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PSU Freshman > BIOL230W Exam 3 > Flashcards

BIOL230W Exam 3 Flashcards

1
Q

Describe the general process of signaling (including signals, receptors, second messengers and final target/effector)

A

Ligand is the chemical signal. The receptor senses the signal, thus a physical change occurs and is typically an integral protein. The effector typically uses secondary messengers to alter proteins by pathway.

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2
Q

Define protein conformation changes and how conformation changes result in changes in function

A

Protein shape determines function (ligand binding to receptor)

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3
Q

What protein components make up a GPCR? (G-Protein Coupled Receptor)

A

Integral membrane protein
Extracellular ligand-binding domain
Intracellular G-protein coupled domain
G-proteins (associated proteins)

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4
Q

3 subunits of G-proteins

A

Alpha, beta, gamma (classified as heteromeric G-protein)

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5
Q

RTK (receptor tyrosine kinase)

A

Tyrosine kinase domain of protein is activated and phosphorylates tyrosines
Once activated, the RTK can phosphorylate other proteins

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6
Q

What protein is phosphorylated first after RTK activation?

A

RTK

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7
Q

What type of ligand binds to intracellular receptors?

A

non-polar

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8
Q

Second messenger definition

A

Intracellular signaling molecules released by the cell in response to extracellular signaling molecules
(Chemicals that relay the signal from the membrane to the cytoplasm)

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9
Q

Effector definition

A

Proteins that are altered in the signal pathway

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10
Q

What type of membrane proteins are receptors for extracellular signals that are impermeable to the membrane?

A

Integral membrane proteins

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11
Q

Describe the role of G-proteins in signaling

A

relay the signals from GPCRs which function as GEFs for G-proteins

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12
Q

What enzyme is activated to produce cAMP

A

Adenyl cyclase

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13
Q

What is one possible effector (target) activated by cAMP?

A

Protein kinase A

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14
Q

Secondary messengers are NOT

A

proteins

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15
Q

How is cAMP synthesized in a cell

A

After ligand binding, activated alpha G-protein stimulates enzyme adenyl cyclase. Uses ATP to make cAMP. cAMP targets effectors

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16
Q

What enzyme is produced to produce IP3 and DAG?

A

Phospholipase C (PLC)

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17
Q

Function of PLC

A

Phospholipase C cleaves the fatty acid chains of a phospholipid in membrane

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18
Q

Compare and contrast kinases and phosphatases

A

Kinases can activate or inactivate a protein and add a phosphate to a protein which alters protein structure. Phosphatase only removes a phosphate.

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19
Q

What type of macromolecule are effectors?

A

Protein whose function is changed in the pathway

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20
Q

G0

A

Cells that have stopped dividing

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21
Q

G1

A

Cells increase in size and phase contains a mechanism to ensure that everything is ready for DNA synthesis

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22
Q

G2

A

contains a mechanism that ensures the cell is ready to enter the M phase

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23
Q

S

A

DNA replication occurs

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24
Q

M

A

Cell growth stops at this stage and cellular energy is focused on the orderly division into two daughter cells

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25
Q

Stages included in interphase

A

G1, S, G2

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26
Q

What is the relationship between a microtubule and alpha/beat tubulin dimers?

A

A microtubule is a polymer of many alpha, beta tubulin dimers

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27
Q

During polymerization, the tubulin dimers are n the ____-bound state

A

GTP

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28
Q

The microtubule end with alpha-exposed subunits is the ___ end, while the microtubule with the beta-exposed subunits is the ___ end

A

minus, plus

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29
Q

Microtubule nucleation

A

Event that initiations polymerization of tubulin dimers to the polymer form (microtubules)

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30
Q

Prophase

A

Replicated chromosomes are condensed, centrosomes nucleate microtubules by the nucleus

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31
Q

Prometaphase

A

Nuclear envelope breaks down. Spindle microtubules begin interacting with kinetochores

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32
Q

Metaphase

A

Pushing and pulling action of kinetochore microtubules cause chromosomes to line up towards middle of cell

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33
Q

Anaphase

A

Sister chromatids separate

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34
Q

Telophase

A

Nuclear envelope reforms, DNA relaxes to euchromatin

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35
Q

Major role of centromere

A

Area of the chromosome where sister chromatids are joined

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36
Q

Kinetochore

A

A complex of proteins that serve as the point of attachment for spindle microtubules during mitosis

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37
Q

Function of cohesion

A

Attach sister chromatids together via cohesion protein

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38
Q

Compared to G1, how much DNA is in the nucleus of a cell in G2?

A

Double

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39
Q

Microtubules form a

A

hollow tube structure

40
Q

How might the lack of GTP affect the stability of a microtubule?

A

MTs can grow (polymerize) or shrink, typically from the + end. Cycle of growing and shrinking= dynamic instability

41
Q

Tubulin monomer is what type of protein

A

G-protein because it binds to GTP and GDP

42
Q

Microtubule monomer

A

a/b tubulin dimers

43
Q

microtubules polarity

A

+ and -

44
Q

Connecting bond microtubules

A

Hydrogen

45
Q

Polymerizing agent microtubules

A

Self-polymerize

46
Q

What organelle nucleates microtubule polymers?

A

Centrosomes (2 centrioles and associated proteins, centrosome duplicates during S phase, migrate to poles of cell through prometaphase)

47
Q

What cellular event allows microtubules to invade the nuclear space during prometaphase?

A

Bind to kinetochores to stabilize microtubules (no longer depolymerize)

48
Q

Centromeres are present during

A

All phases

49
Q

Kinetochores are present during

A

Forms during prophase (M)

50
Q

what does the + end of mitotic microtubules attach to?

A

Kinetochore

51
Q

3 types of mitotic microtubules

A

Kinetochore, polar, astral

52
Q

How does the dynamic instability of the microtubule relate to the attachment of microtubules to chromosomes?

A

attached by hydrogen bond

53
Q

Steps of spindle formation first two steps

A

Prophase (centrosomes migrate to opposite poles, growth of + end)
Prometaphase (nuclear membrane dissolves and attachment of chromosomes to microtubules at kinetochore)

54
Q

Steps of spindle formation last two steps

A

Metaphase (Chromosomes balanced by microtubules forces at midline)
Anaphase (Separation and migration of sister chromatids to opposite poles)

55
Q

What provides the force to position the chromosomes at the center of the cell at metaphase?

A

Motor proteins bind to MT and create force by “walking” on the polymers
Kinesin “walks” along a microtubule track

56
Q

CDK

A

Cyclin-dependent kinase

57
Q

What molecule is required to activate CDK?

A

cyclin

58
Q

What biochemical function does an activated CDK perform?

A

Phosphorylation

59
Q

___levels remain constant while ____ levels can fluctuate depending on cell cycle stage

A

CDK/cyclin

60
Q

Which of the following is an important function of checkpoints in the cell cycle?

A

Ensure DNA is undamaged before replication, cell has enough raw materials to fully replicate, check to see if time is right, check to ensure spindle has formed and chromosomes are aligned correctly

61
Q

G1/S checkpoint

A

Before DNA replication

62
Q

G2/M checkpoint

A

Before entry to mitosis

63
Q

metaphase checkpoint

A

between metaphase and anaphase

64
Q

Function of APC

A

Triggers the transition from metaphase to anaphase by degrading specific proteins

65
Q

Relation between separase, cohesion, and chromatids?

A

Separase degrades cohesin that normally holds the chromatids together. it allows the chromatids to separate

66
Q

What DNA structure does C-myc (a protein) bind in DNA?

A

enhancer regions

67
Q

What result does C-myc have on transcription?

A

Increases transcription

68
Q

Expression of myc can alter the chromatin structure in a nucleus

A

true

69
Q

proto-oncogene vs oncogene

A

Proto-oncogene CAN cause cancer
Oncogene WILL cause cancer

70
Q

How does an oncogene cause cancer?

A

Results in uncontrolled cell growth

71
Q

G1

A

Cell size grows, mRNA and protein synthesized for DNA synthesis

72
Q

S

A

Replicated cell, also DNA repair activity occurs

73
Q

G2

A

Preparation for mitosis; rapid cell growth and protein synthesis (double check for errors)

74
Q

Mitosis

A

Cell division, result is two identical cells

75
Q

G1->S checkpoint

A

3 damage checkpoints occur to ensure proper growth and synthesis of DNA
Damaged DNA result in expression of ATM/R protein

76
Q

G2->M checkpoint

A

Prevents cell from entering mitosis when DNA is damaged

77
Q

Metaphase checkpoint

A

Ensures a bipolar spindle formed and all chromosomes are aligned before anaphase

78
Q

How does cyclin concentration compare to CDK?

A

CDK concentration remains constant as cyclin concentration varies during the cell cycle

79
Q

When is cyclin levels the highest

A

M phase

80
Q

How are CDKs uninhibited

A

Cyclin unbinds and cyclin degraded by proteasome

81
Q

Active cyclin

A

CDK complexes phosphorylation additional target proteins to promote cell cycle progression until cyclin is degraded

82
Q

myc function

A

Triggers mitosis- gain function

83
Q

p53 function

A

Stops mitosis- inhibit function

84
Q

What happens if both p53 and myc do not work?

A

Both alleles removes suppression and uncontrollable division may occur

85
Q

When kinase activity outcompetes p-protein activity, the cell cycle will (proceed/inhibit)

A

Proceed

86
Q

When p-protein activity outcompetes kinase activity, the cell cycle will (proceed/inhibit)

A

Inhibit

87
Q

What enzyme directly degrades cohesin?

A

Separase

88
Q

Cohesin function

A

Holds sister chromatids together.

89
Q

Separase must be regulated to prevent

A

inappropriate separation of sister chromatids

90
Q

Describe the role APC in the metaphase to anaphase transition?

A

Anaphase-promoting complex activator Separase. Inactive APC is activated by a protein called cdc20. Cdc20 is the point of regulation for the metaphase checkpoint to prevent early release of sister chromatids

91
Q

When is the metaphase checkpoint signal on vs off?

A

Turned on when there are unattached kinetochores
Turned off when all are attached

92
Q

If the metaphase checkpoint signal is on, how is anaphase affected

A

Will not occur

93
Q

Inhibition of cdc20 causes inhibition of

A

APC

94
Q

What is the metaphase checkpoint signal?

A

To check if chromosomes are correctly attached to kinetochore/spindles

95
Q

Anueploidy

A

Wrong number of chromosomes in a cell

96
Q

Chromosome missegregation occurs if proteins involved with the signal are

A

Mutated

97
Q
A

PSU Freshman (12 decks)

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