Biol 240 Topic 8

Front 1

What binds to RNA polymerase to direct to promoter? How do different ____ affect transcription?

Back 1

sigma factors, different sigma factors guide to different genes

Front 2

rho-independent vs. dependent translation

Back 2

Dep: rho protein follows RNAP, removes it once @ termination seq

Indep: RNA hairpin loop forms, RNAP dissoc. from DNA (high GC-->AT causes it to break off)

Front 3

How do bacteria align @ correct starting location for transcription?

Back 3

The small ribosomal subunit aligns with shine-delgarno seq.

Front 4

How is bacteria mRNA polycistronic?

Back 4

Multiple shine-delgarno sequences, allow for multiple polypeptides to be made from one mRNA sequence.

Front 5

Regulatory factors (2), permits which condition-spec responses (3)

Back 5

Changes in nutrients/competition, substrate-specificity, metabolism, sporulation

Front 6

Which enzymes are constitutive (active all the time)? Is this practical for all enzymes?

Back 6

Only ATP synthase and TCA cycles enzymes are constitutive? Not practical for all enzymes, as its a waste of energy,

Front 7

Allosteric regulation (activation vs. inhibition)

Back 7

active: Binding of effector allows substrate to bind to enzyme.

inhibition: binding of effector deforms active site to disallow substrate to bind to enzyme.

Front 8

Types of covalent modification (4), purpose?

Back 8

Phosphorylation, Acetylation, Methylation, Glycosylation, alters enzyme conformation.

Front 9

What is an operon?

Back 9

Sequence of structural genes, regulates other related gene's protein synthesis.

Front 10

Positive vs. negative control,

Back 10

Allosteric protein acts to activate mRNA seq, Allosteric protein acts to prevent mRNA seq

Front 11

Negative control of transcription (2 types), which is minor/major of the time

Back 11

Repression: inhibits transcription in response to a signal (minority)

Induction: depression of enzyme production in response to a signal (majority)

Front 12

Positive control of transcription examples (2)

Back 12

Allosteric regulator proteins activate binding of RNAP to DNA

Maltose activator protein only binds DNA in the presence of maltose.

Front 13

How do +vely controlled promoters bind RNAP, effects?

Back 13

binds weakly to the DNA @ activator site, may cause structural damage/interact directly with polymerase

Front 14

What is an effector molecule?

Back 14

A molecule which affects protein production in assoc. with allosteric protein regulators

Front 15

2 types of effector molecules and purposes

Back 15

Co-inducer/activator (turns on enzyme production) and co-repressor (binds and activates a repressor)

Front 16

When is lac operon expressed?

Back 16

When all glucose is consumed (diauxic growth), rapid consumption of glucose causes high growth, lag phase as soon as glucose is running out.

Front 17

Repressor/Effector molecules in the lac operon

Back 17

Repressor protein: LacI, binds to operator, inhibits transcription via blocking RNAP

Effector Molecule: Allolactose, induces transcription via binding to operator's repressor

Front 18

What is the activator protein? How does it do it, when?

Back 18

Cyclic AMP receptor protein (CRP): binds/inc. transcription rates when effector molecule (cAMP) is present, when low glucose.

Effector molecule induces structural change in activator protein, inc. binding site's affinity, RNAP wants to bind to lac operon promoter

Front 19

How can effector molecules inhibit transcription?

Back 19

Binding to the pressor protein, enhancing ability to bind to operator.

Front 20

what is attenuation? Effect if ribosome follows RNAP?

Back 20

Control of transcription via mRNA secondary structure (interaction between translation and transcription)

hairpin loops are formed and the polymerase detaches.

Front 21

What is a quorum? In life and in biology? (4)

Back 21

Members of a group that must be present in order to conduct business (in life).

- In biology, it is a chemical signalling system that allows microbes to communicate.

- Regulates gene expression based on pop. density.

-cells release autoinducer molecules into enviro as pop. density inc.

-detects change in autoinducer levels, causes regulation of gene expression

Front 22

Bioluminescence in A. fischeri, mechanism?

Back 22

lux is a quorum-sensing system found in A. fischeri. Cells only emit light when in light organ of squid.

Mechanism is AHL which stimulates luminescence, LuxI protein catalyzes AHL syn

LuxR interacts with AHL at high conc., binds "lux box" (activator binding site), transcribes luciferase protein genes and LuxI, which forms more AHL

Front 23

Quorum sensing uses (4)

Back 23

motility, conjugation, biofilm formation, pathogenesis

Front 24

Two-component Regulatory systems components, allows for __?, involve 2 other parts?

Back 24

Use one protein as a sensor, use other to control transcription, allows for responses to changes in enviro, involve a sensor kinase (detector) and response regulator

Front 25

What is chemotaxis? How does it work? What does it induce?

Back 25

Chemotaxis is bacteria behaviour modulated by protein activity changes

It senses changes in chemical gradients over time and induces change in durection/duration of flagellar rotation, leads to movement.

Front 26

3 Steps of chemotaxical regulation

Back 26

Response to signal: MCP (methyl-accepting chemotaxis proteins) senses attractant/repellant

Control of flagella rotation: CheY protein, phosphorylated by CheA-P when attract low, CheY-P initiates flagellar reversal

Adaptation: Feedback loops allows system to reset self, allows to detect signal conc., requires methylation of MCP

Front 27

Methylation of MCP regulates _____ during _____? How do highly methylated MCP change in their responses? What will lower attractant levels do to the mMCP?

Back 27

Methylation of MCP regulates attraction during high attractant levels, "adaptation".

Highly methylated MCPs will only respond to high attractant levels, lowered levels of attractant will lead to demethylation.

Front 28

What are regulons? catabolite repression? SOS response? What are two most important regulatory proteins for SOS response?

Back 28

Regulons are sets of coordinated genes, responding to same regulatory system.

Catabolite repression: shutdown of several systems that utilize various nutrients when glucose is present

SOS Response: multigene system for wide scale DNA repair in response to serious DNA damage.

recA and lexA

Front 29

Alternate Sigma Factors, use and recognized by what in E. coli?

Back 29

Alternative Sigma factors are used to direct RNAP to certain genes. In E. coli, promoters are recognized by sigma-70.