BIOL 102 Chapter Notes - Chapter 17: Adenylyl Cyclase, Operon, Cyclic Adenosine Monophosphate

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25 Aug 2016

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Describe the different levels of gene regulation in bacteria. Describe how mutants, with respect to a particular trait, are found. Describe the mechanisms of negative control of transcription. Describe the mechanisms of positive control of transcription. Describe the structure and functioning of the lac operon. Describe the features of the lac operator and lac repressor that allow the repressor to bind to the operator. Bacteria that live in/ on your body outnumber your own cells. Precise control over gene expression is so important because all organisms in the same location in the body ie. small intestine are competing for space and nutrients and therefore a cell needs to use resources efficiently. Individual that synthesizes proteins it doesn"t need has fewer resources to devote to making proteins it needs. Most gene expression is thought to be triggered from signals from the environment. Flow of info from dna to rna to activation of final gene product happens in 3 steps.

Related Questions

1. What is the term when the product of a biochemical pathway inhibits the activity of the first enzyme of a pathway?

		feedback inhibition.
		activator inhibition.
		diffusional regulation.
		enzyme activation.

2. Through control of gene expression, prokaryotes respond to changing __________ conditions.

		internal
		protein
		environmental
		genetic

3. A protein that negatively regulates transcription by binding to the operator is known as the

		operon
		repressor
		activator
		inducer

4. During attenutation, when tryptophan levels are high, the ________ stem-loop forms and transcription ________ the trpL gene.

		1-2, ends just past
		3-4, ends just past
		1-2, continues beyond
		3-4, continues beyond

5. The process of turning on the expression of a gene in response to a substance in the environment is called:

		constituation.
		repression.
		induction.
		catabolism.

6. What is a function of some specific transcription factors?

		to bind to the promoter region of the gene to facilitate the proper alignment of the RNA polymerase
		to bind to the centromere to induce meiosis
		to bind to enhancer regions to help regulate gene transcription
		to bind to the operator to recruit sigma factor

7. How does exposing an E.coli cell to glucose affect the regulation of the lac operon via CAP?

		cAMP binds to CAP and transcription is increased.
		cAMP binds to CAP and transcription is decreased.
		cAMP does not bind to CAP and transcription is increased.
		cAMP does not bind to CAP and transcription is decreased.

8. The lac repressor protein works when mutations in the repressor gene and structural genes are:

		in cis or in trans.
		in trans only.
		in cis only.
		in both prokaryotes and eukaryotes.

scarletwombat949

QUESTION 10

If you can drink milk as an adult, it means that you have inherited a mutation in the promoter of your lactase gene (the gene that encodes the enzyme you need to break down lactose). Predict the effect of this mutation:

		The mutation changes the number of domains in the enzyme, which makes it work more efficiently
		The mutation changes the amino acid sequence of the lactase protein
		The mutation increases the number of copies of the lactase gene that will be found in your genome
		The mutation changes whether the lactase sequence is found in an intron or exon
		The mutation affects the expression of the lactase gene

1.2 points

QUESTION 11

A competitive inhibitor is decreasing the activity of an enzyme. Predict the effect of adding more substrate to the reaction.

		The substrate will increase the reaction rate by binding to the allosteric site
		The substrate will increase the reaction rate by competing with the inhibitor for the active site
		The reaction rate will not change unless the inhibitor can be removed
		The enzyme adjusts its shape so that the substrate, but NOT the competitive inhibitor, can bind
		The substrate will bind to the competitive inhibitor and block its ability to bind to the enzyme

1.2 points

QUESTION 12

What determines where in the genome a transcription regulator will bind?

		Transcription regulators bind to the 5' UTR region of a gene
		Regulators bind via complementary base-pairing to certain DNA molecules
		Covalent bonds form between the transcription regulator and the atoms of the DNA backbone
		Every eukaryotic gene has a different transcription regulator that will bind to the 5' end of the gene
		Transcription regulators bind to specific DNA sequences via multiple weak non-covalent interactions

1.2 points

QUESTION 13

What is the basic premise of cell theory?

		DNA -> RNA -> protein
		All cells arise from pre-existing cells
		DNA provides the complete instructions to create a cell
		The identity of a cell is determined through gene expression patterns
		All cells contain the same four basic macromolecules

1.2 points

QUESTION 14

What is the benefit of using BOTH the lac activator and the lac repressor to control gene expression?

		Using both an activator and repressor enables cells to more accurately determine the amount of lactose available in the environment
		Enzymes to digest lactose are only made when energy is low and lactose is available
		The activator can override the inhibition of the lac operon by the repressor
		The repressor can control the enhancer, while the activator can control the promoter
		When neither the lac activator or repressor is present, expression of the lac operon is too high

1.2 points

QUESTION 15

What is the histone code used for?

		Phosphorylation and acetylation of DNA affect its ability to be compacted
		Changes to the sequence of DNA change whether DNA will wrap around histone proteins
		Covalent modifications of histones affect the ability of the transcription initiation complex to form
		Histones provide the codon sequences needed for translation to occur
		The histone code affects which amino acids will get added to a polypeptide

True or False????? HELP

1. In the field of epidemiology, increased prevalence of a disease in a population is the universal signal that disease control and treatment are not effective.

2. Cytoplasmic membranes of prokaryotes typically contain more proteins than cytoplasmic membranes of eukaryotes microorganisms.
3. Sanger (or dideoxy) DNA sequencing produces relatively short DNA sequence data, but is by far the least expensive DNA sequencing method currently available.
4. The (italicizes) abbreviation lac Z refers explicitly to the beta galactosidase protein/ enzyme.
5. Archaeal pathogens have been linked to some of the most virulent infectious diseases. 6. A bacterial mutant that is unable to make an amino acid required for growth (relative to its wild-type strain is termed an auxotroph.
7. When counting plaques to enumerate phage particles (as in the BIOL2026 Laboratory), the plaque represents lacK, not presence, of bacterial growth.
8. Because of competition with plant roots for nutrients, microbial numbers in the rhizosphere are typically much lower than in surrounding bulk soil.
9. Chemolithoautotrophy is the strategy that facilitates the existence of biological communities deep beneath the earthâs surface and near hydrothermal vents.

10. In a primary treatment (1 Â°) system of a municipal sewage/ wastewater treatment plant, the main goal is to remove ammonium (NH4+) using specific bacterial enrichment cultures.
11. The small intestine in human is the main site of microbial breakdown of partially digested food.
12. Root nodules of legumes contain nitrogen fixing bacteria.
13. Anoxygenic photosynthesis involves using/ removing electrons from H2O.
14. Algae and Cyanobacteria utilize generally the same two-photosystem biochemical mechanisms in the light- reaction of photosynthesis.
15. In bacteria, the only known reason proton motive force is generated is to power ATP synthase in cellular respiration/ oxidative phosphorylation.
16. Anaerobic respiration is only carried out by prokaryotes, however fermentation can be carried out by both prokaryote and eukaryal microorganism.

17. The general structure and biochemical âmotorsâ of flagella are similar between Bacteria and eukaryotic cells, but fundamentally different in the Archaea.
18. Antibiotic resistance genes appeared in microbes (for the first time ever) only after human .. producing and releasing massive amounts of antibiotics to the environment.
19. Experiment by Esther Lederberg, and then later by Luria and Delbruck (that won them a Nobel prize), illustrated that genetic mutations in bacteria arose in the absence of selective pressures, rather than in response to selection.
20. Quaternary sensing is a mechanism used by bacteria to sense other bacteria and regulate gene expression accordingly (e.g. In the case of expressing the liac operon or initiating EPS production in biofilms).

BIOL 102 Chapter Notes - Chapter 17: Adenylyl Cyclase, Operon, Cyclic Adenosine Monophosphate

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