Nucleic acids. Flashcards
Structure of a nucleotide.
-Phosphate group
-Nitrogenous base
-Pentose sugar.
ATP structure.
-3 phosphate groups
-Ribose
-adenine.
ATP condensation and hydrolysis.
Condensation:
-Gains a Phosphate–>tri
-Stores energy(endergonic)
-ATPSynthesase
+30.6KJ/mol
Hydrolysis:
-Release energy
-Loses a phosphate group–>di
-ATPase
-30.6kj/mol
-exogonic.
ATP uses.
-‘universal energy currency’
-stores and transfers energy
-To enable all life processes
-Released from respiration
-Hydrolysis breaks a phosphate bond which releases energy used by the cell.
-relaesed in small,usable amounts
-Travels to where it is needed easily.
Purine bases.
adenine and guanine
pyrimidine bases.
thymine,cytosine,uracil.
Purine structure
2 fused c-n rings.
Pyrimidine structure
Single carbon-nitrogen ring.
DNA structure
-double helix
h bonds between complementary bases
antiparallel strands(read in diff directions)(one 3 prime to 5 prime and vice versa.
-sugar phosphate backbone with phosphodiester bonds
a,g,c,t
RNA structure
-1 strand
-ribose sugar
-a,c,g,u
used in protein synthesis
tRNA structure
-single stranded
-anticodon at bottom
-h bonds between bases
-delivers specific amino acids to ribosomes.
-amino acid binding site
mRNA structure
-single stranded
-long
-synthesised in nucleus
-carries genetic code from nucelus to ribosomes in cytoplasm.
rRNA structure
-large, complex
-made in nucleolus
-added to proteins=ribosomes.
DNA functions
-protein synthesis
-DNA replication
DNA replication process
-DNA helicase unwinds DNA and breaks h bonds between bases
-free nucleotides attach to template strands by comp bases pairing
-DNA polymerase joins free nucleotides together in 5–>3 prime direction by phosphodiester bonds.
-the 2 DNA molecules refold into double helix.
Meselsons and stahls experiment
-bacteria in sol
-contains N15
-sample in centrifuge
-heavy 15 at bottom
-then allowed to replicate once with lighter n14
-15 and 14 in middle mixed
-allowed to replicate again
-14 at top bottom 15 and 14
-proves semi-conservative replication of DNA
Genetic code definition
The genetic code is a linear, triplet, non-overlapping,
degenerate, unambiguous, universal code for the
production of polypeptides
The triplet code
-amino acids coded for by base triplets in DNA
-transcribed to make codons in mRNA
-then sequence of a acids
Exons and introns
exons=nucelotide sequence in dna and pre-mrna-coding
introns=non-coding nucleotide sequence in dna and removed from pre-mrna–.mature mrna
Transcription
-Dna helicase breaks h bonds between bases and unwinds dna
-comp rna nucleotides align
-rna polymerase forms sugar-phosphate backbone
-forms pre-mrna
-premrna that has introns removed via splicing to make mature mrna.
Occurs in nucleus.
Translation
-each trna brings specific amino acid
-ribosome binds to start codon on mrna
-2 amino acids form peptide bonds
-ribosome moves along mrna one codon at time untilstop codon reached.
Occurs in ribosome in cytoplasm.
Further peptide chain modifictaion
-polypeptide chain folded to become proteins
-can be 1,2,3
-carbs,lipids or phosphates can be added as well as other polypeptides to make complete protein(chemical modification).
codon definition
-3 bases on mrna
anticodon definition
-3 bases of trna
One-gene one polypeptide hypothesis.
A particular DNA sequence must be completely present to code for a whole polypeptide then correct protein.
Damage/mutation to any DNA section, certain important functions will be affected(enzymes, antibodies, hormones, transport/structural proteins).
