DNA Flashcards
what is the bonding between the sugar to phosphate backbones
strong covalent phosphodiester bonds.
what are the bases paired by
weak hydrogen bonds
what is the role of DNA
replication to ensure each cell produced by cell division has a copy of the DNA.
Is also used for protein synthesis as the sequence of bases in DNA determines the sequence of amino acids in polypeptides.
role of tRNA
carries amino acids from cytoplasm to ribosome surface ready to make a protein
role of rRNA
bind with proteins to form ribosomes.
what is the universal energy currency
supplies all the chemical reactions i cells with energy
what are the advantages of ATP
easily hydrolysed by one enzyme to release energy-is efficient.
-releases energy in small useable amounts.
-inert.
-easily transported across membranes.
-readily made again by phosphorylation (adding a phosphate.
when ATP is hydrolysed/brocken down to ADP+Pi what happens
energy is released.
what enzyme ctalyses the breakdown of ATP
ATPase
what is he importance of the controlled release of energy
uncontrolled release would cause a temperaure increase that would destroy cells.
what enzyme is used to phosphorylate ADP+pi to ATP
ATPsynthetase
what bacteria is used to show DNA replication and why
e-coli-they reproduce every 20 mins.
describe the steps for e-coli experiment.
e-coli grown on nutrients containing heavy N15 and N15 used in nitrogenous base of DNA.E-coli was then moved to agar containing only N14 and let DNA replicated once. Samples were taken and measured mass of DNA using a density gradient centrifuge. Cesium chloride density gradient gel was used to sepereate light substances like DNA
what substance seperates light substances like DNA
cesium Chloride density gradient gel.
what is the sense strand
codes for protein synthesis.
what sis the promoter region
acts as a switch for genes to control for when needed.
name 4 characteristics of genes
-triplet code
-universal
-non-overlapping
-degenerate
what is meant by degenerate
each amino acid can be coded by more thna one triplet as there are more genetic triplet codes than amino aicds so some amino aicds have more than 1 code.
what is meant by non-overlapping
each read as 3 distinct bases
describe the stages in transcription
-DNA helicase unwind gene and breaks hydrogen bonds
-RNA polumerase binds to template starnd
-free RNA nucelotides binds to complementary base pair and bonded by phosphodiester bonds by RNA polymerase and DNA starnd rewins to form a double helix. RNA seperates at stop signal.
-RNA detaches and travels through nuclear pore.
-
what are the post transcriptional stages
introns splices as unwanted-would have coded for a different amino acid.
what happens in translation
amin acids attach to tRNA which is specific to one amino acid. The sequence of 3 bases on the anticodon is complementary to the codon on mRNA.
