Transcription & Protein Translation

Question 1

What is transcription?

Answer 1

DNA is copied to RNA

Question 2

What is translation?

Answer 2

RNA is used to produce proteins

Question 3

What bases are on RNA

Answer 3

ACGU

Question 4

Ribose sugar with _____ group on 2’ carbon

Answer 4

OH

Question 5

What is RNA single-stranded?

Answer 5

OH on 2’ interferes with double-strand

Question 6

Why is RNA less stable than DNA?

Answer 6

OH on 2’ because of hydrolysis

Question 7

Single strand can fold into _________ structures

Answer 7

Secondary (very complex)

Question 8

________ bonds between base pairs within strands

Answer 8

Hydrogen

Question 9

What are ribozymes?

Answer 9

Catalytic activity, enzymes speed up reaction due to closer proximity

Question 10

Messenger RNA (mRNA)

Answer 10

Forms a template for protein synthesis

Question 11

Transfer RNA (tRNA)

Answer 11

Carries activated amino acids to ribosomes for protein synthesis

Question 12

Ribosomal RNA (rRNA)

Answer 12

Structural core of ribosomes

Question 13

Small nuclear RNAs (snRNA)

Answer 13

Involved in the processing of DNA and RNA in nuclei post transcription mod.

Question 14

tRNA matches ________ to appropriate amino acids

Answer 14

mRNA code

Question 15

What does the TATA box do?

Answer 15

Binds transcription factors, proteins in the nucleus that bind to promoter regions

Question 16

How are transcription factors initiated?

Answer 16

Transcription factors recruit RNA polymerase, RNA polymerase binds & is activated, transcription begins

Question 17

What does RNA polymerase do?

Answer 17

Unwinds DNA, no primer needed, catalyzes phosphodiester bonds, A and U complementary bonds

Question 18

RNA polymerase 1

Answer 18

rRNA

Question 19

RNA polymerase 2

Answer 19

mRNA & snRNA

Question 20

RNA polymerase 3

Answer 20

rRNA, tRNA, & snRNA

Question 21

Post-transcriptional Mods

Answer 21

5’ capping, 3’ poly adenylation, splicing

Question 22

What is the purpose of 5’ capping?

Answer 22

Protects mRNA from 5’ to 3’ exonuclease degradation
Ribosome binding site, a smaller subunit recognizes a 5’ cap & binds to it without the cap proteins and is not translated and can be broken down by 5’ actin nuclease

Question 23

What is the purpose of 3’ polyadenylation?

Answer 23

Protects from 3’-5’ exonuclease degradation, exonuclease will chew up RNA if no 3’ polyadenylation

Question 24

Introns

Answer 24

Non-coding regions

Question 25

Exons

Answer 25

Codes for proteins

Question 26

What does mRNA splicing do?

Answer 26

Removes introns and ligates exons together

Question 27

Alternative splicing

Answer 27

Splicing different combinations of exons, and multiple proteins is possible from one gene

Question 28

What is a codon?

Answer 28

Bases are read in triplets

Question 29

Wobble hypothesis

Answer 29

Only the first two bases of the codon (mRNA) are precisely paired with the anticodon (tRNA)

Question 30

Wobble pairing

Answer 30

tRNA is not exactly on the third position G/U pairing

Question 31

Start Codon

Answer 31

AUG, methionine

Question 32

Point mutation

Answer 32

Single base added, deleted, or changed

Question 33

Frameshift

Answer 33

All codons after mutation are different

Question 34

Missense

Answer 34

Changed base causes a different amino acid

Question 35

Nonsense

Answer 35

Changed base causes a premature stop codon

Question 36

Silent

Answer 36

Changed base has no effect

Question 37

Ribosomal small subunit

Answer 37

Binds and reads mRNA, recruits large ribosomal subunit when it finds AUG

Question 38

Ribosomal large subunit

Answer 38

The docking site for tRNAs (APE), catalyzes peptide bonds between amino acids released from tRNAs

Question 39

Translation initiation steps

Answer 39

1. Small ribosomal subunit binds mRNA 2. tRNA with anticodon UAC binds AUG start codon at P site 3. Large subunit is recruited 4. New tRNA binds codon at A site

Question 40

What is elongation?

Answer 40

Large ribosomal subunit catalyzes peptide bond between amino acids

Question 41

What is translocation?

Answer 41

1. Ribosome move along mRNA to next codon 2. New tRNA binds codon in A site 3. Large subunit catalyzes bond between peptide chain in P site and new amino acid in A site

Question 42

Translation termination steps

Answer 42

1. Ribsome continues moving along mRNA until stop codon is reached in the A site 2. No tRNAs have anticodons to match stop codons 3. Release factor binds stop codon 4. Protein released and ribosome dissociates

Question 43

What is tRNA charged by?

Answer 43

Aminoacyl-tRNA synthetase

Question 44

Why is ATP needed to charge tRNA

Answer 44

ATP cleavage provides energy to link amino acid to tRNA via an ester bond, tRNA can drop amino acid at a ribosome

Question 45

What is Post-translational Modifications?

Answer 45

Mostly, the addition of a group of molecules or the removal of a group or split of Wa protein

Question 46

What is a reversible PTM?

Answer 46

Addition of chemical groups, complex molecules, or polypeptides

Question 47

What is an irreversible PTM?

Answer 47

Amino acid modification, and cleavage

Question 48

What is phosphorylation?

Answer 48

A reversible process in which insulin receptors are phosphorylated and trigger lupus

Question 49

What is ubiquitylation?

Answer 49

A reversible process that marks proteins for destruction if abnormal

Question 50

What is proteolysis?

Answer 50

An irreversible process that removes a group