Gene expression (THe deev)

Question 1

What is a multistep process that ultimately results in the production of a functional gene product (either RNA or protein)

Answer 1

Gene expression

Question 2

True/False: We all started by one single cell

Answer 2

True

Question 3

What are involved in basic cellular functions that are required regardless of cell type or environmental cues. are constitutively expressed and not regulated

Answer 3

Housekeeping genes

Question 4

What are required only in certain cell types and/or only under certain conditions. Various control mechanisms which determine if and when the genes will be expressed.

Answer 4

Regulated genes

Question 5

What genes are only required under certain conditions?

e.g. Betactin(sp?), part of the cytoskeleton

Answer 5

Regulated genes

Question 6

What are the two classifications of genes?

Answer 6

Housekeeping genes and regulated genes

Question 7

True/False: Prokaryotic cells have nucleus and mitochondria.

Answer 7

False they don’t have nucleus or mitochondria
Pro- NO
Eu- DO

Question 8

Is mRNA ready to be translated immediately after transcription?

Answer 8

Yes, in prokaryotic genome whatever is encoded in the mRNA it is ready to be translated into proteins via ribosomes.

Question 9

Transcription happens in _______.

Answer 9

Nucleus

Question 10

Translation happens in _______ via _______.

Answer 10

Cytosol via ribosomes

Question 11

Is RNA ready to be translated into proteins immediately after transcription?

Answer 11

No, There is post-transcriptional, and post-translational control with eukaryotes.

Question 12

After proteins come out of translation are proteins ready to go do their job?

Answer 12

No, they need to be modified or degraded usually in Golgi apparatus via post-translational modification.

Question 13

What is another role of control…“around genetics”

Answer 13

Epigenetics

Question 14

Prokaryotic gene expression involves two regulatory molecules, what are they and what do they do?

Answer 14

Repressors- suppress the transcription of a gene

Activators- increase the transcription of a gene

Question 15

What does the operon contain?

Answer 15

Control region and structural genes

Question 16

What is the goal of any organism?

Answer 16

conserve energy,

“no organism wants to make enzymes that are not useful for anything”

Question 17

What are two types of operons?

Answer 17

Repressible- transcription is usually ON but can be inhibited (repressed)
Inducible- transcription is usually OFF but can be stimulated (induced)

Question 18

What is the inducible operon that we talked about?

Answer 18

Lactose operon (Lac Operon)

Question 19

What is the prefered carbon source for E. coli?

Answer 19

Glucose, but has capability to use other sugars like lactose (only if it is necessary)

Question 20

With Lac Operon if only glucose is present, is the Lac Operon on or off?

Answer 20

OFF

Question 21

What is encoded by lacl gene, always present and bound to the operator, blocks RNA polymerase

Answer 21

Repressor protein is ALWAYS expressed

Question 22

When glucose is sufficient, what happens to the Lac Operon?

Answer 22

Lac Operon is off

Question 23

When only lactose is present, (no glucose) what happens to the Lac Operon?

Answer 23

Lac Operon is on

Question 24

Glucose inhibits _____ ________, so there is no cAMP, cannot form CAP/cAMP complex , cannot initiate transcription

Answer 24

Adenylyl cyclase

Question 25

If both glucose and lactose are present what happens to the Lac Operon?

Answer 25

Lac Operon is off

Question 26

What are the 5 different levels of gene expression in Eukaryotes?

Answer 26

``` (TPTPE) Transcriptional Posttranscriptional Translational Post-translational Epigenetics ```

Question 27

Why do you need more levels of regulation?

Answer 27

We are more complex as eukaryotes

Question 28

What is the only similar level of control between eukaryotic DNA and Prokaryotic DNA?

Answer 28

Transcriptional control

Question 29

Why is transcriptional control just a little different between Eukaryotes and Prokaryotes?

Answer 29

EUK- usually one gene encodes for one protein | PROK- ???

Question 30

Influence expression of genes only on the same chromosome... only controls expression of genes that are downstream.

Answer 30

Cis-acting

Question 31

Where does transcriptional control take place?

Answer 31

Usually embedded in noncoding region of the genome

Question 32

Proteins are also called _______ regulators (transcription factors that interact with regulatory molecules).

Answer 32

Trans-acting

Question 33

Binding of trans-acting regulators (TF) to DNA is achieved by one of the following 3 things:

Answer 33

ZInc Finger leucine zipper helix-turn-helix in the protein

Question 34

What are DNA sequences that increase the rate of initiation of transcription.

Answer 34

Enhancers

Question 35

True/False: Enhancers are typically on different chromosomes.

Answer 35

False: typically on same chromosome

Question 36

What is the role of transcription factors?

Answer 36

DNA binding domain Activation domain- stabilize formation of initiation complex recruit chromatin modifying proteins (i.e. histone acetylase)

Question 37

_______ is a _______ hormone that diffuses into hepatocytes to regulate PEPCK gene expression.

Answer 37

Cortisol, steroid

Question 38

True/False: Over 60% of ~25,000 genes in humans undergo alternative splicing.

Answer 38

True

Question 39

What is an actin filament-binding protein, which undergoes tissue specific alternative splicing to produce multiple isoforms of the protein?

Answer 39

Tropomyosin

Question 40

Apo B mRNA is made in the ______ and __________

Answer 40

liver and small intestine

Question 41

Additional posttranscriptional modification in which base in mRNA is altered.

Answer 41

mRNA editing (e.g. Apo B mRNA)

Question 42

The C residue in the CAA codon for glutamine is deaminated to U changing the sense codon to a ________ or _______.

Answer 42

nonsense or stop codon

Question 43

What is a mechanism of reducing gene expression by repressing translation or increasing degradation of specific mRNAs... (widely used in research and has a lot of potential)

Answer 43

RNA interference (RNAi)

Question 44

Neovascular AMD and VEGF lead to excess _____ ____ behind the retina. First clinical trial of RNAi for this helping macular degeneration.

Answer 44

blood vessels

Question 45

RNAi is mediated by very short RNA (~20-22bp) called ______.

Answer 45

microRNA (miRNA)

Question 46

miRNA acts as a _____ strand to target specific mRNAs that contain complementary sequence.

Answer 46

guide strand

Question 47

What are siRNAs?

Answer 47

double stranded short interfering RNAs (siRNAs) introduced into a cell to trigger RNA interference.

Question 48

What are mobile segments of DNA that move in a random manner from one site to another on the same or a different chromosome?

Answer 48

Transposons

Question 49

What are regions in DNA that are rich in CG that are prone to modifications.

Answer 49

CpG islands

Question 50

Phosphorylation of ___ inhibits GDP-GTP exchange and so inhibits translation at the initiation step.

Answer 50

elF-2

Question 51

When elF-2 is phosphorylated by kinases what happens?

Answer 51

Translation is blocked

Question 52

When elF-2 is not phosphorylated by kinases what happens?

Answer 52

Translation occurs

Question 53

What are the 4 modifications of polypeptide chain?

Answer 53

Trimming Covalent attachments Protein folding by chaperones Protein degredation by ubiquitination

Question 54

Protein degredation happens by?

Answer 54

Ubiquitination

Question 55

Protein folding is directed by what?

Answer 55

Chaperones

Question 56

_______ is loosely packed and is accessible for transcription.

Answer 56

Euchromatin

Question 57

_______ is tightly packed and is inaccessible by transcription.

Answer 57

Heterochromatin