Protein Synthesis - Paper 1

Question 1

What are proteins made up of?

Answer 1

Chains amino acids

Question 2

What is a protein?

Answer 2

A folded chain of amino acids

Question 3

What is an amino acid?

Answer 3

A small molecule which makes up protein

It is NOT a polypeptide chain - a polypeptide is a chain of many amino acids

Question 4

What differentiates between proteins?

Answer 4

Different number and order of amino acids

Question 5

What does it mean for a region of DNA to be non-coding?

Answer 5

It doesn’t directly translate into a protein

Question 6

What is a codon/triplet?

Answer 6

A sequence of three bases in a gene which code for an amino acid

Question 7

What does the order of bases in DNA tell us?

Answer 7

The order for combining amino acids to create a particular protein

Question 8

How can we change the protein made by a gene?

Answer 8

Alter the sequence of bases in that gene
Because the order of amino acids changes how a protein folds together, affecting its structure and function

Question 9

Give the two stages of protein synthesis in order

Answer 9

Transcription
Translation

Question 10

What is mRNA?

Answer 10

A copy of a single gene

Question 11

What is RNA polymerase?

Answer 11

An enzyme that binds to, unzips and synethesises a strand of mRNA complementary to a small section of DNA (a gene)

Question 12

What does RNA polymerase do?

Answer 12

Binds to the DNA just before the specific gene starts
Unzips the DNA strands (by breaking their weak hydrogen bonds between bases) so that the bases are exposed
Synthesises a strand of mRNA complementary to the DNA’s template strand

Question 13

At the beginning of transcription, what is unzipped?

Answer 13

The double stranded DNA

Question 14

What is a template strand?

Answer 14

The strand of DNA the RNA polymerase moved along

Question 15

Give another word for a codon

Answer 15

Triplet

Question 16

What does a triplet/codon do?

Answer 16

Code for a specific amino acid

Question 17

Which comes first in protein synthesis: transcription or translation?

Answer 17

Transcription

Question 18

What is tRNA?

Answer 18

Molecules which bring amino acids to ribosomes during translation in protein synthesis

Question 19

What does tRNA stand for?

Answer 19

Transfer RNA

Question 20

What does mRNA stand for?

Answer 20

Messenger RNA

Question 21

What is an anti-codon?

Answer 21

A sequence of three bases complementary to the codon of the mRNA strand which codes for the amino acid the tRNA molecule it is part of it carrying

Question 22

What is an anti-codon complementary to?

Answer 22

A codon on a strand of mRNA

Question 23

How many bases in a codon?

Answer 23

3
(Because it’s also known as a triplet)

Question 24

Give 3 differences of DNA and mRNA

Answer 24

mRNA is much shorter than DNA - it’s only one gene long
mRNA is only a singe strand - not two like in DNA
mRNA contains the base ‘U’ rather than ‘T’ in DNA

Question 25

What is transcription in protein synthesis?

Answer 25

The process of taking a single gene of DNA and copying it into a structure called mRNA

Question 26

What is translation in protein synthesis?

Answer 26

The process of using an mRNA strand to produce a protein

Question 27

What is a gene?

Answer 27

A **small section of DNA** which codes for a specific protein | bc it has a **specific sequence of bases** coding for a **specific sequence of amino acids** that fold to form a specific protein

Question 28

Why can't DNA leave the nucleus itself?

Answer 28

It's too big

Question 29

Instead of DNA (because it's too big), what structure leaves the nucleus to transfer information to the ribosome for protein synthesis?

Answer 29

mRNA

Question 30

Instead of the base 'T', which base does mRNA have?

Answer 30

U

Question 31

mRNA has the base 'U' instead of which DNA base?

Answer 31

T

Question 32

An 'A' on DNA will be complementary to which mRNA base?

Answer 32

U

Question 33

A 'T' on DNA will be complementary to which mRNA base?

Answer 33

A

Question 34

A 'G' on DNA will be complementary to which mRNA base?

Answer 34

C

Question 35

As the RNA polymerase moves along, what happens to the strands in DNA?

Answer 35

Unzipped just ahead of the RNA polymerase Closed just behind the RNA polymerase ## Footnote So only a small section of the DNA is exposed at once

Question 36

Where does translation occur as part of protein synthesis?

Answer 36

Ribosomes

Question 37

Describe the role of ribosomes in protein synthesis

Answer 37

Bind to mRNA Moves along the mRNA strand, catalysing the formation of peptide bonds between amino acids carried to mRNA by tRNA to produce a polypeptide chain

Question 38

Describe the process of translation as part of protein synthesis

Answer 38

mRNA strand and ribosome bind together An mRNA codon attracts its complementary anti-codon which is part of the tRNA molecule carrying the amino acid it codes for The ribosome moves along the mRNA strand and the process repeats with the ribosome attaching the sequence of amino acids with peptide bonds As the ribosome moves along, the tRNA molecules detatch from the mRNA, leaving the amino acid behind When the ribosome reaches the end of the mRNA strand, the amino acid chain detaches from the ribosome and can then fold up to form a protein

Question 39

What happens in ribosomes?

Answer 39

Protein synthesis (translation)

Question 40

What is the role of tRNA?

Answer 40

To carry amino acids to ribosomes

Question 41

On which molecule would you find an anti-codon?

Answer 41

tRNA

Question 42

A tRNA's anti-codon is complementary to what?

Answer 42

The codon of the mRNA strand that codes for the amino acid that tRNA molecule is carrying

Question 43

Ribosomes join amino acids together with which type of bond?

Answer 43

Peptide bond

Question 44

Give another name for a sequence of amino acids joined together by peptide bonds?

Answer 44

Polypeptide chains

Question 45

What is a polypeptide chain?

Answer 45

A sequence of amino acids joined together by peptide bonds