Lecture 6 Bacterial Genome Replicaiton, Expression, And Reguluation 2 Mecahnisms Of Geneitc Variation

Question 1

Methyl-accepting chemotaxis proteins (MCPs) are chemoreceptors in ______. That binds environmental chemicals and initiates a series of interactions with cytoplasmic proteins that affects _____

Answer 1

Membrane, flagella the rotation

Question 2

Explain how methyl-accepting chemotaxis proteins (MCPs) can affect flagella the rotation

Answer 2

• Activates sensory kinase CheA (wiht help of CheW) which autophosphorylates
• CheA phosphorylase so the response regulator CheY
• CheY governs rotation of flagella

Question 3

When attractant concentration is high MCP is ______. Thus leading to

Answer 3

Methylated (CheR) Thus leading to CheA/CheW is active (phosphorylated) thus phony lasting CheY wich leads to a clockwise (CW) rotation and a thumbless

Question 4

When the attractant concentration decreases MCP is _______ thus

Answer 4

Not methylated (CHeB) thus CheA is inactive (not phosorylated) this means CheY is inactive and the flagellar rotation is counter-clockwise (CCW) and a run occurs

Question 5

What is Quorum sensing

Answer 5

• Cell-to-cell communication mediated by small signaling a molecules such as N-acylhomoserine lactone (AHL)
• couples cells density and intercellular communication to transcription regulation

Question 6

Example of Quorum sensing in V. Fischeri

Answer 6

• High concentrations of AHL produced by increased density of cells diffuse back into the cell, bind to the transcriptional regulator LuxR and active transcription
• LuxR stimulates transcription of the genes for AHL synthase (luxl) and proteins needed for light production

Question 7

Sporulation is another example of global regulatory system in which ______, _______ , ______ and ______

Answer 7

• Phosphorelay, post translational modification of proteins, transcription initiation regulatory proteins and alternative sigma factors play a role.

Question 8

Starvation signal induces production of _______ to lead to sporulation

Answer 8

Alternative sigma factors

Question 9

Explain how starvation leads to alternative sigma factors

Answer 9

Kin A and Kin B phosphorylate Spo0F, which thus makes Spo0F-Phosphate, this phosphorylated Spo0B to make Spo0B-P this phosphorylated Spo0A to make Spo0A to make Spo0A-P which activate sigma f
- Sigma F leads to early sporulation of gene transcription and activates Active sigma G which leads to late sporulation gene transcription

Question 10

Most prevalent form of a gene is called the

Answer 10

Wild type

Question 11

What is a forward mutation

Answer 11

Wild type to mutant form

Question 12

What is a reversion mutation

Answer 12

Mutant phenotype to wild type phenotype

Question 13

What is a suppressor mutation

Answer 13

• A type of reversion mutation ( mutant phenotype to wild type phenotype) that occurs when the second mutation is at a different site than the original mutation but the wild type phenotype is still the same

Question 14

An example of of post translational regulation is control of chemotaxis. Regulatory enzymes control chemotaxis proteins by _____ and ____

Answer 14

• Phosphorelay system

- Covalent modification