Genetics

Question 1

Genetic Code

Answer 1

‘rules’ that convert the nucleotide sequence of a gene to a sequence of amino acids of a protein using mRNA as an intermediary

Question 2

Degenerate Code

Answer 2

some amino acids can be coded by more than one codon and 3 codons are STOP codons

Question 3

Silent Mutation

Answer 3

doesn’t change the amino acid

Question 4

Missense Mutation

Answer 4

Changes amino acid in the protein with no effect on protein function

Question 5

Nonsense Mutation

Answer 5

Codon changes to a stop codon

• causing premature chain termination
• protein is formed as a truncated version
• Protein is non-functional

Question 6

Frameshift Mutation

Answer 6

One or more nucleotides are depleted or inserted into ORF, which causes a change in the codon sequence and a change in the amino acid sequence
*Protein is non-functional

Question 7

Sickle Cell Anemia

Answer 7

missense mutation

• changes Val (hydrophobic) to Glu (-charged+hydrophil)
• changes in conformation of HbA: aggregate, rigid, rod-like structures
• deformed RBCs with poor oxygenation and clogs capillaries

Question 8

Duchenne Muscular Dystrophy

Answer 8

• deletion in the dystrophin gene leading to partial or non-functional dystrophin protein
• OOF deletions give little/no expression of dystrophin protein
• muscle wasting
• frame shift deletions–truncated forms of dystrophin

Question 9

mRNA

Answer 9

• 5’ cap
• -untranslated region
• -Coding region
• -3’untranslated region
• Poly A tails

Question 10

tRNA

Answer 10

• serves as adaptors
• binding site for codons and amino acids
• match amino acids to codons in mRNA
• Clover leaf (2dry structure)
• Anticodon loop
• 3’CCA terminal region

Question 11

3’ CCA terminal region

Answer 11

found in tRNA

-binds the amino acid that matches the corresponding codon

Question 12

Anticodon loop

Answer 12

found in tRNA

-set of three consecutive nucleotides that pair with a complementary codon in mRNA

Question 13

Aminoacyl tRNAs

Answer 13

(tRNA with amino acid)

• AA needs to be activated
• catalyzed by aminoacyl tRNA synthetases which serves as a second genetic code
• each tRNA is charged with the correct AA to maintain fidelity of protein synthesis

Question 14

Activation of Amino Acids

Answer 14

1. Aminoacyl tRNA synthetase catalyzes the addition of AMP to the carboxy end of AA
2. the AA is transferred to the cognate tRNA

Question 15

Ribosomes

Answer 15

assemblers of translational machinery

• large complexes of proteins and rRNA (L+S subunit)
• antibiotics are used to target prokaryotic translational machinery

Question 16

Ribosomal Complex

Answer 16

• Acceptor site
• Peptidyl site
• Empty/Exit site

Question 17

Acceptor Site

Answer 17

(on ribosome)

-mRNA codon exposed to receive aminoacyl tRNA

Question 18

Peptidyl Site

Answer 18

(on ribosome)

-where aminoacyl tRNA is attached

Question 19

Empty/Exit Site

Answer 19

(on ribosome)

-location occupied by empty tRNA before exiting the ribosome

Question 20

Translation

Answer 20

5’ to 3’

• Initiation
• Elongation
• Termination

Question 21

Initiation

Answer 21

(translation)
formation of mRNA, which is a small ribosomal subunit and initiator tRNA pre-initiation complex

-requires the hydrolysis of 1 GTP

Question 22

Elongation

Answer 22

(translation)
-activated AA attached to initiating Methionine by forming a peptide bond

*requires the hydrolysis of 2 GTP per amino acid added

Question 23

Termination

Answer 23

(translation)

• peptide chain is released from ribosomal complex
• requires hydrolysis of 1 GTP

Question 24

Peptidyl transferase

Answer 24

(translation)

- catalyzes peptide bond formation between amino acid in A and P site

Question 25

5' cap

Answer 25

mRNA | -7 methyl guanasine cap

Question 26

Streptomycin

Answer 26

binds 30s subunit to disrupt initiation of translation

Question 27

Shigatoxin

Answer 27

binds to 60s subunit to disrupt elongation

Question 28

Clindamycin/Erythromycin

Answer 28

bind 50s subunit to disrupt translocation of ribosome

Question 29

Tetracyclines

Answer 29

bind 30s subunit to disrupt elongation

Question 30

Peptidyl Transferase

Answer 30

housed in the large subunits of the ribosome

Question 31

Diptheria Toxin

Answer 31

inactivates EF2-GTP and inhibits elongation

Question 32

Prokaryote Ribosome

Answer 32

50s subunit and 30s subunit

Question 33

Eukaryotic Ribosome

Answer 33

60s subunit and 40s subunit

Question 34

Mitochondria Proteins

Answer 34

contain an N terminal hyrophobic alpha helix have TOM or TIM to signal for peptide import

Question 35

Nucleus Proteins

Answer 35

Rich in Lysine and Arginine

Question 36

Peroxisome Proteins

Answer 36

have an SKL sequence (cytosolic pathway)

Question 37

Endoplasmic Reticulum Proteins

Answer 37

Secretory Pathway - go to ER first - have an ER 'retention signal' with amino terminus (positive charge)

Question 38

KDEL

Answer 38

Endoplasmic Reticulum ER retention signal

Question 39

Lysosomal Proteins

Answer 39

have a mannose 6 phosphate signal from secretory pathway...go to ER first

Question 40

Secretory Proteins

Answer 40

have Tryptophan rich domains...from secretory pathway that hit the ER first

Question 41

Heat Shock Proteins

Answer 41

protect the unfolded proteins that are entering the mitochondria via the TOM and or TIM

Question 42

SRP

Answer 42

Signal Recognition Particle--brings together the ER membrane and the ribosome

Question 43

I-Cell Disease

Answer 43

lysosomal storage disorder to the defective tagging of lysosomal proteins with Mannose-6-Phosphate so there is an increase is plasma lysosome levels

Question 44

Chaperone Proteins

Answer 44

needed by large proteins for protection and folding guidance into proper tertiary structure to avoid aggregation and proteolysis

Question 45

Chaperonins

Answer 45

barrel shaped compartments that admit unfolded proteins and catalyze folding in an ATP dependent manner

Question 46

Glycosylation

Answer 46

PTM - O linked form in a serine residue - N linked form in Asparagine *cataract formation

Question 47

Post-Translational Modification of Collagen

Answer 47

Modification is important to collagen Ascorbic acid is necessary for lysyl and proyxl hydroxylases and defects in this enzyme result in disorders such as Erlhers Danlos