Gene expression

Question 1

What percentage of genes in a cell are expressed?

Answer 1

Only a fraction of the genes in a cell are expressed

Question 2

What does gene expression involve?

Answer 2

The transcription, splicing and translation of DNA sequences

Question 3

What is RNA and properties of RNA

Answer 3

RNA is single stranded and is composed of nucleotides containing ribose sugar, phosphate and bases: adenine, uracil, cytosine and guanine.

Question 4

What bases pair in RNA?

Answer 4

Adenine pairs with Uracil and Cytosine pairs with Guanine

Question 5

What are the three types of RNA?

Answer 5

mRNA, tRNA, rRNA
(Messenger RNA) (Transfer RNA) ( Ribosomal RNA)

Question 6

What RNA’s are involved in transcription and translation

Answer 6

mRNA tRNA and rRNA

Question 7

What is mRNA?

Answer 7

mRNA ( messenger RNA ) carries a complementary copy of the genetic code ( DNA ) from the nucleus to the ribosome.

mRNA is only complementary to ONE GENE in DNA

Question 8

where is mRNA transcribed?

Answer 8

mRNA is transcribed in the nucleus and translated into proteins by ribosomes in the cytoplasm

Question 9

where is mRNA translated?

Answer 9

mRNA is translated by ribosomes in the cytoplasm into proteins

Question 10

where does RNA splicing occur?

Answer 10

RNA splicing occurs in the nucleus

Question 11

what is a triplet of bases on mRNA called?

Answer 11

A codon

Question 12

What is a triplet of bases on tRNA called?

Answer 12

An anticodon

Question 13

What does the codon and anticodon code for?

Answer 13

A specific amino acid

Question 14

how does tRNA fold?

Answer 14

tRNA folds due to complementary base pairing

Question 15

What is the function of tRNA?

Answer 15

tRNA carries a specific amino acid to the ribosome for translation

Question 16

Describe the structure of tRNA

Answer 16

tRNA has an attachment site for a specific amino acid at one end
tRNA has an anticodon ( exposed triplet of three complementary bases to mRNA codon ) at the other end

Question 17

What forms the ribosome?

Answer 17

Ribosomal RNA ( rRNA ) and proteins

Question 18

What is the function of rRNA?

Answer 18

To form the ribosomes along with proteins

Question 19

What is stage 1 of transcription?

Answer 19

RNA polymerase moves along the DNA unwinding the double helix at a specific gene and breaking hydrogen bonds between bases.

Question 20

What is stage 2 of transcription?

Answer 20

RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairing to the DNA.

Question 21

What occurs that causes a primary transcript to form a mature transcript?

Answer 21

RNA splicing

Question 22

What occurs in RNA splicing?

Answer 22

Introns are removed and exons are retained and joined together to from a mature mRNA transcript

Question 23

What are exons?

Answer 23

Exons are coding regions of DNA

Question 24

What are introns?

Answer 24

Introns are non coding regions of DNA

Question 25

Is the order of exons changed during splicing?

Answer 25

No, the order of exons is not changed.

Question 26

How does translation begin and end!

Answer 26

Translation begins at a start codon and ends at a stop codon

Question 27

What occurs in translation to produce a chain of amino acids?

Answer 27

Anticodons on tRNA bond to codons by complementary base pairing, translating the genetic code into a sequence of amino acids.

Question 28

What joins amino acids together?

Answer 28

Peptide bonds join amino acids together.

Question 29

What is formed when amino acids are bonded by peptide bonds?

Answer 29

A Polypeptide chain

Question 30

What happens to tRNA as the polypeptide is formed?

Answer 30

tRNA leaves the ribosome to the cytoplasm to pick up another complementary amino acid for further translation.

Question 31

What is alternative RNA splicing?

Answer 31

alternative RNA splicing is the process by which certain exons are retained or left out of the mature mRNA transcript to produce different proteins from one gene

Question 32

What do polypeptides do?

Answer 32

Polypeptide chains fold to form the 3D shape of a protein

Question 33

What are polypeptides held together by?

Answer 33

Hydrogen bonds and * other interactions between individuals amino acids *

Question 34

What is phenotype determined by?

Answer 34

Phenotype is determined by proteins produced as a result of gene expression

Question 35

What else influences phenotype?

Answer 35

Environmental factors.