Molecular Biology Review

Question 1

RNA polymerase moves in what direction?

Answer 1

5’ → 3’ (binds 3’ end of template strand)

Question 2

Which is more likely to have errors, replication or transcription?

Answer 2

Transcription

Question 3

Coding strand

Answer 3

Always the same 3’ → 5’ strand, used to generate RNA strand (RNA sequence will be same as non-coding strand)

Question 4

Uracil replaces what DNA nucleotide?

Answer 4

Thymine

Question 5

RNA processing

Answer 5

Occurs in nucleus → results in mature RNA strand

5’ end capped

Poly-A tail added to 3’ end

Question 6

Function of capping primary RNA

Answer 6

Ensure mRNA’s stability during translation

Question 7

Function of adding poly-A tail to primary RNA strand

Answer 7

1. Protects mRNA from degradation by exonucleases

2. Essential for transcription termination, export from nucleus and translation

Question 8

Introns

Answer 8

Non-coding regions of gene (do not appear in mature RNA transcript → removed in nucleus)

Question 9

Exons

Answer 9

Coding regions of a gene (can be spliced to form multiple proteins)

Question 10

3 types of mature RNA

Answer 10

1. tRNA
2. rRNA
3. mRNA

Question 11

tRNA

Answer 11

1. Binds 1 specific AA

2. Recognizes 1 or more mRNA sequence

Question 12

rRNA

AKA:

Function:

Answer 12

Ribosomal RNA

ribosome = rRNA + protein

1. Orients mRNA & AA complex
2. Ensure accurate reading

Question 13

mRNA contains information for?

Answer 13

Proteins (translation)

Question 14

mRNA turnover rate

Answer 14

Very high (much less stable than tRNA and rRNA) → 1/2 life is hours to days

Allows for amplification of genetic message (multiple copies)

Question 15

Translation

Answer 15

Conversion of mRNA into protein

Question 16

AA sequence is determined by?

Answer 16

Nucleotide sequence

Question 17

Ribosome

Location:

Function:

Answer 17

Cytoplasm

Protein synthesis

Question 18

3 sites on ribosome

Answer 18

A site (aminoacyl): binds newly arriving tRNA

P site (peptidyl): tRNA carrying polypeptide chain residues

E site (exit): tRNA exits from ribosome

Question 19

Codon

Answer 19

Ribosome reads mRNA sequence 3 nucleotides at a time → 64 possible

Question 20

Start codon

Answer 20

AUG

Question 21

Stop codon

Answer 21

1. UAG
2. UGA
3. UAA

Question 22

2 posttranslational modifications and what is their function?

Answer 22

1. Amino acids removed (splicing)
2. Add sugars

→ makes protein active and directs protein to appropriate location

Question 23

Endoplasmic reticulum mostly contains?

Answer 23

Glycoproteins (protein with carbohydrate grop)

Question 24

How does protein attach to ER?

Answer 24

Protein is on ribosome → ER recognizes tag on protein

Question 25

What happens to protein in ER?

Answer 25

Folding and further glycosylation

Question 26

Channel network in ER

Answer 26

Directs protein to proper location in cell

Question 27

Donor molecules and acceptor residues of glycosylation

Answer 27

Donor molecules: nucleotide sugars (ex: ADP-glucose)

Acceptor residues:

1. Asparagine (N)
2. Serine (S)
3. Threonine (T)

Question 28

PCR

Does what:

Discovered by:

Answer 28

Exponentially amplify DNA segment in vitro

Kary Mullis, 1983

Question 29

3 steps of PCR

Answer 29

1. Denaturation (separates DNA strands)
2. Annealing (primers bind DNA)
3. Extension (new DNA synthesized)

Question 30

What is glycosylation directed by?

Answer 30

Enzyme-directed site-specific process (glycosyltranferases)

Question 31

Where does glycosylation occur?

Answer 31

ER and Golgi apparatus

Question 32

What is glycosylation?

Answer 32

Folding, targeting and function of protein