Y12 MW - Protein Synthesis and Mutations (Complete)

Question 1

What is the genome?

Answer 1

All of the coding and non-coding genetic material of an organism

Question 2

What is the proteome?

Answer 2

The entire set of proteins that can be produced by a cell at a certain time

Question 3

What is transcription?

Answer 3

The process of mRNA being produced from DNA

Question 4

What is an expressed protein?

Answer 4

One that can be made

Question 5

Splicing only occurs in ——— cells

Answer 5

Eukaryotic

Question 6

What is a gene?

Answer 6

a base sequence of DNA that codes for a protein

Question 7

What is a gene loci?

Answer 7

The fixed position of a gene on a particular DNA molecule / chromosome

Question 8

What is a triplet?

Answer 8

A sequence of 3 nitrogenous bases which code for a specific amino acid

Question 9

What is a codon?

Answer 9

A sequence of 3 RNA bases

Question 10

What is an anticodon?

Answer 10

A sequence of 3 nucleotide bases at one end of a tRNA molecule which is complementary to the mRNA codon

Question 11

What is an exon?

Answer 11

The sequences within a gene which code for the polypeptide

Question 12

What is an intron?

Answer 12

The non-coding sequence of bases in a gene that do not code for the amino acid sequence. They are removed during splicing

Question 13

What are the properties of the genetic code?

Answer 13

Non-overlapping
Degenerate
Universal

Question 14

What does it mean that the genetic code is universal?

Answer 14

A particular triplet codes for the same amino acid in all living organisms

Question 15

What does it mean that the genetic code is non-overlapping?

Answer 15

The triplets are read sequentially

Question 16

What does it mean that the genetic code is degenerate?

Answer 16

More than one DNA triplet codes for the same amino acid

Question 17

What is the structure of tRNA?

Answer 17

tRNA is made up of linear RNA nucleotides which are folded into a “cloverleaf” shape. This is held together by hydrogen bonds between the complementary base pairs

Question 18

What is the structure of mRNA?

Answer 18

mRNA is made up of short, linear RNA nucleotide sequences that carry the genetic code for the construction of a polypeptide

Question 19

Does splicing take place inside or outside of the nucleus?

Answer 19

Inside of the nucleus

Question 20

What is the structure of a chromosome?

Answer 20

A chromosome is made up of two identical chromatids which are joined at the centromere

Question 21

What are homologous chromosomes?

Answer 21

A pair of chromosomes which have identical genes

Question 22

True or false? Only one DNA strand acts as a template to code for proteins

Answer 22

True

Question 23

How many different amino acids are there?

Answer 23

20

Question 24

What is the process of transcription?

Answer 24

DNA helicase unwinds the DNA strands in a section of the DNA molecule by breaking the hydrogen bonds between the bases
One DNA strand acts as a template
Free RNA nucleotides diffuse into position with their complementary base pair (A with U and C with G)
RNA polymerase joins the RNA nucleotides by forming phosphodiester bonds
This forms a mRNA molecule
The pre-mRNA is then spliced to remove the introns
The nature mRNA now only contains exons

Question 25

What does it mean that mRNA is unstable?

Answer 25

It is broken down and destroyed rapidly (meaning continuous production of proteins e.g hormones and enzymes does occur)

Question 26

Does splicing occur in prokaryotic cells?

Answer 26

No as prokaryotic mRNA does not contain introns

Question 27

What is translation?

Answer 27

Where mRNA is translated and an amino acid sequence is produced

Question 28

What is the process of translation?

Answer 28

mRNA leaves the nucleus through the nuclear pores to the ribosome in the cytoplasm
Codon on the mRNA is complementary to the anti-codon on tRNA so the tRNA pairs with the mRNA and hydrogen bonds form between the codon and anti-codon
tRNA carries a specific amino acid so the sequence of codons on the mRNA determines the order of amino acids
Peptide bonds form between the amino acids held close on the ribosome
The tRNA detaches and collects another amino acid from the cytoplasm
The ribosome moves along the mRNA molecule

Question 29

What is a mutation?

Answer 29

A change in the nucleotide base sequence of DNA

Question 30

How does a mutation occur?

Answer 30

Spontaneously as DNA is being replicated when a cell divides by mitosis or meiosis
By mutagenic agents

Question 31

What is a base substitution?

Answer 31

Where one nucleotide is replaced with another, containing a different base

Question 32

What is a deletion mutation?

Answer 32

This is where there is a loss of a nucleotide, causing the frame to shift

Question 33

What is an inversion mutation?

Answer 33

Where two nucleotides are swapped around

Question 34

What is a duplication mutation?

Answer 34

Where an addition of the same nucleotide occurs again in the sequence, causing a frame shift

Question 35

What is a translocation mutation

Answer 35

Where a part of the DNA sequence is removed and placed in a different area of the DNA

Question 36

Many mutations affect the ————— of a protein molecule

Answer 36

Tertiary structure

Question 37

What is a mutagen? Give examples of this

Answer 37

A mutagen is anything which causes a mutation
These include ionising radiation, UV radiation and certain chemicals e.g benzene in crude oil