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21 Cards in this Set

  • Front
  • Back

What does the nucleotide consist of?

A pentose sugar


A phosphate group


An organic group:C,A,G,T,U



A phosphodiester bond

The bond between the pentose sugar of one mononucleotide and the phosphate group of another

Ribonucleic acid

It is made of the pentose sugar which is usually ribose.


It is also made up of four organic bases which are Uracil,Adenine ,Guanine and Cytosine


One type transfers genetic information from the DNA to the ribosomes

The types of RNA are:

messenger RNA


transport RNA


Ribosomal RNA

DNA structure

It is also made of a deoxyribose sugar and organic bases which are Adenine,Guanine , Cytosine and Thymine


It is made of two strands which are joined together by hydrogen bonds

Double helix

The uprights of phosphate and deoxyribose wind around one another to form a double helix

The DNA molecule is stable because?

(i)The phosphodiester bond protects the more chemically reactive organic bases inside the double helix



What are the functions of DNA

It is very stable can therefore be passed from generation to generation without change


It's two separate strands are joined by hydrogen bonds which are easily separated during replication


It is immensely large therefore carries a large amount of information





process of semi conservative replication

The hydrogen bonds joining the base pairs are broken down by DNA helicase


The two strands of DNA unwind and act as templates for activated polynucleotides to join in


The nucleotides are joined together by DNA polymerase


Each of the new DNA contains one original and new strand

The conservative model

It suggested that the original molecule remained intact and a separate daughter DNA is built from new molecules


Of the two molecules produced,one would be entirely new and one would be entirely original

The structure of ATP

a ribose sugar


adenine phosphates

How ATP stores energy

The bonds between phosphate molecules are unstable so have a low activation energy. When broken they therefore release a considerable amount of energy


only the terminal phosphate is released


ATP +H2O to produce ADP a phosphate molecule and energy


This happens by hydrolysis and ATP hydrolase is also involved

synthesis of ATP

It involves the addition of a phosphate molecule to ADP

Roles of ATP

It is an immediate source of energy source


why ATP is a better energy source compared to glucose


Each ATP molecule releases less energy than glucose molecules.


The energy for reactions released is therefore much smaller and manageable quantities


The hydrolysis of ATP to ADP is a single process which only requires one step to produce energy. Whilst energy from glucose is a long series of reactions and therefore energy takes longer to be released

Uses of ATP

Metabolic processes


secretion


active transport


movement


activation of molecules



Functions of water

Specific heat capacity:Since water molecules stick together,it takes more energy to separate them. It takes more energy to heat a given mass of water,that is water has specific water capacity




Latent heat of vaporisation:H bonding between water molecules means that it requires a lot of energy to evaporate 1 gram of water




Cohesion and surface tension in water:Water has large cohesive forces which allow it to be pulled through a tube

Importance of water to living organisms



In metabolism is used to break down many complex molecules by hydrolysis


Water is a major raw material in photosynthesis


It also acts as a solvent


Its evaporation in living organisms allow them to cool off

why can base pairing not take place between adenine and cytosine and guanine with thymine

Hydrogen bonds link the base pairs. The molecular structure are such that the hydrogen bonds cannot form between adenine and cytosine and guanine and thymine

A hypotheisis

An explanation of something based on scientific logic and reasoning

why ATP an immediate source of energy?

Energy is released very rapidly. ATP requires only one step to produce energy and the energy is directly transferred to the reaction requiring it

explain how ATP can make an enzyme catalysed reaction take place more readily

It transfers one of its phosphate to the molecule and this lowers the activation energy,enzymes work by lowering the activation,they therefore have less work to do so function more readily.