Gene Expression 1.3

Question 1

what is a phenotype

Answer 1

physical and chemical state of an organism

Question 2

what controls gene expression

Answer 2

controlled by the nucleus

Question 3

what determines your phenotype

Answer 3

determined by proteins by using the code in DNA, when a gene is expressed the section of DNA is made into a protein

Question 4

structure of RNA

Answer 4

protein synthesis takes place on the ribosomes which are outside the nucleus in the cytoplasm

Question 5

What does mRNA do and what is it made up from

Answer 5

mRNA carries the genetic code out of the nucleus to the ribosome
it is made up of RNA nucleotides

Question 6

describe a molecule of RNA

Answer 6

single stranded
uracil
ribose sugar
found in nucleus and cytoplasm

Question 7

describe a molecule of DNA

Answer 7

double stranded
thymine
deoxyribose sugar
carries a copy of the DNA from the nucleus to the ribosome

Question 8

what is tRNA

Answer 8

takes a specific amino acid from the cytoplasm to the ribosome

Question 9

what is rRNA

Answer 9

forms the ribosome

Question 10

what is transcription

Answer 10

the synthesis of the mRNA from a section of DNA, controlled by RNA polymerase

Question 11

first 3 stages of transcription

Answer 11

1. RNA polymerase moves along the gene unwinding & unzipping DNA double helix
2. Free mRNA nucleotides join with complementary nucleotides on DNA template
3. weak hydrogen bonds form between base pairs

Question 12

stages 4-6 of transcription

Answer 12

4. strong chemical bonds form between the sugar and one RNA nucleotide and phosphate of the next
5. weak hydrogen bonds break between the complementary
   bases allowing mRNA to peel off the DNA
6. molecule is called a primary mRNA transcript

Question 13

stages 7-10 of transcription

Answer 13

7. introns are removed from the primary mRNA transcript
8. exons are retained
9. exons are spliced/joined together to form the mature mRNA transcript
10. mature mRNA transcript passes out of the nucleus into the cytoplasm where it joins to a ribosome

Question 14

what is translation

Answer 14

the synthesis of a protein under the control of mRNA
every 3 bases(triplet) on the mRNA is called a codon

Question 15

what is transfer RNA (tRNA)

Answer 15

found in the cytoplasm
single strand of nucleotides folded in a particular way
will carry the amino acid to the ribosome

Question 16

first 4 stages of translation

Answer 16

1. ribosome binds to 5’ end of mature mRNA transcript
2. tRNA has an anticodon and an amino acid attachment site
3. tRNA collects a specific amino acid
4. tRNA carries the amino acid to the ribosome

Question 17

last 4 stages of translation

Answer 17

5. anticodon of tRNA pairs up with a codon of mRNA
6. repeated for many tRNA and amino acids are brought adjacent to each other in correct sequence
7. peptide bonds form between adjacent amino acids to produce polypeptide chain
8. stop codon is reached which stops translation