Post on 15-Jan-2016
21 - 1CH110 – Nucleic Acids
Nucleic acidsNucleic acids
Nucleic acidsNucleic acids: – Maintain genetic informationMaintain genetic information– Determine Protein SynthesisDetermine Protein Synthesis
DNADNA = deoxydeoxyribonucleic acid– “Master Copy” for most cell information.– Template for RNA
RNA =RNA = ribonucleic acid– Transfers information from DNA– Template for Proteins
21 - 2CH110 – Nucleic Acids
Nucleic AcidsNucleic AcidsChromosomes
(in nucleus)
Have genesgenes
1 gene
1 enzyme
EnzymesEnzymes determine determine
external & internal characteristicsexternal & internal characteristics
21 - 3CH110 – Nucleic Acids
NUCLEIC ACIDSNUCLEIC ACIDS
Long chains (polymers) of repeating nucleotides.nucleotides.– Each nucleotide has 3 parts:3 parts:
A A phosphate unitphosphate unit H H
OO
H
H
OH
H
H
HO
A sugarsugar
A heterocyclic heterocyclic Amine BaseAmine BaseN
H
P OH
O
OH
HO
21 - 4CH110 – Nucleic Acids
NucleoNucleottide ide = phosphate + sugar + base= phosphate + sugar + baseNucleoNucleottide ide = phosphate + sugar + base= phosphate + sugar + base
P
O
O
ON
H H
OH
OH
H
H
O
-N-glycosidiclinkage
-N-glycosidiclinkage
BaseBase
SugarSugar
PhosphatePhosphate
Nucleoside = Nucleoside = sugar + basesugar + baseNucleoside = Nucleoside = sugar + basesugar + base
21 - 5CH110 – Nucleic Acids
Nucleic AcidsNucleic Acids
Nucleic AcidsNucleic Acids = polymerspolymers of Nucleotides.Nucleotides.
phosphate sugar
base
SS SS SSSSSSSS
BB BB BBBBBBBB
PPPP PP PPPPPP
21 - 6CH110 – Nucleic Acids
THE SUGAR PARTTHE SUGAR PART• The major difference between RNA and DNA is
the different form of sugar used.
OHOCH2
H HHH
OH OHOH
OHOHOCH2
H HHH
OH HH
OH
Ribose C5H10O5
in RNADeoxyDeoxyRibose C5H10O4
in DNA
The difference is at carbon #2carbon #2.
21 - 7CH110 – Nucleic Acids
The Nitrogenous BasesThe Nitrogenous Bases
5 bases5 bases used fall in two classestwo classes
Purines Purines & & PyrimidinesPyrimidines
N
N
N
NH
A double ringdouble ring (6 & 5 members)
A single ringsingle ring(6 membered)
N
N
21 - 8CH110 – Nucleic Acids
Pyrimidines:Pyrimidines:
The Nitrogenous BasesThe Nitrogenous Bases
Purines:Purines:N
N
N
N
NH2
H
N
N
N
NH
H2N
O
H
N
N
O
O
CH3
H
HN
N
O
O
H
H N
NO
H
H
NH2
Adenine (A)Adenine (A)Adenine (A)Adenine (A) Guanine (G)Guanine (G)Guanine (G)Guanine (G)
Thiamine (T)Thiamine (T)In In DNADNA only onlyThiamine (T)Thiamine (T)In In DNADNA only only
Uracil (U)Uracil (U)In In RNARNA only only
Uracil (U)Uracil (U)In In RNARNA only only
Cytosine (C)Cytosine (C)Cytosine (C)Cytosine (C)
21 - 9CH110 – Nucleic Acids
Nucleotides Di- & Tri- Phosphates Nucleotides Di- & Tri- Phosphates
P
O
OH
HO OH
Adenosine 5’-monophosphate(AMP)
Adenosine 5’-monophosphate(AMP)
riboseribose
AdenineAdenineN
N
N
N
NH2
P
O
O
HO
H H
OH
OH
H
OH
O
1'
2'3'
4'
5'
21 - 10CH110 – Nucleic Acids
Adenosine 5’-monophosphate(AMP)
Adenosine 5’-monophosphate(AMP)
riboseribose
AdenineAdenine
P
O
OH
HO OH
N
N
N
N
NH2
P
O
O
O
H H
OH
OH
H
OH
OP
O
HO
O 1'
2'3'
4'
5'
Adenosine 5’-diphosphate (ADP)Adenosine 5’-diphosphate (ADP)
Nucleotides Di- & Tri- Phosphates Nucleotides Di- & Tri- Phosphates
21 - 11CH110 – Nucleic Acids
Adenosine 5’-monophosphate (AMP)
Adenosine 5’-monophosphate (AMP)
riboseribose
AdenineAdenine
Adenosine 5’-diphosphate (ADP)Adenosine 5’-diphosphate (ADP)
Adenosine 5’-triphosphate (ATP)Adenosine 5’-triphosphate (ATP)
P
O
O
HO O
N
N
N
N
NH2
P
O
O
O
H H
OH
OH
H
OH
OP
O
O
O 1'
2'3'
4'
5'
Nucleotides Di- & Tri- Phosphates Nucleotides Di- & Tri- Phosphates
21 - 12CH110 – Nucleic Acids
H
N
N
N
N
NH2
P
O
O
H H
OH
OH
H
O
OH
1'
2'3'
4'
5'
H
HN
N
N
NP
O
O
H H
OH
OH
H
O
OH
O
H2N
1'
2'3'
4'
5'
1'
2'3'
4'
5'
H
N
P
O
O
H H
OH
OH
H
O
OH
N
O
O
CH3
Primary structurePrimary structure
21 - 13CH110 – Nucleic Acids
H
N
N
N
N
NH2
P
O
O
H H
OH H
O
OH
H
HN
N
N
NP
O
O
H H
OH H
O
O
O
H2N
H
N
P
O
O
H H
OH
OH
H
O
N
O
O
CH3
O
1'
2'3'
4'
5'
1'
2'3'
4'
5'
1'
2'3'
4'
5'
Primary structurePrimary structure
Phosphate bondsPhosphate bondslink DNA or RNAlink DNA or RNAnucleotides togethernucleotides togetherin a linear sequence.
Similar to proteinswith their peptide
bonds and sidegroups.
5’
3’
Adenine (A)
Guanine (G)
Thymine (T)
21 - 15CH110 – Nucleic Acids
Base pairing and hydrogen bondingBase pairing and hydrogen bonding
N
N
O| |
- H
N - H
N
NN
N
O| |
H - N
N
N O| |
O| |
H3C
- H
guanine cytosine
thymine adenineN
N N
N|
HH
N
21 - 16CH110 – Nucleic Acids
Complementary Base PairingPosition of H bonds and distance match with:
DNA - DNA - Secondary StructureSecondary Structure
21 - 17CH110 – Nucleic Acids
Hydrogen bondingHydrogen bonding
Each base wants toform either two or three hydrogen bonds.
That’s why only certain bases will form pairs.
G
T
C
A
C G
A
C
T
G
21 - 18CH110 – Nucleic Acids
Sugar-Sugar-phosphate phosphate backbonebackboneDNA coilscoils around outsideoutside of of attached attached basesbases like a spiral stair case.
Results in a double helix structure.
21 - 19CH110 – Nucleic Acids
The double helixThe double helix
The combination of the stairstep sugar-phosphate backbone and the bonding between pairs resultsin a double helix.
The combination of the stairstep sugar-phosphate backbone and the bonding between pairs resultsin a double helix.
Distance betweenbases = 0.34 nm
2 nmbetweenstrands
One complete
twist is 3.4 nm
21 - 20CH110 – Nucleic Acids
DNA - DNA - Secondary StructureSecondary Structure
Complementary Base Pairing
21 - 22CH110 – Nucleic Acids
• Crick and Watson (1962 Nobel Prize)
– Proposed the basic structure of DNA
– 2 strands wrap around each other
– Strands are connected by H-bonds between the amines.• Like steps of a spiral
staircase
21 - 23CH110 – Nucleic Acids
ChromosomesChromosomes
Chromosomes consists of DNA strands coiledaround protein - histomes. The acidic DNA’s areattracted to the basic histones.
21 - 24CH110 – Nucleic Acids
21 - 25CH110 – Nucleic Acids
ChromosomesChromosomes
The normal number of chromosome pairs varies among the species.
AnimalAnimal Pairs Pairs PlantPlant PairsPairsMan 23 Onion 8Cat 30 Rice 14Mouse 20 Rye 7Rabbit 22 Tomato 12Honeybee, White pine 12
male 8 Adder’s 1262female 16 tounge fern
21 - 28CH110 – Nucleic Acids
TTCC
AA
SS SSSS SSSSSS
GG TT CCAA
PPPP PP PPPPPP
CC GG
GG
DNA: Self - ReplicationDNA: Self - Replication
21 - 29CH110 – Nucleic Acids
GGGGAA
SS SSSS SSSSSS
GG TT CCAA
PPPP PP PPPPPP
CC GG
DNA: Self - ReplicationDNA: Self - Replication
TT CCCC
21 - 30CH110 – Nucleic Acids
Replication of DNAReplication of DNA
ReplicationReplication occurs on both halvesboth halvesin opposite directions.opposite directions.
21 - 31CH110 – Nucleic Acids
DNA DNA ReplicationReplication
21 - 32CH110 – Nucleic Acids
RNA synthesisRNA synthesis
In the first step, RNA polymeraseRNA polymerase bindsto a promotorpromotor sequenceon the DNA chain.
This insuresinsures that transcription occurs in the correct directioncorrect direction.
The initial reaction is toseparate the twoseparate the twoDNA strandsDNA strands.
21 - 33CH110 – Nucleic Acids
RNA synthesisRNA synthesis
initiationsequence
terminationsequence
‘Special’ baseSpecial’ basesequencessequences in theDNA indicatewhere RNARNAsynthesis startssynthesis startsand stops.and stops.
21 - 34CH110 – Nucleic Acids
RNA synthesisRNA synthesis
Once the terminationsequence isreached, thenew RNA moleculenew RNA moleculeand the RNA synthaseare released.released.
The DNA recoils.The DNA recoils.
21 - 35CH110 – Nucleic Acids
• The messenger RNAmessenger RNA (mRNA) move outside the nucleus to the cytoplasmto the cytoplasm where RibosomesRibosomes are anxiously awaiting their arrival.
rRNA40 S
60 SrRNA
21 - 36CH110 – Nucleic Acids
• The messenger RNAmessenger RNA (mRNA) move outside the nucleus to the cytoplasmto the cytoplasm where RibosomesRibosomes are anxiously awaiting their arrival.
rRNA40 S
60 SrRNA
21 - 37CH110 – Nucleic Acids
• The messenger RNAmessenger RNA (mRNA) move outside the nucleus to the cytoplasmto the cytoplasm where RibosomesRibosomes are anxiously awaiting their arrival.
rRNA40 S
60 SrRNA
21 - 38CH110 – Nucleic Acids
• The messenger RNAmessenger RNA (mRNA) move outside the nucleus to the cytoplasmto the cytoplasm where RibosomesRibosomes are anxiously awaiting their arrival.
rRNA40 S
60 SrRNA
21 - 39CH110 – Nucleic Acids
rRNA40 S
60 SrRNA
Ribosomal RNA – rRNARibosomal RNA – rRNA: Platform for protein synthesis. Holds mRNA in place and helps assemble proteins.
21 - 40CH110 – Nucleic Acids
40 S
AUG GCU AUG UUG
5’
3’
rRNArRNA
60 S
•The RibosomesRibosomes are like train stationslike train stations
–The mRNA is the trainmRNA is the train slowly moving through the station.
rRNArRNA
Codons
mRNAmRNA
21 - 41CH110 – Nucleic Acids
Transfer RNA Transfer RNA - tRNA- tRNA =• relatively small small compared to other RNA’s
(70-90 bases.)70-90 bases.)• transports amino acidstransports amino acids to site of protein synthesis.
A
C
C
A
C
C
U
C
G
U
CU
U
C
G
G
G
G
G
CC GGG
CC GG
A CGG
CC GGU
C
C
C
C
U
C
A
U
G
G
A
G
G
G
G
GU
U
CC G
U
C GC
AU
G
G
C
U
AG U
A GU
G
GC
HO-A
C
C
A
C
C
U
C
G
U
CU
U
C
G
G
G
G
G
CC GGG
CC GG
A CGG
CC GGU
C
C
C
C
U
C
A
U
G
G
A
G
G
G
G
GU
U
CC G
U
C GC
AU
G
G
C
U
AG U
A GU
G
GC
HO-
21 - 42CH110 – Nucleic Acids
Anticodons on t-RNAAnticodons on t-RNA
A
C
C
A
C
C
U
C
G
U
CU
U
C
G
G
G
G
G
CC GGG
CC GG
A CGG
CC GGU
C
C
C
C
U
C
A
U
G
G
A
G
G
G
G
GU
U
CC G
U
C GC
AU
G
G
C
U
AG U
A GU
G
GC
HO-
Site of aminoacid attachment
Site of aminoacid attachment
Three base anticodon site
Three base anticodon site
Point ofattachmentto mRNA
Point ofattachmentto mRNA
21 - 43CH110 – Nucleic Acids
Amino acid codonsAmino acid codons
alanine GCA, GCC, GCGGCU, AGA, AGG
arginine AGA, AGG, CGACGC, CGG, CGU
asparagine AAC, AAUaspartate GAC, GAU cysteine UGC, UGUglutamate GAA, GAGglutamine CAA, CAGglycine GAA, GCC, GGG
GGUhistidine CAC, CAUisoleucine AUA, AUC, AUUleucine CUA, CUC, CUG
CUU, UUA, UUG
lysine AAA, AAGmethionine AUGphenylalanine UUC, UUUproline CCA, CCC
CCG, CCUserine UCA, UCC
UCG, UCU AGC, AGU
threonine ACA, ACC ACG, ACU
tryptophan UGGtyrosine UCA, UCUvaline GUA, GUC
GUG, GUU
21 - 45CH110 – Nucleic Acids
Protein SynthesisProtein Synthesis1: Activation1: Activation
Each AA is activated by reacting with an ATP
The activated AA is then attached to particular tRNAtRNA... (with the correct anticodon)
C G A
fMET
anticodon
activated AA
21 - 46CH110 – Nucleic Acids
60S
TranslationTranslation
40S
AUG GCU AUG UUG mRNA
5’
3’
Initiationfactors
ribosome unit
U A C
fMET
PPsitesite AA site site
21 - 47CH110 – Nucleic Acids
U A C
fMET
TranslationTranslation
40S ribosome unit
AUG GCU AUG UUG mRNA
5’
3’
60S
PPsitesite AA site site
C G A
Ala
21 - 48CH110 – Nucleic Acids
ribosome unit
AUG GCU AUG UUG mRNA
5’
3’
TranslationTranslation
U A C
fMET
C G A
Ala
peptide bondforms
21 - 49CH110 – Nucleic Acids
ribosome unit
GCU UUC UUGmRNA
5’
3’
TranslationTranslation
C G A
Ala
peptide bond
Met
Z Z Z
Amino Acid
AU G
U A C
U A C
21 - 50CH110 – Nucleic Acids
ribosome unit
GCU UUC UUGmRNA
5’
3’
TranslationTranslation
C G A
Ala
peptide bondforms
Met
? ? ?
???
AU G
U A C
21 - 53CH110 – Nucleic Acids
Recombinant DNARecombinant DNA
Bacterium
Remove gene segment
DNAPlasmid sticky ends
Cut genefor insulin
Replace inbacterium
21 - 54CH110 – Nucleic Acids54
Learning CheckLearning Check
What is the sequence of bases in mRNA producedfrom a section of the template strand of DNA that
hasthe sequence of bases: 3’–C–T–A–A–G–G–5’?
1. 5’–G–A–T–T–C–C–3’
2. 5’–G–A–U–U–C–C–3’
3. 5’–C–T–A–A–G–G–3’
21 - 55CH110 – Nucleic Acids55
SolutionSolution
What is the sequence of bases in mRNA producedfrom a section of the template strand of DNA that
hasthe sequence of bases: 3’–C–T–A–A–G–G–5’?
3’–C–T–A–A–G–G–5’?
2. 5’–G–A–U–U–C–C–5’
21 - 56CH110 – Nucleic Acids56
The following section of DNA is used to build a mRNA
for a protein. 3’—GAA—CCC—TTT—5’
A. What is the corresponding mRNA sequence?
B. What are the anticodons on the tRNAs?
C. What is the amino acid order in the peptide?
Learning CheckLearning Check
21 - 57CH110 – Nucleic Acids57
3’—GAA—CCC—TTT—5’ DNAA. What is the corresponding mRNA sequence?
5’—CUU—GGG—AAA—3’ mRNA
B. What are the anticodons for the tRNAs?mRNA codons CUU GGG AAAtRNA anticodons GAA CCC UUU
C. What is the amino acid order in the peptide? mRNA 5’—CUU—GGG—AAA—3’ Leu — Gly — Lys
SolutionSolution