Biochem-Exam 2 Flashcards Preview

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Flashcards in Biochem-Exam 2 Deck (34)
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1
Q

What occurs in the ribosomes tunnel?

A

A peptide bond is formed between two amino acids

2
Q

Is energy required when catalysis occurs in the tunnel?

A

NO

3
Q

What sites do amino acids move through the ribosome (in order)?

A

Remember, APE (but read right to left) A site P site E site

4
Q

In which direction do ribosomes read an mRNA strand?

A

5’ –> 3’

5
Q

What are the two DNA strands called, and which one is used to make mRNA?

A

Coding strand and Template Strand, and the Template Strand is use when making mRNA

6
Q

What is unique to RNA Polymerase as compared to DNA Polymerase?

A

It unwinds DNA. It adds new bases and proofreads in the same active sight. This is called back-tracking

7
Q

How do you calculate delta G (Free Energy of Activation)?

A

(Free Energy of the Transition State) - (Free Energy of the Substrate)

8
Q

What is the equation for the the reaction velocity?

A

V=k[S1][S2]

9
Q

What is the equation for the the reaction rate constant?

A

k=[S]CTe^-(deltaG**/(RT))

10
Q
A
11
Q

What are the stop codons?

A

UAA

UGA

UAG

12
Q

What are the Eukaryotic ribosome subunits called?

A
13
Q

How does synthetase work?

A

It binds tRNA with its correct amino acid.

There is an editing site that checks for the correct aa

It requires the cleavage of 2 high-energy phosphate bonds to operate

14
Q

What stops DNA replication?

A
15
Q

What binds the beta subunit of the RNA pol complex?

A

Rifampicin (R…P=RNA Pol)

16
Q

What does Puromycin do?

A

(Remember “P” for Protein)

Stops growing protein by binding in the A site of ribosome

17
Q

What does Cycloheximide do?

A

Think -hex-=6

Binds 60S subunit, inhibits peptide bond formation

18
Q

What does Erythromycin do?

A

(Think “E” is the 5th letter of the alphabet)

Binds the 50S subunit and inhibits translocation

19
Q

What does Tetracycline do?

A

(Tetra=4??? PSYC, its actually 3)

Binds 30S subunit and inhibits aa-tRNA binding

20
Q

What does Ricin do?

A

Cytotoxic

B subunit binds surface carbs and facilitates cell entry

A** subunit (A for in_A_**ctivates)

N-glycoside hydrolase inactivates ribosomes

21
Q

What is the OTHLIL accronym used for?

A

Oxireductase

Transferase

Hydrolase

Lyase

Isomerase

Ligase

22
Q

What does Oxireductase do?

A

Transfers electrons

23
Q

What do spliceosomes (ssDNA) do?

A

Cut out the introns in mRNA, and ligate the exons back together

24
Q

Which enzyme has a specificity pocket for non-polar/aromatic side chains?

A

Chymotrypsin

25
Q

Which enzyme has a specificity pocket for cationic side chains?

A
26
Q

Which enzyme has a specificity pocket for small side chains?

A
27
Q

Why is metallic mercury toxic?

A

It has a high affinity for Cysteine side chains (sulfhydryl group)

28
Q

What does Rifampicin?

A

(Think “R”NA “P”olymerse)

Inhibits RNA Polymerase

29
Q

Which enzyme chymotrypsin or carboxypeptidase A is allosteric?

A

Carboxypeptidase A

30
Q

What is an allosteric enzyme?

A

Allosteric enzymes are enzymes that change their conformational ensemble upon binding of an effector, which results in an apparent change in binding affinity at a different ligand binding site.

31
Q

Which enzyme, chymostrypsin or carboxypeptidase A has an acyl-enzyme intermediate?

A

Chymotrypsin

32
Q

How does competitive inhibition change the V vs [S] curve?

A

Vmax remains unchanged, but the curve shifts to the right

33
Q

How does non-competitive inhibition change the V vs [S] curve?

A

Vmax is REDUCED and the V vs [S] curve shifts down

34
Q

In order to maintain V, what needs to happen to [S] in competitive inhibition?

A

[S] needs to increase