Q2-F12/Translation and dynamic regulation of proteins

Question 1

what are the 5 key components for translation?

Answer 1

Question 2

What are the characteristics of genetic code?

Answer 2

Question 3

What is sickle cell anemia cuased by?

Answer 3

a missense mutation in the beta-globin gene

a single nucleotide subsitution (A to T) in the codon for aa 6

it converts a glutamic acid codon (GAG) to a valine codon (GTG)

Question 4

What does sickle cell anemia do do hemoglobin molecules?

Answer 4

the change in the aa seq causes the hemoglobin molecules to crystallize when O2 levels in the blood are low. this causes the RBC’s to sickle and get stuck in small vessels

Question 5

What structure is tRNA?

Answer 5

secondary

Question 6

what is the Wobble exception to base pairing?

Answer 6

some tRNA anticodons can pair with more than one codon, can go against watson crick base pairing

3rd position can tolerate more mispairing than the 1st or 2nd

https://www.youtube.com/watch?v=zHfiWXQIA2Q

Question 7

What are the 3 sites on the ribosome?

Answer 7

Question 8

What are the 2 parts of initiation of translation?

Answer 8

1. assembly of components required for chain formation
2. recognition of start codon by a tRNA_met molecule

Question 9

What provides the required energy in translation?

Answer 9

GTP

Question 10

What are the 3 main parts of translation?

Answer 10

initiation, elongation, termination

Question 11

elongation in translation involved the addition of amino acids to the ______ end of the growing polypeptide chain

Answer 11

carboxyl (c-terminus)

Question 12

what facilitates the formation of peptide bonds between adjacent amino acids in translation?

Answer 12

peptidyltransferase

Question 13

explain elongation in translation.

Answer 13

Question 14

what causes termination in translation?

Answer 14

a stop codon

Question 15

What is the stop codon recognized by?

Answer 15

a release factor

Question 16

What happens when a release factor binds to the A site?

Answer 16

the newly synthesized protein is released and the tRNA-ribosome-mRNA complex is disassembled

Question 17

What are some ways we can regulate protein activity?

Answer 17

Question 18

Protein turnover is a normal process. What does it ensure?

Answer 18

it ensures a protein fit for purpose. it can also be used as a mechanism to turn off a pathway, reduce activity in a cell, or stop a process.

Question 19

What happens to proteins with key regulatory functions and why?

Answer 19

Proteins with key regulatory functions often rapidly turned over or degraded in order to keep them under tight regulation

Question 20

Why is rapid protein turnover nessessary sometimes?

Answer 20

Rapid turnover of proteins is necessary to allow their levels to change quickly in response to external stimuli.

Question 21

when do proteins get degraded/when does normal protein turnover occur?

Answer 21

Question 22

what are the role of cyclins in protein degradation?

Answer 22

cyclins are made to help get into the cell cycle and are degraded when the cell wants to turn them off

when proteins get activated, some of them get cleaved in the process and need to be replaced

Question 23

what are the 2 ways proteins are degraded?

Answer 23

Question 24

Where do lysosomes come from?

Answer 24

the ER

Question 25

Are lysosomes acidic or basic?

Answer 25

HIGHLY acidic (pH=4) they have proton pumps that pump H+ ions into lysosomes to reduce the pH

Question 26

What do lysosomes have in them?

Answer 26

Have degradative enzymes (acid hydrolases) that are only active at low pH – protects cytosolic proteins from activities if they leak out

Question 27

What can lysosomes degrade?

Answer 27

Question 28

what is it called when proteins are labelled or tagged for degradation?

Answer 28

polyubiquitination

Question 29

once a protein is polyubiquinated, that protein is recognized by the __________ and degraded

Answer 29

proteasome

Question 30

what is a proteasome

Answer 30

it is a multiprotein, barrel shaped complex

Question 31

What does a proteasome contain in it?

Answer 31

protease enzymes

Question 32

Where are proteasomes found?

Answer 32

in the nucleus or cytoplasm

Question 33

What are some common post translational modifications of proteins?

Answer 33

Question 34

explain ligand binding.

Answer 34

Question 35

Explain proteolytic cleavage.

Answer 35

A zymogen is a type of pro-enzyme. When a pro-enzyme is attached to a protein, that protein is inactive. The cleavage of the pro-enzyme from this protein, turns the protein from inactive to active

Question 36

Explain the reversible phosphorylation of proteins.

Answer 36

Phosphate is on serine, threonine, and tyrosine residues when you add/remove (kinase/phosphatase) a phosphate, you can... - alter the proteins function - mark for degradation - alter localization - promote interactions

Question 37

what is chronic myelogenous leukemia?

Answer 37

CLM is uncontrolled growth of myeloid cells in the bone marrow until they all spill out into the blood. this is bad because all the "normal healthy cells" get crowded out and its harder for them to survive because theres more competition for nutrients. This causes cytopenia, which is a reduction in the number of healthy cells.

Question 38

What causes chromic myelogenous leukemia?

Answer 38

A chromosome translocation that results in a Philedelphia chromosome. A portion of Chromosome 9s long arm switches with Chromosome 22s long arm. This obviously results in a modified Chromosome 9 and Chromosome 22 (22-is called the Philedelphia Chromosome). What then happens is a Chromosome 22 gene called Breakpoint Cluster Region (BCR) sits right next to a Chromosome 9 gene called ABL. When they combine, it forms a fusion gene called BCR-ABL. The BCR-ABL gene codes for a protein also called BCR-ABL. This protein turns on enzymes called tyrosine kinase that help with cell division. This is kinda like BCR-ABL is an on/off switch and it is stuck in the on-position. Since its always on, it forces myeloid cells to keep dividing quicker than they should, which causes them to spill out into the bloodstream.

Question 39

How is Chronic Myelogneous leukemia treated?

Answer 39

it is treated with an tyrosine kinase inhibitor like Gleevec/Glivec/Imitinib that specifically targets BCR-ABL.