3.4.2 DNA + Protein Synthesis

Question 1

What are the 2 processes

Answer 1

Transcription

Translation

Question 2

How do proteins form

Answer 2

In a condensation reaction

Question 3

What 4 structures can proteins take

Answer 3

Primary
Secondary
Tertiary
Quaternary

Question 4

Proteins are very important biological molecules

What can they be e.g

Answer 4

Enzymes,pigments,structural molecules e.g collagen,transport molecules etc

Question 5

What are proteins made up of

Answer 5

Many amino acids held together by peptide bonds

Question 6

What codes for each amino acids

Answer 6

3 bases (a triplet)

Question 7

How many amino acids are there

Answer 7

20

Question 8

Why do most amino acids have more than 1 triplet code

Answer 8

As the triplet code is degenerate

Question 9

What does DNA provide the instructions for

Answer 9

Building amino acids into a long sequence of nucleotides

Question 10

What form is a complementary section of part of the nucleotide sequence in DNA made in (in transcription)

Answer 10

pre-mRNA

Question 11

What happens to pre-mRNA after transcription

Answer 11

It gets spliced

Question 12

What is mRNA used as in translation

Answer 12

A template to which tRNA molecules attach + the amino acid it carries is linked to form a polypeptide

Question 13

What exposes the nucleotides at the start of transcription

Answer 13

DNA helicase breaks the hydrogen bonds between DNA bases separating the 2 strands

Question 14

In transcription, what moves along one of the exposed strands (template strand)
What happens

Answer 14

RNA polymerase

Causes nucleotides to join with individual complementary nucleotides from the ‘pool’ in the nucleus

Question 15

What are the 2 exposed strands called in transcription

Answer 15

Template strand

Copy strand

Question 16

Why is the other exposed strand called the copy strand

Answer 16

As the pre-mRNA that forms is a copy of this strand

Question 17

What joins with A,G,C+T on a template strand

Answer 17

A - U
G - C
C - G
T - A

Question 18

What builds up pre-mRNA in transcription

Answer 18

RNA polymerase adding the nucleotides one at a time

Question 19

Why are only about 12 bases pairs exposed at one time in transcription

Answer 19

As the DNA strands rejoin behind it

Question 20

When is the pre-mRNA molecule complete

Answer 20

When RNA polymerase reaches a stop codon in DNA and detatches

Question 21

What 2 sections is DNA made up of

Answer 21

Exons - code for protein

Introns - dont

Question 22

What’s splicing

Answer 22

The removal of introns so they don’t interfere with protein synthesis + the joining of exons

Question 23

What is made following splicing

Answer 23

mRNA

Question 24

How does mRNA leave the nucleus

What’s it attracted to where translation will occur

Answer 24

Leaves nucleus via nuclear pore

Attracted to ribosomes for translation

Question 25

How can a gene code for up to a dozen different proteins

Answer 25

As exons sections can be rejoined in different combinations

Question 26

What can affect pre-mRNA splicing | E.g

Answer 26

Mutations | E.g Alzheimer’s is due to splicing failures forming non-functional polypeptides

Question 27

What is translated into an amino acid sequence maki up a polypeptide Where does this take place

Answer 27

``` The codons (triplets) on mRNA On ribosomes ```

Question 28

how does translation occur

Answer 28

Ribosomes become attached to the start codon (AUG) at one end of the mRNA molecule Then the tRNA molecule with the complementary anti-codon sequence (UAC) moves to the ribosome + pairs up with the mRNA

Question 29

What does the tRNA carry in translation

Answer 29

An amino acid e.g methionine

Question 30

What happens once 1 tRNA molecule pairs up with the mRNA

Answer 30

Another tRNA molecule with a complimentary anti-codon pairs with the next codon on mRNA The ribosomes move along mRNA, bringing the 2 tRNA molecules together

Question 31

When does translation stop

Answer 31

Until the polypeptide chain is complete (meets a stop codon)

Question 32

How fast is translation

Answer 32

Rapid- about 15 amino acids can be joined each second

Question 33

What’s a proteins primary structure like

Answer 33

Single stranded polypeptide chain

Question 34

How can a protein form it’s secondary structure

Answer 34

Polypeptide chain may coil/pleat

Question 35

How can a protein form it’s tertiary structure

Answer 35

Secondary structure fold

Question 36

Where does the protein go after translation

Answer 36

Passes into ER for transportation Then passed from RER to the Golgi inside vesicles Golgi packages protein in a vesicle that fuses with the cell membrane and releases the protein from the cell