Nucleic Acids Flashcards
1
Q
What does DNA do + why is it important?
A
- codes for sequence of AA in primary structure of a protein, which determines final 3D structure + function of a protein
2
Q
What is a nucleotide made up of?
A
- a pentose sugar (deoxyribose/ribose)
- a nitrogenous base (A,T/U,G,C)
- phosphate group
3
Q
How are polynucleotides formed?
A
- by condensation reactions between the deoxyribose sugar + phosphate group, creating a phosphodiester bond
4
Q
What is the structure of DNA?
A
- ribose = pentose sugar
- adenine, thymine, cytosine, guanine
- made of 2 long strands held together by hydrogen bonds between bases forming double helix structure
5
Q
What is the structure of RNA?
A
- short polynucleotide
- single stranded
- ribose = pentose sugar
- adenine, guanine, cytosine, uracil
6
Q
What is the function of tRNA?
A
- to transfer the genetic code from DNA in nucleus to ribosomes
7
Q
Why is DNA a stable molecule?
A
- phosphodiester backbone
- hydrogen bonds link organic base pairs, many hydrogen bonds collectively add to the strength of the molecule
8
Q
How is the structure of DNA related to its functions?
A
- long molecule so can store lots of info
- hydrogen bonds allow the molecule to unwind allowing itself to be replicated
- specific complementary base pairing so mutations are rare
- **strong phosphate backbone ** so not easily affected by external envi.
9
Q
What is the process of DNA replication?
A
Semi-conservative replication
10
Q
Describe DNA replication.
A
- DNA helicase breaks hydrogen bonds linking the base pairs of DNA, forming 2 strands exposing the nucleotide bases
- both strands act as a template for free DNA nucleotides to join by complementary base pairing
- DNA polymerase joins adjacent DNA nucleotides forming complementary new strands of DNA
- 2 identical molecules of DNA are formed (each w half original DNA + half new DNA)
11
Q
What is the purpose of semi-conservative replication?
A
- ensures there’s genetic continuity between generations of cells (inherit all genes from parent cell)
- important as cells need replacing regularly (+ for growth) + need to carry out same function
12
Q
What are the key properties of water?
A
- it is a metabolite in chemical reactions (e.g. hydrolysis, photosynthesis, respiration)
- it is a solvent for reactions so allows transport of substances
- has a high specific heat capacity, it buffers changes in T°C
- has a large latent heat of vaporisation, providing a cooling effect by loss of water through evaporation
- has strong cohesion between water molecules, supporting water columns in plants + providing surface tension
13
Q
What do hydrogen ions do?
A
- lowers pH of solutions + impact enzyme function + haemoglobin function
14
Q
What do iron ions do?
A
- a component of haemoglobin in the transport of O2
15
Q
What do sodium ions do?
A
- involved in co-transport of glucose + AA in absorption
16
Q
What do phosphate ions do?
A
- component of DNA (forms phosphodiester bonds w deoxyribose) + ATP (makes ADP more reactive)
