DNA

Question 1

what is the bonding between the sugar to phosphate backbones

Answer 1

strong covalent phosphodiester bonds.

Question 2

what are the bases paired by

Answer 2

weak hydrogen bonds

Question 3

what is the role of DNA

Answer 3

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.

Question 4

role of tRNA

Answer 4

carries amino acids from cytoplasm to ribosome surface ready to make a protein

Question 5

role of rRNA

Answer 5

bind with proteins to form ribosomes.

Question 6

what is the universal energy currency

Answer 6

supplies all the chemical reactions i cells with energy

Question 7

what are the advantages of ATP

Answer 7

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.

Question 8

when ATP is hydrolysed/brocken down to ADP+Pi what happens

Answer 8

energy is released.

Question 9

what enzyme ctalyses the breakdown of ATP

Answer 9

ATPase

Question 10

what is he importance of the controlled release of energy

Answer 10

uncontrolled release would cause a temperaure increase that would destroy cells.

Question 11

what enzyme is used to phosphorylate ADP+pi to ATP

Answer 11

ATPsynthetase

Question 12

what bacteria is used to show DNA replication and why

Answer 12

e-coli-they reproduce every 20 mins.

Question 13

describe the steps for e-coli experiment.

Answer 13

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

Question 14

what substance seperates light substances like DNA

Answer 14

cesium Chloride density gradient gel.

Question 15

what is the sense strand

Answer 15

codes for protein synthesis.

Question 16

what sis the promoter region

Answer 16

acts as a switch for genes to control for when needed.

Question 17

name 4 characteristics of genes

Answer 17

-triplet code
-universal
-non-overlapping
-degenerate

Question 18

what is meant by degenerate

Answer 18

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.

Question 19

what is meant by non-overlapping

Answer 19

each read as 3 distinct bases

Question 20

describe the stages in transcription

Answer 20

-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.
-

Question 21

what are the post transcriptional stages

Answer 21

introns splices as unwanted-would have coded for a different amino acid.

Question 22

what happens in translation

Answer 22

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.