structure of DNA & protein synthesis

Question 1

what is DNA?

Answer 1

a polymer made from four
different nucleotides

Question 2

what does a nucleotide consist of?

Answer 2

a common sugar and
phosphate group with one of four different bases attached to the sugar

Question 3

what are the four bases?

Answer 3

A, C, G, T

Question 4

which bases pair with which?

Answer 4

A and T
C and G

Question 5

what is nucleotide an example of?

Answer 5

a monomer

Question 6

what does the order of bases control?

Answer 6

the order in which amino acids are coded

Question 7

what codes for an amino acid?

Answer 7

a sequence of three bases in the gene, a codon

Question 8

mRNA

Answer 8

messenger ribonucleic acid

Question 9

DNA

Answer 9

deoxyribonucleic acid

Question 10

what is DNA made up of?

Answer 10

repeating nucleotide units

Question 11

list 3 examples of proteins

Answer 11

-enzymes: amylase
-hormones: insulin
-structural proteins: collagen

Question 12

describe protein synthesis

Answer 12

1. the base sequence of the gene is copied into a complementary template molecule (mRNA)
2. the mRNA passes out of the nucleus and into the cytoplasm
3. the mRNA molecules attaches to a ribosome
4. amino acids are brought to the ribosome on carrier molecules (tRNA) to add to the growing protein chain
5. the ribosome reads the triplet of bases on the mRNA and uses it to join together the correct amino acids in the correct order
6. when the protein chain is complete it folds up to form a
   unique shape, enabling the proteins to do their job

Question 13

where does transcription take place in?

Answer 13

nucleus

Question 14

where does translation take place in?

Answer 14

cytoplasm

Question 15

what do the long strands of DNA consist of?

Answer 15

alternating sugar and phosphate
sections

Question 16

explain how the structure of DNA affects the protein made

Answer 16

the order of bases in DNA determines the sequence of amino acids in proteins

Question 17

what is a mutation?

Answer 17

a random change in an organism’s DNA

Question 18

when do mutations occur?

Answer 18

continuously, can occur spontaneously

Question 19

what do mutations do?

Answer 19

• change the sequence of the DNA bases in a gene, which produces a genetic variant
• as the sequence of DNA base codes for the sequence of amino acids that make up a protein, mutations to a gene sometimes lead to changes in the protein that it codes for

Question 20

what effect do mutations have on the protein?

Answer 20

• usually very little or not effect
• some can seriously affect as it can change the shape of proteins, affecting their abilities to function

Question 21

3 types of mutations

Answer 21

• insertions
• deletions
• substitutions

Question 22

describe insertions

Answer 22

• where a new base is inserted into the DNA base sequence where it shouldn’t be
• an insertion changes way the groups of three bases are read which can change the amino acids they code for
• they can have a knock on effect on the bases further on in the sequence

Question 23

describe deletions

Answer 23

• when a random base is deleted from the DNA base sequence
• they change the way that the base sequence is read and have knock-on effects further down the sequence

Question 24

describe substiutions

Answer 24

• substitution mutations are when a random base in the DNA base sequence is changed to a different base