(2) Nucleic Acids Flashcards
what 3 components make up a nucleotide
pentose sugar
phosphate group
nitrogen containing organic base (C,G,A,T,U)
where is the phosphodiester bond between 2 mononucleotides
between the deoxyribose sugar of one mononucleotide and the phosphate group of the other
what is ribonucleic acid
a polymer made up of nucleotides. single relatively short polynucleotide chain where the pentose sugar is always ribose
what type of bond joins bases
hydrogen bonds as they are relatively weak so can break when dna needs to replicate
why is dna a stable molecule
the phosphodiester backbone protects the more chemically reactive organic bases inside the double helix
hydrogen bonds link the organic base pairs
(3 hydrogen bonds between C-G so higher proportion of c-g pairings the more stable the molecule)
also interactive forces between the base pairs that hold the molecule together (base stacking)
what are 5 ways that dna molecules are adapted to carry out their functions
- very stable, passes down generations and rarely mutates
- 2 strands joined by hydrogen bonds with can separate easily during dna replication and protein synthesis
- large so can carry a lot of genetic info
- base pairs are within deoxyribose-phosphate backbone so genetic info is somewhat protected from chemical and physical forces
- base pairing leads to dna being able to replicate and info can be transferred as mRNA
what is nuclear division and cytokinesis
nuclear division- process by which nucleus divides (mitosis or meiosis)
cytokinesis- follows nuclear division and is the process where the whole cell divides
4 requirements for semi-conservative replication
dna polymerase enzyme
source of chemical energy
4 types of nucleotide each with their bases of adenine guanine cytosine or tymine
both strands of the dna molecule act as a template for the attachment of these nucleotides
what 3 things does ATP contain
adenine (nitrogen containing organic base)
ribose (pentose sugar that acts as a backbone)
phosphates (chain of 3 phosphate groups)
how does atp release energy
bonds between the phosphate groups are unstable and so have low activation energy and so are easily broken. when they do break they release energy
what is the equation for atp releasing energy
ATP + H2O = ADP + Pi + E
what enzyme is used for the atp to adp + energy reaction
ATP hydrolase
how does adp reform to make atp
energy is used to add an inorganic phosphate as it is a reversible reaction
catalysed by ATP synthase (condensation reaction as water is removed)
what 3 ways does the synthesis of ATP from ADP occur
1) in chlorophyll containing plant cells during photosynthesis (photophosphorylation)
2) in plant and animal cells during respiration ( oxidative phosphorylation)
3) in plant and animal cells when phosphate groups are transferred from donor molecules to ADP (substrate level phosphorylation)
2 reasons why atp is a better immediate energy source than glucose
1) each atp molecule releases less energy than a glucose molecule and so the energy is released in smaller more manageable quantities rather than the greater and less manageable release of energy from a glucose molecule
2) hydrolysis of ATP to ADP is a single reaction that releases immediate energy but breakdown of glucose is a series of reactions and therefore takes longer
