Protein Synthesis

Question 1

Transcription

Answer 1

DNA–> mRNA
Occurs in the nucleus

Question 2

Translation

Answer 2

mRNA–> Protein
construction of polypeptide chain with help of tRNA
Occurs in the Cytoplasm

Question 3

Central Dogma of Molecular Biology

Answer 3

The explanation of the process that describes how DNA becomes RNA becomes protein.

Question 4

mRNA

Answer 4

A copy of a gene formed from complementary base-pairing rules of the template DNA strand that can leave the nucleus.

Question 5

tRNA

Answer 5

Strand of RNA that folds on itself with the anticodon on one end and the corresponding amino acid to the codon.

Question 6

Translation Unit

Answer 6

Ribosome reading mRNA and building polypeptide chain with the help of tRNA.

Question 7

Promoter

Answer 7

Tells enzyme to begin transcription
Begins with TATA box

Question 8

Termination Sequence

Answer 8

Tells enzyme to stop transcription

Question 9

Exon

Answer 9

Expressed portion of gene that tells the exact type and sequence of amino acids to use to build polypeptide chain

Question 10

Intron

Answer 10

ONLY IN EUKARYOTES
Unexpressed portion of gene that doesn’t directly code for proteins.
May have functions, (regulates gene expression, RNA transcription, chromosome structure), unknown functions, or no function at all.

Question 11

Silent Mutation

Answer 11

Substitution mutation where the substituted nucleotide does not change the amino acid that is coded for.

Question 12

Nonsense Mutation

Answer 12

Substitution mutation where the substituted nucleotide changes to code for a stop codon.

Question 13

Missense Mutation

Answer 13

Substitution mutation where the substituted nucleotide changes the amino acid that is coded for.

Question 14

Substitution Mutation

Answer 14

One or more nucleotides is substituted by another nucleotide with a different base.

Question 15

Insertion Mutation

Answer 15

The addition of one or more nucleotides that may or may not cause a frameshift.

Question 16

Deletion Mutation

Answer 16

The deletion of one or more nucleotides that may or may not cause a frameshift.

Question 17

Duplication Mutation

Answer 17

A segment of the chromosome is replicated so there are multiple copies of that segment.

Question 18

Frameshift

Answer 18

Shifting of sequential readings of codons so a different set of three bases are read, leading to different sequence of amino acids following the mutation. Caused by insertion and deletion mutations (if nucleotides are inserted or deleted in multiples of three, frame shift will not be caused).

Can result in developmental issues or even death.

Question 19

Codon

Answer 19

Each set of three nucleotides in translation that codes for a specific amino acid

Question 20

Start Codon

Answer 20

The sequence of three bases that begins translation (AUG; Methionine)

Question 21

Stop Codon

Answer 21

The sequence of three bases that ends translation (UAA, UAG, or UGA)

Question 22

Template Strand

Answer 22

The DNA strand that the mRNA is made from.

Question 23

mRNA cap

Answer 23

In eukaryotes, when introns are removed from pre-mRNA, the 5’ end is capped with modified guanine nucleotides.

Question 24

mRNA Poly-A tail

Answer 24

In eukaryotes, when introns are removed from pre-mRNA, a tail is added to the 3’ end by an enzyme that consists of 50-250 adenine nucleotides.

Question 25

Anticodon

Answer 25

The complementary nucleotides to the mRNA codons delivered with amino acids by tRNA.

Question 26

Transcription process (6)

Answer 26

1. RNA polymerase unwinds DNA
2. RNA polymerase places complementary nucleotides on template strand of DNA
3. Transcription ends when termination sequence is read
4. (E) Introns are removed from the mRNA by spliceosomes
5. (E) The 5’ end is capped and a poly-A tail is added on the 3’ end
6. (E) mRNA is transported out of the nucleus

Question 27

Translation process

Answer 27

7. Translation unit (mRNA and ribosome subunits) is brought together
8. The small subunit scans the mRNA until it finds the start codon
9. Initiator tRNA hydrogen bonds to the codon
   10&11. 3 spaces on ribosome: tRNA takes up the first and second spot, a third tRNA takes up thrid spot while tRNA is first spot shifts out leaving the amino acid. Then tRNA is spots two and three shift over into the first and second spots. tRNA that just left goes back to get another anticodon and amino acid.
10. Steps 10 and 11 repeat until stop codon is read. A release factor binds instead of a tRNA and a water molecule is added in place of the amino acid to finish off the polypeptide chain.
11. The polypeptide chain is released
12. When all needed polypeptide chains are produced, the translation unit falls apart
13. The finished polypeptide chain moves into the rough ER for folding and modification to become a functional protein.

Question 28

Peptidyl transferase

Answer 28

An enzyme that covalently bonds amino acids in translation.