Exam 3

Question 1

Transcriptional control

Answer 1

Controlling when and how often a given gene is transcribed.(occurs most often H-bonding occurs)

Question 2

RNA Processing control

Answer 2

Controling how an RNA transcript is spliced or other wise processed( RNA splicing)

Question 3

mRNA transport and localization control

Answer 3

Selecting which mRNA’s are exported from the nucleus to the cytosol (mRNA export transport and localization control)

Question 4

mRNA degradation control

Answer 4

Regulating how quickly certain mRNA molecules are degraded (mRNA half-life).

Question 5

Translation control

Answer 5

Selecting which mRNA’s are translated into protein by ribosomes(selection and speed of translation)

Question 6

Protein degradation control

Answer 6

Regulating how rapidly specific protiens are destroyed after they have been made;

Question 7

Protein activity control

Answer 7

Protien activity control/ regulation

Question 8

Promoter

Answer 8

region of a gene binds the enzyme RNA polymerase and correctly orients the enzyme to begin its task of making an RNA copy of the gene.

Question 9

motifs

Answer 9

t

Question 10

What is the DNA recognition sequence for the first general transcription factor that binds to the promoter.

Answer 10

TATA Box

Question 11

o Complex with many binding motifso
o RNA polymerase requires general transcription factors
o Regulatory proteins control expression from a distance
o Promoter DNA location on nucleosome can affect initiation of transcription

Answer 11

Eukaryotic gene regulation

Question 12

How do transcription regulators, general transcription factors, and RNa polymerase gain access to such DNA?

Answer 12

o Nucleosomes can inhibit initiation of transcription if they are positioned over a promoter, b.c they physically block the assembly of the general transcription factors or RNA polymerase on the promoter.
o Such chromatin packaging may have evolved in part to prevent leaky gene expression by blocking the initiation of transcription in the absence of the proper activator proteins.

Question 13

List the types of Transcription regulations

Answer 13

• Combinations of transcription regulators for one gene
• A single protein coordinates different genes
• Combinations of transcriptional regulator for different cell types
• Reprogramming of differentiated cells

Question 14

• Master transcription regulator activates transcription of its own gene in addition to that of other cell-type-specific genes

Answer 14

Positive feedback loop

Question 15

miRNA

Answer 15

Small noncoding RNA that controls gene expression by base-pairing with a specific mRNA to regulate its stability and its translation.

Question 16

MicroRNA’s control gene expression by

Answer 16

base pairing with specific mRNA’s and inhibiting their stability and translation.

Question 17

RNA interference

Answer 17

Cellular mechanism activated by double-stranded RNA molecules that results in the destruction of RNAs containing a similar nucleotide sequence. It is widely exploited as an experimental tool for preventing the expression of selected genes (gene silencing).

Question 18

Step to miRNA destruction of mRNA

Answer 18

Precursor miRNa transcript is processed to form a double stranded intermediate & exported to cytoplasm.
Further processed to form a mature, single stranded miRNA.
Form RISC complex
search for complementary mRNA.
Rapidly degrades the mRNA or transferred to cytoplasm for degradation.

Question 19

Plasma membrane

Answer 19

a protein studded fatty film so thin that it cannot be seen directly in the light microscope. Every cell on earth uses such a membrane to separate and protect its chemical components from the outside environment

Question 20

most common phospholipid

Answer 20

Phosphatidycholine

Question 21

Cholesterol stiffens bilayer by

Answer 21

making it less flexible and less permeable

Question 22

In eukaryotic cells new phospholipids are manufactured by

Answer 22

enzymes bound to the cytosolic surface of the endoplasmic reticulum.

Question 23

Flippases

Answer 23

The golgi apparatus contains enzymes that remove specific phopholipids from the side of the bilayer facing the exterior space and flip them into monoloayer that faces the cytosol.

Question 24

• The action of flippases and similar enzymes in the plasma membrane initiates and maintains the _______________ of the phospholipids that is characteristic of the membranes of animal cells.

Answer 24

asymmetric arrangement

Question 25

______ is an enzyme that randomly transfers phospholipid molecules from one monolayer to the other allowing the membrane to grow as a bilayer.

Answer 25

Scramblase

Question 26

are involved in transport of nutrients, metabolites, and ions across the lipid bilayer.

Answer 26

Membrane Protiens

Question 27

________ usually crosses the lipid bilayer as an alpha helix.

Answer 27

A transmembrane polypeptide chain

Question 28

The main component of the cell cortex is the

Answer 28

dimeric protein spectrin, a long, thin, flexible rod. It forms a meshwork that provides support for the plasma membrane and maintains the cells biconcave shape

Question 29

Define Membrane Potential

Answer 29

Voltage difference across a membrane due to a slight excess of positive ions on one side and of negative ions on the other.

Question 30

Ion channels

Answer 30

proteins that allow only certain kinds of ions to cross the membrane in the direction of their concentration gradient.

Question 31

Active transporters

Answer 31

actively move ions into or out of cells against their concentration gradient

Question 32

State the mechanism of action potential propagation

Answer 32

A depolarizing stimulus locally depolarized the axon.
Voltage sensitive Na+ channels are opened
Inward movement of Na+ action potential generated at that site.
local current passively flows down the axon & depolarizes the adjacent region of the axon.