Ch 18Ch 18

Gene RegulationGene Regulation

HOMEWORK MONDAY

Read and outline 18.1 We are not covering this in notes. Be thorough! Make note of any questions you may have for when we go

over this Tuesday in class. Answer concept check 18.1 Due TUESDAY 3-11

TUESDAY Read and outline 18.3

We are not covering this in notes. Be thorough! Make note of any questions you may have for when we go

over this Wednesday in class. Answer concept check 18.3 Due WEDNESDAY 3-12

WEDNESDAYWEDNESDAY Read and outline 19.2 and 19.5Read and outline 19.2 and 19.5 Concept check for these sectionsConcept check for these sections Due THURSDAYDue THURSDAY

Gene Regulation in Bacteria Cells vary amount of specific enzymes by _______________

gene transcription turn genes on or turn genes ______ Turn genes on example:

if bacterium encounters new sugar (energy source), like lactose, then it needs to start making enzymes used to _______________ lactose

Turn genes off example: if bacterium has enough tryptophan then it

_______________ need to make enzymes used to _______________ tryptophan

REGULATING

OFF

DIGEST

DOESN’TBUILD

Bacteria group genes together Operon

Genes grouped together with related _______________. Example: all enzymes in a metabolic pathway

Promoter = __________________ binding site Single promoter controls _______________of all genes in

operon Transcribed as one unit & a _________ mRNA is made

Operator = DNA binding site of _______________ protein

FUNCTIONS

RNA POLYMERASE

TRANSCRIPTION

SINGLEREPRESSOR

Operon Model When gene is turned

ON: Polymerase binds to

_______________ Gene is

_______________ Operon:

Operator, promoter & genes they control: serve as a ______________ for gene regulation

When gene is turned off: Repressor binds to ___________ site Blocks RNA Polymerase

Diagram

PROMOTER

TRANSCRIBED

MODEL

OPERATOR

How can genes be turned off? _______________protein

binds to DNA at operator site _______________RNA polymerase blocks _______________

REPRESSOR

BLOCKINGTRANSCRIPTION

REPRESSIBLEENZYMES

NEEDEDINACTIVE

ENZYMES

PROTEINBIND

REPRESSES

ALLOSTERIC

trp operon 1 trp operon 2 (Watch half only) (Watch half only)trp operon 3

INDUCIBLE

GLUCOSE

OFF

RELEASE

LINKSLINKS

choose narrated Boring Man 1 Boring Man 2Boring Man 2

ANABOLICSYNTHESIZING

CATABOLIC

AVAILABLE

Control of Eukaryotic Genes Evolution of Gene Regulation

Prokaryotes Single-celled Evolved to grow & divide _______________ Must respond quickly to changes in _________

environment exploit _______________ resources

Gene regulation turn genes on & off rapidly

flexibility & _________________ _______ levels of enzymes for synthesis & digestion

RAPIDLYEXTERNAL

TRANSIENT

REVERSABILITYADJUST

Eukaryotes Multicellular Evolved to maintain constant _______________ conditions

while facing changing external conditions __________________

Regulate body as a whole _______________& development

Specialization Turn on & off large number of genes

Must coordinate the body as a _______________ rather than serve the needs of individual cells

INTERNAL

HOMEOSTASIS

GROWTH

WHOLE

PATHWAY

CONTROLTRANSCRIPTION

ENHANCER

PROTEINSENHANCED

Pg 365 fig 19.5

On a separate piece of paper, please compare/contrast the trp operon and the lac operon.

EXONS

AMOUNT

WEEKSINTERFERING

BIND

DEATH

5’ATTACHMENT

PROTEIN

TRANSPORT

UBIQUITINPROTEASOME

LABELPOLYPEPTIDE

RAPIDLY

MACHINEDISPOSER

PROTEINS

RECYCLING

Pg 370 fig 19.10

On the same sheet of paper from yesterday, please describe 4 different ways eukaryotic genes are controlled.

Chapter 20Chapter 20

DNA Technology and GenomicsDNA Technology and Genomics

Understanding and Manipulating Genomes Recombinant DNA (do not confuse with recombinants in genetics)

Definition- DNA in which nucleotide sequences from two __________________ sources (__________) are combined in vitro into the same DNA molecule.

Basis of genetic __________________ Def: manipulation of genes for ______________ purposes Examples: Protein products such as __________________

and blood-clotting factors, much more. Biotechnology- manipulation of ______________ or their

components to make useful __________________. Ex: microbes used to make wine and cheese, ___________

breeding (exploiting naturally occurring mutations of genetic recombination.)

DIFFERENT SPECIES

ENGINEERINGPRACTICAL

HORMONES (HGH)

ORGANISMSPRODUCTS

SELECTIVE

DNA Cloning Problems with DNA

DNA molecules are very ________. Genes occupy only a small portion of DNA (others are

__________________ nucleotides) Gene may be only 1/__________________ of a

chromosome. Gene __________________- method to prepare well-defined

gene-________ pieces of DNA in __________________copies.

LONG

NON-CODING100,000

CLONINGSIZED MULTIPLE

Cloning and Applications Common approach of DNA cloning uses bacteria (E. coli) and

their __________________. Plasmids- small circular DNA molecules that _____________

separate from bacterial chromosomes Plasmids are first __________________ from bacterial

cells Foreign DNA is then ______________ into the plasmid. Resulting plasmid is __________________ to bacterial cell

producing a __________________bacterium It can then reproduce to form a ____________. Clone of cells contains __________________copies of

the gene.

PLASMIDSREPLICATE

ISOLATEDINSERTED

RETURNEDRECOMBINANT

CLONEMULTIPLE

Cloned genes are useful: To make many copies of a particular _________. To produce a __________________ product

Copies of cloned genes can be isolated for __________________ or to give an organism a new __________________capability.

Ex. Pest __________________ can be transferred into plants of different species. (Potato famine)

__________________ such as human growth hormone can be harvested from bacterial ___________ carrying the cloned gene for a protein.

Why is DNA cloning valuable Protein-coding genes are very ________- 1 ppm, so the ability

to clone such rare fragments can make something rare more ___________________.

GENEPROTEIN

RESEARCHMETABOLIC

RESISTANCE

PROTEINSCULTURES

RARE

AVAILABLE

Restriction Enzymes Definition- restriction _______________ protect the bacterial

cell against intruding DNA and work by ________ foreign DNA (restriction).

ENDONUCLEASESCUTTING

How they work: Restriction enzymes are ________________ and recognize

a particular DNA sequence (restriction site). They then cut both DNA strands at specific ________

within the restriction site. DNA of bacterial cell is __________________ from cell’s

own restriction enzymes by adding _______________ (_____) groups to adenines or cytosines within sequences recognized by enzyme.

SPECIFIC

POINTS

PROTECTEDMETHYL

CH3

More details about restriction enzymes Most sites are __________________: nucleotides are

identical when read from 5’3’ direction. Ex: 5’GAATTC 3’

Most recognize sequences of 4-8 __________________. Restriction __________________- pieces of DNA cut by

restriction enzymes. Same restriction enzymes result in _______________

fragments. Useful restriction enzymes ___________ sugar-phosphate

backbones in both DNA strands in a ______________ way. Resulting double stranded fragments have at least one

single stranded end- __________________

SYMMETRICAL

NUCLEOTIDESFRAGMENTS

SAME

CLEAVE

STAGGERED

STICKY END

Sticky ends can form hydrogen-bonded __________________ with complementary sticky ends on ___________ DNA molecules cut with the same enzyme.

DNA ____________ can permanently bind the two fragments by forming a covalent bond between the sugar-phosphate backbone.

BASE PAIRSOTHER

LIGASE

Restriction enzyme animation

Cloning Eukaryotic Gene in Bacterial Plasmid Original plasmid is a cloning __________________- DNA

molecule can carry foreign DNA into a cell and __________________ there.

Cloning vectors can be isolated, manipulated to form __________________ plasmids by insertion of foreign DNA in vitro, and then __________________into bacterial cells.

Cells reproduce rapidly and __________________ foreign DNA carried.

plasmid vectorplasmid vector

VECTOR

REPLICATES

RECOMBINANTREINTRODUCED

MULTIPLY

Producing Clones of Cells not boring man boring man Human genomic DNA is isolated and vector from bacterial

plasmid is isolated. Plasmid carries two genes: ampR (E.coli resistant to

__________________) and lacZ (encodes B-galactosidase which hydrolyzes __________________). lacZ gene contains a single copy of restriction site.

Both plasmid and human DNA are ___________ by the same restriction enzyme producing sticky ends. Plasmid is cut once while human DNA is cut at __________________ fragments.

The human DNA and plasmid fragments are __________________ which allows base pairing between __________________ sticky ends. DNA ligase is then added __________________ plasmid and human DNA fragments.

AMPICILLINLACTOSE

DIGESTED

MANY

MIXEDCOMPLEMENTARYJOINING

Resulting plasmids can be recombinant (contain __________________ DNA), be a combination of two plasmids, or a ____________________version of the original plasmid.

DNA resulting from step c is then mixed with bacteria with a __________________ in lacZ gene making them unable to __________________ lactose.

Cells take up foreign DNA by __________________. Some cells acquire a recombinant plasmid with gene of

interest and others acquire plasmid with _________ gene. Cloning step: bacteria are plated on ______________(nutrient

medium) containing ampicillin and X-gal. This allows us to identify clones of cells

__________________with recombinant plasmid.

HUMANNONRECOMBINANT

MUTATIONHYDROLYZE

TRANSFORMATION

ANOTHERAGAR

TRANSFORMED

How to recognize clones carrying recombinant plasmids Only cells with plasmid will reproduce since they have ampR

gene allowing __________________to ampicillin in the medium and will __________________.

Once clone contains 105 cells it can be seen as a _________________ on the agar.

__________________of colonies allows us to determine colonies of bacteria with recombinant plasmids from those with nonrecombinant plasmids.

Colonies with nonrecombinant plasmids with intact lacZ are __________________ because they produce B-galactosidase which hydrolyzes X-gal and produces a __________________ product.

Colonies with recombinant plasmids will be white because there is no __________________B-galactosidase.

RESISTANCEDIVIDE

COLONYCOLOR

BLUE

BLUE

FUNCTIONAL

Each dot represents a colony of cells.

Identifying Clones Carrying Gene of Interest Look for the Gene Itself

Nucleic Acid __________________- DNA of the gene is detected by ability to base-pair with complementary sequence on __________________ nucleic acid molecule.

If a part of the nucleotide sequence of the gene of interest is known, a nucleic acid ______________ can be used.

Nucleic acid probe- a short complementary molecule of __________________________ nucleic acid (DNA or RNA).

Example: sequence of DNA on gene of interest: 5’ GGCTAACT 3’

HYBRIDIZATION

ANOTHER

PROBE

SINGLE STRANDED

Probe molecules are labeled with __________________ isotopes so that it can be tracked.

The probe molecules will hydrogen bond to the complementary part of the __________________ gene.

Heat or chemicals are used to __________________the cells’ DNA to make it single stranded and able to base pair with the probe.

RADIOACTIVE

DESIREDDENATURE

Example Filter paper is pressed against the plate

__________________ cells to the filter. The filter is treated to break cells and

__________________ DNA. Radioactive probe molecules are __________________

with the filter and allows it to base pair with complementary DNA.

Filter paper is laid under film while exposing __________________ areas.

Colonies carrying gene of interest have been _________.

TRANSFERRING

DENATUREINCUBATED

RADIOACTIVE

LOCATED

Cloned Genes in DNA Libraries Genomic _________- set of thousands of DNA ____________

from a genome, each carried by a plasmid, phage, or other vector. Advantage of phages over plasmids is that phages can carry a

_________ DNA segment. Complementary DNA(___________) Library Only represents ____________ of a genome- genes that were

____________ into mRNA. Start with mRNA extracted from cells, reverse

__________________ (RT) is used to make single stranded _______ from _______, then DNA polymerase will complete the second strand of DNA.

LIBRARY SEGMENTS

LARGERcDNA

PARTTRANSCRIBED

TRANSCRIPTASEDNA mRNA

Use of DNA libraries Genomic library use

Want to clone a gene but unsure in what cell ______ it is expressed or _________ to obtain cell type.

Interested in _______________ sequences or introns of a gene.

cDNA use interested in _______________ sequence of genes Studying genes responsible for specialized

_______________ of cell types Changes in _______________ of gene _______________

TYPEUNABLEREGULATORY

CODING

FUNCTIONSPATTERNS EXPRESSION

Cloning and Expressing Eukaryotic Genes Having cloned eukaryotic gene function in a bacterial host can be

difficult due to the _______________ of gene expression in prokaryotes and eukaryotes.

Expression vector- cloning vector that contains a highly active _______________ promoter upstream of a restriction site where eukaryotic gene can be inserted in the correct _______________ frame.

Bacterial host recognizes the promoter and ___________ to express the foreign gene.

Expression vectors allow _______________of eukaryotic proteins in bacterial cells.

DIFFERENCES

PROKARYOTIC

READINGCONTINUES

SYNTHESIS

Another problem can result when _______________are present in eukaryotic genes and can be solved by using ______ (only exons).

Yeast Artificial Chromosomes (_________) Yeast cells are single-celled fungi that are easy to grow and

have _______________. YACs _______________eukaryotic chromosome with foreign

DNA. YACs act and divide ___________ in mitosis and can carry

_______________ DNA segment than plasmid vectors. Electroporation

Brief electrical pulse applied to a solution containing cells creating brief holes in their ________________________ allowing DNA to enter.

INTRONScDNA

YACs

PLASMIDSCOMBINE

NORMALLYLONGER

PLASMA MEMBRANES

Polymerase Chain Reaction (PCR) When DNA is ________ or impure, PCR can be used to make

copies. A specific target segment with one or many DNA molecules is

_______________ many times in a test tube. PCR can make billions of copies of a target segment of DNA in a

few _______________, much faster than the _______________it would take to obtain the same number of copies by screening a DNA library for a clone.

Procedure (1 cycle) The reaction mixture is heated to _______________the DNA

strands It is cooled to allow _______________ to anneal (hydrogen

bond) to strands Heat stable DNA polymerase _______________ primers in

5’3’ direction.

SCARCE

COPIED

HOURSDAYS

DENATURE

PRIMERS

EXTENDS

PCR is also very specific. Very small amounts of DNA can be used and it can be

partially _______________. By the end of the third cycle, one-fourth of the molecules are

_______________ to the target segment Each successive cycle, the number of identical pieces will

_________, soon outnumbering all other DNA molecules. Limitations: cannot _______________ gene cloning in cells when

__________ amounts of a gene are desired. Errors can limit number of good copies made.

Impact on biotechnology DNA from 40,000 year old ___________________ DNA from fingerprints, blood, tissue, or semen at _______

scenes DNA from single ____________ cells for prenatal diagnosis

of genetic disorders

DEGRADED

IDENTICAL

DOUBLESUBSTITUTE

LARGE

WOOLY MAMMOTHCRIME

EMBRYONIC

PCR Rap

PCR song

Original WATW song

Restriction Fragment Analysis- detects _______________ in nucleotide sequence of DNA Gel Electrophoresis

Uses a gel as a tool to separate nucleic acids or proteins based on ______, electrical charge, and other physical ____________. (Figure 20.8).

Nucleic acids carry _______________ charges on phosphate groups and travel toward positive electrode.

Longer molecules are __________ more than shorter molecules which allows separation of DNA fragments by __________.

Gel electrophoresis separates a mixture of linear DNA molecules into ________, each consisting of DNA molecules that have the same length.

Band created reflects the restriction enzyme used and starting molecule.

DIFFERENCES

SIZE PROPERTIES

NEGATIVE

IMPEDEDLENGTH

BANDS

Uses: Provides a way to prepare pure sample of individual

_______________. Useful for _______________ two different DNA molecules

Example: two alleles for a gene will be cut at different sites and will display different mixtures of ___________.

Sickle Cell disease (figure 20.9) Southern blotting

__________ gel electrophoresis and nucleic acid hybridization

Reveals not only whether a particular sequence is present but also the _____ of the restriction fragments that contain the sequence.

FRAGMENTSCOMPARING

FRAGMENTS

COMBINES

SIZE

Example: three people: normal, heterozygous carrier, homozygous person for sickle cell disease. (p.395 Fig 20.10)

Electrophoresis of DNA contains _______________ bands to distinguish the three.

By use of southern blotting, we can _______________ bands that include parts of B-globin gene.

Probe will be complementary to B-globin gene and will ____________ to B-globin gene.

When film is laid over the paper, radioactivity can be seen which allows the mutant alleles to be _____.

TOO MANY

DETECT

BIND

SEEN

Restriction Fragment Length Polymorphisms (__________) Differences in restriction sites on homologous

chromosomes resulting in different restriction fragment _______________.

RFLP can serve as a genetic marker for a locus in the _______________.

RFLPs can be ___________ and analyzed by southern blotting.

RFLPs can serve as genetic __________ for making linkage maps.

Frequency which two RFLP markers are inherited is a measure of ___________ of two loci on a chromosome.

RFLPs

PATTERNS

GENOMEDETECTED

MARKERS

CLOSENESS

Mapping Genomes Human Genome Project

Project that aimed to map the human genome starting in _____. The nucleotide sequence of the majority of DNA in each

human chromosome was obtained by ___________. Three Stages: 1. Genetic (_________) mapping. 2. Physical

mapping. 3. DNA _______________ Genetic (linkage mapping)

_______________ provides the number of chromosome and overall banding pattern.

Some genes were already located by fluorescence in situ hybridization (FISH).

Using cytogenetic maps, a linkage map was constructed by ordering genetic _______________ (_______________, simple sequence DNA, etc.)

1990

2003LINKAGE

SEQUENCING

KARYOTYPE

MARKERSRFLPs

Physical Mapping Distances _______________ markers are expressed in

physical measure (number of __________________ along DNA).

Physical map is made by cutting DNA of each chromosome into a number of restriction _______________ and determining original _______________ of fragments in chromosomal DNA.

Make fragments that overlap and use probes to find _______________ to determine sequence.

First cloning vector is a YAC or bacterial artificial chromosome (BAC).

Once long fragments are _______________, they are cut into smaller pieces, cloned and then _______________ again.

BETWEENBASE PAIRS

FRAGMENTSORDER

OVERLAPS

ORDERED

SEQUENCED

DNA sequencing Goal is to determine the _______________ sequence of

each chromosome. If many copies of a DNA fragment up to _______ base

pairs is available, the sequence can be determined by a sequencing ______________.

Chain-termination method could not be used for _______________ chromosome.

NUCLEOTIDE

MACHINE

HUMAN

800

Venter’s idea (Whole-genome _________ approach)- ________ genetic mapping and physical mapping stages

Cut DNA from many copies of entire chromosome into fragments _______________ enough for sequencing.

Clone fragments in _______________. Sequence each _______________. Use computer software to _______________the

fragments into one sequence. How does the approach to genome mapping used in the Human

Genome Project differ from shotgun approach?

SHOTGUNSKIP

SHORTVECTORS

FRAGMENTASSEMBLE

Ch 21Ch 21

Cloning and Stem CellsCloning and Stem Cells

Differential Gene Expression Cell _________________ (_________________)

Different cells result as a result of gene ____________ and not from differences in cell’s ________________.

Differentiation occurs during _________________as specific genes are turned on and off by regulatory mechanisms.

DIFFERENTIATION SPECIALIZATIONEXPRESSION

GENOMESDEVELOPMENT

Evidence of Genomic _________________: Plants All cells have the same genes. Question: What happens to ___________ after cell

differentiation? Do skin cells contain _________________ genes that

specify eye color (or anything else) or is it permanently inactive or gone completely?

_________________ cells: the ability to _________________ and then divide to give rise to ______ the specialized cell types in an organism.

Carrot Plant Experiment: Differentiated cells were taken from the ___________ of a

carrot plant. These cells were placed into a culture medium where they

were allowed to grow into normal adult plants. Each of the plants was _________________ to the parent.

EQUIVALENCE

GENES

FUNCTIONING

TOTIPOTENTDEDIFFERENTIATE ALL

ROOTS

IDENTICAL

Cloning Definition: using one or more somatic cells from a

multicellular organism to make an individual that is _________________ identical. Each individual made this way is a ___________.

Evidence of Genomic Equivalence: Animals Nuclear _________________: Scientists removed the

____________ of an unfertilized egg cell or zygote and replaced it with the nucleus of a ________________ cell.

GENETICALLYCLONE

TRANSPLANTATIONNUCLEUS

DIFFERENTIATED

Researchers used tadpoles in order to do this and used a variety of differentiated cells.

The ______________ the donor was, the more likely it would develop into tadpoles (higher __________ potency).

Less differentiated cells worked ___________ than fully differentiated cells.

Conclusions Something in the nucleus does _____________ as animal

cells differentiate. Nuclear potency is _________________ as cell

differentiation progresses. Scientists agree that nuclei of most differentiated animal

cells have _____ the genes required for making the entire _________________.

YOUNGERNUCLEAR

BETTER

CHANGE

RESTRICTED

ALLORGANISM

Cloning of Mammals (adults) Dolly (1997-2003)- Lamb cloned from an _____________

sheep by nuclear transplantation Procedure

Cultured mammary glands in nutrient-poor medium (semi-___________) causing a stop of the _________________ and resulting in __________________.

These cells were then _____________ with sheep egg cells that had their nuclei removed.

The resulting diploid cells divided to form early embryos which were implanted in the uterus of a surrogate ________. Out of several hundred implanted embryos, Dolly was born.

ADULT

STARVED CELLDEDIFFERENTIATION

FUSED

MOTHER

Dolly’s DNA was _________________to that of the donor nucleus DNA.

Death of Dolly Dolly suffered from a lung disease that is seen in much older

sheep and was ____________. Some believe that her cells were “________” than normal

sheep. Other cloning: mice, cats, cows, horses, pigs. “All twins are clones, but not all clones are twins.” Example:

__________ Cat- calico cat Implications:

IDENTICAL

EUTHANIZEDOLDER

COPY

South Korea 2004: Human Cloning? Nuclear transplantation occurred and eggs were stimulated to

____________ and some reached the ____________ stage (early embryonic stage), they were _______ allowed to develop beyond this stage.

Ethics of cloning. ___________ with animal cloning

Only a small _________________ of cloned embryos develop to birth

Cloned animals exhibit various _____________ Cloned mice are prone to obesity, pneumonia, liver failure

and early _________.

DIVIDE BLASTOCYSTNOT

PROBLEMSPERCENTAGE

DEFECTS

DEATH

Low efficiency of cloning and high incidence of _________________. DNA in embryonic cells from cloned embryos have more

______________ groups than DNA in equivalent cells from ______________ embryos This suggests that reprogramming is not always

________________ DNA methylation helps gene ______________ and

the misplacement of these methyl groups may interfere with pattern of gene expression needed for _______________ embryonic development.

ABNORMALITIES

METHYLUNCLONED

COMPLETEREGULATION

NORMAL

Stem Cells of Animals Stem cell- relatively _________________ cell that can

reproduce itself and under appropriate conditions, differentiate into _________________ cells of one or more types.

Stem cells are able to _________________their own cells and can generate cells that can have _________ differentiation pathways.

Many animal embryos have _________________ stem cells which can result in differentiated cells of any type.

Stem cells can be isolated at the ______________ stage (blastocyst in humans).

In culture, embryonic stem cells _________________ indefinitely and can differentiate into specialized cells depending on the _________________ they are in.

UNSPECIALIZED

SPECIALIZEDREPLENISH

VARYING

TOTIPOTENT

BLASTULA

REPRODUCE

CULTURE

Adults also have a variety of stem cells that can replace __________________ specialized cells as needed.

Adult stem cells are considered _________________ as they are able to give rise to multiple but not ________ cell types. Blood marrow stem cells can give rise to all the kinds of

__________ cells and stem cells in the intestinal wall can regenerate the various cells forming the lining of the ______________.

Adult _____________ stem cells continue to produce certain kinds of nerve cells.

Adults have a very ______________ amount of stem cells. Scientists are learning how to identify, isolate adult stem cells

from tissues and have been able to ________ these cells in culture. In the right culture conditions, we have been able to have

these cells _________________ into specialized cells.

NONREPRODUCINGPLURIPOTENT

ALL

BLOOD

INTESTINEBRAIN

SMALL

GROW

DIFFERENTIATE

What does the future hold? The more research and information we gain, we can apply

these _________________. Goal: supply _______ to _______ damaged or diseased

organs. Examples:

Insulin-producing ____________ cells for diabetics Specific brain cells for people with _________________

or Huntington’s. Currently, embryonic stem cells are more ____________

than adult stem cells. Ethics and politics discussion.

MEDICALLYCELLS REPAIR

PANCREATICPARKINSON’S

PROMISING

Now, stem cells are gathered from patients undergoing _________________ treatment or from long-term cell cultures with cells isolated from _________________ embryos.

Embryo cloning _________________cloning- the main goal of cloning to

produce embryonic stem cells to treat __________. Is it ok to clone humans? Is it ok to clone embryos for

therapeutic reasons?

INFERTILITYDONATED

THERAPEUTICDISEASE