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psu freshman > BIO230W Exam 4 > Flashcards

BIO230W Exam 4 Flashcards

1
Q

Will DNA at the origin be heterochromatic or euchromatic?

A

Chromatin must be remodeled to be euchromatic as opposed to heterochromatic

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2
Q

Describe the A-T, G-C base pairs at origins of replications

A

More AT base pairs compared to GC so easy to bind to and separate

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3
Q

What protein complex binds to the origin before helicase is loaded?

A

Origin Recognition Complex identifies and binds to origin (specific DNA region)

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4
Q

During which cell cycle stage is the full pre-replication complex bound to DNA?

A

G1

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5
Q

MCM

A

DNA modifying helicase (enzyme) that separates DNA strands at the origin

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6
Q

What three components make up the pre-replication complex (PRC?)

A

Origin recognition scaffold (ORC, cdt1, cdc6), helicase loader, helicase

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7
Q

How does the concentration of geminin relate to the ability of a cell to replicate its genome in this experiment?

A

Geminin and MCM helicases is loaded in G1, but not activated until S phase.

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8
Q

When is the MCM double helicase activated?

A

S phase

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9
Q

What is the role of geminin?

A

Blocks additional helicase loading during S-phase, G2 phase, and through mitosis

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10
Q

When is geminin active?

A

S, G2, and M

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11
Q

Why does geminin not block replication during S-phase?

A

Geminin prevents reloading of active MCM helicases after G1 by directly binding to cdt1. Geminin allows replication to occur b/c G1 was loaded before S-phase. prevents more replication than allocated in G1.

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12
Q

What would be the result if a cell lacked geminin?

A

80% of cells would successfully replicate

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13
Q

Which component of the replisome keeps separated strands of DNA from reannealing?

A

SSDBP (Single-stranded DNA binding protein)

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14
Q

How many replication forks are there in one replication bubble?

A

One bubble has two forks

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15
Q

What type of macromolecule is the primer for DNA polymerase?

A

proteinW

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16
Q

How many primers are present on the leading strand compared to the lagging strand?

A

Lagging strand has multiple primers (RNA), b/c it is done with okazaki fragments. leading strand only has 1 primer.

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17
Q

Describe processivity in relation to the action of DNA polymerase

A

The amount of catalytic cycles an enzyme can complete with a substrate without breaking

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18
Q

Direction of polymerization of transcription and replication

A

5’ to 3’

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19
Q

Direction that template is read of transcription and replication

A

3’ to 5’

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20
Q

Polymerizing enzyme of transcription

A

RNA polymerase

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21
Q

Polymerizing enzyme of replication

A

DNA polymerase

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22
Q

Template of transcription and replication

A

DNA

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23
Q

Increased processivity would cause

A

replication to be faster and more efficient b/c CLAMP proteins would not need to work to keep the enzyme and substrate together

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24
Q

3 steps of PCR

A

Denature, anneal and extend

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25
Q

PCR function

A

Amplifies a specific region of DNA by cycling 3 steps 30-40 times

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26
Q

What happens to the temperature in the PCR as it moves from the denature step to the annealing step?

A

Stays the same

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27
Q

How is DNA denatured in PCR?

A

Increased heat

28
Q

What happens to the DS (double-strand) vs SS (single-strand) nature of the DNA as you add heat?

A

DS decrease, SS increase

29
Q

Taq polymerase

A

allows for high thrughout and increased specificity

30
Q

Klenow

A

E.coli DNA polymerase

31
Q

2 purposes of a primer

A

2 roles in PCR
-Specify the region of DNA to be amplified
-Provide a free 3’ OH

Must consider Tm when designing the primer
-Too high= difficult to remove
-Too low= loses specificity

32
Q

Two main functions of the ECM

A

1) Helps with adhesion and/or cell signaling

33
Q

ECM adhesion

A

help cell-cell ECM attachment, mechanical support, and cell motility

34
Q

Signaling functions ECM

A

integrate cells into tissues, provide positional information, and aids in growth

35
Q

Focal adhesions

A

Cell/ECM interactions that involves integral membrane proteins and ECM

36
Q

Proteoglycans

A

Proteins with sugar chains
-Attracts water to hydrate tissue to inhibit compression
-Negatively charged b/c sulfate or carboxyl groups sugars

37
Q

Collagen (fibrous protein)

A

Most common form long fibers in the ECM
Collagen molecules consist of 3 interacting protein in a triple helix
Long fiber structure gives tissue strength and flexibility

38
Q

Fibronectin (adhesive protein)

A

Initiate signal pathway into cell. Proteins interact to form fibrils in ECM, fibrils interact with cells to regulate essential cell functions (growth, differentiation, migration during tissue development)

39
Q

Activation of integrin

A

Activation triggers conformation change from bent to unbent–> leads to downstream signaling events

40
Q

The ____ contains a RGD peptide motif

A

Ligand (motif assists in recognition of ligand)

41
Q

In what ways is collagen synthesis different from fibronectin synthesis?

A

FN-> signaling
Collagen-> enzymatically assemble

42
Q

In what ways is collagen synthesis similar to fibronectin synthesis?

A

Transcribed +translated IN the cell-> ER-> exported (FN)
Collagen interactions and fibril-fibril interactions

43
Q

Significance of elevated integrin and FAK activity in cancerous cells

A

FAK promotes cancer progression and metastasis
Integrins might contribute to migration, proliferation, and survival in tumor cells

Both contribute to activating anti-apoptopic pathways, cell proliferation, invasion of surrounding tissues (metastasis) and angiogenesis (formation of new blood vessels)

44
Q

breast cancer relates to the

A

increase or stiffness of tissue. In a cancerous cell, there is increased collagen in ECM

45
Q

Collagen

A

Translated into ER, quaternary structure, enzymatic modification required for assembly, signaling pathway initiated, quaternary inside cell (NOT signaling pathway for assembly)

46
Q

Fibronectin

A

signaling pathway for assembly, Translated into ER, quaternary structure, signaling pathway initiated, quaternary inside cell (NOT enzymatic modification required for assembly or quaternary structure inside cell)

47
Q

What cells are motile in the first stage of wound repair?

A

Fibroblasts, white blood cells

48
Q

What attracts fibroblasts?

A

Chemo-attractants

49
Q

Function of fibroblasts

A

Reconstruct the extracellular matrix in the wound

50
Q

Why does the action of the fibroblast come before the movement of the epithelial cells into the wound?

A

Provides structure for new epithelial cell movement

51
Q

What happens to the basement membrane as the EMT progresses?

A

Basement membrane needs to degrade temporarily so the cells can move

52
Q

As the epithelial specific gene expression becomes repressed and the mesenchymal specific gene expression is activates, export of which ECm component would you expect to increase?

A

fibronectin

53
Q

What is the result of the signaling patheay transduced by focal adhesions between integrin and fibronectin?

A

promote motility

54
Q

Two types of cell-to-cell junctions

A

Tight junctions and anchoring junctions

55
Q

What effect do desmosomes have on motility

A

Inhibits bc promotes sttength and polarity within epithelial cells

56
Q

What effect do hemidesmosomes have on motility

A

Promotes bc interact with ECM allows increased motility

57
Q

What effect do tight junctions (occludin) have on motility

A

Inhibits bc force regulation of what enters/exits cells and holds cells together

58
Q

How might a loss of E-cadherin (Desmosomes) function and a gain of N-cadherin (hemidesmosomes) affect a cell?

A

may not hold onto each other but the ECm. Cells become more motile

59
Q

Why is disruption of occludin function required for motlity

A

Occludin does not interact with cytoskeleton of other cells, but if its degraded, things can move around the cell instead of inside the cell

60
Q

Chemotaxis

A

cell movement in response to an environmental cue

61
Q

How is the formation of two types of protusions similar?

A

Formation of cell protusions at leading edge is actin-dependent and related to increased actin organization

62
Q

Two functions of focal adhesion

A

Attachment forms stable interactions with the ECM and signaling deals with moving and cell division

63
Q

What type of enzyme is required for focal adhesion detachment?

A

Proteases (calpain)

64
Q

Which two steps of ameboid movement require the establishment of ligand/receptor binding? What are the ligands?

A

Step 1) Cell polarity is regulated by signaling molecules that create a ‘leading’ edge and ‘trailing’ edge through cytoskeleton changes
Step 3) Cell adhesion-Cells protusions form stable interactions with the eCm that are continuous with the cytoskeleton called focal adhesions

65
Q

Metastasis

A

Movement of cancer cells from one location of body to another

66
Q

What does metastasis require

A

Requires cancer cells to acquire invasive phenotype

67
Q

Epithelial cells must break through the

A

basement membrane to invade other tissues

psu freshman (12 decks)

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