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Med School > CTCS Quiz 2 > Flashcards

CTCS Quiz 2 Flashcards

0
Q

How long does it take between successive mitoses?

A

~24 hours, but this can be variable.

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1
Q

How long does mitosis las for a cell in culture?

A

1 hour.

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2
Q

In which phase dose repair of the genome occur?

A

S phase.

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3
Q

Early Prophase

A

Chromatin make chromosomes, spindle fibers begin to form.

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4
Q

Late Prophase

A

Nuclear envelope goes away, chromosomes attach to spindles.

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5
Q

Metaphase

A

Chromosomes align at metaphase plate, held in tension by the opposing spindle fibers.

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6
Q

Anaphase

A

Sister chromatids are pulled apart, spindle poles start to move apart from each other.

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7
Q

Telophase

A

Chromatids arrive at poles, nuclear envelopes reform around decondensing chromsomes, cleavage furrow begins begins and causes cytokinesis.

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8
Q

Are the key mechanisms governing M phase conserved?

A

Yes. They are conserved in all species (yeast to man).

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9
Q

What can cause a cell cycle to stop in M phase?

A

unattached chromosomes or incorrect spindle assembly.

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10
Q

What can cause the cell cycle to arrest in G1?

A

Damaged DNA.

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11
Q

What can cause the cell cycle to arrest in G1 or G2?

A

DNA damage or unreplicated DNA.

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12
Q

What regulates the main events of the cell cycle?

A

Cdk-Cyclin complexes.

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13
Q

How does the cell make sure not to go backwards?

A

It destroys certain proteins after they are used,- ie destruction of M-cyclin

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14
Q

What does MPF stand for and what makes it?

A

M-phase Promoting Factor.

It is made by: 1) a Cdk catalytic subunit (Cyclin Dependent Kinase), 2) M-cyclin (or cyclin B sometimes)

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15
Q

What is M-Cdk?

A

Mitosis- Cyclin-Dependent Kinase

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16
Q

How quickly are MTs renewed during mitosis?

A

All are renewed with a half life of 15 secs.

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17
Q

How many directions can an individual motor protein travel on a spindle?

A

One. Some MPs can go towards the plus end, some towards minus end.

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18
Q

What actions can motor proteins have on spindles?

A

Slide, push, pull

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19
Q

What happens with M-Cdk is destroyed?

A

Mitosis ends.

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20
Q

What are some key structural features of cytokinesis?

A
  1. Actin and myosin filaments make contractile ring.
  2. Nuclear envelopes and membrane-bound organelles reformed.
  3. Golgi and other organelles send membrane to site of fission to help heal.
21
Q

What are the three major filaments found in a cell?

A

Intermediate Filaments, MTs, and Actin Filaments

22
Q

Which filaments are polar?

A

MTs and Actin

23
Q

Which two filaments are important for cell motility?

A

Actin and MTs

24
Q

What makes up MTs, Microfilaments and IFs?

A

MTs: Tubulin
MFs: Actin
IFs: Nestin, Vimentin, Keratins, Desmins, etc. (not important to memorize)

25
Q

How is MT made?

A
  1. Heterodimers with alpha and beta tubulin

2. GTP must be bound to both alpha and beta subunits

26
Q

What is the inner and outter diameter of MTs? How wide is an alpha or beta unit?

A

Inner: 14 nm
Outter: 25 nm
Alpha/Beta: 4-5 nm

27
Q

How is Actin polymerized?

A

G actin makes dimers, then trimers, then they elongate at the barbed end (+ end). It now becomes known as F actin.

28
Q

What is required for polymerization of actin?

A
  1. G-acting has to be above critical concentration.

2. ATP-Mg bound to actin

29
Q

Are IFs polarized?

A

No

30
Q

Where are IFs found in the cell?

A

Everywhere.

31
Q

What property does IF have?

A

Rope-like properties, high tensile strength.

32
Q

How are actin filaments regulated?

A

G and F-Actin binding proteins.

33
Q

How do G-actin binding proteins work?

A

They bind to the monomers and either add them to the actin, or they prevent them from going to the actin. These different proteins compete for the actin substrates.

34
Q

What are Actin Related Proteins (ARP)?

A

ARP2/3 induces nucleation at branched junction at 70 degrees animals.

35
Q

What do formins do?

A

They elongate actin filaments.

36
Q

What do Rho proteins do?

A

They determine the structure of the actins. Other proteins do this, too, but they determine whether the actin makes stress fibers, lamellipodia, filopodia, etc.

37
Q

Is MT growth symmetric?

A

No, it is assymetric.

38
Q

What are the 2 mechanisms that regulate MT dynamics?

A
  1. Inherent properties of tubulin assembly.

2. MT associated proteins.

39
Q

What does a GTP cap do to MTs?

A

It can prevent depolymerization. But if hydrolysis catches up to the tip, as soon as the tip is mostly GDP, then rapid depolymerization occurs.

40
Q

What is one function of a microtubule associated protein (MAP)?

A

The can act as spacers in neuronal cells.

41
Q

What can happen to MTs when they are stabilized?

A

They can be modified. They are always modified with the plus end in the direction of the moving cell.

42
Q

Can protein cap MTs to stabilize them?

A

Yes.

43
Q

Are stabilized MTs affected by drugs?

A

No.

44
Q

What fills most of the extracellular space in connective tissue?

A

Glycosaminoglycans (GAGs). They are unbranched polysaccharide chains, repeating units, and one sugar is always an amino sugar.

45
Q

What is one of the simplest GAGs?

A

Hyaluronic acid. It can be made up of 25,000 repeating units.

46
Q

What is a proteoglycan?

A

An ECM protein, heavily glycosylated, and one chain must be a GAG.

47
Q

How does the Na/K pump work?

A
  • 3 Na out, 2 K in

- requires ATP

48
Q

What is one of the reasons why a high extracellular Na+ concentration is important?

A

Na+ is used to help bring other molecules back into the cell with cotransport (symport). It has to be flowing along its gradient in order to do this.

49
Q

How does Na+ help to regulate acidity inside the cell?

A

Antiport. For every Na+ that enters cell, one H+ leaves the cell.

50
Q

What is the difference between GAGs and Proteoglycans?

A

GAGs: occupies lots of space and make gels.
Proteoglycans: composed of GAGs bonded to a core protein.

Med School (24 decks)

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