Nucleic acids Flashcards
what are nucleic acids
conatin C,H,O,N and P formed from many nucleotides linked in a chain
how are nucleotides made up
pentose monosaccharide (sugar)
phosphate group acidic and negatively charged
nitrogenous base1,2 carbon rings as well as nitrogen
nucleotide bonds
5th carbon phosphate group reacts with 3rd carbon OH group to form phosphodiester bonds many nucleotides form a sugar phosphate backbone
broken by hydrolysis which releases Individual nucleotides
DNA
deoxyribose sugar 1 less O atom than ribose
who types of bases
purines: larger bases , double carbon ring structure (A,G)
pyrimidines- smaller base, single carbon ring structure (T and (C)
How do the bases react
A-T
G-C
double helix DNA
made of two stand of polynucleotides wrapped around each other strands are held by H bonds . Each strand has a phosphate group 3’ at one end and a OH 5’ group at the other. Strands are antiparallel meaning they run in opposite directions
what are the base pair rules
adenine and thymine = 2 H bonds
Cytosine and guanine = 3 H bonds
complementary base pairing
how does the pairing aid the structure
small pyrimidine always pairs with larger paring maintains distance with backbones(parallel)
who determined the structure of DNA
Watson and Crick 1953
RNA?
transfer of genetic material from DNA, DNA too long a molecule ant cannot leave the nucleus during protein synthesis
what is the pentose sugar in RNA
ribose
What is thymine replaced by in RNA
Uracil which is a pyrimidine 2 H bonds with adenine
Semi-conservative replication
Double helix unwinds
H bonds holding complementary bases are broken
free nucleotides pair with the complementary bases( activated)
H bonds form between the two bases and phosphodiester bonds hold together the nucleotides
two molecules of DNA produced one old strand and a new one (semi-conservative)
which enzyme unwinds the strand
DNA helicase travels along the backbone and breaks any H bonds between bases
what enzyme catalyses the formation of phosphodiester bonds
DNA polymerase
what are replication errors
when an incorrect bases are matched and incorrect sequence occurs in newly copied strand(mutation)
genetic code, DNA
DNA codes for sequence of amino acids to form proteins (genetic code)
Triplet code
Every 3 bases is called a codon(triplet code) which codes for an amino acid
a section of DNA that codes for an entire protein is called a gene
degenerate code
one codon acts as a start codon if its in the middle of the gene it codes for (methionine) and 3 stop codons that don’t code for amino acid signal chain end
code is non-overlapping(each base in sequence only read once)
many codons can code for the same amino acid so degenerate
what is transcription
the formation of a smaller molecule that carries the genetic code for proteins synthesis
sense and antisense strands
when the two strands unwind one sense strand that does code for proteins 5’ to 3’ and an anti sense strand that doesn’t code for proteins 3’ to 5’ which acts as a template so the complementary strand forms the sense strand
what happens to thymine
replaced with uracil that binds with adenine
how are the nucleotides joined
RNA polymerase , transcription stops at the end of the gene and short Mrna detaches and leave nuclear pore. DNA double helix reforms
what are ribosomes made of
proteins and ribosomal Rrna
maintains structural stability of protein synthesis sequence
Translation
after leaving nucleus RNA binds to specific place on small ribosome subunit is it is held in place for translation
Trna(transfer rRNA) have complementary bases called anticodons on one side of the molecule that bind to the RNA using normal base pair rules, it also has an amino acid on its other end that corresponds to the codon
As the trna molecules bind to the complementary bases and bring amino acids the begin for form the primary sequence of the amino acid chain
2 trnas can be bound at a time
the amino acids form peptide bonds with the aid of the enzyme peptidyl transferase(rRNA component of ribsomes)
ATP
adenosine triphosphate
nitrogenous base, pentose sugar, 3 phosphate groups
base always adenine and 3 phosphate groups
how does ATP release energy
small amount of energy required to release the last phosphate but it releases a lot of energy when done
30.6KJ mol-1
ATP hydrolysis equation
ATP + H2O -> ADP +Pi + energy
ATP as an energy store
very instable so its not a good long term store fats and carbs are better energy stores, break down of these molecules(energy released) used to form ATP. phosphorylation is the attachment of a phosphate group made to ADP(condensation releases water)
ATP - ADP conversion happening constantly so cells don’t need a large store for it ( good immediate energy store)
properties of ATP
small- moles easily in and out of cells
water soluble- energy requiring reactions happen in aqueous environments
energy released in small quantities- used for cellular needs and is not wasted as heat
easily regenerated- recharged with energy
