4.6.1.5 DNA Structure

Question 1

What does DNA stand for?

Answer 1

• deoxyribonucleic acid

Question 2

What is DNA?

Answer 2

• polymer
• contains instructions for the body

Question 3

What are chromosomes?

Answer 3

• structures made up of long molecules of DNA founding the nucleus of the cells

Question 4

What is DNA made up of?

Answer 4

• nucleotides

Question 5

What is each nucleotide made up of?

Answer 5

• one sugar molecule
• one phosphate group which formed the backbone
• one of the four types of organic bases

Question 6

What are the four types of organic bases?

Answer 6

• A
• C
• G
• T

Question 7

What is the structure of a DNA molecule?

Answer 7

• two DNA strands twisted together, creating a double helix
• each base is connected to another base in the other strand

Question 8

What are the complimentary base pairs?

Answer 8

• A and T
• G and C

Question 9

What does the order of bases form?

Answer 9

• a code

Question 10

What codes for an amino acid?

Answer 10

• each group of three bases (triplet)

Question 11

What do the amino acids form when joined together?

Answer 11

• protein

Question 12

What determines what type of protein is formed?

Answer 12

• order of bases in DNA

Question 13

How many types of amino acids are there?

Answer 13

• 20

Question 14

What are the non-coding DNA responsible for?

Answer 14

• switching genes on and off
• e.g. controlling whether the gene is used to form a protein or not

Question 15

What is protein synthesis?

Answer 15

• the process of producing a protein from DNA

Question 16

What does it mean if a gene is expressed?

Answer 16

• if a gene coded to make a protein

Question 17

What can’t the genetic code for making a protein I DNA do?

Answer 17

• move out of the nucleus as it is too big

Question 18

What do the DNA strands do

Answer 18

• pull apart from each other
• mRNA nucleotides match to their complimentary bases on the strand

Question 19

What is mRNA?

Answer 19

• messenger RNA
• different type of nucleotide

Question 20

What happens when mRNA nucleotides are joined together?

Answer 20

• create a new strand called mRNA strand which is a template of the original DNA

Question 21

What does the mRNA do that the genetic code for making a protein can’t?

Answer 21

• move out of the nucleus and then into the cytoplasm and then ribosomes

Question 22

What happens at the ribosomes?

Answer 22

• the bases on the mRNA are read in threes to code for an amino acid

Question 23

How are the corresponding amino acids brought to the ribosomes?

Answer 23

• carrier molecules

Question 24

What do the amino acids do when brought to the ribosomes?

Answer 24

• connect together to form a protein

Question 25

What happens when the chain of amino acids is complete?

Answer 25

- protein folds to form a unique 3D structure

Question 26

What does the proteins specific shape help it do?

Answer 26

- carry out its role

Question 27

What are the roles of proteins?

Answer 27

- enzymes - hormones - structural protein

Question 28

What is an enzyme?

Answer 28

- biological catalyst that speeds up the rate of reaction

Question 29

What is a hormone?

Answer 29

- chemical messengers that send signals around the body

Question 30

What is a structural protein?

Answer 30

- strong proteins in order to form structures like collagen

Question 31

What do mutations do to the sequences of bases DNA?

Answer 31

- change it

Question 32

What are the three ways mutations change the sequence of bases in DNA?

Answer 32

- base inserted in the code - base deleted from the code - base is substituted

Question 33

Why is a base being inserted into the code change the sequence?

Answer 33

- changes the way it is read - may change all the amino acids coded for after insertion

Question 34

Why is a base being deleted change the sequence?

Answer 34

- change the way it is read - may change the amino acids that were coded for after deletion

Question 35

Why is a base being substituted change the sequence?

Answer 35

- only change one amino acid or may not - this is because the new sequence can sometimes still code for the same amino acid

Question 36

What does a change in the type/sequence of amino acids do?

Answer 36

- affect the way the amino acids fold and therefore the structure

Question 37

What are the serious effects that come with mutations?

Answer 37

- substrate won't fit into active site so cannot act as a protein - structural protein may lose its shape

Question 38

Where else can mutations occur if not in amino acid sequences?

Answer 38

- in the non-coding parts that control whether the genes are expressed

Question 39

Why does variation between two organisms arise?

Answer 39

- coding DNA that determines proteins are their activities - non-coding DNA that determines which genes are expressed