Nucleic acids Flashcards
what are nucleotides?
monomers of DNA and RNA and are phosphate esters of pentose sugars
what’s the role of nucleotides in metabolic pathways
- can regulate or fuel them due to high energy phosphate bonds
- also form coenzymes like NADP
components in a nucleotide
- phosphate group bonded to C3 or C5 via condensation reaction
- pentose sugar: ribose in RNA, deoxyribose in DNA
- nitrogenous base bonded to C1: adenine (A), cytosine (C), guanine (G), and thymine (T)
bond between phosphate and sugar in a nucleotide is
phosphodiester bond
bond between base and sugar in a nucleotide is
glycosidic bond
which bases are PURines and their features
- Guanine and Adenine
- 2 C rings
which bases are pyrimidines and their features
- Cytosine and Thymine
- 1 C ring
what’s ATP
- Adenosine triphosphate
- made up of 3 phosphate groups, a ribose sugar and the base adenine
what type of reaction forms ADP + Pi from ATP (+H2O)
hydrolysis
what type of reaction forms ATP (+H2O) from ADP + Pi
condensation
what happens when ATP is hydrolysed
- small amount of energy is released which fuels many processes
- high energy bonds exist between phosphates
what can ADP be hydrolysed to
AMP
what can AMP be hydrolysed to
adenosine
what’s deoxyribonucleic acid
- a polynucleotide containing genetic information and is found in all eukaryotic cell nuclei
structure of DNA
- double helix with complementary bases, A-T, C-G
- large, storing lots of info in bases
- sugar phosphate backbone that protects the bases
- antiparallel strands join via H bonds
how many H bonds are there between A-T
2
how many H bonds are there between C-G
3
what’s the 3’ and 5’ end dictated by
dictated by phosphate bonding to C3 or C5 of sugar
which organisms are suitable for DNA extraction and purification
- strawberries
- kiwis
- peas
outline the stages in DNA extraction and purification
- macerate the tissue using mortar and pestle
- add a strong detergent (washing up liquid)
- add cold ethanol
- remove salts and concentrate the DNA
what’s the purpose of adding cold ethanol to DNA
allows DNA to precipitate out of solution
what’s removing salts and concentrating the DNA
to purify it further
what’s the purpose of macerating the tissue in DNA extraction
to break cell walls
what’s the purpose of adding detergent in DNA extraction
dissolves the plasma membrane, which releases the DNA into the solution
what’s meant by DNA replication occurring by semi-conservative replication during interphase
each new molecule contains and old and a new strand
Outline the process of DNA replication
- DNA helicase breaks H bonds between the bases in the double helix
- free nucleotides pair up with their complementary bases 5’ to 3’ ( leading strand)
- DNA polymerase catalyses the condensation reaction forming phosphodiester bonds between DNA nucleotides
- DNA ligase joins okazaki fragments (formed by DNA polymerase) of DNA together on the lagging strand (3’ to 5’) as DNA polymerase only works 5’ to 3’
what’s a gene
- a length of DNA that codes for a polypeptide
- the code leads to a specific primary structure and final protein shape
what does the genetic code show
which bases code for which amino acid
what are are the 3 features of the genetic code
- degenerate
- universal
- non-overlapping
explain how the genetic code is degenerate
some amino acids coded by more than one triplet
explain how the genetic code is universal
the same code in all organisms
explain how the genetic code is non-overlapping
each base is only read once
what are the two stages in protein synthesis
transcription and translation
what’s transcription
process where mRNA is produced from DNA
outline transcription
- the gene unzips and H bonds between the bases break
- free RNA nucleotides bond to their complementary bases on template strand, forming H bonds, catalysed by RNA polymerase.
- mRNA polymerase passes out of the nucleus to a ribosome
- mRNA is a copy of the coding strand
where are ribosomes made
nucleolus
what are ribosomes made of
2 subunits, each containing roughly equal ratios of rRNA and protein
what’s translation
the process where mRNA is used to produce polypeptides
outline translation
- ribosome binds to mRNA
- the anti-codon on tRNA molecule will bind to a complementary codon
- tRNA will have a specific amino acid attached
- a second tRNA molecule with attached amino acid will bind
- the ribosome catalyses a condensation reaction, forming a peptide bond
- tRNA molecules leave their amino acid to find new ones
- this process continues until a stop codon is reached
