Molecular Biology - Ch 22

Front 1

Translation - literally

Back 1

To express in another language while retaining the original sense

Front 2

Translation (in Biology)

Back 2

DNA/RNA code of nucleotides to the protein code of amino acids

Front 3

mRNA triplet = codon

Back 3

an RNA "word" of 3 "letters"

Front 4

Four binding sites on mRNA impotrant for protein synthesis

Back 4

mRNA Binding site
A Site - Binds each newly arriving tRNA with its attached Amino Acid
P Site - where the tRNA carrying the growing PolyPeptide chain resides
E site - from which the tRNA Exits the Ribosome after discharging its amino acid

Front 5

tRNAs, also called ______ ______, bind to
1:
2:

Back 5

tRNAs, also called _adaptor _ _molecules_, bind to
1: Amino Acids
2: the correct codon on mRNA

Front 6

anticodon

Back 6

triplet of nucleotides in tRNA that recognizes the appropriate codon in mRNA by complementary base pairing

Front 7

aa tRNA

Back 7

AminoAcyl tRNA, tRNA with amino acid attached.

Front 8

aa tRNA Synthetase

Back 8

links amino acids to their corresponding tRNA

Front 9

Wobble Hypothesis

Back 9

Flexibility in codon-anti-codon binding allows some unexpected base pairs to form

Front 10

Translation Initiation - Process

Back 10

- - 3 initiation factors, IF1, 2 & 3 bind to small ribosomal subunit
- GTP attaches to IF2
- - mRNA & activated tRNA carry the first aa bind to the small ribosomal subunit
- base pairing between ribosome binding site on mRNA and an rRNA sequence (the ribosome's mRNA binding site) holds mRNA in place
- AUG (start) codon is placed at P Site of the ribosome
- tRNAmet inserts methionine
- tRNAfmet carries a converted methionine and acts as an initiator (prokaryotes only)
- IF3 is released when first base pairs

Front 11

tRNAmet

Back 11

tRNA that carries a Methionine.

Front 12

tRNAfmet

Back 12

tRNA that carries a converted form of Methionine. Common initiator tRNA that starts the process of translation in prokaryotes

Front 13

In prokaryotes, when ________ enters the P site, its anticodon base pairs with AUG and ___ is released

Back 13

In prokaryotes, when _tRNAfmet_ enters the P site, its anticodon base pairs with AUG and _IF3_ is released

Front 14

Translation Elongation - Process

Back 14

- EF-Tu, a protein elongation factor, beings the next aa-tRNA to the A Site. Anticodon will base pair with the complementary mRNA codon
- peptidyl transferase activity is catalyzed, the aa at the P site is released from the tRNA and a peptide bond joins it to the aa at the A site.
- mRNA moves over 3 nucleotides placing next codon at A site & PP chain in P Site
- empty tRNA moves from P site to E site and exits
- aa tRNA moves into A Site
- repeat

Front 15

Peptidyl Transferase

Back 15

A ribosyme that catalyzes peptide bonds in a ribosome

Front 16

Translational Translocation

Back 16

Movement of mRNA across a ribosome by a distance of 3 nucleotides, bringing the next codon into position for translation. Requires EF-G

Front 17

EF-Tu & EF-Ts

Back 17

Protein elongation factors that convey the aminoacyl tRNA to the A site of the ribosome

Front 18

Translational Termination

Back 18

- Signalled by stop codon(s)
- Release factors bind to stop codon when it reaches A site
- protein finishes folding

Front 19

Polyribosomes/polysomes

Back 19

multiple ribosomes reading the the same mRNA

Front 20

Proteins synthesized in the cytoplasm may . . .

Back 20

. . . remain in cytosol,
import to an organelle
Go to Nucleus (nuclear localization sequences)
Endomembrane sequence (signal sequence)
mitochondria/chloroplast (transit sequence)

Front 21

3 types of mutations:

Back 21

missense
nonsense
silent

Front 22

Silent mutation

Back 22

minor mutation which leads to no change in protein

Front 23

missense mutation

Back 23

change in amino acid sequence

Front 24

nonsense mutation

Back 24

change in amino acid sequence which cause stop codons