95 WJEC Biology AS Level - Marianne Izen - 2nd Edition (Nucleic Acids And Their Functions) Flashcards
What are nucleic acids?
Nucleic acids are polymers, made of monomers called nucleotides.
What is a polynucleotide?
A molecule containing many nucleotides is a polynucleotide.
How long can a polynucleotide be?
Polynucleotides may be millions of nucleotides long.
What are the components of a nucleotide?
A nucleotide has three components:
- A phosphate group
- A pentose sugar
- An organic base
How are the three components of nucleotides combined?
They are combined by condensation reactions:
Tell me about the structure of the phosphate group?
The phosphate group has the same structure in all nucleotides.
What is the pentose in RNA?
What is the pentose in DNA?
The pentose is ribose in RNA
The pentose is deoxyribose in DNA.
What is the other name for the organic base?
Nitrogenous base
What are the groups of organic bases?
There are two groups of organic bases:
- Pyrimidine bases
- Purine bases
What are the pyrimidine bases?
The pyrimidine bases are
- thymine
- cytosine
- uracil
What are the purine bases?
The purine bases are
- adenine
- guanine.
What makes changes in biological systems?
In biological systems it is chemical energy that makes changes.
This is because chemical bonds must make or break for reactions to happen.
How do autotrophic organisms get chemical energy?
Autotrophic organisms convert other forms of energy into chemical energy:
Name some chemoautotrophic organisms.
What energy do they use?
- Some bacteria
- Archaea
They use the energy derived from oxidation of electron donors e.g. H2, Fe2+, H2S.
Name some photoautotrophic organisms.
What energy do they use?
- Green plants
They use light energy in photosynthesis.
Name some heterotrophic organisms.
What energy do they use?
Animals
They derive their chemical energy from food.
Where do organisms store chemical energy?
Organisms store chemical energy mainly in lipids and carbohydrates.
What molecule makes energy available?
The molecule that makes the energy available when it is needed is adenosine triphosphate, ATP.
How much ATP do we make and break down everyday?
How much ATP does the body contain?
What can you conclude from this?
We make and break down about 50 kg ATP every day.
The body only contains about 5 g ATP.
Hence ATP is is not an energy store.
What is ATP otherwise called as?
Why?
It is sometimes called the ‘energy currency of the cell.
It is so called because it is involved when energy changes happen.
When is ATP synthesised?
When is ATP broken down?
ATP is synthesised when energy is made available, such as in the mitochondria.
It is broken down when energy is needed, such as in muscle contraction.
Nucleotide (Key-Term)
Monomer of nucleic acid comprising a pentose sugar, a nitrogenous base and a phosphate group.
Pyrimidine bases (Key-Term)
Class of nitrogenous bases including thymine, cytosine and uracil.
Purine bases (Key-Term)
Class of nitrogenous bases including adenine and guanine.
What do you need to remember about the spelling of nucleotides?
Take care with spelling: ‘pyrimidine’ not ‘pyramidine’; ‘thymine’ not ‘thiamine”.
Cytosine and thymine contain the letter ‘Y’; so does pyrimidine.
Chemoautotrophic (Key-Term)
An organism that uses chemical energy to make complex organic molecules.
Photoautotrophic (Key-Term)
An organism that uses light energy to make complex organic molecules, its food.
(ATP) Adenosine triphosphate (Key-Term)
A nucleotide in all living cells.
Its hydrolysis makes energy available.
It is formed when chemical reactions release energy.
What do we know about the estimates for the mass of ATP stored and metabolised by the body?
Estimates for the mass of ATP stored and metabolised by the body vary greatly.
Draw a diagram of:
- Structure of a nucleotide
- Purine skeleton
- Pyrimidine skeleton
