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CHAPTER 7GENETICS(Part 2)

Resilience expense 1CONTENT DNA ReplicationModels of DNA ReplicationDNA Replication Process

Genetic code and its features

Protein synthesis: Transcription and TranslationTranslation in prokaryotes and eukaryotesTranslation Initiation, Elongation and Termination steps.BIO095 (2013/2014)CONTENT Gene Regulation and expression

Mendelian geneticsMonohybrid inheritanceDihybrid inheritanceExtension of Mendelian Genetics

Population GeneticsGene populationHardy-Weinbergs PrincipleFactor that change the frequency in population BIO095 (2013/2014)PART 2(1) LEARNING OBJECTIVES Explain about the DNA replication process.

Summarize how DNA replicates (semiconservative) by citing the Meselson and Stahls experiment.

Outline the flow of genetic information process in cells, from DNA RNA Proteins via looking at the transcription and translation process.

BIO095 (2013/2014)(2) LEARNING OBJECTIVES Explain the concept of operon and gene regulation.

Describe the components of lac operon and their functions in E. coli.

Describe the mechanism of the operon in the absence and presence of lactose.

BIO095 (2013/2014)(3) LEARNING OBJECTIVES Define important terms in genetics.

Describe Mendel Principles of Segregation and Independent Assortment.

Explain population genetics, gene pool, allele frequencies and genetic equilibrium.

State and explain five assumptions of Hardy-Weinberg Law fro genetic equilibrium.

Calculate allele and genotype frequencies. BIO095 (2013/2014)The Concept of Operon and Gene RegulationOperon model describes the mechanism for the control of gene expression in bacteria

Some of the bacterial genes will be expressed only when it is necessary.

The operon model was proposed by Jacob and Monod (in 1961) on E. coli BIO095 (2013/2014)7The Jacob and Monod hypothesis of gene controlProtein synthesis is regulated by operon systemInvolved operon which consists of : i. Promoter ii Operator iii Structural genes

BIO095 (2013/2014)8Operon is controlled by regulator gene

The Jacob and Monod hypothesis of gene controlBIO095 (2013/2014)9Regulator gene (R) / Lac I contain genetic information for the synthesis of repressor protein

The Components Of Lac Operon And Its Function In E.Coli10

ii. Promoter (P) site for the attachment of RNA polymerase which is needed to start transcription11

iii. Operator (O) site for the attachment of the repressor protein12

iv. Structural genes (S) One to several genes determining the amino acids sequence of the protein133 structural genes :Function unknowntransacetylaseLac A (S3)Facilitate the uptake of lactose into the cell

Lactose permeaseLac Y (S2)hydrolyze lactose to glucose & galactose

-galactosidase Lac Z (S1)FunctionEnzyme producedStructural genes14

v. Operon A group of structural genes and regulating genes that function as a unit. (Operon = Structural gene + operator + promoter )BIO095 (2013/2014)15i. Lactose (inducer) present

The Mechanism Of The Operon In The Absence And Presence Of Lactose16

The lac operon (lactose present)Lactose enter E.coli and converted to Allolactose, an isomer of lactose, Allolactose binds to the repressor protein which is produced by regulator gene17

The repressor protein changes shapeand it cannot bind to the operatorThe operon is activated.

The lac operon (lactose present)18

RNA polymerase binds to promoter.Transcription of structural genes takes place to form mRNAThe lac operon (lactose present)19The translation of mRNA occur.The enzymes -galactosidase , permease and transacetylase are producedLactose is hydrolysed into galactose and glucose

20ii. Lactose (Inducer) absent 21

If the lactose (inducer) is absent, the repressor attaches itself to the operator & blocked part of promoterThe lac operon (lactose absent)22RNA polymerase cannot bind to the promoterThe operon is not active- Transcription is blocked by repressor-operator complex

The lac operon (lactose absent)23The lac operon (lactose absent)

No transcription occur & the 3 structural enzymes cannot be synthesizedBIO095 (2013/2014)24The end of Part 2!!