Gene Expression

Question 1

what is meant by a genotype

Answer 1

sequence of DNA bases

Question 2

what is meant by a phenotype

Answer 2

physical and chemical characteristics of an organism determined by its genotype

Question 3

what is gene expression

Answer 3

involves the DNA sequences being transcribed and translated to make a protein

Question 4

what are proteins made of

Answer 4

amino acids

Question 5

what is a polypeptide

Answer 5

a chain of amino acids joined together by peptide bonds

Question 6

what gives a protein it’s shape

Answer 6

the order of amino acids determines a proteins shape and therefore their function

Question 7

what determines the order of amino acids

Answer 7

the sequence of DNA bases in the gene the proteins codes for

Question 8

what are the 3 types of RNA

what do they do?

Answer 8

• mRNA (messenger RNA): carries a copy of code from DNA in the nucleus to ribosome
• tRNA (transfer RNA): carries specific amino acids to ribosome where they can be linked together into a polypeptide
• rRNA (ribosomal RNA): ribosome is site of protein synthesis, made up of rRNA and proteins

Question 9

which enzyme is required to make a molecule of mRNA

Answer 9

RNA Polymerase

Question 10

what are the differences between DNA and RNA?

Answer 10

DNA - Double stranded
RNA - Single Stranded

DNA - Adenine + Thymine
RNA - Adenine + Uracil

DNA - Deoxyribose Sugar
RNA - Ribose Sugar

Question 11

What is transcription

Answer 11

makes a copy of DNA using mRNA

Question 12

stages of Transcription

Answer 12

1. RNA Polymerase unzips DNA
2. Free RNA nucleotides line up with complementary base pairs in DNA
3. A-U G-C
4. Hydrogen bonds form

Question 13

what is a codon?

Answer 13

a triplet of bases on mRNA molecule which codes for a specific amino acid

Question 14

what is an anticodon?

Answer 14

a triplet of based on tRNA molecule that matches up with a codon on mRNA

Question 15

which process allows the formation of a mature mRNA transcript?

Answer 15

RNA splicing

Question 16

what happens during RNA splicing?

Answer 16

the introns are removed, and the exons are joined together to form the mature mRNA transcript

Question 17

what is an intron

Answer 17

a non coding region of mRNA primary transcript which is removed during RNA splicing

Question 18

what is an exon?

Answer 18

a coding region of dna

Question 19

what is a ribosome made of?

Answer 19

rRNA abs proteins

Question 20

where does translation begin?

Answer 20

at a start codon

Question 21

where is mRNA translated into proteins?

Answer 21

by ribosomes in the cytoplasm

Question 22

what is the structure of tRNA molecule?

Answer 22

an anticodon at one end and an attachment site for a specific amino acid at the other.
Folded due to complementary base pairing

Question 23

what is the process which makes a protein using the information carried in mRNA?

Answer 23

Translation

Question 24

stages of translation

Answer 24

1. tRNA picks up an amino acid and takes it to the nucleus
2. anti codons + codons pair up using complementary base pairing
3. peptide bonds form between amino acids
4. tRNA released to pick up new amino acid

4

Question 25

where does translation end?

Answer 25

stop codon

Question 26

which process can allow many different proteins to be expressed from one gene?

Answer 26

Alternative RNA splicing

Question 27

how do you produce different mature mRNA transcripts from the same primary transcript?

Answer 27

by retaining different exons

Question 28

how many codons code for one amino acid?

Answer 28

one

Question 29

how many bases are in a codon

Answer 29

three

Question 30

how many bases code for one amino acid?

Answer 30

three