2.3 and 2.4 Flashcards
(24 cards)
What is a nucleotide?
A biological molecule made from
- Pentose sugar
- A nitrogenous base
- A phosphate group
It contains the elements Carbon Hydrogen Oxygen Nitrogen And Phosphorus
They are monomers that make up DNA
What is the difference between RNA and DNA?
RNA has the bases A,U,C or G
and has a ribose sugar
DNA has the bases A,T,C or G
and has a deoxyribose sugar
What is a purine?
It contains two carbon-nitrogen rings joined together
They are Adenine and Guanine
What is a pyrimidine?
It contains only one Carbon-Nitrogen ring
Is smaller than a purine base
They are Cytosine and Thymine
What is the names of all the bases?
Adenine Guanine Cytosine Thymine Uracil
What is the structure of DNA?
Double helix shape
What do nucleotides help regulate?
Metabolic pathways
Where is DNA found?
Nucleus
Explain protein synthesis?
Transcription: A section of DNA unwinds (catalysed by DNA helicase) and acts as a template. The section is then copied to make mRNA (catalysed by RNA polymerase). The mRNA then leaves the nucleus and enter the cytoplasm where it is held by a ribosome. The instruction will be complimentary to the DNA strand with Thymine being replaced by Uracil.
Translation: In the cytoplasm, tRNA picks up amino acids. One end of tRNA carries one amino acid and the other end has a triplet code sequence that is complimentary to the codon on mRNA (known as anti codon). Once the mRNA is in the cytoplasm and attached to a ribosome, it is read by tRNA. tRNA molecules line up against mRNA.
What are DNA strands made up of?
Polynucleotides
Why do the bases have specific pairs?
A purine must always pair with a pyrimidine to give equal sized rings on the double helix
What is a phosphorylated nucleotide?
A nucleotide with added phosphate groups
What is the structure of ADP?
It contains the base adenine, the sugar ribose and two phosphate groups
What is the structure of ATP?
It contains the base adenine, the sugar ribose and three phosphate groups
What process is used to add phosphate groups to a molecule?
Phosphorylation
Explain the synthesis and breakdown of polynucleotides?
Nucleotides join together between the phosphate group of one and the sugar of another, forming a phosphodiester bond.
They are broken down in to nucleotides by breaking the phosphodiester bonds
What is an enzyme?
Globular proteins
Biological catalysts that speed up metabolic reactions in living organisms
Describe the lock and key analogy
It describes the fact that only a specific substrate will fit the active site of an enzyme
Describe the induced fit theory
It states that the active site is not rigid but is flexible allowing the shape to change slightly when a substate renters but then returns to its original shape once the product is released
How does temperature affect enzyme activity?
The rise in temperature makes the enzyme molecule vibrate more increasing the rate of reaction
If the temp goes above a certain level then the vibration breaks some of the bond holding the enzyme’s tertiary structure
This changes the shape of the active site
The substrate can therefore no longer fit
When the enzyme is denatured there is no reaction
At this point the enzyme is denatured
How does pH affect enzyme activity?
Small changes of the pH, either side of the optimum pH slows the rate of reaction as the shape of the active is disrupted.
If the normal optimum pH is restored the shape of the active site is restored
At extremes of the pH the active site may permanently change
When the enzyme is denatured it cannot change the reaction
How does substate concentration affect enzyme activity?
If there is no substrate present then no reaction can take place
As the substate is added, the concentration increases so the rate of reaction increases
As the concentration of substate is increased even further the reaction will reach its maximum rate
How does enzyme concentration affect enzyme activity?
As the enzyme concentration increases, more active sites become available
Therefore there’s more successful collisions between enzymes and substrates
If substrate concentration increases then the rate of reaction increases until maximum rate
If the enzyme concentration is increased further it will have no effect on the rate of reaction
This is beachside all active sites have been used
Enzyme concentration is no longer the limiting factor
What is the function of catalase?
It is a enzyme that works inside cells to catalyse the breakdown of Hydrogen Peroxide to harmless oxygen and water
