Lecture 8 Flow of genetic information

Question 1

from DNA to protein

Answer 1

DNA (replication, repair, recombination)
->
RNA (transcription)
-> 
protein (translation)

genes not transcribed equallt

Question 2

RNA

Answer 2

ribose instead of deoxyribose
U (Uracil) instead of T (Thymine)

single-stranded, can create secondary structures

mRNA, tRNA, rRNA

Question 3

RNA polymerase

Answer 3

enzyme synthesizing RNA, three different types in Eukarya

Question 4

holoenzyme

Answer 4

RNA polymerase (core) + sigma-factor

needs to form in order to start the transcription

Question 5

transcription

Answer 5

DNA, RNA pol, mRNA

Question 6

promoter

Answer 6

DNA sequences that mark the initiation of transcription (recognized by RNA pol holoenzyme)

if transcription starts at +1, promoter sequences are at postions -35 and -10

variations in the space between (15-19 nt) gives promoters different strength

Question 7

initiation of transcription

Answer 7

The polymerase needs trancription factors.

RNA Pol II needs the general trancription factors that help:

• Find and identify the promoter
• Position the polymerase correctly
• Help with the local DNA denaturation
• Change the polymerase to the elongation mode when needed

Question 8

measure of how much our GOI is expressed

Answer 8

the GOI is replaced by a reporter gene (coding for a fluorescent protein), still under the control of the promoter that normally controls the GOI

Question 9

measure expression of all genes

Answer 9

RNA seq
- diff samples of isolated mRNA
- see how many copies that are sequenced
- ratio
DNA microarray
- diff samples of mRNA
- converted to ctDNA and labeled with fluorochrome
- hybridized to microarray
- see level of expression based on color

Question 10

transcripts in Bacteria vs Eukarya

Answer 10

bacteria simple

Euakarya involves splicing
transcription inside the nucleolus, translation in the cytoplasm
5’ cap and poly-A tail

Question 11

processing factors

Answer 11

The CTD of RNA polymerase brings in different processing factors as transcription goes on

Different phosphorylation patterns of
CTD attract different processing factors
at different times

Question 12

operon

Answer 12

genes that are transcribed together are called operons

Question 13

gene organisation

Answer 13

picture

Question 14

splicing

Answer 14

• only in Euakarya
• cut out of the introns
• done by the spliceosome, recognize specific sequences to catalyze the splicing reaction

Question 15

Introns always start with … and end with …

Answer 15

GU

AG

Question 16

Polyadenylation

Answer 16

For:

1. Stability
2. Nuclear transport
3. Translation

Question 17

mR NA goes to the … to be translated

Answer 17

cytoplasm

Question 18

translation

Answer 18

Synthesis of the polypeptide chain, based on the mRNA transcript.
The synthesis is carried out on ribosomes.
Amino acids needed to build the protein are transported to the ribosome by tRNAs

Question 19

codons/anticodons

Answer 19

Ribosome “reads” the genetic code
Codons on mRNA and ”read” by anti-codons on tRNA tRNAs bring in amino acids
Each amino acid corresponds to one or more codons

Question 20

Aminoacyl tRNA stynthetases

Answer 20

amino acid + tRNA + ATP → aminoacyl-tRNA + AMP + PPi

Question 21

Ribosome

Answer 21

picture

Question 22

stop codon

Answer 22

UAA
UAG
UGA

When a stop codon comes along, relase factor binds instead of a tRNA, translation stops, and the ribosome dissociates

Question 23

Polyribosome (polysome)

Answer 23

A series of ribosomes simultanously translates a eukaryal mRNA. Note the important position of cap- and polyA-associated proteins

Question 24

proteasome

Answer 24

enzyme digesting incompletely folded protein