Gene Expression

Question 1

Does a Prokaryote have more than one cell?

Answer 1

NO

Question 2

The genetic information of DNA is stored as a certain sequence of…

Answer 2

Nitrogenous Bases

Question 3

Cytosine pairs with…

Answer 3

Guanine

Question 4

Because each strand runs in opposite directions, DNA can be considered as…

Answer 4

Anti-parallel

Question 5

In which direction is DNA synthesised?

Answer 5

From 5’end to 3’end

Question 6

A codon of DNA corresponds to…

Answer 6

a complementary codon on an strand of mRNA.

Question 7

A codon on a strand of mRNA corresponds to (next step in process)…

Answer 7

An anticodon on a tRNA

Question 8

A tRNA anticodon corresponds to…

Answer 8

A certain amino acid

Question 9

Why does the sequence of amino acids matter?

Answer 9

Hydrogen bonding between amino acids affect the overall shape of the produced polypeptide chain, and therefore the function of the final protein.

Question 10

A part of DNA that does not code for a protein is called what?

Answer 10

An intron.

Question 11

What is the equivalent of a START codon for DNA?

Answer 11

Prometer

Question 12

Multiple codons code for one amino acid. what is this attribute called, and what is its use?

Answer 12

Degeneracy of the Code, and it is there to minimise the effect of point mutations, and provide redundancy against the harmful expression of mutations.

Question 13

Why does mRNA exist?

Answer 13

1: the DNA is too precious to leave the cell (there are enzymes and other hazards in the cytoplasm that could damage the DNA and cause harmful mutations and loss off important genetic information
2: A Gene can be expressed multiple times at once (i.e. multiple strands of mRNA can be sent out to produce multiple proteins, wouldn’t be possible with one copy of the gene)
3: Double-stranded DNA is too big to get out of the narrow nuclear pore, while mRNA is not.

Question 14

What is a frame shift mutation?

Answer 14

An insertion or deletion mutation where the number of bases added or removed is not a multiple of 3

Question 15

What is the definition of a mutation?

Answer 15

A mutation is a PERMANENT change in the base sequence of DNA.

Question 16

What are mutations that do not result in a frame shift called?

Answer 16

Point mutations (inversion, substitution, or addition/deletion where number added/removed is a multiple of 3)

Question 17

Which are more dangerous: Frame shifts or point mutations? Why

Answer 17

Frame shifts are more dangerous because they affect a large number or codons, including start and stop codons. They greatly affect the resulting makeup and length of the polypeptide chain, changing the overall protein’s shape and most likely rendering it useless.

Question 18

Why are point mutations less harmful than frame shift mutations?

Answer 18

They only affect one codon. Due to degeneracy of the code, there is also a chance that regardless of the mutation, the correct amino acid will be produced, and the protein will have the correct shape. As only one amino acid is affected, it could be that the overall shape of the resulting protein is similar enough to the one intended that the protein could still be useful.

Question 19

What is a metabolic pathway?

Answer 19

A series of biochemical reactions where the product of one reaction is the substrate for the next.

Question 20

In a metabolic pathway, if one step is removed (due to a mutation, for example), will the other steps be able to carried out?

Answer 20

No, as the required substrate will be not be present. Worse, the precursor substrate will build up.