Transcript/Translate 16/17 Bio

Question 1

Transcription

Answer 1

Make RNA using DNA as a template.
Occurs in the nucleus of eukaryotic cells. Pre- RNA is made then modified to final mRNA. In prokaryotes mRNA directly forms.

Question 2

Main transcription enzyme

Answer 2

RNA polymerase. Separates the two DNA strands and nucleotides are joined together as they base pair. No primer is needed.

Question 3

Promoter

Answer 3

Area where RNA polymerases attaches and initiates transcription.

Question 4

3 stages of transcription

Answer 4

Initation, elongation, termination

Question 5

Initiation in transcription

Answer 5

RNA polymerase goes to the promoter region. DNA helix unwinds and begins synthesis. Eukaryotic promoter includes A and T 25 nucletodies upstream from the transcriptional start point, TATA box.
Prokaryotes have a Pribnow box.

Question 6

Transcription factors

Answer 6

Proteins that recognize the promoter site and binding occurs.

Question 7

Transcription initiation complex (TIC) components

Answer 7

Transcription factors and RNA polymerase

Question 8

Elongation in transcription

Answer 8

RNA polymerase moves along DNA strand, RNA nucletoides are added to the 3’ end. G and C, A and U.
Adding Codons.
Only one strands of DNA is transcribed, our template strand (anti sense strand).

Question 9

RNA polymerase vs DNA polymerase

Answer 9

RNA polymerase does not proofread for any errors. An error during transcriptions gives a bad protein and not transmitted gene missense if it occurred in DNA.

Question 10

Termination in Transcription

Answer 10

Remove RNA poly from the DNA. The terminator sequence is transcribed. Still needs post transcription mods
Prokaryotes and Eukaryotes have different mechanisms for termination.

Question 11

Post transcription Mods

Answer 11

The transcript gets a cap at the 5’ end. The cap is a 3 phosphate groups. At the 3’ end a poly A tail is added.

Question 12

Spliceosome

Answer 12

small nuclear ribonucleoproteins (snRNP) and other proteins form a complex that the cutting occurs.

Question 13

Introns

Answer 13

Cut out of mRNA, exons are kept

Question 14

Translation

Answer 14

Synthesis of a polypeptide under direction of RNA in the cytoplasm.
rRNA, mRNA, and tRNA work outside the nucleus. Assembly at ribosomes (both in prokaryotes and euk)

Question 15

tRNA reaction joining aa

Answer 15

Aminoacyl tRNA synthetase.

Bonds at the 3’ end.

Question 16

Start codon

Answer 16

AUG - methionine (contains a sulfur)

Question 17

Ribosome has 4 binding sites

Answer 17

mRNA binding site and 3 tRNA binding sites: A,P,E

Question 18

Polypeptide synthesis takes place at

Answer 18

Peptidyl and aminoacyl sites

P and A site

Question 19

P site

Answer 19

holds the tRNA attached to the growing polypeptide chain.

Question 20

A site

Answer 20

holds the tRNA with it’s associated aa to the polypeptide chain.

Question 21

E site

Answer 21

tRNA is discharge at this site.

Question 22

Eukaryotic ribosomes are made in the

Answer 22

Nucleolus of the cell

Question 23

Eukaryotic proteins and drugs

Answer 23

Eukaryotic proteins have larger size and differ in their proteins thus drugs can be designed to kill bacteria by targeting their ribosomes.
E.g. Tetracycline works by inhibiting prokaryotic ribosomal function.

Question 24

Ribosomes

Answer 24

Are made of proteins and RNA. A ribozyme is an RNA molecule that functions as an enzyme.

Question 25

Initiation in Translation

Answer 25

mRNA attaches to the ribosome. Anticodon (P site) matches with AUG (A site).

Question 26

Elongation in translation

Answer 26

Peptide bond between aas. Translocation occurs: A moves to P, and P moves to E for release.

Question 27

Wobble hypothesis

Answer 27

3rd base of the codon and 3 base of the tRNA might not always be complimentary.

Question 28

Termination in translation

Answer 28

When a stop codon is read, a release factor is a protein that binds to our ribosome.

Question 29

The genetic code is degenerate

Answer 29

Many of the 64 codons are redundant.

Question 30

Stop Codons

Answer 30

UAA, UGA, UAG

Question 31

Point mutation

Answer 31

Single base pair of gene is affect.
Sickle cell anemia. Glueatmic acid is replaced by Valine on the beta chain of hemoglobin. HbS (sickled hemoglobin) is more + because there is less “-“ charge.

Question 32

Base pair substitution:

Answer 32

One nucleotide and its compliment base has changed into another.
If a wrong aa is made, its a missense mutation. If a stop codon is made, its a nonsense mutation.

Question 33

Frameshift mutation

Answer 33

Reading frame changes due to an insertion or deletion of nucleotide pairs in a gene.

Question 34

Transposons

Answer 34

Jumping genes.

Question 35

Mutagens

Answer 35

Chemical or physical agent that interacts with DNA and cause a mutation.
Physical mutagens Rays, Gamm Rays.
Chemical mutagens include aromatic amines, nitrous acids, benzene.
Most mutagens can be carcinogens but not always.

Question 36

Two thymine bases next to each other

Answer 36

Dimerize. Too many thymine dimers can either doe or undergo malignant transformation.