Post-Exam 4 Material

Question 1

What are the 4 MAIN types of post translational modification?

Answer 1

1) Covalent Modification
2) Non-covalent Modification
3) Folding using chaperones
4) Ubiquitination

Question 2

Modifications of the peptide bond are usually carried out by enzymes called

Answer 2

peptidases or proteases

Question 3

Disulfide cross linking is a type of PTM involving the amino acid side chains. What is an example of this?

Answer 3

Process of preproinsulin being synthesized into insulin. Summary of this is after membrane transport the leader sequence is cut off (by protease) then the resulting proinsulin folds creating the disulfide bonds b/w cysteine’s lastly the connecting sequence is cleaved leaving mature insulin as the product.

Question 4

Does proinsulin or insulin run faster on polyacrylamide gel?

Answer 4

Insulin because it is lighter in weight. Proinsulin will be at the top of the gel because it is heavier in weight.

Question 5

________ is a form of PTM whenever the LYS in histone tail is added with acetyl coA and HAT to allow entry of enzymes for transcription.

Answer 5

Acetylation

Question 6

_____ _______ anchors proteins into the cell membranes to the C terminus.

Answer 6

GPI Anchors

Question 7

_________ is a form of PTM that is known in the example of vitamin C being needed in a reaction that takes Fe3+ to Fe2+

Answer 7

Hydroxylation

Question 8

Enzymes that add on a PO4 group to an OH side chain are called

Answer 8

kinases

Question 9

Enzymes that remove a PO4 group from a phosphorylated side chain are called

Answer 9

phosphatases

Question 10

What protein is a kinase needed in EUK transcription?

Answer 10

TFIIH

Question 11

What is the most abundant form of PTM?

Answer 11

Glycosylation

Question 12

N lined glycosylation occur on ___ side chains because of the NH3 group.

Answer 12

ASN

Question 13

O linked glycosylation occurs on ___ and ___ because the bond attaches to the OH group.

Answer 13

SER, THR

Question 14

_____ attaches to the histidine group via Fe.

Answer 14

Heme

Question 15

This is an example of a non covalent modification. It involves the ___ _____ domains used for DNA recognition example being the nuclear hormone receptors.

Answer 15

Zinc finger

Question 16

_____ assits in protein folding

Answer 16

Chaperonin

Question 17

______ is a type of PTM that is highly conserved. This involves its protein using it to degrade other proteins. This needs energy to function. It is the last form used to degrade proteins.

Answer 17

Ubiquitin

Question 18

What is the protein that makes mRNA into cDNA?

Answer 18

reverse transcriptase

Question 19

What are the basic steps in recombinant DNA experiment?

Answer 19

1) Preparation of DNA (vector and target DNA)
2) Cleavage of DNA in particular sequences (Restriction enzymes AKA endonucleases)
3) Ligation of DNA fragments (joining of the fragments)
4) Introduction of recombinant DNA into compatible host cells (genetic transformation)
5) Replication & expression of recombinant DNA in host cells
6) Identification of host cells that contain the recombinant DNA of intrest (Screening and selecting)

Question 20

_____ are needed for reconstruction. They have to cut vector and pop in the target of gene to that region.

Answer 20

Endonucleases

Question 21

_____ will join the target DNA to the plasmid

Answer 21

Ligase

Question 22

What are plasmids?

Answer 22

independently replicating DNA “circles” (because PRO DNA). Foreign DNA can be inserted into the plasmid and replicated.

Question 23

What are restriction enzymes?

Answer 23

cut DNA at highly specific regions AKA endonucleases

Question 24

What do restriction enzymes recognize in nucleotides?

Answer 24

They recognize palindromic sequences which are inverted repeats

Question 25

What is the best option to use for target DNA and why?

Answer 25

cDNA is the best option to use because it has an actual copy of the mRNA and it has NO introns

Question 26

What is the process of cDNA preparation?

Answer 26

mRNA is converted into cDNA using reverse transcriptase, then there will be an attachment of oligo T’s to cDNA and the mRNA will be degraded. Next, a primer and polymerase will be added to make a copy of this cDNA to create a double stranded cDNA. This is what is used to insert into a plasmid.

Question 27

What is the most common method in determining DNA sequences?

Answer 27

Dideoxy method AKA the sanger method

Question 28

______________ are also known as chain terminators.

Answer 28

dideoxynucleotides

Question 29

What will happen if you incorporate a dideoxy?

Answer 29

There will be an H in the 3’ position and that means it will stop transcription. There will be no attack and will NOT result in a phosphodiester bond.

Question 30

What is the DNA sequencing procedure?

Answer 30

DNA sequence, primer, 4 normal dNTP’s (one of which is radioactively labeled for visualization). The mixture is then split among 4 test tubes. DNA poly is then added and synthesis begins. When these test tubes are then run through a gel, the smallest MW will be located on the bottom (5’ end) and the largest MW will be located on the top (3’ end).