Nucleic Acids Flashcards
What does ATP stand for?
adenine triphosphate (nucleotide)
define nucleotide
polymers made from monomers known as nucleotides
What are the components of a nucleotide?
Penrose sugar, phosphate group, organic nitrogenous base
What are the components of ATP?
adenine, ribose, 3 phosphate groups
why is ATP referred to as the universal energy currency?
usable form of energy used by all living cells. carries energy from energy releasing reactions to energy consuming reactions
how does ATP release energy?
hydrolysis reaction with ATPase. exergoic reaction (produces 30.6KJ energy). becomes ADP
how does ADP form ATP?
condensation reaction with ATP synthase. Endergonic reaction (takes energy). energy stored in bonds
5 roles of ATP
1) active transport, 2) metabolic processes, 3) movement, 4) nerve transmission, 5) secretion
why is ATP better than glucose as an energy source?
uses less enzymes, one step, immediate energy, can release small amounts of energy, easily transported
What are pyramidine bases?
smaller and single rings. thynine, cytosine and uracil
What are purine bases?
larger with double rings. adenine and guanine
What does DNA stand for.
deoxyribonucleic acid
What are the functions of DNA?
carries genetic code for protein synthesis which is replicated in cell division
describe the structure of DNA
2 polynucleotide strands twisted in double helix held together between base pairs by hydrogen bonds. strands anti parallel. Penrose sugar= DEOXYRIBOSE. Bases: adenine, thynine, guanine, cytosine
how is a polynucleotide formed?
covalent bond between sugar and phosphate formed by condensation. hydrogen bonds hold base pairs together.
What is the bond between two nucleotides?
phosphodiester
What is the bond between complimentary base pairs?
hydrogen
describe the process of DNA replication
H bonds between bases break by DNA helicase. 2 strands separate so unwind. each strand is template. free DNA nucleotides align opposite complimentary bases. DNA polymerase catalysts condensation reaction to join them. each new molecule has one stand from original template and one new one.
describe the conservative DNA theory
DNA produces two daughter DNA. one has both originals and one has two daughter chains
describe the semi conservative theory
DNA molecules separate. each act as template and produce one new strand each.
describe evidence for semi conservative replication
meselson-stahl experiment. bacteria grown from 15N (heavy) to label N containing base. put on culture of 14N to replicate. density of DNA of each generation extracted and centrifuged. first gen= all intermediate in mass. second gen= 1/2 intermediate, 1/2 light
why was e.coli used?
easy to culture. DNA not in nucleus
What does RNA stand for? what is it used for.
Ribonucleic acid for protein synthesis
describe the structure of RNA
single stranded polynhcleotide. Penrose sugar= ribose. bases= adenine, uracil, guanine and cytosine
two differences between DNA nucleotide and RNA nucleotide
1) deoxyribose vs ribose. 2) thymine vs uracil
three differences between DNA polymer and RNA polymer
1) double stranded vs single stranded. 2) large vs small. 3) 1 type vs 3 types (rRNA, mRNA, tRNA)
What is the function of mRNA?
messenger. single stranded that carries genetic code for specific protein from DNA in nucleus -> ribosomes in cytoplasm
What is the function of rRNA?
ribosomal. this + protein = ribosomes. translates genetic code and hounds amino acids to form polypeptides. made by nucleolus.
What is the function of tRNA?
transfer. transfers specific amino acid to ribosome. clover leaf shape held by H bonds. AA attaches one end with anticodon at opposite end.
describe genetic code
DNA stores genetic info coded in sequence of bases. three determine sequence of amino acids that are joined together to form polypeptide.
define gene
section of DNA that codes for specific polypeptide
define codon.
series of 3 bases that code for amino acid in mRNA only
how many possible codes? how many amino acids?
64 possible codes with 20 amino acids
describe the properties of the genetic code
LINEAR, TRIPLET, NON-OVERLAPPING, DEGENERATE, UNABIGUOUS, UNIVERSAL CODE
define introns
non coding nucleotide- repeated. spliced out after transcription. number of repeats that causes generic variation.
define exons
coding sequences that are left behind and spliced together by ligase to form mature DNA
difference between eukaryotes and prokaryotes regarding introns and exons
eukaryotes= introns= discontinuous genes. prokaryotes= exons= continuous genes
what comes first: transcription or translation
transcription
describe the process of transcription
1) gene unwind by DNA helicase- H bonds break. 2) activated rRNA nucleotides H bond with complimentary base pair by RNA polymerase-> mRNA. 3) mRNA= complimentary to template (T=U) 4) DNA reminds. 5) mRNA release out of nuclear pore to ribosome
describe ribosomes
protein + rRNA. free in cytoplasm or RER. large and small subunit. large subunit= 2 attachment sites for tRNA. small subunit= binds to mRNA
describe the process of translation
initiation: ribosome attaches to start codon on mRNA. codon on mRNA H bond to anticodon on tRNA. elongation: two amino acids form peptide bond. first tRNA leaves ribosome and ribosome moves along one codon. next tRNA binds. termination: stop codon reached
two types of mutation
1) deletion: nucleotide removed which effects amino acid sequence. 2) substitution: base is change- less impact as other bases same
describe protein production
DNA codes for amino acids. mRNA made in transcription. ribosomes synthesise mRNA. RER transports protein, Golgi body modifies and packages it, released by exocytosis
