Ch. 5.3- Protein Synthesis

Question 1

Define protein synthesis. What is another name for it?

Answer 1

Genetic information in the cell is read and used to make gene products. Also called gene expression.

Question 2

Define transcription

Answer 2

When genes are copied into a new format. RNA

Question 3

Translation

Answer 3

Reading of mRNA to make proteins.

Question 4

What is the first step (initiation) of transcription?

Answer 4

1) RNA polymerase binds to the promoter (beginning region of the gene in DNA) The RNA polymerase then unwinds the DNA to reveal a single stranded template of the gene that will be transcribed into RNA.

Question 5

What is the second step (elongation) of transcription?

Answer 5

During elongation, the enzyme advances along the single strand of DNA laying down complimentary ribonucleotides.

Question 6

What is the third step (termination) of transcription?

Answer 6

Happens when the RNA polymerase reaches the end of the gene. Termination sequence signals the polymerase to fall of the DNA and the new RNA transcript is released.

Question 7

Where does transcription occur in eukaryotes and prokaryotes?

Answer 7

Eukaryotes- happens in nucleus

Prokaryotes- happens in the cytoplasm

Question 8

Define reverse transcription

Answer 8

When some cells and viruses use RNA as a template to build copy DNA.

Question 9

What is the term for cells and viruses that carry out reverse transcription?

Answer 9

Reverse transcriptases

Question 10

What are the three types of RNA used in proteins synthesis?

Answer 10

mRNA
tRNA
rRNA

Question 11

What does mRNA do?

Answer 11

Carries genetic messages in genetic triplet code (codons) and is translated to build a protein.

Question 12

What does tRNA do?

Answer 12

Cloverleaf shaped molecule that serves as a an adaptor that ushers amino acids into the ribosome during proteins synthesis.

Question 13

What does rRNA do?

Answer 13

Takes on complex stem and loop structures and combines with proteins to build ribosomes.

Question 14

Where are codons found?

Answer 14

only in mRNA.

Question 15

What is the role of codons?

Answer 15

They specify the amino acid type to be built or signal the stop of translation.

Question 16

What are the descriptive terms for mRNA that carry code for multiple types of amino acids as apposed to carrying code for only one.

Answer 16

Polycystronic

Monocystronic

Question 17

What is the role of tRNA?

Answer 17

They bring the correct amino acid to the ribosome. These carry an anticodon loop that is complimentary to the codon part of mRNA which ensures that the right amino acids arrive in the right order.

Question 18

What is the role of rRNA?

Answer 18

They all help ribosomes “read” or scan an mRNA molecule and form peptide bonds between amino acids to build a protein- making complex three dimensional structures.

Question 19

Define exon

Answer 19

The segments of mRNA sequences that are decoded to build proteins.

Question 20

Define introns

Answer 20

The segments of mRNA code that are not decoded to build proteins. These determine how much protein is made and what protein is present in a cell.

Question 21

Define splicing

Answer 21

When intones are cut out of the mRNA in the nucleus so that the correct sequence of RNA code can be read by the ribosomes outside the nucleus.

Question 22

What is the name of the thing that does the splicing in the removal of introns?

Answer 22

Spliceosome

Question 23

Define sense condons

Answer 23

Codons that encode amino acids

Question 24

Define non-sense condons

Answer 24

codons that encode stop signals

Question 25

What is the core structure of amino acids made out of?

Answer 25

A Amine and a Carboxyl groups

Question 26

What are the three sites of a ribosome?

Answer 26

Exit site (E), peptidyl site (P), and acceptor site (A).

Question 27

Define polysomes

Answer 27

Collections of many ribosomes on a single mRNA strand.

Question 28

What are the three phases of translation?

Answer 28

Initiation
Elongation
Termination

Question 29

What happens in translation during initiation?

Answer 29

Ribosome attaches to mRNA till it find a “start code” where it adds the first amino acid

Question 30

What happens in translation during elongation?

Answer 30

Ribosomes attach to mRNA and elongate the protein. Then tRNA bring amino acids in an anticodon formation that (if matched to the condon formation of mRNA correctly) are bonded by the ribosome with a peptide bond. tRNA enters via the A site and leaves via the E site of ribosomes.

Question 31

Define peptide bonds

Answer 31

Type of covalent bond where the amine group of an Amino acid covalently bonds with the carboxyl group of another Amino acid. This forms polypeptides of proteins. This chemistry happens in the P and A sites of the ribosomes.

Question 32

Where does the initiator tRNA enter the ribosome?

Answer 32

The P site.

Question 33

What happens during translation in the termination phase?

Answer 33

The ribosome encounters a “stop” or “nonsense” codon, and translation is terminated.

Question 34

What is another term for a “stop codon”

Answer 34

A nonsense codon