DNA

Question 1

who discovered DNA in 1953?

Answer 1

James Watson and Francis Crick (officially)
Rosalind Franklin

Question 1

what did Watson and Crick do?

Answer 1

interpreted the x-ray diffraction patterns produced by Rosalind Franklin to propose a model for the molecule of life

Question 1

what does DNA stand for?

Answer 1

Deoxyribose Nucleic Acid

Question 1

what was their model called?

Answer 1

helical model

Question 2

what is DNA?

Answer 2

molecule of heredity

Question 2

what’s the formula for DNA?

Answer 2

Belongs to pentose sugar C5H10O5
deoxyribose means O4

Question 2

what’s the structure of DNA?

Answer 2

It is a long macromolecule of polymer consisting of two helical chains coiled around a common axis.
The monomers of these chains are nucleotides

Question 2

describe the nucleotides

Answer 2

of a 5-carbon sugar a phosphate group and a nitrogen containing organic base

Question 2

what are the organic bases called?

Answer 2

Adenine, Guanine, Thymine, Cytosine

Question 2

describe the properties of each base

Answer 2

Adenine and Guanine are the larger bases, described as PURINES.
Thymine and Cytosine are the two smaller bases, described as PYRIMDINES.

Question 2

whats a purine?

Answer 2

it has two rings

Question 3

whats a pyrimidine?

Answer 3

made of 1 ring- when we pair them we get 3 rings meeting in the middle.

e.g. Thymine is a pyrimidine base- a single nitrogen containing ring is part of its structure

Question 3

what’s the position of a chromosome called?

Answer 3

locus

Question 4

what’s a gene?

Answer 4

short section of DNA that codes for a protein – has a specific locus on a chromosome

Question 5

what’s a recessive gene?

Answer 5

non-functioning protein (doesn’t do its job) e.g. cystic fibrosis

Question 6

what’s a dominant gene?

Answer 6

functioning protein (always does its job) e.g. Huntington’s disease

Question 7

what’s a type of nucleic acid?

Answer 7

ATP
Adenosine Triphosphate

Question 8

name some reactions ATP is essential for

Answer 8

Photosynthesis, respiration, movement, metabolism, active transport, thermoregulation, bioluminescence

Question 9

how is ATP used in metabolism?

Answer 9

Light energy is converted by plants into chemical energy during ph/s -> The chemical energy from ph/s in the form of organic molecules, is converted into ATP during respiration -> ATP is used by cells to preform useful work

Question 10

how does ATP release energy?

Answer 10

the 3 phosphate groups are joined together by 2 high energy bonds.
when hydrolysed the bond breaks which releases a large amount of energy

Question 11

what is ADP?

Answer 11

Adenosine diphosphate.

Question 12

what enzyme catalyses the hydrolysis of ATP?

Answer 12

ATPase

Question 13

what is lost during the hydrolysis of ATP/making of ADP?

Answer 13

the phosphate group

Question 14

in ways can ATP reform to make ADP+Pi?

Answer 14

1. Photophosphorylation
2. Oxidative photophosphorylation
3. Substrate–level phosphorylation

Question 15

when does photophosphorylation happen?

Answer 15

occurs in the chlorophyll during photosynthesis

Question 16

when does oxidative photophosphorylation happen?

Answer 16

occurs in the mitochondria during the electron transport chain (part of respiration)

Question 17

when does substrate-level phosphorylation happen?

Answer 17

when phosphate groups are transferred from donor molecules to ADP

Question 18

why could ATP be a better source than glucose?

Answer 18

-The energy released from the splitting of ATP into ADP releases energy in small, manageable bursts -Hydrolysis of ATP to ADP is a single reaction, glucose breakdown requires a long series of reactions It is immediate energy souce bc its made by 1 reaction

Question 19

advantages of ATP:

Answer 19

-instant source of energy in the cell -releases energy in small amounts as needed -it is mobile and transports chemical energy to where it is needed in the cell -Universal energy carrier and can be used in many different chemical reactions

Question 20

what are the 4 differences between DNA and RNA?

Answer 20

-RNA has the sugar ribose instead of deoxyribose -RNA has the base uracil instead of thymine - RNA is usually single stranded - RNA is usually shorter than DNA

Question 21

where is the phosphodiester bond created?

Answer 21

between the sugar of one DNA molecules and the phosphate of another

Question 22

steps for DNA replication

Answer 22

1.An enzyme called helicase attaches to the DNA molecule and moves along its length (unzipping). 2. Hydrogen bonds holding the DNA strands together are broken and the two strands of the helix begin to sperate. 3.The enzyme DNA polymerase join together the activated nucleotides to form the new sugar-phosphate backbone 4.Free nucleotides from the nucleoplasm are attracted to their complementary bases on each separated strand of DNA 5.The nucleotides bond together by the enzyme DNA polymerase 6.Two identical DNA molecules are formed

Question 23

what did Watson and Crick propose?

Answer 23

during replication, the strands of DNA separate and each strand acts as a template from the formation of a new strand of DNA. OG strand is conserved

Question 24

describe the molecular structure of DNA and explain how a sequence of DNA is replicated in the bacteria (7)

Answer 24

made of nucleotides Adenine, Cytosine , Thymine , Guanine sugarlgosphate backbone AT CG held by hydrogen bonds semi conservative replication DNA polymerase

Question 25

explain why specific base pairing is important in DNA replication (3)

Answer 25

to make exact copies the base sequence must be the same as the original DNA. both strands act as a template

Question 26

explain how the structure of DNA is related to its function (6)

Answer 26

-sugar phosphate backbone gives strength -coiling gives compact shape -long molecule allows info to be stored -double helix protects weak hydrogen bonds -chains held together by weak hydrogen bonds -chains can split for replication

Question 27

describe two features of DNA which make it a stable molecule (3)

Answer 27

strong sugar phosphate backbone coiling reduces chance of molecular damage as it protects hydrogen bonds

Question 28

explain how DNA replicates (5)

Answer 28

hydrogen bonds are broken semi conservative replication nucleotides line up complimentary base pairing AT CG DNA polymerase

Question 29

explain why DNA replication is described as semi-conservative (2)

Answer 29

each strand acts as a template

Question 30

explain why DNA replication is described as semi-conservative (2)

Answer 30

each strand acts as a template