protein synthesis quiz

Question 1

why does the cell need to make RNA?

Answer 1

DNA is housed in the protective nucleus of the cell
- protein synthesis occurs outside the nucleus in the ribosome
- dna is too important to leave the nucleus, and RNA intermediate is needed to bring genetic info outside the nucleus

Question 2

what is the structure of RNA?

Answer 2

• ribose sugar instead of deoxyribose
• uracil instead of thymine
• can travel between nucleus and cytoplasm
• in protein synthesis (mRNA, tRNA, and rRNA)

Question 3

central dogma of molecular biology

Answer 3

DNA to RNA to Protein

Question 4

protein synthesis occurs in what 2 steps

Answer 4

transcription and translation

Question 5

what 3 stages does transcription and translation occur in

Answer 5

initiation, elongation, termination

Question 6

what is the initiation stage of transcription

Answer 6

RNA polymerase binds to the DNA at the promoter

Question 7

what is the elongation stage of transcription

Answer 7

using DNA as a template, binds the mRNA using paired nitrogenous bases (A-U, C-G)

Question 8

what is the termination stage of transcription

Answer 8

leaves the nucleus

Question 9

what is the initiation stage of translation

Answer 9

ribosomes binds to mRNA

Question 10

what is the elongation of translation

Answer 10

• ribosomes mRNA in sets of nucleotides codes called a codon
• each codon translates codes for a different amino acid

Question 11

what is the termination stage of translation

Answer 11

polypeptide chain created and released

Question 12

promoter region is usually high in

Answer 12

As and Ts

Question 13

why are promoter regions high in As and Ts

Answer 13

so RNA polymerase expends less energy opening up the DNA helix (bc its only 2 hydrogen bonds instead of 3)

Question 14

only 1 DNA strand is used as the..

Answer 14

template strand (3’ 5’)

Question 15

the strand not used for transcription is known as the….

Answer 15

coding strand (5’ to 3’)

Question 16

terminator sequence is when…

Answer 16

RNA polymerase recognizes the end of a gene

Question 17

the primary transcript is known as..

Answer 17

the newly synthesized mRNA that disassociates from the DNA template strand

Question 18

post transcript modification only occurs in what cells

Answer 18

eukaryotic

Question 19

what post transcript modifications are made

Answer 19

• 5’ cap and Poly A Tail added to 3’ end
• introns, leaving behind exons
• mRNA is now known as mRNA transcript following all modifications

Question 20

purpose of 5’ cap

Answer 20

to protect mRNA from digestion by nucleus and phosphatases as it exits and enters cytoplasm, also used to initiate translation

Question 21

purpose of Poly-A-Tail

Answer 21

added to 3’ end of primary transcript by poly-A-polymerase to protect it from degradation later on

Question 22

what are introns

Answer 22

non-coding regions

Question 23

what are exons

Answer 23

coding regions

Question 24

introns are cut out by what

Answer 24

spliceosomes, which also joins remaining exons together

Question 25

each triplet of nucleotides is called a

Answer 25

codon

Question 26

what is the start codon

Answer 26

AUG

Question 27

what do tRNA do

Answer 27

ribosomes alone cannot synthesize polypeptide chain, tRNA must deliver the correct amino acids to the polypeptide building site

Question 28

what are anticodons

Answer 28

sequence of 3 bases at the end of one lobe of tRNA

Question 29

what do anticodons do

Answer 29

written in the 3' to 5' direction, and recognizes and is complementary to the codon of the mRNA - at the end of the strand is an attachment site for the corresponding amino acid specified by the mRNA codons

Question 30

ribosomes

Answer 30

the site of protein synthesis - a complex that contains a cluster of proteins and rRNA which are linear strands of RNA - ribosomes have binding sites for the mRNA transcript and the amino acid (tRNA molecules)