Deck 11: How Genes Are Controlled

Question 1

The basis of cellular differentiation is

A)mutation.
B)selective gene expression.
C)the operon.
D)cloning.

Answer 1

B

Question 2

Which of the following statements regarding stem cells is false?

A)Adult stem cells are partway along the road to differentiation.
B)Embryonic stem cells can give rise to all the different specialized cells in the body.
C)Adult stem cells are present in adult tissues.
D)Adult,but not embryonic,stem cells can be grown in laboratory culture.

Answer 2

D

Question 3

Which of the following statements about microarrays is false?

A)Microarrays use fluorescently labeled cDNA molecules to identify particular genes expressed at a particular time.
B)Microarrays are used to determine which genes are active in different tissues or in tissues of different states of health.
C)Microarrays use tiny portions of double- stranded RNA fragments from a large number of genes.
D)Microarrays enable scientists to determine the activity of thousands of genes at once.

Answer 3

C

Question 4

In this drawing of the lac operon,which molecule is an inactive repressor?

A)molecule A
B)molecule B
C)molecule C
D)molecule D

Question 5

Which of the following permits a single gene to code for more than one polypeptide?

A)alternative RNA splicing
B)retention of different introns in the final version of the different mRNA strands
C)genetic differentiation
D)addition of different types of caps and tails to the final version of the mRNA strands

Question 6

Mutations in the proto- oncogene ras and the tumor suppressor gene p53

A)increase protein synthesis by the cell.
B)can improve the chance of avoiding cancer as one ages.
C)disrupt normal regulation of the cell cycle.
D)can enhance further mutations,which can develop into cancer.

Question 7

Small pieces of RNA that can regulate translation of mRNA are called

A)monoRNA.
B)microRNA.
C)minuteRNA.
D)miniRNA.

Question 8

The tortoiseshell pattern on a cat

A)is the result of a homozygous recessive condition.
B)results from X chromosome inactivation.
C)is a result of alleles on the Y chromosome.
D)usually occurs in males.

Question 9

The lac operon of E.coli is _ when the repressor is bound to lactose.

A)inactive
B)cloned
C)unregulated
D)active

Question 10

In a prokaryote,a group of genes with related functions,along with their associated control sequences,defines

A)an operon.
B)a transposon.
C)an allele.
D)a locus.

Question 11

In multicellular organisms,the coordination of cellular activities relies on

A)operons.
B)cell receptors that detect transcription factors.
C)cell- to- cell signaling and signal transduction pathways.
D)the availability of certain "key" nutrients as cells divide.

Question 12

Proteins that bind to DNA and turn on operons by making it easier for RNA polymerase to bind to a promoter are called

A)repressors.
B)operators.
C)activators.
D)regulators.

Question 13

Both prokaryotic and eukaryotic cells use to turn certain genes on or off.

A)proteins
B)intron segments
C)nucleosome packing
D)RNA transcriptase

Question 14

A single cell,the zygote,can develop into an entirely new organism with many different specialized cells.Which of the following statements about this process is false?

A)Differentiation of the zygote into a multicellular organism results from selective gene expression.
B)The zygote contains all of the genetic information required for the development of many different cell types.
C)The descendant cells specialize by a process known as differentiation.
D)Additional genetic information for the formation of specialized cells is passed on to the developing embryo via the placenta.

Question 15

To initiate a signal transduction pathway,a signal binds to a receptor protein usually located in the

A)nucleus.
B)plasma membrane.
C)cytoplasm.
D)ER.

Question 16

Adult stem cells have limited therapeutic potential

A)due to their excessive numbers in tissues.
B)because they are fully differentiated.
C)because they lack a complete set of genes.
D)because their developmental potential is limited to certain tissues.

Question 17

Transcription factors attach to

A)plasma membrane receptors.
B)DNA.
C)signal molecules.
D)mRNA.

Question 18

A gene that can cause cancer when present in a single copy in a cell is called a(n)

A)enhancer gene.
B)carcinogen.
C)proto- oncogene.
D)oncogene.

Question 19

The expression of the tryptophan operon is controlled by

A)a repressor that is active when it binds to tryptophan.
B)an activator that turns the operon on by binding to DNA.
C)a repressor that is active when it is alone.
D)a repressor that is inactive when it binds to lactose.

Question 20

Mutations in the p53 gene can lead to cancer by

A)increasing the production of growth hormones,which trigger faster cell cycles.
B)causing the production of a faulty protein that is no longer able to inhibit cell division.
C)promoting the expression of mRNA that can interact with DNA,resulting in new mutations.
D)causing the production of excessive amounts of relay proteins.

Question 21

Which of the following is not a factor that contributes to normal cells becoming cancerous?

A)one or more of the cell's genes being removed by a virus
B)the conversion of a proto- oncogene to an oncogene
C)damage to a tumor- suppressor gene
D)excessive replication of proto- oncogenes

Question 22

Which of the following possible uses of reproductive cloning is still considered by most to be an unresolved ethical issue?

A)cloning mammals for the production of potentially valuable drugs
B)the reproductive cloning of humans
C)the production of organs in cloned pigs for transplant into humans
D)the production of genetically identical animals for experimentation

Question 23

In plants,most differentiated cells retain

A)the ability to dedifferentiate,but then cannot return to their original differentiated state.
B)a complete set of their genes,and retain the ability to express those genes under certain circumstances.
C)only a tiny fraction of their original set of genes.
D)a complete set of their genes,but lose the ability to express most of those genes.

Question 24

A gene operon consists of

A)a promoter only.
B)a regulatory gene only.
C)a transcribed gene only.
D)transcribed genes,an operator,and a promoter.

Question 25

Which of the following mechanisms of controlling gene expression occurs outside of the nucleus?

A)RNA splicing
B)adding a cap and tail to RNA
C)DNA packing/unpacking
D)translation

Question 26

Yeast are able to communicate with each other

A)through chemical signaling.
B)by close cell- to- cell contact.
C)only if they can touch each other and have merged cell walls.
D)with pseudopodia.

Question 27

Which of the following mammals has not yet been cloned and brought through the complete gestation cycle?

A)human
B)cow
C)cat
D)pig

Question 28

The coding regions of a gene (the portions that are expressed as polypeptide sequences)are called

A)exons.
B)redundant coding sections.
C)proto- oncogenes.
D)introns.

Question 29

Which of the following statements regarding DNA packing is false?

A)Prokaryotes have proteins analogous to histones.
B)Highly compacted chromatin is generally not expressed at all.
C)DNA packing tends to promote gene expression.
D)A nucleosome consists of DNA wound around a protein core of eight histone molecules.

Question 30

Signal transduction pathways

A)originally evolved in vertebrates.
B)are found strictly in multicellular organisms,which require cell- to- cell communication.
C)are mechanisms of communication that probably evolved in ancient prokaryotes.
D)are limited for use in sexual identification.

Question 31

The carcinogen known to cause the most cases and types of cancer is

A)ultraviolet light.
B)plutonium.
C)alcohol.
D)tobacco.

Question 32

Which of the following statements about fruit fly development is false?

A)Cascades of gene expression routinely direct fruit fly development.
B)The location of the head and tail ends of the egg is primarily determined by the location of sperm entry during fertilization.
C)Homeotic genes regulate batteries of other genes that direct the anatomical identity of body parts.
D)One of the earliest development events is the determination of the head and tail ends of the egg.

Question 33

Cancer of the colon is caused by

A)the proto- oncogene,lac.
B)several somatic cell mutations.
C)exposure of colon cells to a mutagen.
D)a single gene mutation.

Question 34

The use of cloning to produce special embryonic stem cells is called

A)reproductive cloning.
B)therapeutic cloning.
C)transplantational cloning.
D)regenerative cloning.

Question 35

The term "gene expression" refers to the

A)fact that individuals of the same species have different phenotypes.
B)process by which genetic information flows from genes to proteins.
C)flow of information from parent to offspring.
D)fact that each individual of a species has a unique set of genes.

Question 36

The cloning of Dolly the sheep

A)demonstrated that the nuclei from differentiated mammalian cells can retain their full genetic potential.
B)revealed that cloned mammals most resemble the egg donor.
C)demonstrated,for the first time,that eggs are haploid and body cells are diploid.
D)demonstrated that differentiated cells contain only a fraction of their full genetic potential.

Question 37

RNA splicing involves the

A)addition of a nucleotide "cap" to the molecule.
B)removal of introns from the molecule.
C)removal of exons from the molecule.
D)addition of a nucleotide "tail" to the molecule.

Question 38

The relationship between DNA and chromosomes is most like

A)thread wrapped around a spool.
B)the candy shell surrounding the chocolate in a piece of M & M candy.
C)an egg yolk inside of an egg.
D)a spoon cradling some peas.

Question 39

A homeotic gene

A)is found only in adult somatic cells.
B)represses gene transcription and promotes mRNA translation.
C)determines which end of the egg will become the head and which end will become the tail.
D)serves as a master control gene that functions during embryonic development by controlling the developmental fate of groups of cells.

Question 40

Which of the following is likely to occur in E.coli cells that are grown in skim milk?

A)The lac operon is shut off and the cells will not produce lactose- utilizing enzymes.
B)The trp operon is turned on but the bacteria will not produce lactose- utilizing enzymes.
C)The trp repressor is activated and the cells will produce lactose- utilizing enzymes.
D)The trp operon and the lac operon are both switched off.

Question 41

In female mammals,the inactive X chromosome in each cell

A)can be activated if mutations occur in the active X chromosome.
B)is broken down,and its nucleotides are degraded and reused.
C)becomes a Barr body.
D)is absorbed and used in energy production.

Question 42

The genes for the enzymes of glycolysis

A)are inactive in all metabolizing cells,but the genes for specialized proteins are expressed in all cell types.
B)and the genes for all specialized proteins are expressed in all metabolizing cells.
C)are active in all metabolizing cells,but the genes for specialized proteins are expressed only in particular cell types.
D)and the genes for all specialized proteins are expressed in all embryonic cells.

Question 43

Which of the following processes occurs when a salamander regenerates a lost limb?

A)Certain cells in the limb dedifferentiate,divide,and then redifferentiate to form a new limb.
B)A new salamander develops from the lost limb.
C)The homeotic genes of the regenerating cells turn off.
D)Oncogenes that cause accelerated cell division are turned on.

Question 44

Which structure in this figure shows one complete nucleosome?

A)structure A
B)structure B
C)structure C
D)structure D

Question 45

All of the following mechanisms are used to regulate protein production except

A)protein breakdown.
B)protein activation.
C)DNA editing.
D)the breakdown of mRNA.

Question 46

A signal outside a cell triggers changes in the transcription and translation inside the cell through

A)protein breakdown.
B)signal transduction pathways.
C)post- translational editing.
D)protein activation.

Question 47

Which of the following statements regarding cancer risk factors is false?

A)Eating 20-30 grams of plant fiber daily and reducing the intake of animal fat can reduce your risk of developing colon cancer.
B)Factors that alter DNA and make cells cancerous are called carcinogens.
C)Mutagens are usually not carcinogens.
D)X- rays and ultraviolet radiation are two of the most potent carcinogens.

Question 48

Which of the following statements about proto- oncogenes is false?

A)Proto- oncogenes are normal genes with the potential to become oncogenes.
B)A mutation in a tumor- suppressor gene can stop cell division immediately.
C)Many proto- oncogenes code for growth factors.
D)A mutation must occur in a cell's DNA for a proto- oncogene to become an oncogene.

Question 49

The lac operon in E.coli

A)allows the bacterium to resist antibiotics in the penicillin family.
B)regulates the rate of binary fission.
C)coordinates the production of tryptophan- utilizing enzymes when it is present.
D)prevents lactose- utilizing enzymes from being expressed when lactose is absent from the environment.

Question 50

Why can some plants be cloned from a single cell?

A)Plant cells are capable of self- renewal by utilizing cellular components from adjacent cells.
B)Plant cells can produce genes to replace those lost during development.
C)Plant cells can dedifferentiate and give rise to all of the specialized cells required to produce an entire plant.
D)Plant cells do not differentiate even when mature,so any cell can grow into an entire plant.

Question 51

The development of colon cancer occurs slowly,and colon cancer is more frequently seen in the elderly than the young.This is most likely because

A)four or more somatic mutations must occur to give rise to the cancer,which takes time.
B)cancer cells don't have mitochondria,so they grow slowly.
C)cancer cells have to wait until new blood vessels grow into the area,which takes much time.
D)most cancer mutations interfere with mitosis,so cell division occurs more slowly.

Question 52

miRNA can be used by

A)viruses to stop the production of new proteins.
B)researchers to induce the production of more mRNA.
C)cells to prevent infections from double- stranded RNA viruses.
D)researchers to artificially turn on gene expression.