AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

Genetic Genetic control of control of protein protein

structure structure and and

functionfunction

AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

The structure of DNA and RNAThe structure of DNA and RNA

Genetic material of living organisms Genetic material of living organisms is either DNA or RNA.is either DNA or RNA.

DNA – Deoxyribonucleic acidDNA – Deoxyribonucleic acid RNA – Ribonucleic acidRNA – Ribonucleic acid

GenesGenes are lengths of DNA that code are lengths of DNA that code for particular proteins.for particular proteins.

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DNA and RNA are polynucleotidesDNA and RNA are polynucleotides

Both DNA and RNA are Both DNA and RNA are polynucleotides.polynucleotides.

They are made up of smaller They are made up of smaller molecules called nucleotides.molecules called nucleotides.

DNA is made of two polynucleotide strands:DNA is made of two polynucleotide strands:

RNA is made of a single polynucleotide strand:RNA is made of a single polynucleotide strand:

Nucleotide NucleotideNucleotide

Nucleotide

Nucleotide

Nucleotide

Nucleotide

Nucleotide

Nucleotide Nucleotide Nucleotide Nucleotide

NucleotideNucleotide Nucleotide

Nucleotide

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Structure of a nucleotideStructure of a nucleotide

A nucleotide is made A nucleotide is made of 3 components:of 3 components:

AA Pentose sugar Pentose sugar This is a 5 carbon This is a 5 carbon

sugarsugar The sugar in DNA is The sugar in DNA is

deoxyribosedeoxyribose.. The sugar in RNA is The sugar in RNA is

riboseribose..

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Structure of a nucleotideStructure of a nucleotide

A A Phosphate groupPhosphate group Phosphate groups Phosphate groups

are important are important because they link because they link the sugar on one the sugar on one nucleotide onto the nucleotide onto the phosphate of the phosphate of the next nucleotide to next nucleotide to make a make a polynucleotide.polynucleotide.

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Structure of a nucleotideStructure of a nucleotide A A Nitogenous baseNitogenous base

In DNA the four bases In DNA the four bases are:are:– ThymineThymine– AdenineAdenine– CytosineCytosine– GuanineGuanine

In RNA the four bases In RNA the four bases are:are:– UracilUracil– AdenineAdenine– CytosineCytosine– GuanineGuanine

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Nitrogenous bases – Two typesNitrogenous bases – Two types

PyramidinesPyramidines

Thymine - TThymine - T

Cytosine - CCytosine - C

Uracil - UUracil - U

PurinesPurines

Adenine - AAdenine - A

Guanine - GGuanine - G

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Sugar phosphate bonds (backbone Sugar phosphate bonds (backbone of DNA)of DNA)

Nucleotides are Nucleotides are connected to each connected to each other via the other via the phosphate on one phosphate on one nucleotide and the nucleotide and the sugar on the next sugar on the next nucleotidenucleotide

A PolynucleotideA Polynucleotide

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James Watson (L) and Francis Crick (R), and the model James Watson (L) and Francis Crick (R), and the model

they built of the structure of DNAthey built of the structure of DNA

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X-ray diffraction photograph of the X-ray diffraction photograph of the DNA double helix DNA double helix

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Base pairingBase pairing

The Nitrogenous The Nitrogenous Bases pair up with Bases pair up with other bases. For other bases. For example the bases example the bases of one strand of of one strand of DNA base pair with DNA base pair with the bases on the the bases on the opposite strand of opposite strand of the DNA.the DNA.

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AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

The Rule:The Rule: Adenine always base pairs with Adenine always base pairs with

Thymine (or Uracil if RNA)Thymine (or Uracil if RNA)

Cytosine always base pairs with Cytosine always base pairs with Guanine.Guanine.

This is beacuse there is exactly This is beacuse there is exactly enough room for one purine and one enough room for one purine and one pyramide base between the two pyramide base between the two polynucleotide strands of DNA.polynucleotide strands of DNA.

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Complementary base pairingComplementary base pairing

PurinesPurines PyramidinesPyramidines

Adenine Adenine ThymineThymine

AdenineAdenine UracilUracil

GuanineGuanine CytosineCytosine

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Nature of the Genetic MaterialNature of the Genetic Material Property 1Property 1 - it must contain, in a - it must contain, in a

stable form, information encoding stable form, information encoding the organism’s structure, function, the organism’s structure, function, development and reproductiondevelopment and reproduction

Property 2Property 2 - it must replicate - it must replicate accurately so progeny cells have the accurately so progeny cells have the same genetic makeupsame genetic makeup

Property 3Property 3 - it must be capable of - it must be capable of some variation (mutation) to permit some variation (mutation) to permit evolutionevolution

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Replication of DNA and Replication of DNA and ChromosomesChromosomes

Speed of DNA replication:Speed of DNA replication: 3,000 nucleotides/min in human 3,000 nucleotides/min in human 30,000 nucleotides/min in 30,000 nucleotides/min in E.coliE.coli

Accuracy of DNA replication: Accuracy of DNA replication: Very precise (1 error/1,000,000,000 nt)Very precise (1 error/1,000,000,000 nt)

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Meselson and Stahl (1958)Meselson and Stahl (1958)

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AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

Origins initiate Origins initiate replication at replication at different times.different times.

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AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function

AS Biology. Gnetic control of proteiAS Biology. Gnetic control of protein structure and functionn structure and function