Lecture 4.B

Question 1

where do rna’s go to make a protein once they have decoded the dna

Answer 1

Bring all the RNAs to a ribosome which will use them to make the protein.

Question 2

what is a Gene expression

Answer 2

Process by which information stored in ageneis used to make a geneproduct: mRNA, tRNA, rRNA, protein

Question 3

what is Transcription

Answer 3

information in DNA (genes) is used to make RNA molecules (mRNA, rRNA & tRNA).
DNA does NOT get turned into RNA NOT COPY

enzymes “read” the nucleotide sequence in DNA to make a complementary RNA stand.

Question 4

what is Translation

Answer 4

information in mRNA used to make a protein.

mRNA does NOT get turned into a protein.

Question 5

… add RNA nucleotides to make an RNA molecule that is complementary to the DNA template strand

Answer 5

enzymes

Question 6

what are rRNA

Answer 6

rRNA: enzyme in ribosomes: CATALYSES THE FORMATION OF PROTEINS

rRNA joins the aa together (peptide bonds).

Question 7

what are mRNA

Answer 7

mRNA has a linear structure and carries genetic information copied from DNA

Question 8

what are tRNA

Answer 8

polynucleotide containing an anti-codon region that binds to codons AND another region that binds to amino acids

Question 9

what comes in the ribosome during the translation

Answer 9

Translation:

mRNA & tRNA meet rRNA at the ribosomes

Question 10

how do mRNA leave the nucleus after transcription

Answer 10

via nuclear pores

Question 11

what are codon?

Answer 11

sequence of 3 mRNA nucleotides that corresponds to a specific amino acid or a stop signal

Question 12

what are the Ingredients for translation?

Answer 12

mRNA
tRNA
rRNA
Amino acids
Release factor
Ribosome
Energy

Question 13

what is the start codon

Answer 13

AUG, which codes for the aa methionine

Question 14

what does an Anticodon do

Answer 14

pairs with complementary codon in mRNA

Question 15

describe the process of translation

Answer 15

1. mRNA binds to ribosome
2. Anti-codon region of 1st tRNA binds to codon of mRNA (“P site” of ribosome)
3. 2nd tRNA binds at the “A site” to the 2nd codon of mRNA
4. rRNA of ribosome forms peptide bond b/w aa 1 + 2
5. 1st tRNA (had Met) leaves without its amino acid

Question 16

what are the stages of translation

Answer 16

initiation
elongation
termination

Question 17

what is a release factor

Answer 17

protein, not a tRNA, binds to the stop codon (same protein recognizes all 3 stop codons)

Question 18

Where do the aa come from ?

Answer 18

cells can make some aa: these are called nonessential aa (since you don’t have to get them from your diet)
9 Essential aa: those that you can’t make at all or make enough of to meet your needs. have to get the from diet

Question 19

what strategies to fasten the transcription ?

Answer 19

1. Many different genes transcribed at same time
2. One mRNA translated multiple times
   Polyribosomes