dna 2

DNA - Added slides

Bases and Nucleosides/tides Use these to draw out the various bases. You need to know the exact structure of all the bases and how their differences affect their H-bonding patterns

Figure 24.5: Purine Derivatives

Copyright 2014 by Nelson Education Ltd. 24-7

PresenterPresentation NotesFigure 24.5 Other naturally occurring purine derivatives hypoxanthine, xanthine, and uric acid.

Nucleosides

How does a Nucleoside differ from a Nucleotide?

A ribose+adenine nucleoside = adenosine. What are the others called (Dont forget Uracil +ribose!)?

What would their names be if the sugar was deoxyribose? dUMP is called deoxyuridylate or deoxyuridine monophosphate. What are

the other monophosphates called? Triphosphates?

Figure 24.6: Keto-Enol Tautomerism of Uracil


PresenterPresentation NotesFigure 24.6 The keto-enol tautomerism of uracil.

Figure 24.7: Tautomerization of Guanine


PresenterPresentation NotesFigure 24.7 The tautomerization of the purine guanine.

Figure 24.8: The UV Absorption Spectra of Nucleotides


PresenterPresentation NotesFigure 24.8 The UV absorption spectra of the common ribonucleotides.

ATP Magic molecule?

Adenosine: A Nucleoside with Physiological Activity

Adenosine functions as an autacoid, or local hormone, and neuromodulator.

Circulating in the bloodstream, it influences blood vessel dilation, smooth muscle contraction, neurotransmitter release, and fat metabolism.

Adenosine is also a sleep regulator. Adenosine rises during wakefulness, promoting eventual sleepiness.

Caffeine promotes wakefulness by blocking the binding of adenosine to its neuronal receptors.



PresenterPresentation Notes Adenosine functions as an autacoid, or local hormone, and neuromodulator. Circulating in the bloodstream, it influences blood vessel dilation, smooth muscle contraction, neurotransmitter release, and fat metabolism. Adenosine is also a sleep regulator. Adenosine rises during wakefulness, promoting eventual sleepiness. Caffeine promotes wakefulness by blocking binding of adenosine to its neuronal receptors.

Figure 24.23: Unusual Bases in RNA


PresenterPresentation NotesFigure 24.23 Unusual bases in RNA.

Figure 24.10: Ribonucleosides


PresenterPresentation NotesFigure 24.10 The common ribonucleosides.

Figure 24.11: Ribonucleotides


PresenterPresentation NotesFigure 24.11 Structures of the four common ribonucleotides AMP, GMP, CMP, and UMP. Also shown: 3-AMP.

Figure 24.12: cAMP and cGMP


PresenterPresentation NotesFigure 24.12 The cyclic nucleotide cAMP and cGMP.

Figure 24.13: Formation of ADP and ATP


PresenterPresentation NotesFigure 24.13 Formation of ADP and ATP by the successive addition of phosphate groups via phosphoric anhydride linkages. Note that the reaction is a dehydration synthesis.

Figure 24.17: The Watson-Crick Base Pairs


PresenterPresentation NotesFigure 24.17 The Watson-Crick base pairs A:T and G:C.

DNA Replication

Centrifugation

Pic from : http://stevegallik.org/sites/all/images/centrifugation_1.jpg

Winter 2009 BIO 273 DNA Replication 43

Double strand unwinds and unzips break the H-bonds

between nitrogenous bases

at origin of replication requires enzymes

helicase Replication forks

Site where new strands are built

two forks at each origin

Step 1- Unwinding


Step 2 - Priming How do you start making the

new DNA strand? use an RNA primer (< 10

nucleotides) RNA polymerase

(primase) joins matching RNA nucleotides to DNA template strands

primer grows 5 to 3

helicase

primaseRNA primer

replication fork


Free DNA nucleotides bind to complementary bases on the template (old) strand H-bonding of bases add one at a time

DNA polymerase Joins each new DNA

nucleotide to the previous one

starts on primer joins sugar to

phosphate can only add to the 3

end

Step 3 DNA Strand Formation


Problem: replication occurs on both template strands strands are antiparallel, but DNA can only grow in one direction

grows 5 to 3 Solution:

One strand replicated continuously (grows 5 to 3) Leading strand

Other strand replicated as a series of short fragments Lagging strand Discontinuous formation (each piece grows 5 to 3) Numerous RNA primers & DNA fragments (Okazaki

fragments) DNA polymerase removes the RNA primers DNA ligase joins the short DNA fragments together

Strand Formation


Strand Formation on both templates

Example of Chromatin Structure and expression relationship

PresenterPresentation NotesMicrobial control of heterochromatin. In response to infection by the bacterium L. monocytogenes, (This is Listeria - a pathogenic bacteria you may have heard of. It can cause many problems in humans including Gastroenteritis and Fatal Meningitis) host cell immune response genes (IFN-stimulated genes) are repressed by host proteins that form a silencing complex. The bacterial protein LntA relieves this repression. For some viral infections, lytic viral genes aresilenced by host cell complexes similar to those controlled by L. monocytogenes. Viral factors that promote either latency or entry to lytic phase must directly or indirectly control the activity of these silencing complexes. In both cases, the spatial and temporal signals that govern these important decisions remain unclear.From: Science (2011), 331, p 1271 http://www.sciencemag.org/content/331/6022/1271.full.pdf

Example of Chromatin Structure and expression relationship

The previous slide shows the transition of chromatin structure from Heterochromatin to Euchromatinallowing transcription of these genes

Heterochromatin =

Euchromatin =

Transcription =

Gene Expression =


DNA Replication - Animations

DNA replication

DNA replication 2

DNA polymerase / Replication of a Chromosome


DNA Repair

Occasionally a few bases inserted incorrectly during replication

DNA polymerase can repair the mistakes Proof-reading function make sure incorrect base not

inserted (checks template) If wrong base:

exonuclease (part of DNA polymerase) removes wrong base inserts correct base

prevents mutations

DNA - Added slidesBases and Nucleosides/tides Use these to draw out the various bases. You need to know the exact structure of all the bases and how their differences affect their H-bonding patternsSlide Number 3Slide Number 4Slide Number 5Slide Number 6Figure 24.5: Purine DerivativesSlide Number 8NucleosidesSlide Number 10Figure 24.6: Keto-Enol Tautomerism of UracilSlide Number 12Figure 24.7: Tautomerization of GuanineSlide Number 14Figure 24.8: The UV Absorption Spectra of NucleotidesSlide Number 16ATP Magic molecule?Slide Number 18Adenosine: A Nucleoside with Physiological ActivitySlide Number 20Slide Number 21Slide Number 22Figure 24.23: Unusual Bases in RNASlide Number 24Figure 24.10: RibonucleosidesSlide Number 26Figure 24.11: RibonucleotidesSlide Number 28Figure 24.12: cAMP and cGMPSlide Number 30Figure 24.13: Formation of ADP and ATPSlide Number 32Figure 24.17: The Watson-Crick Base Pairs Slide Number 34DNA ReplicationSlide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40CentrifugationSlide Number 42Step 1- UnwindingSlide Number 44Step 2 - PrimingSlide Number 46Step 3 DNA Strand FormationSlide Number 48Strand FormationSlide Number 50Strand FormationSlide Number 52Example of Chromatin Structure and expression relationshipSlide Number 54Example of Chromatin Structure and expression relationshipSlide Number 56DNA Replication - AnimationsSlide Number 58DNA RepairSlide Number 60

dna 2

Documents

nelson education

binding of adenosine

unusual bases

various bases

smooth muscle contraction

neurotransmitter release

blood vessel dilation

common ribonucleosides