Unit 3 - Transcription & Translation

Question 1

Overview

Transcription

Answer 1

Converts DNA to RNA

Question 2

Overview

Which strand of DNA is transcribed?

Answer 2

template strand

Question 3

Overview

Which direction does RNA transcribe itself?

Answer 3

5’ to 3’

Question 4

Overview

Which direction does RNA move on the template strand?

Answer 4

3’ to 5’

Question 5

Overview

RNA polymerase

Answer 5

Transcribes DNA on the template strand

Question 6

Overview

mRNA

Answer 6

codes for protein

Question 7

Prokaryotic Transcription

RNA Polymerase

Answer 7

A large enzyme with several channels

Question 8

Prokaryotic Transcription

Core enzyme

Answer 8

synthesizes RNA

Question 9

Prokaryotic Transcription

Sigma Factor

Answer 9

• recognizes promoter on DNA
• opens DNA helix
• relaesed after initiating transcription

Question 9

Prokaryotic Transcription

Promoter

Answer 9

located on non-template strand found in
-10 or -35 box

Question 10

Prokaryotic Transcription

How does transcription stop?

Answer 10

• RNA polymerase reaches a termination signal on DNA causing a “hairpin loop”
• polymerase and transcript fall off DNA

Question 11

Overview

Promoter

Answer 11

• can only read 3’ to 5’ or 5’ to 3’
• found on either strand
• strand it is on becomes non-template strand
• recognized by sigma factor

Question 12

Eukaryotic Transcription

DNA Packing

Answer 12

• creates chromatin (DNA + protein)
  *

Question 13

Eukaryotic Transcription

How many RNA Polymerase do eukaryotes have?

Answer 13

3

Question 14

Eukaryotic Transcription

TATA Box

Answer 14

Recognized by TATA binding protein (TBP

Question 15

Eukaryotic Transcription

TATA Binding Protein

Answer 15

Sub-unit of TF2D, opens DNA Helix for other promoters

Question 16

Eukaryotic Transcription

Describe transcription initiation.

Answer 16

1. TATA box is recognized by TBP (TF2D), which opens helix
2. Other promoters pile on to create an initiation complex
3. RNA Polymerase II binds to DNA and transcripts (only TF2D remains)

Question 17

Eukaryotic Transcription

Where does transcription occur?

Answer 17

Nucleus

Question 18

Eukaryotic Transcription

Describe RNA Polymerase II

Answer 18

• transcribes DNA to RNA
• has a phosphoryated tail

Question 19

Eukaryotic Transcription

Describe the process of RNA processing.

Answer 19

• different factors bind to the polymerase tail
• the factors bind to the RNA as it is transcribed

Question 20

Eukaryotic Transcription

Which end of the RNA does the cap bind to?

Answer 20

5’ (attatches at the start)

Question 21

Eukaryotic Transcription

Exons

Answer 21

Region on mRNA that codes for protein

Question 22

Eukaryotic Transcription

Intron

Answer 22

Region on mRNA that does not code for protein

Question 23

Eukaryotic Transcription

What is splicing?

Answer 23

Introns are removed based on sequences near ends, can result in different functioned proteins from the same gene

Question 24

# Eukaryotic Transcription Spliceosomes

Answer 24

Bind to two ends of intron and removes it from strand by forming the intron into a loop, consists of 5 snRNPs

Question 25

# Translation What is translation?

Answer 25

mRNA is translated into amino acids/peptide chains (proteins)

Question 26

# Translation Comapre eukaryotic and prokaryotic translation.

Answer 26

Eukaryotic translation can only occur after transcription, prokaryotic translation and transcription is synchronous

Question 27

# Translation Genetic Code

Answer 27

Relationship between nucleotide sequence (codon) and amino acid, 64 codons, 20 amino acids

Question 28

# Translation Which amino acids only have one codon?

Answer 28

MET and TRP

Question 29

# Translation Is genetic code unveirsal?

Answer 29

Mostly, certain fungi and mitochondria have different codes

Question 30

# Translation frame-shift mutations

Answer 30

When the a base is added/removed and shifts reading frame, leading to different proteins

Question 31

# Translation tRNA

Answer 31

Transfer RNA: "adapters" that hold amino acids in place to interact with codons

Question 32

# Translation How does mRNA specify amino acids?

Answer 32

tRNA

Question 33

# Translation wobble hypothesis

Answer 33

Some tRNAs pair with a codon with the wrong third base

Question 34

# Translation Describe redundancy in base-tRNA pairing.

Answer 34

Since multiple codons assosiate with the same amino acid, codons that begin with the same 2 bases can have more than 1 tRNA, ignoring the 3rd base

Question 35

# Translation aminoacid tRNA synthase

Answer 35

activates amino acid with ATP and site where amino acid transfers to tRNA

Question 36

# Translation Describe how amino acids attatch to their tRNAs

Answer 36

* tRNA synthase binds amino acid and ATP * amino acid is activatied by ATP (AMP) * tRNA binds to synthase * amino acid is transferred to tRNA and detattches from synthase

Question 37

# Translation Ribosomes

Answer 37

catalyze peptide bond formation and match tRNAs to codons

Question 38

# Translation How does translation start?

Answer 38

* translation initiator factor finds 5' cap * initiator tRNA scans mRNA from 5' to find start codon (AUG) * small ribosomal subunits attatches and attracts the large

Question 39

# Translation How does translation stop?

Answer 39

* ribosome hits a stop codon * release factor binds to A-site * adds water to end amino-acid chain * everything falls off mRNA

Question 40

# Translation Is a ribsome an enzyme or ribozyme?

Answer 40

ribozyme; most of its acitivty brought on my RNAs

Question 41

# Translation When does the protein fold into its shape?

Answer 41

As chain is translated, it starts to fold