BIOL 1000 Chapter Notes - Chapter 14: Genomic Imprinting, Oncogene, Microrna

43 views3 pages

lavendersnake691

29 Jun 2018

School

Department

Course

Professor

For unlimited access to Textbook Notes, a Class+ subscription is required.

CHAPTER 14: Control of Gene Expression

14.1 Regulation of Gene Expression in Prokaryotic Cells

Transcriptional control involves short-term changes that turn specific

genes on or off in response to changes in environmental conditions. Change in

gene activity is controlled by regulatory proteins that recognize operators (short

segment that is binding sequence for regulatory protein) of operons (cluster of

prokaryotic genes & DNA sequences involved in their regulation).

Regulatory proteins may be repressors, which slow rate of transcription

of operons, or activators, which increase rate of transcription.

Some repressors are made in active form (where they bind to operon’s

operator & inhibit its transcription) Combination with an inducer blocks activity

of the repressor and allows operon to be transcribed. Other repressors are made

in inactive form (where they’re unable to inhibit transcription of an operon

unless they combine with a corepressor)

Activators are made in inactive form (where they can’t bind to their

binding site next to operon). Combining with another molecule like nucleotide,

converts activator into form in which it binds with binding site & recruits RNA

polymerase, thus stimulating transcription of the operon.

Lac operon for lactose metabolism is transcribed when an inducer

inactivates a repressor & is also repressed by a positive regulatory system.

Transcription of the trp operon genes for tryptophan biosynthesis is repressed

when a repressor is activated by tryptophan.

14.2 Regulation of Transcription in Eukaryotes

Operons are not in eukaryotes, instead genes that encode proteins with

related functions are scattered through genome while being regulated in

coordinated manner.

3D arrangement of AA chains within/between domains produces motifs:

helix-turn-helix, zinc finger, & leucine zipper. Coactivator: multiprotein

complex that forms a bridge between the activators at the enhancer & proteins at

the promoter, causing DNA to form a loop.

2 general types of gene regulation: short-term (involved relatively rapid

changes in gene expression in response to environmental or physiological

conditions changing) and long-term (involves changes in gene expression

associated w/ development & differentiation of an organism)

Regulated at transcriptional level (where most regulation occurs) and at

posttranscriptional, translational, & posttranslational.

Regulation of transcription initiation involves proteins binding to gene’s

promoter & regulatory sites. At promoter, general transcription factors bind &

find more resources at oneclass.com

Unlock document

This preview shows page 1 of the document.
Unlock all 3 pages and 3 million more documents.

Already have an account? Log in

Document Summary

14. 1 regulation of gene expression in prokaryotic cells. Transcriptional control involves short-term changes that turn specific genes on or off in response to changes in environmental conditions. Change in gene activity is controlled by regulatory proteins that recognize operators (short segment that is binding sequence for regulatory protein) of operons (cluster of prokaryotic genes & dna sequences involved in their regulation). Regulatory proteins may be repressors, which slow rate of transcription of operons, or activators, which increase rate of transcription. Some repressors are made in active form (where they bind to operon"s operator & inhibit its transcription) combination with an inducer blocks activity of the repressor and allows operon to be transcribed. Other repressors are made in inactive form (where they"re unable to inhibit transcription of an operon unless they combine with a corepressor) Activators are made in inactive form (where they can"t bind to their binding site next to operon).

Related Questions

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

BIOL 1000 Chapter Notes - Chapter 14: Genomic Imprinting, Oncogene, Microrna

Document Summary

Get access

Related Documents

BIOL 1000 Chapter Notes - Chapter 14: Proteasome, Methylation, Chromatin

BIOL 1000 Lecture Notes - Lecture 15: Gene Expression, Regulatory Sequence, Nuclear Dna

BIOL 1000 Chapter Notes - Chapter 13&14: Atp Hydrolysis, Signal Peptide, The Sequence

Related Questions