Biology 113: Book Questions

Front 1

What is cellular differentiation?

Back 1

The structural anfunctional specialization of cell types during development of an organism.

Front 2

What evidence supports the view that differentiation is based on regulating gene expression rather than on irreversible changes in the genome?

Back 2

Each cell type must be expressing certain genes that are not expressed in the other cell type.

Front 3

What is the difference between reproductive and therapeutic cloning?

Back 3

Reproductive cloning results in the production of a live individual, whereas therapeutic cloning produces stem cells.

Front 4

A certain mutation in E. Coli makes the lac operator unable to bind the active repressor. How would this effect the cell?

Back 4

The cell would wastefully produce the enzymes for lactose metabolism continuously even in the absence of lactose.

Front 5

How does dense packing of DNA in chromosomes prevent gene expression?

Back 5

RNA polymerase and other proteins required for transcription do not have access to tightly packed DNA.

Front 6

Explain why many eukaryotic genes are longer than the corresponding mRNAs that leave the nucleus.

Back 6

Many eukaryotic genes have introns; RNA splicing removes these regions from the mRNA transcripts before they leave the nucleus.

Front 7

Once mRNA encoding a particular protein reaches the cytoplasm, what are four mechanisms that can regulate the amount of the active protein in the cell?

Back 7

Breakdown of the mRNA; regulation of translation; alteration of the protein (by polypeptide cutting) and breakdown of the protein

Front 8

How can a signal molecule from one cell alter gene expression in a target cell without entering the target cell?

Back 8

By binding to a receptor protein in the membrane of the target cell and triggering a signal-transduction pathway that activates transcription factors

Front 9

How can a mutation in a tumor-suppressor gene contribute to the development of cancer?

Back 9

A mutated tumor-suppressor gene may produce a defective protein unable to function in a pathway that normally inhibits cell division (that is, normally suppresses tumors).

Front 10

Why is most breast cancer considered nonhereditary?

Back 10

Most breast cancers are associated with somatic mutations, not inherited mutations that are passed from parent to offspring via gametes.

Front 11

Of all known behavioral factors, which one causes the most cancer cases and deaths?

Back 11

Tobacco use

Front 12

Your bone cells, muscle cells, and skin cells look different because ____.

a) different kinds of genes are present in each kind of cell
b) they are present in different organs
c) different genes are active in each kind of cell
d) different mutations have occurred in each kind of cell

Back 12

c) different genes are active in each kind of cell

Front 13

What kinds of evidence demonstrate that differentiated cells in a plant or animal retain their full genetic potential?

Back 13

The abilities of these cells to produce entire organisms through cloning.

Front 14

The most common procedure for cloning an animal is called ____.

Back 14

nuclear transplantation

Front 15

What is learned from a DNA microarray?

Back 15

which genes are active in a particular sample of cells

Front 16

Which of the following is a valid difference between embryonic stem cells and the stemells found in adult tissues?

a) In laboratory culture, only adult stem cells are immortal
b) In nature, only embryonic stem cells give rise to all the different types of cells in the organism
c) Only adult stem cells can be made to differentiate in the laboratory
d) Only embryonic stem cells are found in every tissue of the adult body

Back 16

b) In nature, only embryonic stem cells give rise to all the different types of cells in the organism

Front 17

A group of prokaryotic genes with related functions that are regulated as a single unit, along with the control sequences that perform this regulation, is called a(n) _____.

Back 17

operon

Front 18

the regulation of gene expression must be more complex in multicellular eukaryotes than in prokaryotes because _____.

Back 18

in a multicellular eukaryote, different cells are specialized for different functions

Front 19

A eukaryotic gene was inserted into the DNA of a bacterium. The bacterium then transcribed this gene into mRNA and translated the mRNA into protein. The protein produced was useless; it contained many more amino acids han the protein made by the eukaryotic cell. Why?

Back 19

The mRNA was not spliced as it is in eukaryotes.

Front 20

What is the difference between oncogenes and proto-oncogenes? How does one turn into the other? What purpose do proto-oncogenes serve?

Back 20

Proto-oncogenes are normal genes involved in the control of the cell cycle. Mutation or viruses can cause them to be converted to oncogenes, or cancer-causing genes. Proto-oncogenes are necessary for normal control of cell division.

Front 21

A mutation in a single gene may cause a major change in the body of a fruit fly, such as an extra pair of legs or wings. Yet it takes the combined action of many genes to produce a wing or leg. How can a change in just one gene cause such a big change in the body? What are such genes called?

Back 21

Homeotic genes are master control genes that regulate many other genes during development.

Front 22

What is recombinant DNA technology?

Back 22

A set of methods for creating a DNA molecule that carries DNA originating from different sources

Front 23

Corn that carries a bacterial gene is an example of a ______ organism.

Back 23

transgenic or genetically modified

Front 24

Why are plasmids valuable tools for producing recombinant DNA?

Back 24

Plasmids can carry virtually any foreign gene, are small, are easily taken up by bacteria, and are replicated by their bacterial host cells.

Front 25

Name three different ways that a gene of interest can be obtained.

Back 25

The gene can be isolated from a genomic library created by a shotgun approach, produced from mRNA using reverse transcriptase, or synthesized from scratch.

Front 26

Why is only the slightest trace of DNA at a crime scene often sufficient for forensic analysis?

Back 26

Because PCR can be used to produce enough molecules for analysis

Front 27

You use a restriction enzyme to cut a DNA molecule. The base sequence of this DNA is known, and the molecule has a total of three restriction sites clustered close together near one end. When you separate the restriction fragments by electrophoresis, how do you expect the bands to be distributed in the electrophoresis lane?

Back 27

Three bands near the positive pole at the bottom of the gel (small fragments) and one band near the negative pole at the top of the gel (large fragment).

Front 28

Put these three techniques in the order that would allow you to create a DNA fingerprint from a minuscule crime scene sample: gel electrophoresis, PCR, treatment with restriction enzymes.

Back 28

PCR, treatment with restriction enzymes, gel electrophoresis.