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Biochemistry (III) > Cell Cycle > Flashcards

Cell Cycle Flashcards

1
Q

Name the stages of Cell Cycle?

A

G1
S
G2
M

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2
Q

What is the cell what happens in G1

A

Active metabolism and accumulation of building blocks and energy.
The cell grows and synthesis all protein necessary,
Make glucose

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3
Q

What happen in S phase

A

DNA is synthesizes

DNA replication occurs- each DNA molecule produce identical copy, centrosomes is duplicated

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4
Q

What happens in G2

A

Active metabolism and protein synthesis, duplication of organelles

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5
Q

What happen in Mitosis

A

Cell division and end up with two cells

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6
Q

What are the phases of mitosis?

A
  1. Prophase
  2. Prometaphase
  3. Metaphase
  4. Anaphase
  5. Telophase
  6. Cytokinesis
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8
Q

What happens during prometaphase?

A
  • Chromosomes continue to condense
  • Mitotic spindle microtubules attach to kinetochores
  • centrosomes move toward opposite poles
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9
Q

What happens during metaphase?

A
  • Mitotic spindle is fully developed, centrosomes are at apposite pole of the cell
  • chromosomes are lines up. At the metaphase plate
  • Each sister chromatic is attached to a spindle fiber originating from opposite poles
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10
Q

What happens in Anaphase?

A
  • Cohesin proteins binding the sister chromatids together break down
  • Sister chromatids (now called chromosomes) are pulled toward opposite poles
  • non-kinetochore spindle fibers lengthen, Elongsting the cell
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11
Q

What happens in telophase?

A
  • Chromoseomes arrive at opposite poles and begin to decondense
  • nuclear envelope material surround each set of chromosomes
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12
Q

What happens during G0- resting?

A

A period in the cell cycle in which cell exist in a quiescent state.

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13
Q

What is a quiescent state?

A

The cell is neither dividing nor preparing to divide

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14
Q

The majority of cells in the human body have irreversible withdrawn from the cell cycle into either of two thing?

A
  • a terminally differentiated state (neurons, myocytes or surface epithelial cells of skin and mucosa) a do not re-enter the cell cycle
  • a reversible quiescent G0 phase (stem cells, glia cells, hepatocytes or thyroid follicular cells) - capable to return to the cell cycle
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15
Q

What type of cells are stuck in the terminally differentiated state?

A

Neurons

Myocytes or surface epitheirak cells of skin and mucosa

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16
Q

What cells are able to re-enter the cell cycle?

A

Stem cells
Glia cells
Hepatocytes
Thyroid follicular cells

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17
Q

How does control of the cell cycle occur? (3)

A
  1. Regulation at internal checkpoints.
  2. Regulatory molecules
  3. Regulation by external signals
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18
Q

What Happens in Prophase?

A
  1. Prophase- chromosomes condense and become visible
    - splinter fibers emerge from the centrosome
    - nuclear envelop breaks down
    - Nucleous Disappear
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19
Q

How many check points does the cell cycle have and where are they?

A

3 check points
1. G1
G2
M

20
Q

What happens in the G1 checkpoint?(4)

A

The cell check for

  1. Cell size
  2. Nutrients
  3. Growth factors
  4. DNA damage
21
Q

What happens in the G2 checkpoint? (2)

A

The cell checks for

  1. Cell size
  2. Accurate DNA replication
22
Q

What happens in the M checkpoint?

A

The cell check for chromosome attachment to the spindle

23
Q

How is the cell cycle controlled through regulatory molecules?

A
  1. Positive regulation- cycling and cdk

2. Negative regulation - Rob, p53, and p21

24
Q

How does positive regulation of the cell cycle through cycling and cdk happens?

A
  • changes of different cycling throughout the cell cycle
  • direct correlation between cycling accumulation and the three major cell cycle checkpoints
  • Harp decline of cycling is degraded by cytoplasmic enzymes
  • Cyclins are only active when bond to the respective cyclin- dependent kinase
25
Q

What enzyme is responsible for degrading Cyclin?

A

Cytoplasmic enzymes

26
Q

What does Cyclin have to be bond to in order for it to be active?

A

Cyclin-dependent kinase

27
Q

What does Rb protein do and How does negative regulation through Rb regulates the cell cycle?

A

Rb- retinoblastoma protein: prevent initiation of the cell cycle in G1 phase.

How?
Unphosphorylated Rb binds transcription factor E2F. Therefore E2F cannot bind the DNA and transcription is blocked.

28
Q

What is E2F responsible for?

A

Controls transcription of 500 genes necessary for transition into G2

29
Q

What happens when Rb gets phosphorylated?

A

Cell growth triggers the phosphorylation of Rb. Phosphorelated Rb releases E2F, .which binds the DNA and turns on gene expression, this advancing the cell cycle.

30
Q

Is p53 a transcriptional inhibitor or activator?

A

Inhibitor.

31
Q

What is the end results of M phase?

A

Formation of 2 daughter cells!

32
Q

How does p21 regulates the cell cycle?

A

P21 prevents cell cycle progression

33
Q

How does p21 prevent cell-cycle progression? (2)

A
  1. Inhibiting the activity of Cyclin E associated CDK2

2. Therefore preventing E2F mediated gene transcription and cell cycle progression

34
Q

What is mitogens?

A

It’s an external stimuli that causes the cells to proliferate (return to G1 if in G0)

35
Q

How does mitogen induce the cell to proliferate?

A
  1. Can be provided by extracellular matrix (intergins)

2. Can be extracellular signal from more distant sources

36
Q

Mitogens

Intergins:

  • cell to matrix contact is called _______
  • cell to cell contact is called ______

Extracellular Distance sources:

  • ___________ EGF, VEGF, NGF, FGF
  • ___________ IL-1, IL-6
A

Mitogenic
Antimitogenic (contact inhibition)

Growth factors
Cytokines

37
Q

Name the 6 types of Growth factors

A
  1. Platelet- derived growth factor (PDGF)
  2. Epidermal growth factor (EGF)
  3. Fibroblast growth factor (FGF)
  4. Insulin-like growth factor 1 (IGF-1)
  5. Vascular endothelial growth factor (VEGF)
  6. Nerve growth factor (NGF)
38
Q

PDGF is present in the ____ of _____ from which it is released during activation - participates in ______ ______

EGF stimulated the _______ of epithelial cells and some other cells. It acts primarily in ________

FGF are a family of at lease ___(how many) proteins that act in four different _____ (type of receptors) and they stimulate ______ (type of cell) and other types of cells

A

a-granules of platelets , participate in wound healing

Proliferation, tissue of origin

22 proteins, tyrosine kinase receptors, stimulate fibroblasts

39
Q

IGF-1 is released from ____ in response to _____ hormone

VEGF produced by cells that stimulates ____ and _____ (new blood vessel formation)

NGF stimulated the growth and differentiation (but not mitosis) of ____ ______ neurons (type of neurons)

A

Liver, growth

Vasculogenesis, angiogenesis

Postganglionic sympathetic neurons

40
Q

Abnormal uncontrolled cell cycle over period of time can lead to development of ____

A

Neoplasms (tumors)

Note: Tumors are group of cells that have undergone unregulated growth and will often form a mass or lump, but may be distributed diffusely

41
Q

What are the 6 hallmarks of cancer, which are required to produce a malignant tumor?

A
  1. Cell growth and division absent the proper signals
  2. Continuous growth and division even given contract signals
  3. Avoidance of programmed cell death
  4. Limitless number of cell divisions
  5. Promoting blood vessel construction
  6. Invasion of tissue and formation of metastases
42
Q

What are oncogenes?

A

The are mutated normal genes that encode positive cell cycle regulators that chases a cell to become cancerous.

43
Q

What are Tumor suppressor genes?

A

Genes that encode for negative regulator proteins that will suppress uncontrolled cell division like Rb, p53,p21

44
Q

How does p53 regulates the cell cycle?

A
  • has the ability to repress transcription and to promote apoptosis through direct interaction with apoptosis regulators in the cytosol
  • indices cell cycle arrest.

Biochemistry (III) (8 decks)

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