Unit 6 - topic 3

Question 1

proteins

Answer 1

polypeptides made up of amino acids

Question 2

amino acids are linked by

Answer 2

peptide bonds

Question 3

gene expression

Answer 3

• process by which DNA directs the synthesis of proteins
• includes two stages: transcription and translation
• occurs in all organisms

Question 4

transcription

Answer 4

• synthesis of RNA using information from DNA
• allows for the “message” of DNA to be transcribed
• occurs in nucleus

Question 5

translation

Answer 5

• synthesis of a polypeptide using information from RNA
• a nucleotide sequence becomes an amino acid sequence
• occurs at the ribosome

Question 6

messenger RNA

Answer 6

synthesized during transcription using a DNA template

Question 7

mRNA carries information from DNA (nucleus) to

Answer 7

ribosomes in cytoplasm

Question 8

transfer RNA molecules are important in the process of

Answer 8

• translation
• each tRNA can carry a specific amino acid

Question 9

tRNA can attach to mRNA via

Answer 9

• their anticodon
• a complementary codon to mRNA
• allow information to be translated into a peptide sequence

Question 10

ribosomal RNA

Answer 10

• rRNA helps form ribosomes
• helps link amino acids together

Question 11

DNA contains the

Answer 11

sequence of nucleotides that codes for proteins
sequence is read in groups of three called the triplet code

Question 12

during transcription

Answer 12

only one DNA strand is being transcribed
known as the template strand (aka the noncoding strand, minus strand, or antisense strand)

Question 13

mRNA molecules formed are

Answer 13

antiparallel and complementary to the DNA nucleotides

Question 14

base pairing

Answer 14

A-U and C-G

Question 15

mRNA nucleotide triplets are called

Answer 15

codons

Question 16

codons code for

Answer 16

amino acids

Question 17

amino acid chart

Answer 17

64 different codon combinations
61 code for amino acids
3 are stop codons
universal to all life

Question 18

redundancy

Answer 18

more than one codon codes for each amino acid

Question 19

reading frame

Answer 19

codons on the mRNA must be read in the correct groupings during translation to synthesize the correct proteins

Question 20

three steps in transcription

Answer 20

• initiation
• elongation
• termination

Question 21

initiation

Answer 21

• RNA polymerase molecules attach to a promoter region of DNA
• do not need a primer to attach

Question 22

promoter regions are

Answer 22

upstream of desired gene to transcribe

Question 23

initiation eukaryotes

Answer 23

• promoter region is called TATA box
• transcription factors help RNA polymerase bind

Question 24

initiation prokaryotes

Answer 24

RNA polymerase can bind directly to promoter

Question 25

elongation

Answer 25

- RNA polymerase opens the DNA and reads the triplet code of the template strand moves in the 3’ to 5’ direction mRNA transcript elongates 5’ to 3’ - RNA polymerase moves downstream only opens small sections of DNA at a time pairs complementary RNA nucleotides growing mRNA strand peels away from the DNA template strand DNA double helix then reforms - a single gene can be transcribed simultaneously by several RNA polymerase molecules helps increase the amount of mRNA synthesized increases protein production

Question 26

termination prokaryotes

Answer 26

- transcription proceeds through a termination sequence - causes a termination signal - RNA polymerase detaches - mRNA transcript is released and proceeds to translation - mRNA does NOT need modifications

Question 27

termination eukaryotes

Answer 27

- RNA polymerase transcribes a sequence of DNA called the polyadenylation signal sequence - codes for a polyadenylation signal (AAUAAA) - releases the pre-mRNA from the DNA - must undergo modifications before translation

Question 28

three modifications that must occur to eukaryotic pre-mRNA

Answer 28

- 5’ cap - Poly-A tail - RNA splicing

Question 29

5' cap (GTP)

Answer 29

5’ end of the pre-mRNA receives a modified guanine nucleotide “cap”

Question 30

Poly-A-tail

Answer 30

3’ end of the pre-mRNA receives 50-250 adenine nucleotides

Question 31

both the 5’ cap and the poly-A tail function to

Answer 31

- help mature mRNA leave nucleus - help protect mRNA from degradation - help ribosomes attach to the 5’ end of mRNA when it reaches the cytoplasm

Question 32

RNA splicing

Answer 32

sections of the pre-mRNA, called introns, are removed and then exons are joined together

Question 33

introns

Answer 33

intervening sequence, do not code for amino acids

Question 34

exons

Answer 34

expressed sections, code for amino acids

Question 35

alternative splicing

Answer 35

a single gene can code for more than one kind of polypeptide

Question 36

once all modifications have occurred, pre-mRNA is now considered

Answer 36

mature mRNA and can leave the nucleus and proceed to the cytoplasm for translation at the ribosomes