Unit 4 - Ch 13 - Protein Syntheses

Question 1

DNA

Answer 1

Deoxyribonucleic Acid

Question 2

RNA

Answer 2

Ribonucleic Acid

Question 3

Unique features of RNA (4)

Answer 3

1. Uracil substitutes for Thymine
2. Ribose substitutes for Deoxyribose
3. Single Stranded
4. Non-helical

Question 4

Uracil and Thymine

Answer 4

almost identical in structure except for one functional group (CH3 in place of H)
- Both pair with Adenine

Question 5

Ribose vs Deoxyribose

Answer 5

ribose has one more oxygen than deoxyribose

Question 6

Types of RNA

Answer 6

mRNA
rRNA
tRNA

Question 7

mRNA

Answer 7

messenger RNA; between DNA and ribosomes

a. Codon - a 3-base sequence

Question 8

rRNA

Answer 8

ribosomal RNA - forms ribosomal subunits

Question 9

tRNA

Answer 9

transfer RNA; delivers amino acids from cytoplasm to the ribosome

a. Anticodon - a 3-base sequence complementary to the codon in mRNA

Question 10

Transcription

Answer 10

• Protein synthesis

formation of mRNA from DNA via RNA polymerase

Question 11

Transcription location

Answer 11

Occurs within the nucleus

Question 12

Transcription steps (4)

Answer 12

1. DNA unzips - break H-bonds between the base pairs via RNA polymerase
2. mRNA nucleotides complementary pair on sense (one) strand from promoter to terminator - catalyzed by RNA polymerase
3. mRNA leaves nucleus - exits via nuclear pores
4. DNA reforms double helix

Question 13

Codon Characteristics (6)

Answer 13

1. Linear
2. No overlap
3. 3 bases nucleotide bases per codon = 1 amino acid
4. Redundant
5. Universal - (nearly) - basis for GMO’s
6. Continuous for 1 polypeptide

Question 14

Translation

Answer 14

Synthesize a protein based upon the instructions in the mRNA codons

Question 15

Translation Location

Answer 15

Occurs at the ribosomes

Question 16

Translation Steps (4)

Answer 16

1. Activation
2. Initiation
3. Elongation
4. Termination

Question 17

Activation in Translation

Answer 17

Specific amino acids attach to tRNA by aminoacyl-tRNA synthetase (requires ATP)

• “loading tRNA”
• occurs multiple times per protein

Question 18

Initiation in Translation

Answer 18

mRNA arrives at ribosome (rRNA) and tRNA binds complementary to codon sequence
- occurs once per protein

Question 19

Elongation in Translation

Answer 19

Adjacent amino acids are bonded together via peptide bonds formed via condensation reaction - occurs multiple times per protein

Question 20

Termination in Translation

Answer 20

Polypeptide is released at stop codon - brings in a release factor - occurs once per protein