Nucleic Acids Flashcards
What does rna Do
Transfers genetic information from dna to ribosomes
What does a nucleotide contain
A pentose sugar, nitrogen containing base and a phosphate group
What are the components of a dna nucleotide
Deoxyribose, phosphate group and either A,C,T or G
The components of RNA
Ribose, phosphate group and either A,C,G or Uracil
How and where is a phosphodiester bond formed
From a condensation reaction between the sugar and a new phosphate between 2 nucleotides
Describe the dna structure (Watson and crick)
A double helix made of 2 long polynucleotides, joined by hydrogen bonds between specific base pairs
The physical look of RNA
A single, short polynucleotide chain
How is DNA adapted to carry out functions
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
The two stages of cell division
Nuclear division and cytokinesis
What is need for semi conservative replication to take place
4 different bases, both strands to act as template, DNA polymerase, a source of chemical energy to drive the process
How does semi conservative replication ensure genetic continuity
Because genetic information is passed on as each strand serves as a template for the new one
Describe the process of semi conservative replication
- 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
Which direction is the new strand synthesised in
5 to 3
What is the structure of ATP
Adenine (nitrogen containing organic base) , ribose (pentode sugar) and 3 phosphates
Is ATP a nucleotide
Yes
How does ATP store energy
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
Describe the hydrolysis of ATP
Water is used to convert ATP to adenosine Diphosphate with an inorganic phosphate group and is catalysed by ATP hydrolase
Which enzyme catalyses hydrolysis ATP
ATP hydrolase
Describe the synthesis of ATP
Energy can be used to add an inorganic phosphate to ADP to reform ATP
Which enzyme catalyses the synthesis of ATP
ATP synthase
What can the inorganic phosphate released be used for
To phosphorylate other compounds, often making them more reactive
What kind of reaction is the synthesis of ATP
Condensation
In what 2 ways does ATP synthesis occur with addition of a phosphate
During photosynthesis or during respiration
Is ATP a short or long term energy source
A short term immediate energy source
Why is ATP a better immediate energy source than glucose
Releases less energy so is more manageable and the hydrolysis is a single reaction which is quicker than the breakdown of glucose
Can ATP be stored
No it has to be made
What processes is ATP used in
Phosphorylation of compounds, making them more reactive, active transport, muscle contraction, anabolism (in protein synthesis). Secretion during exocytosis
ATP is useful in many biological processes, exemplain why (e.g. what features does it have that makes it useful)
- 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
Describe the evidence for semi conservative replication (meselsohn and stahl)
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
What is the difference between conservative and semi conservative replication
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
How does the structure of DNA result in accurate replication
- 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
