

The most important tumor suppressor genes associated with cell cycle control?

Back 37

P53 and Rb proteins

Front 38

ASC (Adultstemcells) are present in?

Back 38

most tissues and organs as tissue stem cells - a small portion of all tissue cells

Front 39

Adultstemcells (ASC) present in?

Back 39

Found in tissues of adult organisms, multipotent (hematopoetic cells) or unipotent (muscle satellite cells);

Front 40

Intestinal epithelial cells are completely replaced within?

Back 40

a few days

Front 41

The bone is completely replaced within?

Back 41

10 years

Front 42

The epidermis is renewed within?

Back 42

two months.

Front 43

Mitogens is a?

Back 43

chemical substance(protein) that encourages a cell to commence cell division, triggering mitosis

Front 44

mitogens stimulate cell devision by?

Back 44

relieving intracellular negative controls (ex. RB) that block progress through the cell cycle. This is done by activating 1/S-Cdk complexes

Front 45

Three major Extracellular groups that control cell division, cell growth and apoptosis:

Back 45

mitogens, Growth factors and Survival factors

Front 46

Some signaling proteins may be both mitogens and growth factors - example?

Back 46

PDGF, they help to maintain the proper cell size during proliferation.

Front 47

growth factors stimulation leads to what within the cell?

Back 47

They lead to the accumulation of proteins and other macromolecules by increasing the rate of synthesis and reducing degradation processes(of cyclins)

Front 48

why is Survival factors used?

Back 48

to maintain only the cells that are needed, and only where they are needed.

Front 49

How can Survival factors protect against apoptosis?

Back 49

They induce Bcl-2, prevent leakage of mitochondrial proteins (Cyt C)

Front 50

Name 1 anti-apoptotic protein and what do they do?

Back 50

Bcl-2,
These proteins maintain the integrity of mitochondrial membranes and prevent leakage of mitochondrial proteins(Cytochrome C)

Front 51

Name 2 pro-apoptotic proteins and what do they do?

Back 51

Bax and Bak (both from Bcl-2 protein family)
They form channels in the mitochondrial membrane
-> cytochrome c leaks out together with IAP inhibitors

Front 52

Name 1 Extracellular inhibitory protein:

Back 52

Myostatin(TGT-beta family) -
inhibits the proliferation of myoblasts that fuse to form skeletal muscle cells

Front 53

Stages of apoptosis?

Back 53

Initiation phase, Effector phase, Degradation phase

Front 54

What are caspases?

Back 54

intracellular proteases(proteins) that will trigger Apoptosis

Front 55

stress-induced apoptotic pathway (intrinsic) – can be induced by?

Back 55

increased concentration of calcium ions in the cell,
oxidative stress,
DNA damage,
degradation of microtubules

Front 56

Mechanisms of Intrinsic pathway(apoptosis)?

Back 56

involves the action effectors of the Bcl-2 family (Bax + bak), which induce leakage of mitochondrial proteins and cytochrome c–dependent caspase activation.

Front 57

Cell differentiation is regulated by?

Back 57

the activation of genes coding for transcription factors which activate other genes, resulting in expression of receptors for growth differentiation

Front 58

The INK4 family (p15, p16, p18, p19) acts on?

Back 58

selective effects on cyclin D/CDK4 and cyclin D/CDK6.

Front 59

The CIP/WAF family(p21, p27, p57) acts on?

Back 59

acts on all CDKs

Front 60

Apoptosome is a ?

Back 60

complex composed of Apaf-1 protein, cytochrome c and caspase-9.

Front 61

caspase-9 on the Apoptosome is a initiator capase and do what?

Back 61

Cleaves Pre-caspase 3 into active caspase 3

Front 62

IAPs are what and do what?

Back 62

"Inhibitors of Apoptosis", inhibits caspase

Front 63

midbody is what?

Back 63

The midbody structure contains bundles of microtubules derived from the mitotic spindle which compacts during the final stages of cell division.

Front 64

synaptonemal complex?

Back 64

protein structure that forms between chromosomes during meiosis and that is thought to mediate chromosome pairing, synapsis, and recombination

Front 65

chiasmata is what?

Back 65

the point at which members of a chromosome cross over

Front 66

progenitors cells are?

Back 66

like a stem cell, has a tendency to differentiate into a specific type of cell, but is already more specific than a stem cell and is pushed to differentiate into its "target" cell.

Front 67

what happens during epigenetic modification?

Back 67

alters the extent to which the DNA is wrapped around the histones, becomes more or less transcribed

Front 68

stem cell niche is a?

Back 68

microenvironment where stem cells are found, maintain adult stem cells in a quiescent state

Front 69

stem cell niche in adults is "activated" when?

Back 69

after tissue injury, the surrounding micro-environment actively signals to stem cells to either promote self renewal or differentiation to form new tissues.

Front 70

metaplasia?

Back 70

Cells change cell type to suite the environment better

Front 71

quiescence?

Back 71

cells that are reversible in G0 stage

Front 72

senescent?

Back 72

Old cells that will no longer divide yet has active metabolism

Front 73

phosphatidylserine?

Back 73

A phospholipid component that is on the inner leaflet, during apoptosis it flips and is on the external side and is recognized by macrophages.

Front 74

The INK4 family (p15 p16, p18, p19) acts on?,

Back 74

selective effects on cyclin D/CDK4 and cyclin D/CDK6.

Front 75

The CIP/WAF family(p21,p27, p57) acts on?,

Back 75

acts on all CDKs

Front 76

IAPs are what and do what?

Back 76

"Inhibitors of Apoptosis", inhibits caspase

Front 77

What are Kinases?

Back 77

type of enzyme that transfers phosphate groups from ATP to specific substrates, a process referred to as phosphorylation.

Front 78

What are Cytochrome c?

Back 78

is a small heme protein found in inner membrane of the mitochondrion,essential component of the electron transport chain

Front 79

What are Caspases?

Back 79

Family of proteases, major effector of apoptosis process

Front 80

PCNA

Back 80

(proliferating cell nuclear antigen) – coenzyme of polymerase δ(Delta) is a marker of phase S and is permanently associated with the nucleus

Front 81

The importance of the restriction point R (G1 phase checkpoint)

Back 81

• Cell must decide whether to:
- leave the cell cycle temporarily(stateof
quiescense)
- Finally leave the cell cycle(aging),
- Enter the cellcycle,
- differentiate,
- die.

Front 82

Cdk inhibitory proteins are active during what phase and why?

Back 82

Cdks are inactive for most of the G1 phase

Delay in the progression of cells into the next phase of the cell cycle - S phase - gives them time for growth stimulated by growth factors leading eventually to the next division.

- The inhibition of G1 phase terminates when G1 cyclins accumulate after stimulation of the cells to divide by growth factors

Front 83

The molecular mechanisms responsible for the inhibition of the cell cycle at specific checkpoints:

Back 83

protein inhibitors of Cdks – block the formation or activity of one or more of the cyclin-Cdk complexes;

p53 protein – transcription factor with tumor suppressor properties

Front 84

Mechanisms of extrinsic pathway(apoptosis)?
+initiated by?

Back 84

death receptor – initiated apoptotic pathway – is initiated by engagement of plasma membrane death receptors (TNF-R, CD95);

Leads directly (No BCL-2 involvement) to activation of caspases 8 -> caspases 3

Front 85

cdc25c phosphatase do what

Back 85

Remove inhibitory phosphorylation from CDK1 -> mitosis