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Cell Biology > Lecture 17 study guide > Flashcards

Lecture 17 study guide Flashcards

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1
Q

True or False: transcription factors can work by recruiting chromatin remodeling complexes and histone modifying enzymes?

A

true

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2
Q

What is the function of chromatin remodeling

A

increase access to transcriptional start sites

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3
Q

Define epigenetics

A

Changes in gene function without change in DNA sequence

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4
Q

Which of the following is true:
a. Epigenetic modifications propagate to daughter cells
b. Epigenetic modifications may not always propagate to offspring

A

Both are true

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5
Q

What are the two major mechanisms of epigenetic changes

A

DNA methylation
histone modification

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6
Q

Fill in the blanks: DNA methylation suppresse_____ gene expression by attracting transcription _____

A
  1. Suppresses, repressors
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7
Q

What enzyme is responsible for methylating cytosine?

A

methyltransferases

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8
Q

True or False: In humans, most histone modifications are erased in the gametes

A

true

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9
Q
  1. In higher eukaryotes, most of the genome encodes what special type of RNA?
A

Regulatory RNA

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10
Q

What is the function of miRNA?

A

Degrade mRNA or reduce their translational efficiency

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11
Q

What is the function of siRNA?

A

protect cells from foregin RNA

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12
Q

A certain miRNA has the following sequence: 5’ AUCAUCAUCCGUG 3’
a. If it encounters double stranded RNA with the following sequence what will happen? 3’ UAGUAGUAGGCAC 5’
b. What if it encounters dsRNA with this sequence? 3’ CGCGCUUAAGGCAC 5

A
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13
Q

KiFill in the blank: Gcn2 is a _____ that is activated by _____ tRNA and ______ the translation initiation factor eLF2.

A

Kinase
uncharged
phosphorylates

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14
Q

Phosphorylated eLF2 eventually blocks what major cell process?

A

translation

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15
Q

True or False: p53 is only degraded during the cell cycle stages.

A

false

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16
Q

What stops p53 degradation?

A

DNA damage detection

17
Q

What is the main function of the p53/p21 pathway?

A

Arrest of DNA replication until the DNA damage can be repaired.

18
Q

What happens if the cell takes too long to fix DNA damage in terms of p53 accumulation?

A

p53 accumulation works as a timer. If too much accumulates the cell undergoes apoptosis.

19
Q

What are the three parts to cell signaling? (Think what is happening inside and outside of the cell)

A

a. Sensing of an extracellular signal
b. Transduction of that signal inside the cell
c. Resulting regulation of function

20
Q

If a cytoskeletal protein is the target of a cell signal then what is the likely resulting regulation?

A

Altered cell shape or movement

21
Q

Describe the phenomenon known as “community effect.”

A

positive feedback enhances and stabilizes signal and results in a “community effect”

22
Q

What are the six types of cell communication? Give a brief description of each

A

a. 1. Contact dependent: Cell to cell contact. Actual contact between cells using a receptor and a ligand.
b. 2. Synaptic: close, directed release of a transmitter molecule from a neuron
c. 3. Paracrine: short distance release of a chemical messenger that is not necessarily directed to a specific cell.
d. 4. Endocrine: long distance release of a chemical messenger.
e. 5. Autocrine: self communication by releasing a chemical messenger that the cell itself takes up.
f. 6. Gap Junctions: sending chemical messengers from one cell to another via gap junctions.

23
Q

Enzyme X requires activation by two different cell signals to be transduced before it activates. What is this an example of?

A

Signal integration

24
Q

What is the benefits of signaling scaffolds?

A

increase speed, efficiency and specificity of signal transduction

25
Q

Name two methods of signal adaptation or desensitization.

A

Cell surface receptors and Intracellular receptors.

26
Q

What are the two types of receptors?

A

cell surface receptors
intracellular receptors

27
Q

Which of the following are a possible signal for an intracellular nuclear receptor?
a. Insulin (large, polar)
b. Testosterone (A non-polar steroid)
c. Acetylcholine (smaller, polar)

A
  1. B- testosterone
28
Q

What are the three amino acids that can be phosphorylated?

A

Ser
Thr
Try

29
Q

Define second messenger

A

small molecules or ions that relay the signal from the plasma membrane to every part of the cytosol and nucleus

30
Q

What are the three types of cell surface receptor families important for this class?

A

G protein coupled receptors, Receptor Tyrosine Kinases, Notch Receptors

Cell Biology (18 decks)

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