Biochemistry 2280A Chapter Notes - Chapter 9: Small Interfering Rna, Asteroid Family, Chromatin

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blushyak979

25 Dec 2016

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Cell differentiation: achieved by control of gene expression, as all cells in an organism have the same genome. Gene expression: process by which cells selectively direct synthesis of many thousands of proteins and rna encoded in their genome. The different cell types of a multicellular organism contain the same dna. Different cell types produce different sets of proteins. Housekeeping proteins: proteins common to all cells of a eukaryote. Cataloging cell"s rna: can allow for examination of gene expression. A cell can change the expression of its genes in response to external signals. Hormones: ligand binding can trigger increase or decrease in gene expression. Gene expression can be regulated at various steps along central dogma. Controls for various intermediates that don"t need to be formed. Transcriptional regulators: proteins that bind to dna and control gene expression. Promoter: region of gene that binds rna polymerase orienting it for transcription. Regulatory dna sequences: used to switch genes on and off.

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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

Hello can you help me with the following questions:

1. Which part of an udder was transferred to an empty oocyte to clone the sheep Dolly?

a. blastocyst (I think its this one)

b. meiotic spindle

c. intact udder cell

d. nucleus

2. What is the principle of nuclear equivalence?

a. Differentiated cells have lost DNA that codes for other cell types.

b. All nuclei are the same shape.

c. Only nuclei of germ cells contain DNA capable of producing an entire organism.

d. The genome of every somatic cell contains information capable of generating any other cell type in the body.

3. A gene contains 6 exons, numbered 1-6. Which of the following mRNA isoforms is not a possible transcriptional product of this gene?

a. 1-2-3-4-5-6

b. 2-5-3-4

c. 2-4-5-6

d. 5-6

4. Which of the following is a mechanism used to alter gene expression using mRNA transcripts?

a. Different stability (longevity) of mRNA transcripts

b. Inhibition of translation of certain mRNAs

c. Production of small RNA molecules (microRNAs) that block translation

d. All of the above

e. None of the above

5. You have recently started working in an embryology lab and have obtained a large number of unfertilized zebrafish oocytes. You decide to treat the oocytes with RNAse (a protein that will degrade RNAs, but leave DNA proteins intact) prior to fertilizing them. Will the resulting embryos develop into normal fish?

a. Yes, because RNAs from sperm cells can replace those lost from the egg.

b. Yes, because intact DNA is the only factor required for development to proceed.

c. No, because RNAse treatment will damage the structure of the oocyte.

d. No, because maternal mRNAs are required for the early stages of development.

Biochemistry 2280A Chapter Notes - Chapter 9: Small Interfering Rna, Asteroid Family, Chromatin

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