1.3- gene expression

Question 1

what is a genotype?

Answer 1

alleles an organism has for a particular characteristic

Question 2

what is a phenotype?

Answer 2

appearance of an organism

Question 3

what are genes?

Answer 3

DNA sequences that code for particular proteins

Question 4

what are alleles?

Answer 4

different forms of a gene

Question 5

what determines an organisms phenotype?

Answer 5

proteins produced as a result of gene expression

environmental factors also have influence

Question 6

3 types of RNA involved in transcription and translation

Answer 6

messenger RNA
transfer RNA
ribosomal RNA

Question 7

4 bases of RNA

Answer 7

adenine - uracil

cytosine - guanine

Question 8

function of mRNA

Answer 8

carries a copy of the DNA code from the nucleus to the ribosome

Question 9

function of tRNA

Answer 9

folds due to complementary base pairing

each tRNA molecule carries its specific amino acid to the ribosome

Question 10

function of rRNA

Answer 10

rRNA and proteins form the ribosome

Question 11

what is a codon?

Answer 11

group of 3 bases which codes for an amino acid

Question 12

2 stages of protein synthesis

Answer 12

transcription
(RNA splicing)
translation

Question 13

what happens during transcription?

Answer 13

mRNA carries a copy of the DNA code from the nucleus to the ribosome

Question 14

4 steps of transcription

Answer 14

DNA double helix is unwound by RNA polymerase

hydrogen bonds between base pairs break, separating the two strands

as RNA polymerase breaks the bonds, it synthesises a primary mRNA transcript using RNA nucleotides which form hydrogen bonds with the exposed DNA strand by complementary base pairing

non-coding sections called introns are removed from primary mRNA transcript and coding sections called exons are joined together from the mature mRNA transcript by RNA splicing where the order of exons remains unchanged

Question 15

8 steps of translation

Answer 15

the mRNA molecule travels through the cytoplasm and attaches to the ribosome

tRNA molecules transport specific amino acids to the ribosome

each mRNA codon codes for a specific amino acid

first codon of an mRNA molecule is a start codon which signals beginning of translation

anti-codons and codons match up and form complementary base pairs

peptide bonds join the amino acids together and form the polypeptide

used tRNA molecules exit the ribosome and collect another specific amino acid

last codon of an mRNA molecule is a stop codon which signals the end of translation

Question 16

what is at the 3’ end of a tRNA molecule?

Answer 16

attachment site for a specific amino acid

Question 17

what is at the opposite end of the 3’ of a tRNA molecule?

Answer 17

3 nucleotides with exposed bases

Question 18

what are the exposed bases of a tRNA molecule called and what do they do?

Answer 18

anticodons

match up against the codons of the mRNA

Question 19

what happens after translation?

Answer 19

polypeptide chains fold to form the three-dimensional shape of a protein held together by hydrogen bonds and other interactions between individual amino acids

Question 20

5 types of proteins

Answer 20

structural proteins

receptors proteins

antibodies

hormones

enzymes

Question 21

what is alternative RNA splicing?

Answer 21

when different proteins can be expressed from one gene

Question 22

how are different mature mRNA transcripts produced?

Answer 22

depending on what exons are retained from the same primary transcript