Gene Expression (3)

Question 1

What is a genotype?

Answer 1

Is the combination of genes that a cell contains.

Question 2

How is a cell’s genotype determined?

Answer 2

The sequences of bases in the genes determines the genotype of a cell.

Question 3

What is a phenotype

Answer 3

A phenotype is the physical expression of the genes in a cell.

Question 4

How is a cell’s phenotype determined?

Answer 4

It is determined by the proteins that are synthesised when the genes are expressed.

Question 5

How much of the genes in a cell are expressed?

Answer 5

Only a fraction of the genes in a cell are expressed.

Question 6

What affects gene expression?

Answer 6

The influence of environmental factors whether it be inside or outside (intra or extra-cellular).

Question 7

What controls gene expression?

Answer 7

Gene expression is controlled by the regulation of the processes of transcription and translation.

Question 8

What is a protein made up of?

Answer 8

One or more polypeptide chains.

Question 9

What does RNA (Ribonucleic acid) do?

Answer 9

Provides a bridge between DNA and protein synthesis.

Question 10

Where is RNA found?

Answer 10

Nucleus and Cytoplasm.

Question 11

What are the three different forms of RNA?

Answer 11

rRNA
tRNA
mRNA

Question 12

What does rRNA (ribosomal RNA) do?

Answer 12

It binds to proteins to form ribosomes which are the site of protein synthesis.

Question 13

What does mRNA (messenger RNA) do?

Answer 13

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

Question 14

What does tRNA (transfer RNA) do?

Answer 14

It pick up and carries a specific amino acid from the cytoplasm and carries it to the ribosome.

Question 15

What is RNA in term of structure?

Answer 15

It is a single stranded molecule that is composed of nucleotides, which just like DNA contain a phosphate, a base and a sugar.

Question 16

What is an RNA nucleotide made up of?

Answer 16

Base, ribose sugar and a phosphate.

Question 17

What are the four bases that an RNA nucleotide can contain?

Answer 17

Adenine, uracil, cytosine and guanine

Meaning there are 4 different kinds of nucleotides.

Question 18

What are the base pairing rules in RNA?

Answer 18

Adenine - Uracil
Guanine - Cytosine

Question 19

What holds the bases together in an RNA nucleotide?

Answer 19

Weak hydrogen bonds.

Question 20

What holds the nucleotides together in RNA?

Answer 20

Strong sugar (ribose) phosphate bonds.

Question 21

What are amino acids?

Answer 21

They are the building blocks of proteins.

Question 22

How many amino acids are there that exist naturally within cells?

Answer 22

20.

Question 23

How many bases is DNA made up of?

Answer 23

4

Question 24

How many amino acids could be coded for with the bases in DNA?

Answer 24

4 which would not be enough as when given a two letter code it would only result in 16 possible arrangements which is not enough as there are 20.

Question 25

What is a triplet code?

Answer 25

A triplet code is a code consisting of 3 bases.

Question 26

How many variations of amino acids can a triplet code produce?

Answer 26

64 which is more than enough as the required amount is 20.

Question 27

How many bases/nucleotides code for an amino acid?

Answer 27

3.

Question 28

What are the 2 main processes that take place during protein synthesis?

Answer 28

Transcription and Translation.

Question 29

What is the first step in protein synthesis?

Answer 29

Transcription.

Question 30

What does the process of transcription require?

Answer 30

DNA (to act as a template for the new RNA molecule)
RNA polymerase
A supply of four different nucleotides
ATP