Nucleic Acids

Question 1

What does rna Do

Answer 1

Transfers genetic information from dna to ribosomes

Question 2

What does a nucleotide contain

Answer 2

A pentose sugar, nitrogen containing base and a phosphate group

Question 3

What are the components of a dna nucleotide

Answer 3

Deoxyribose, phosphate group and either A,C,T or G

Question 4

The components of RNA

Answer 4

Ribose, phosphate group and either A,C,G or Uracil

Question 5

How and where is a phosphodiester bond formed

Answer 5

From a condensation reaction between the sugar and a new phosphate between 2 nucleotides

Question 6

Describe the dna structure (Watson and crick)

Answer 6

A double helix made of 2 long polynucleotides, joined by hydrogen bonds between specific base pairs

Question 7

The physical look of RNA

Answer 7

A single, short polynucleotide chain

Question 8

How is DNA adapted to carry out functions

Answer 8

It is a very stable structure which passes down and rarely mutating
Strands are joined with H bonds which allows them to separate during replication
Very large (more information)
Having base pairs protected by backbone, generic info is protected
Base pairing means easy replication

Question 9

The two stages of cell division

Answer 9

Nuclear division and cytokinesis

Question 10

What is need for semi conservative replication to take place

Answer 10

4 different bases, both strands to act as template, DNA polymerase, a source of chemical energy to drive the process

Question 11

How does semi conservative replication ensure genetic continuity

Answer 11

Because genetic information is passed on as each strand serves as a template for the new one

Question 12

Describe the process of semi conservative replication

Answer 12

1. Dna helicase unwinds and unzips the dna molecule, separating two strands and breaking hydrogen bonds (both strands act as templates) 2. Free activated rna nucleotides are attracted to their complementary base pairs (complementary base pairing) 3. DNA polymerase joins adjacent nucleotides and phosphodiester bonds are formed and H bonds reform 4. Example of semi conservative replication

Question 13

Which direction is the new strand synthesised in

Answer 13

5 to 3

Question 14

What is the structure of ATP

Answer 14

Adenine (nitrogen containing organic base) , ribose (pentode sugar) and 3 phosphates

Question 15

Is ATP a nucleotide

Answer 15

Yes

Question 16

How does ATP store energy

Answer 16

The bonds between the 3 phosphates are unstable so have low activation energy (easily broken) when they break they release energy and one phosphate is removed

Question 17

Describe the hydrolysis of ATP

Answer 17

Water is used to convert ATP to adenosine Diphosphate with an inorganic phosphate group and is catalysed by ATP hydrolase

Question 18

Which enzyme catalyses hydrolysis ATP

Answer 18

ATP hydrolase

Question 19

Describe the synthesis of ATP

Answer 19

Energy can be used to add an inorganic phosphate to ADP to reform ATP

Question 20

Which enzyme catalyses the synthesis of ATP

Answer 20

ATP synthase

Question 21

What can the inorganic phosphate released be used for

Answer 21

To phosphorylate other compounds, often making them more reactive

Question 22

What kind of reaction is the synthesis of ATP

Answer 22

Condensation

Question 23

In what 2 ways does ATP synthesis occur with addition of a phosphate

Answer 23

During photosynthesis or during respiration

Question 24

Is ATP a short or long term energy source

Answer 24

A short term immediate energy source

Question 25

Why is ATP a better immediate energy source than glucose

Answer 25

Releases less energy so is more manageable and the hydrolysis is a single reaction which is quicker than the breakdown of glucose

Question 26

Can ATP be stored

Answer 26

No it has to be made

Question 27

What processes is ATP used in

Answer 27

Phosphorylation of compounds, making them more reactive, active transport, muscle contraction, anabolism (in protein synthesis). Secretion during exocytosis

Question 28

ATP is useful in many biological processes, exemplain why (e.g. what features does it have that makes it useful)

Answer 28

1. It releases energy in small manageable amounts 2. It is broken down in one step (quickly hydrolysed) means energy is available rapidly (immediate source of energy) 3. It is reformed/ made again 4. It cannot pass out of a cell

Question 29

Describe the evidence for semi conservative replication (meselsohn and stahl)

Answer 29

They grew N14 and N15 bacteria, then transferred the N15 bacteria to an N14 medium to replicate for one generation and centrifuged the results to separate out the different weights. Found that after 1 gen, the dna had one heavy N15 strand and one light N14 strand

Question 30

What is the difference between conservative and semi conservative replication

Answer 30

Conservative means the original dna remains intact and a new daughter dna is produced with completely new material. Semi conservative is when original dna is split into 2 strands and each is replicated in the mirror image so each has one old and one new strand

Question 31

How does the structure of DNA result in accurate replication

Answer 31

1. There are 2 strands so semi conservative replication is possible 2. Complementary Base pairing/ H bonds hold strands together but are weak and easily broken which allows strands to separate. 3. Base sequences act as template