lecture 14

Question 1

what is at the beginning of every protein sequence?

Answer 1

AUG
- methionine is at the beginning of every amino acid sequence but does not need to be there when it is matured

Question 2

Translation is

Answer 2

the synthesis of protein from mRNA

Question 3

Translation
-what and where?

Answer 3

takes info from nucleic acids (ribonucleotides) and translates it into proteins (amino acids)

takes place in the cytosol

Question 4

Genetic code is

Answer 4

a set of triplet code codons in mRNA or DNA that codes form amino acids

Question 5

genetic code— what dictates the amino acid?

Answer 5

the first two bases
*makes sense if we look at the table

Question 6

open reading frame (ORF) definition

Answer 6

a reading frame that has the potential to code for a protein or peptide

Question 7

ORF details

Answer 7

the first base of the ORF is a start codon
ends with a stop codon
usually more than 50 codons

Question 8

4 types of mutations

Answer 8

missense
nonsense
silent
frameshift

Question 9

missense mutation

Answer 9

a single nuc change results in a codon that codes for a diff amino acid

Question 10

nonsense mutation

Answer 10

point mutation that results in a premature stop codon

Question 11

silent mutation

Answer 11

takes place in nonessential part of a gene. no effect on the gene product

Question 12

tRNA function

Answer 12

acts as a bridge between RNA and protein

Question 13

aminoacyl-tRNA synthesases

Answer 13

couples the correct amino acid to the correct tRNA molecule using ATP

–> when coupled, the tRNA is “charged”

Question 14

ribosomes function in translation

Answer 14

translation is conducted by ribosomes in the cytoplasm

Question 15

ribosomes are large complexes of

Answer 15

rRNA (2/3) and protein (1/3)

Question 16

ribozymes are

Answer 16

RNA molecules w catabolic activity

Question 17

what dictates the structure of the ribozyme?

Answer 17

rRNA in ribosomes

rRNA allows for the catabolic activity of ribosomes

Question 18

3 sites on the ribosome

Answer 18

A= aminoacyl-tRNA site
P= peptidyl-tRNA site
E= exit site

Question 19

what is the difference between translation in bacteria compared to eukaryotes?

Answer 19

v similar but in bacteria:

-mRNA has no 5’ cap so the small subunit recognizes the “Shine-Dalgarno” sequence instead

-bacteria has polysictronic mRNA

-each individual gene will have a shine-dalgarno sequence so each product is translated independently

Question 20

polycistronic mRNA

Answer 20

several genes encoded on the same mRNA transcript

(bacteria has this)

Question 21

monocistronic mRNA

Answer 21

eukaryotes have this

one gene encoded on the mRNA transcript?

Question 22

polyribosomes
how are they made?

Answer 22

a single mRNA transcript can be translated by several ribosomes at the same time to form a polyribosome

Question 23

polyribosomes
-increases what?
-occurs in?

Answer 23

increases overall rate of protein synthesis

occurs in both euk and prok

Question 24

proteases

Answer 24

enzymes that degrade proteins

Question 25

proteosomes

Answer 25

a large protein machine that degrades proteins in euk

unfolds proteins and degrades them

Question 26

autocatalysis

Answer 26

the ability to catalyze rxns that lead to production of molecules like itself

• RNA molecules can catalyze their own synthesis