Nucliec Acid

8/2/2019 Nucliec Acid

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Nucleic Acid


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Nucleic Acids

Nucleic Acids

Structures of Nucleic Acids

DNA Replication

RNA and Transcription


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Genetic material of cells

GENES units of genetic material thatCODES FOR A SPECIFIC TRAIT

Called NUCLEIC ACIDS

DNA is made up of repeating moleculescalled NUCLEOTIDES


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Genetic Diversity

Differentarrangements ofNUCLEOTIDES in anucleic acid (DNA)

provides the key toDIVERSITY amongliving organisms.


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The Code of Life

The code of the chromosome is the

SPECIFIC ORDER that bases occur.

A T C G T A T G C G G


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6

Most Macromolecules arePolymers

Polymers are made by stringingtogether many smaller molecules called

monomers Nucleic AcidMonomer


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Name the organelle and give its

function.

Cell Parts Review

Animal Plant

Nucleus

Ribosome

Endoplasmic Reticulum: aids in processing

carbohydrates, lipids and proteins for exportfrom the cell

Endoplasmic Reticulum

Golgi Body

Nucleus: control body of the cell; contains the

genetic material (DNA)

Golgi Aparatus: modifies, sorts, and packages

materials from the ER for storage in the cell orsecretion outside the cell

Ribosome: site where proteins are made


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Central Dogma

DNA ---------------- RNA-------------- protein

Replication

transcription translation


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Central Dogma

Replication DNA making a copy of itself

Making a replica

Transcription DNA being made into RNA

Still in nucleotide language

Translation RNA being made into protein Change to amino acid language


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Nucleic Acids

Store hereditary informationContain information for making all

the bodys proteins

Two types exist --- DNA &

RNA


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Nucleotides

Nucleic acids consist of nucleotides thathave a sugar, nitrogen base, and phosphate

nucleoside

Sugar

Base

PO4


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Nucleic Acids- DNA & RNA1. Made of monomers called nucleotides; The

nucleotides are made of phosphate (PO4), amonosaccharide, and a nitrogenous base.

2. There are four nitrogenous bases used by DNA:Adenine (A), Thymine (T), Guanine (G), and Cytosine (C ). RNA uses one called Uracil (U) rather thanthymine.

3. RNA is a single strand, while DNA is made of 2separate strands. They stick together by H-bondingbetween the N-bases.


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Nitrogen-Containing Bases

N

N

N

NH

NH2

N

N

O

CH3

O

H

H

N

N

N

N

O

H

NH2H

N

N

NH2

CH3

O

H

N

N

O

CH3

O

H

H

adenine (A) thymine (T)

guanine (G) cytosine (C) uracil (U)


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Sugars

O OHCH2

OHOH

HO HO O OHCH2

OH

ribose deoxyribose

(no O)


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Nucleosides in DNA

Base Sugar Nucleoside

Adenine (A) Deoxyribose Adenosine

Guanine (G) Deoxyribose GuanosineCytosine (C) Deoxyribose Cytidine

Thymine (T) Deoxyribose Thymidine


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Nucleosides in RNA

Base SugarNucleoside

Adenine (A) ribose

Adenosine

Guanine (G) riboseGuanosine

Cytosine (C) ribose CytidineUracil (U) ribose Uridine


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Example of a Nucleotide

O

OH

N

N

NH2

O

CH2OP

O

O-

O-

deoxyctyidine monophosphate (dCMP)


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Nucleotides in DNA and RNA

DNA

dAMP Deoxyadenosine monophosphate

dGMP Deoxyguanosine monophosphate

dCMP Deoxycytidine monophosphatedTMP Deoxythymidine monophosphate

RNA

AMP adenosine monophosphateGMP guanosine monophosphate

CMP cytidine monophosphate

UMP uridine monophosphate


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Structure of Nucleic Acids

Polymers of four nucleotides

Linked by alternating sugar-phosphate bonds

RNA: ribose and A, G, C, U

DNA: deoxyribose and A,G,C,T

nucleotide nucleotide nucleotide nucleotideP sugar

base

P sugar

base

P sugar

base

P sugar

base


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Nucleic Acid Structure

3,5-phosphodiester bond

O

N

N

NH2

O

CH2

OP

O

O-

O-

OH

O

N

N

NH2

CH2OP

O

O-

OH

O

N

N

AMP

CMP

3

5


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Nucleic AcidsNitrogenous base

(A,G,C, or T)

Phosphategroup

Thymine (T)

Sugar

(deoxyribose)Phosphate

BaseSugar

Nucleicacids arepolymers ofnucleotides

Nucleotide


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Nucleotide Nucleic acid monomer


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Nucleic Acids

Polymer of ribofuranosiderings linked by phosphate

ester groups. Each ribose is bonded to

a base.

Ribonucleic acid (RNA)

Deoxyribonucleic acid(DNA)

=>


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What is located in the nucleus?

Nucleus

Chromosome

DNA

Nucleic Acid

Nucleotide


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What does the DNA of all these

organisms have in common?

They all share a universal

genetic code.


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DNA


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A HISTORY OF DNA

Discovery of the DNA double helix

A. Frederick Griffith Discovers that a factor

in diseased bacteria can transform harmlessbacteria into deadly bacteria (1928)

B. Rosalind Franklin- X-ray photo of DNA.

(1952)

C. Watson and Crick- described theDNA molecule from Franklins X-ray.

(1953)

SEE p. 292-293


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Purpose of DNA

Why do we have DNA?

-Tells the genetic information


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DNA Structure A DNA molecule consists of a double helix of two

polynucleotide chains that are oriented antiparallel toeach other

The chains are held together by H-bonds between thebases of each nucleotide.

Nucleotides consist of a sugar, a base, and a phosphate(Fig. 4.16).

There are four bases in DNA: adenine (A), Thymine (T),Guanine (G), Cytosine (C).

These bases exhibit complementary base pairing:

A pairs with T

G pairs with C.


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Structure of DNA

-D-2-deoxyribofuranose is the sugar.

2 deoxy indicate lack ofOH grp at 2 position

Heterocyclic bases are cytosine, thymine

(instead of uracil), adenine, and guanine. Linked by phosphate ester groups to form the

primary structure.

Sugar(Furanose) joind phospahatethrough C-3

and C-5 OH group Base-Suger is called nucleoside


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What is a Nucleotide?

H

H2

H H

H3

HH

H

H

H

O

O

O

C C

C

N

N

PO

O

O

C

C

C C

C

O

OO

C

C

1.

2.

3.

1.

2.

3.

1. Phosphate Group2. 5-Carbon Sugar

(Dexoyribose or Ribose)

3. Nitrogen Base1. Phosphate Group

2. 5-Carbon Sugar

(Dexoyribose or Ribose)

3. Nitrogen Base

Nucleotides, too


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Remember DNA Nucleotides make up

nucleic acid Are made up of

monomers

Double helix shape

Store geneticinformation

Help make proteins

Examples: DNA &RNA

sugar

phosphate

nitrogenbase


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Nucleotides There are four nitrogen bases making up

four different nucleotides.

Adenine

Guanine

Thymine

Cytosine

Pyrimidines

PurinesA

C

G

T

N base


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Base Pairings

=>


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Bases

Each DNAnucleotide hasone of the

following bases: Thymine (T) Cytosine (C)

Adenine (A) Guanine (G)

Adenine (A)

Guanine (G)Thymine (T)

Cytosine (C)


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DNA Backbone Structure Alternate phosphate and sugar (deoxyribose), phosphate

ester bonds


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Chargaffs Base Pair Rules Adenine always bonds with thymine. A = T

Guanine always bonds with Cytosine. G C

A

CG

T


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Erwin Chargaff Chargaff discovered that DNA contains

the same amount of adenosine asthymine and the same amount ofcytosine as guanine.

A A

A AA

A

AT

T

T

T T

T

T

C

CC G G

G


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C

G

A

A

T

G

NucleotideP

SN-b

Pairing DNA Nucleotides What is a nucleotide?

Rule

A toC to

TG

What is the base pairing rule? What would be the complementary

nucleotide pairing?

DNA


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DNA

Two strands ofDNA join

together toform a double

helix

Basepair

Double helix


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Double Helix of DNA

Two complementarypolynucleotidechains are coiled

into a helix. Described by

Watson and Crick,1953.

=>

3E d5E d


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3End

3End 5End

5End

DNA

DOUBLE

HELIX

laddershapedmolecule


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Double Helix of DNA

DNA contains two strands of nucleotides

H bonds hold the two strands in a double-helix structure

A helix structure is like a spiral stair case Bases are always paired as AT and G-C

Thus the bases along one strand

complement the bases along the other


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DNA Double Helix

Base pairing by unique hydrogen bonds

C - G and A - T pairs


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DNA Replication

SemiconservativeModel:

1. Watson and Crick

showed: the two strandsof the parental moleculeseparate, and eachfunctions as a templatefor synthesis of a new

complementary strand.

. Parental DNADNA Template

New DNA


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(1961)Watson & Crick proposed

DNA controlled cell function byserving as a template for PROTEINstructure.

3 Nucleotides = a triplet or CODON

(which code for a specific AMINO ACID)See p.303

AMINO ACIDS are the building blocksof proteins.

Replication Quiz


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1. Why is replication necessary?

2. When does replication occur?

3. Describe how replication works.

4. Use the complementary rule tocreate the complementary

strand:

A---?

G---?C---?T---?A---?

G---?A---?G---?C---?

A---?G---?T---?

Replication Quiz

Replication Quiz


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1. Why is replication necessary?

So both new cells will have the correctDNA2. When does replication occur?During interphase (S phase).

3. Describe how replication works.Enzymes unzip DNA andcomplementary nucleotides joineach original strand.

4. Use the complementary rule tocreate the complementary strand:

A---TG---C

C---GT---AA---TG---C

A---TG---CC---GA---TG---CT---A

Replication Quiz


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Replicationof DNA

DNA

Replication

Replication


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DNA Replication

=>


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DNA Replication DNA replication

creates an exactcopy of a DNAmolecule.

Replicationoccurs duringinterphase of thecell cycle.

Followingreplication, mitosis

can occur.


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Complementary Base Pairs

Two H bonds for A-T

Three H bonds for G-C


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Learning Check NA1

Write the complementary base sequencefor the matching strand in the followingDNA section:

-A-G-T-C-C-A-A-T-G-C-


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Solution NA1

Write the complementary base sequencefor the matching strand in the followingDNA section:

-A-G-T-C-C-A-A-T-G-C-

-T-C-A-G-G-T-T-A-C-G-


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DNA Replication

DNA in the chromosomes replicates itselfevery cell division

Maintains correct genetic information Two strands of DNA unwind

Each strand acts like a template

New bases pair with their complementary base

Two double helixes form that are copies oforiginal DNA


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Replication

Remember that DNA is selfcomplementary

Replication is semiconservative

One strand goes to next generation

Other is new

Each strand is a template for the other

If one strand is 5 AGCT 3

Other is: 3 TCGA 5


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DNA Replication

The enzyme DNA polymerase catalyzes theprocess of DNA duplication.

Hydrogen bonds between paired bases break andnew nucleotides that are brought in by DNApolymerase base pair with the original strand.

The resulting double-stranded DNA moleculescontain one strand from the original molecule andone new complementary strand.


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DNA Unwinds

G- -C

A- -T

C- -G

T- -A

G-CA-TC-G

T-A


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DNA Copied with Base Pairs

Two copies of original DNA strand

G-C G-C

A-T A-T

C-G C-G

T-A G-A


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DNA Transcription

DNA can unzipitself and RNAnucleotides matchup to the DNA

strand.

Both DNA & RNAare formed fromNUCLEOTIDES andare called NUCLEICacids.

See p.301


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DNA Translation

The cell usesinformation frommessenger RNAto produce proteins

See p.304-305

We will

discuss detailsof this on a

later date


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AMAZING DNA FACTS

DNA from a single humancell extends in a singlethread for almost 2 meters

long!!!

It contains informationequal to some 600,000

printed pages of 500 wordseach!!!

(a library of about 1,000 books)


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What is RNA?

DNA must have a helper

molecule.

RNA stands for

RiboNucleic Acid RNA is a single stranded

nucleic acid made up of

monomers callednucleotides

sugar

phosphate

nitrogenbase


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RNA Ribonucleic Acid

Ribose sugar

has an extra

OH orhydroxylgroup

It has thebase uracil(U) insteadof thymine

(T)

Nitrogenous base(A,G,C, or U)

Sugar (ribose)

Phosphategroup

Uracil


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A

B

C

RNA Nucleotides

A - Sugar (ribose)

B - Phosphate

C - Nitrogen base

sugar

phosphate

nitrogenbase

Name the parts of the nucleotide.


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Rules for Base Pairing Cytosine pairs with Guanine

Adenine pairs with Uracil

Notice that RNA has Uracil(not thymine)

A = U

C = G

Rules for Base Pairing


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Rules for Base Pairing

C = G

A = U

3 DNA strand

5 DNA strandRNA strand

C

A

T

G

G

U

C

A

St t f RNA


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Structure of RNA

=>

Rib l tid


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Ribonucleotides

Add phosphate at 5 carbon.


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What is the function of RNA?

Carries DNAs message code

Helps make protein

Types of RNA

Messenger RNA (mRNA)

Transfer RNA (tRNA) Ribosomal RNA (rRNA)


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Phosphate Group

Nitrogen Base

Sugar

(ribose)

RNA


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3-Types of RNA

Messenger RNA (mRNA) Takes info fromnucleus to the ribosome. Contains thecodon.

Transfer RNA (tRNA) Brings amino acidswith complementary base pairs to themRna at the ribosome. Contains the

anticodon. Ribosomal RNA (rRNA) Makes up one

of the subunits of the ribosomes

RNA Codes for


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RNA Codes forAmino Acids

The nitrogen bases in RNAcode for amino acids.

A triplet of nitrogen basescodes for one amino acid.

The triplet is called a

codon.


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DNA VS RNA- Nucleic acidsDNA RNA

Structure Double Helix Single Strand

Sugar Deoxyribose Ribose

Nitrogen Bases Adenine thymineCytosine Guanine

Adenine UracilCytosine Guanine

Function Stores andtransmits geneticinformation

Messenger: takesinfo from nucleusto ribosome

Overall process of protein


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p psynthesis

transcription translation

DNA RNA Protein


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What does the chain of amino acidsrepresent?

Threonine

Arginine

Glycine

Glycine

Proline

Asparagine

ProlineAlanine

Polypeptide Chain A Protein

Genetic Code


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The genetic code is preserved in theprocess of transcription followed by

translation. Each of the twenty different amino acids is

represented in the DNA molecule by a tripletof three nucleotides called a triplet code

also known as the genetic code. For example CGT represents one amino acid

while GCA represents another.

Triplets of nucleotides also provide stop andstart signals for protein synthesis.

C d


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Codons One codon codes for one amino acid.

A sequence of amino acids is a protein.

EX: ACG = amino acid (threonine)CGC = amino acid (arginine)

GGA = amino acid (glycine)

ACG

GGA

GGC

CCA

AAC

CCG

GCCCGC

Threonine

Arginine

Glycine

Glycine

Proline

Asparagine

Proline

Alanine

Amino Acid

protein

G i C d


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Genetic Code

Nucleotides read in triplet codons 5 -3

Each codon translates to an amino acid

64 possible codons 3 positions and 4 possiblities (AGCU) makes

43 or 64 possibilities

Degeneracy or redundancy of code Only 20 amino acids

Implications for mutations

DNA


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G ti C d


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Genetic Code

G ti C d


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Genetic Code

Not everything translated

AUG is start codon

Find the start codon

Also are stop codons

To determine aa sequence

Find start codon

Read in threes

Continue to stop codon

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