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Biochemistry - MOD2 - Protein Biosynthesis
pgs 17-39
35
Chemistry
Professional
09/28/2010

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Term
large subunit of ribosome is made up of ...
Definition
28S, 5.8S, 5S pieces of rRNA
Term
small subunit?
Definition
18S
Term
prokaryotes, small subunit of ribosome is ------ and large subunit is -----
Definition
16S

25S and 5S rRNA
Term
where is amino acid attached on tRNA
Definition
3' end on A residue of the CCA tail
Term
how many codons are there?
Definition
64 codons

61 specify for amino acids

3 are stop codons
Term
is the tRNA that carries the initial Met different from the one that carries it to the ORF?
Definition
yes

tRNAi-Met carries initial Methionine
tRNA-Met does the rest
Term
wobble
Definition
codons for one amino acid can vary in last base pair of codon but still carry same amino acid
Term
aminoacyl-tRNA synthetase
Definition
links amino acid to its tRNA

20 of these enzymes, each for its own aa

has proofreading feature

structural features (such as anticodon) guide this enzyme to correct tRNA

driven by ATP

AA + ATP ---Aminoacyl-tRNA Synthetase---> Aminoacyl-AMP + PPi ---tRNA--->
Aminoacyl-tRNA + AMP
Term
what does process of translation include (4 steps??)
Definition
1. Amino Acid Activation

2. Initiation

3. Elongation

4. Termination
Term
what does initiation in prokaryotes require?
Definition
initiatior tRNA (tRNAi-Met)

protein initiation factors (like transcription factors)

GTPs

mRNA and ribosomes (obviously)
Term
what does initiation in eukaryotes require?
Definition
need multiple protein factors called eIF's (eukaryotic Initiation Factors)

tightly controlled and very detailed - more flashcards to come...
Term
where does formyl group that is added to first Met residue come from?
Definition
N^10 -formyl-tetrahydrofolate
Term
shine dalgarno sequence
Definition
forms hydrogen bonds with a complementary sequence on the 16S rRNA within the 30S (small) subunit
Term
what makes up the pre-initiation (of translation) complex?
Definition
three initiation factors (IF-1, IF-2 and IF-3)

fMet-tRNAi(Met)

mRNA

and GTP
Term
eukaryotic steps of translation initiation
Definition
1. form first ternary complex [Met-tRNAi(Met) + eIF-2 + GTP] **notice not formyl Met (like prok)**

2. form initiator tRNA-ribosome complex (ternary complex + 40S subunit with eIF-3)

3. form pre-initiation complex [eIF-4F binds to cap, then binds eIF-4A and eIF-4B which bind to 40S subunit]

4. form 80S initiation complex [40S subunit goes along 5'-UTR until it finds AUG (SCANNING); once AUG found, GTP is hydrolyzed and bound eIFs are released allowing 60S subunit to join]

5. recycle eIF-2
Term
recycling of eIF-2
Definition
Term
Cycloheximide
Definition
stops elongation in eukaryotes
Term
erythromycin
Definition
stops translocation in prokaryotes
Term
Neomycins
Definition
stopes translation at multiple sites in prokaryotes
Term
Puromycin
Definition
stops peptide transfer both euks and proks

has VERY REACTIVE AMINO GROUP -- acts like amino group of an aa; binds to carbonyl group of peptidyl-tRNA in P site

resembles 3' end of tyrosyl-tRNA
Term
Ricin
Definition
stops translation at multiple sites in eukaryotes
Term
Streptinomycin
Definition
stops initiation and elongation in prokaryotes
Term
tetracyclins
Definition
stops AA-tRNA binding
Term
EF-2-GTP
Definition
moves aminoacyl-tRNA from A to P site
Term
diphtheria
Definition
this pathogen/disease secretes a toxic enzyme that enters cells and catalyzes the following reaction

EF-2 + NAD+ (ACTIVE) <-----------> ADP-ribosyl-EF-2 + nicotinamide (INACTIVE)

basically, this pathogens toxin inactivates EF-2, which is crucial in moving aminoacyl-tRNAs from A to P sites

no EF-2 = no elongation = no protein
Term
mannose-6-phosphate residues
Definition
signal on enzymes that are destined for lysosomes

recognized by the (blank)-(blank)-(blank) receptor

these (blank)-(blank)-(blank) residues help send lysosomal enzymes to lysosomes
Term
I cell disease (mucolipidosis II)
Definition
disorder of protein targeting

patients with this disease suffer from severe PSYCHOMOTOR RETARDATION, SKELETAL/JOINT DEGENERATION, and high mortality rate (death by age 10)

deficiency in GlcNAc-1-P-transferase enzyme --> leads to ABSENCE OF manose-6-phosphate residues

thus, lysosomal enzymes/proteins not delivered to lysosomes

also results in increase in serum levels of lysosomal enzymes (since they are thrown out of cell) AND build up of waste products within cells

build up of INCLUSION BODIES (also called [blank]) --> waste buildup in cell
Term
postranslational modifications
Definition
acetylation

carboxyglutamation

glycosylation

hydroxylation

methylation

phosphorylation

prenylation
Term
acetylation
Definition
one of 7 post translational modification of a protein

do this to histones

results in gene activation
Term
carboxyglutamation
Definition
one of 7 post translational modification of a protein

several blood clotting proteins - prothrombin and factor X

convert glutamic acid to gama-carboxyglutamic acid

these residues are necessary for these proteins to bind calcium ion and participate in blood clotting
Term
glycosylation
Definition
one of 7 post translational modification of a protein

all about producing glycoproteins (adds carbs to protein backbones)

abnormal in CYSTIC FIBROSIS
electrolyte transport in lung, pancreas, and liver defective; thick mucous secretions; chronic obstructie lung disease
CFTR (cystic fibrosis transmembrane conductance regulator) --> the membrane glycoprotein --> NOT PROPERLY GLYCOSYLATED
Term
CYSTIC FIBROSIS

CFTR
Definition
this disease is caused by improper glycosylation of a membrane glycoprotein termed (blank)

electrolyte transport in lung, pancreas, and liver defective;

thick mucous secretions;

chronic obstructive lung disease

(blank) --> the membrane glycoprotein --> NOT PROPERLY GLYCOSYLATED
Term
hydroxylation

hydroxylating
Definition
one of 7 post translational modifications of a protein

involves (blank-ing) specific proline and lysine residues in collagen

stabilizes collagen molecule
Term
methylation
Definition
one of 7 post translational modifications of a protein

happens in histones but is not acetylation
Term
prenylation

prenyl group
Definition
one of 7 post translational modifications of a protein

add a (blank) group to protein

this anchors the protein onto cell membranes
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