Ch 14Mendel and

the Gene Idea

The Father of Genetics Mendel intro Mendel Bio

Gregor Mendel’s Garden and Museum

Brno, Czech RepublicAll pictures taken by and are the property of:

Chris JohnstoneVHS Class of 2004

CSUF Class of 2011 (BS in Physics)SDSU Class of 2013 (MS in Medical Physics)

Mendel’s Garden

Mendel’s Garden

The Abbey/Monastery where Mendel worked

Statue of Mendel

Mendel’s Equipment

Mendel’s Equipment

Mendel’s Desk

Mendel’s Approach to GeneticsWhy _______ plants?

Mendel chose pea plants because there are many _______________ and _______________.Character: a heritable (capable of being ________

down) feature Ex: Flower color, Hair color

_______________: different _______________ for a character Ex: purple or white flower color

PEA

VARIETIES CHARACTERS

PASSED

TRAIT CHOICES

Mendel could strictly _______________which plants mated with which._______________: pollen producing organs _______________: egg- bearing organ.

CONTROL

STAMENCARPEL

Pea plants usually self-_______________.Mendel used cross-pollination (between

_______________ plants). Mendel took immature __________ of a plant before they produced pollen and dusted ____________ from another plant onto the altered flowers. Figure 14.2 p. 252.

Each zygote developed into a plant _________ encased in a seed then the seeds were planted.

FERTILIZEDIFFERENT

STAMENSPOLLEN

EMBRYO

Mendel chose “_______________” traits.Example: plants’ flowers were either purple or

white.Mendel used varieties that were __________________.

True-breeding plants only have offspring of the _______________ variety.

True-breeding plants with purple flowers self-pollinate to offspring that all have _______________ flowers.

EITHER-OR

TRUE-BREEDING

SAME

PURPLE

ExperimentMendel usually cross-pollinated two

_______________, true-breeding pea varietiesEx. Plants with purple flowers bred with plants

with white flowers (both true-breeding)._________________: mating to cross two true-

breeding varieties.The true-breeding parents are referred to as the P

generation (_______________).Offspring are the F1 generation (1st ________

generation)F1 generation self-pollinate to produce an F2

generation (second filial generation)What if??? If Mendel stopped with the F1

generation, he would have missed the _______________ of inheritance.

CONTRASTING

HYBRIDIZATION

PARENTAL

FILIAL

PATTERNS

P (Parental) Generation

F1 Generation

F2 Generation

Law of _______________: Experiments_______________ model of Inheritance: F1 hybrids from

a cross between purple flowered and white flowered plants would result in offspring with pale purple flowers. ______________.

Mendel discovered that the offspring had a ________ of approximately ________ purple to _____ white offspring.Mendel concluded that the gene for white flowers

did not _______________from the F1 but that the purple gene was _______________ the color of the plants.

Mendel called these _______________ traits and _______________ traits.Purple is ____________ over white which is why the

F1 generation was purple.The _______________ of white-flowered plants in the

F2 generation is evidence that the gene causing the ___________ trait (white) did not disappear because it was crossed with purple flowered plants.

BLENDINGSEGREGATION

BLENDED

RATIOTHREE ONE

DISAPPEARAFFECTING

DOMINANTRECESSIVE

DOMINANT

APPEARANCE

RECESSIVE

Mendel did similar experiments with six other characters and the results were similar: a ________ phenotypic ratio existed.

Developing the Law of Segregation: Mendel’s ModelAlternative versions of genes result in

_______________ in characters. (alternative versions of genes= _______________)Ex. Genes for flower color exist in two types:

white and purple (alleles)On a chromosome: Same locus, same gene, may

be a _______________allele.p.255 Fig 14.4

3:1

DIFFERENCESALLELES

DIFFERENT

Key concept:Law of Segregation:

In the formation of gametes, the paired genes separate  (segregate) in such a way that each gamete is equally likely to contain either member of the pair. 

The alleles separate from one another during formation of gametes. As a result, each offspring receives only one of the alleles which control a particular trait. 

        Example : If the parents genotype is Rr for a given trait, then half of the gametes would carry "R" and the other half will carry "r".

http://mendeliangenetics.weebly.com/law-of-segregation.html

For each character, an organism inherits ________ alleles: one from each _________.In a diploid organism, each _______________cell

contains two sets of chromosomes, one from each parent.

The same genetic locus is present _________ in a somatic cell (one from each parent).The alleles at the respective __________ may be

the same or different.Example: Eye color

TWOPARENT

SOMATIC

TWICE

LOCI

If two alleles at a locus differ, then the _______________ allele determines the organism’s appearance; the recessive allele has no _____________ effect on the appearance.The dominant allele will “_______” the recessive

allele from showing.Mendel’s F1 plants had both ____________ for both

purple and white flowers but looked purple because the allele for purple flowers is DOMINANT over white.

Two alleles for a heritable character (_______________) separate (_______________) during gamete formation and end up in different gametes. This is the law of segregation.Therefore, an egg or sperm gets only ______ of the

two alleles that are present in somatic cells. Due to _____________.

DOMINANT

VISIBLE

HIDE

ALLELES

GENESEGREGATE

ONE

MEIOSIS

Referring to chromosomes, segregation corresponds to the distribution of _______________ chromosomes to different gametes in meiosis (Anaphase I).

If an organism has identical alleles for a character (_________________) that character is present in all gametes.

If an organism has different alleles, _____% of the gametes receive the dominant and _____% receive the recessive allele.

HOMOLOGOUS

TRUE-BREEDING

5050

Half of the gametes have purple-flower allele and half have white flower allele.Self-pollination: egg with a purple-flower allele

has an _____________ chance of being fertilized by a sperm with a purple-flower allele as a sperm with a __________ flower allele. The same applies for an egg with a white-flower allele.

There are ___ possible combinations of sperm and egg.

Punnett square- diagram used to predict _______________ combinations from a cross between individuals with known genetic makeup.

EQUALWHITE

4

ALLELE

Punnett Square:

Results? Does it match 3:1 phenotypic ratio?

Genetics Vocabulary _______________: organism having a pair of identical

alleles for a gene. (____ or ___) True breeding.

_________________: an organism that has two different alleles for a gene. (___)

HOMOZYGOUSPP pp

HETEROZYGOUSPp

_______________ (think ___________ appearance): organism’s traits (what it _______________ like)

_______________ (think ____________): genetic make up (what combination of __________ it has)Why do we need to distinguish?

Due to dominant and recessive alleles, ____________ doesn’t always tell us what alleles (genes) are present.

Ex. PP and Pp will both look purple, but one has an allele for white flowers.

PHENOTYPE PHYSICALLOOKS

GENOTYPE GENESALLELES

APPEARANCE

Practice:

Testcross If a _______________and not _______________of an

organism is known, a test cross can be used to figure out the genotype.

A cross can be made with the organism with just the known phenotype and a homozygous _______________organism.

Example: Pea plants come in two heights, tall and short. Mr. Bell wants to determine if the tall plant he has in his office is a true-bred tall plant. Design a punnett square to show what he can do to figure out if his plant is a true-bred tall plant.

PHENOTYPE GENOTYPE

RECESSIVE

What can we learn? If only the dominant phenotype appears,

the unknown has a homozygous dominant genotype (TT x tt= _____% Tt ______% tt).

If the recessive phenotype appears, the unknown has a heterozygous genotype. (Tt x tt = ___% Tt and ___ % tt)

100 0

5050

Law of Independent Assortment _______________ cross: a cross between two

organisms that are heterozygous for one character. The second law of inheritance is based on

experiments following two characters at the same time. We’re going to follow Mendel’s experiments with seed color and seed shape.

Seeds: Color: _______________ (dominant) or Green

(recessive) Shape: Round [and smooth] (dominant) or

_______________ (recessive)

MONOHYBRID

YELLOW

WRINKLED

Mendel’s Law of Independent Assortment

Two or more pairs of alleles segregate independently of one another during gamete formation.

http://fig.cox.miami.edu/~cmallery/150/mitosis/c13x9independent-assortment.jpg

Cross of two true-breeding pea varieties that differ in both characters: _________x _________

The result will be dihybrids: organisms heterozygous for both characters (_____________)

Question: Do the alleles for the two characters always stay together (Y with ___ and y with __)? Or are the characters inherited independently of each other?

To answer, we need to look at F2 generation. Dihybrid Cross (_________ x __________) If alleles sort dependently, we expect a

phenotypic phenotypic ratio of ________ yellow, round seeds

If alleles sort independently, this means they are packaged into ____________ in all possible combination of alleles

Figure 14.8

YYRR yyrr

DIHYBRIDS

R r

YyRr YyRr

3:1

GAMETES

What would be the possibilities for each gamete?

______________________If the sperm of the classes are mixed with the

eggs of the classes, there are ______ equally probable ways they can combine in the F2 generation. (_______________)

Cross:

What is the phenotypic ratio? _______________

YR, Yr, yR, yr

164 X 4

9:3:3:1

Summary Mendel repeated the experiment for his

characters and always saw a __________ ratio. If characters are observed _____________, there is a

_______ phenotypic ratio for each of the separate characters: 3 yellow: 1 green and 3 round: 1 wrinkled.

In a single character, alleles segregate if it were a _______________ cross.

Law of Independent Assortment: each pair of alleles segregates independently of other pairs of alleles during gamete ___________________.

This only applies to allele pairs on _______________ chromosomes.

Genes located in close proximity on the same chromosome are usually inherited _______________…. Usually, but more in Ch. 15.

9:3:3:1SEPARATELY

3:1

MONOHYBRID

FORMATIONDIFFERENT

TOGETHER

Mendel and Probability _____________: the likeliness an event will occur

(scale 0-1) Example: flip of a coin. ½ heads and tails Each event is _______________. Previous events

have no effect on the outcome of the next event. Alleles _______________into gametes independently

of different alleles.

PROBABILITY

INDEPENDENT

SEGREGATE

MULTIPLICATION & ADDITION RULESTo determine the probability of two or more

independent events:

MULTIPLICATION RULE: Multiply the probability of one event by the probability of the other

What is the probability two coins tossed simultaneously will both end up on heads?

½ X ½ = ¼

http://www.arborsci.com/CoolStuff/CoinFlip.jpg

MULTIPLICATION RULE WORKS FOR PREDICTING GENETIC CROSSES, TOO

Tt X TtWhat is the probability offspring will be tt ?

½ X ½ = ¼

Punnett by Riedell

Each egg has a ½ chance of passing on t.

Each sperm has ½ chance of passing on t.

Rules of Probability __________________ rule: to determine the

probability of two simultaneous events, we multiply the probability of one event by the probability of the other event.

Ex: Probability that a coin will land heads twice:

MULTIPLICATION

Ex: Monohybrid Cross for Yellow Seeds (_______________)Each gamete has a ____ chance of carrying the

dominant (Y) or recessive (y) allele.Probabilities: YY= _____________ yy=

_______________ Yy=?For a heterozygote, gametes can combine to

produce Yy offspring in two independent and mutually _______________ways: Y from sperm and y from egg or y from sperm and Y from egg.

_______________rule: probability that any one of two more mutually exclusive events will occur can be calculated by adding their _______________ probabilities.

Yy= __ (Y from sperm or egg) + __ (y from sperm or egg) = __

Yy X Yy1/2

½ X ½ ½ X ½

EXCLUSIVE

ADDITION

INDIVIDUAL

¼ ¼ ½

ADDITION RULETo figure out the probability of an offspring being

heterozygous (Tt)

1st probabilityT from momt from dad

½ X ½ = ¼

Punnett by Riedell

T can come from mom and t from dad ORt can come from the mom and T from the dad but not both (events are mutually exclusive)

2nd probabilityt from momT from dad½ X ½ = ¼

¼ + ¼ = ½

Complex Genetics Problems with Probability Rules

Consider a _______________cross between two plants with yellow, round seeds.

What is the probability that the offspring of this cross will have a genotype of yyRr? Show your work. (259)

What is the probability that the offspring of this cross will have a genotype of YYrr? Show your work.

DIHYBRID

Trihybrid Cross: ______________________ for three genes: purple flowers, yellow, round seeds.

What would be the probability that offspring from this cross would be predicted to exhibit the recessive phenotypes for at least two of the three characters?

Pg 259

HETEROZYGOATS ;-)

Inheritance Patterns Spectrum of _______________

_______________dominance: Heterozygotes display dominant phenotype and are ______________________ from homozygous dominant organisms.

This is what we are used to studying.

DOMINANCE

COMPLETEINDISTINGUISHABLE

_________________: Two alleles both affect the phenotype in separate, unique ways. Think BOTH.

Example: Human MN blood: determined by codominant alleles for two specific molecules on the surface of red blood cells: M and N molecules.

MM have red blood cells with __ molecules only

NN have red blood cells with __ molecules only

_____ have both M and N molecules (codominant since BOTH traits are present).

CODOMINANCE

MN

MN

_______________Dominance: Hybrids have a phenotype _____________ the two phenotypes of the parents.

Example: Red snapdragons (_______________) x White snapdragons (_______________)

Offspring will all have a genotype of Rr and appear _____, because heterozygotes have less _____ pigment than homozygous dominant plants.

INCOMPLETEIN BETWEEN

DOMINANTRECESSIVE

PINK RED

Relationship between dominance and phenotype (Round v. Wrinkled Shape)

The round allele codes for the synthesis of an _______________ that helps convert sugar to starch in the seed. The seeds are wrinkled because the sugar builds up in recessive seeds which cause the _______________ intake of water, swelling the seed. When the seed dries, the _______________appear.

ENZYME

OSMOTIC

WRINKLES

Example: Tay-Sachs disease: _______________dominance

It is a genetic disorder in humans where the brain cells of a baby with are unable to _______________specific lipids as the enzyme that does so is not functional.

Lipids build up in brain causing seizures, blindness, and _________________ of motor and mental performance.

A child affected with Tay-Sachs dies within a _______________.

In order to display the disease, two copies of the allele need to be present (________________) so the allele qualifies as _______________. (organism level)

But, individuals who are heterozygous for Tay-sachs have an _________________ activity level for the enzyme (in between the two homozygotes) and produce both enzymes. (codominance at _______________ level).

RELATIVE

METABOLIZE

DEGENERATION

FEW YEARS

HOMOZYGOUS

RECESSIVE

INTERMEDIATE

BIOCHEMICAL

_______________: Dominant allele not always most _______________.condition where individual is born with extra

fingers or toes (1 in ____ in USA)

POLYDACTYLYPREVALENT

400

Multiple AllelesABO Blood Type (Letters refer to __________________ A

and B that appear on red blood cell)Four possible _______________: Blood type: A, B, AB,

OFour blood groups result from combinations of

_________ different alleles for the enzyme (I) that attaches A or B carbohydrate to red blood cells.IA adds A carbohydrate while IB adds B

carbohydrate and I has ____________.Six possible _______________ giving _______

phenotypes.IA and IB are _______________ to I. So I will be

written as i. 

CARBOHYDRATES

PHENOTYPES

THREE

NEITHER

GENOTYPES FOURDOMINANT

Genotypes and their Phenotypes:

GENOTYPEPHENOTYPE

(BLOOD TYPE)AA

AO

BB

BO

OO

AB

A

A

B

B

O

AB

Why significant?Blood types need to be matched in order for safe

blood ________________.Which blood type is the universal donor?

Universal acceptor?

TRANSFUSIONS

GENOTYPE PHENOTYPE

CAN ACCEPT

AA A

AO A

BB B

BO B

AB AB

OO O

A, O

A, O

B, O

B, O

A, B, AB, O

O

EpistasisEpistasis occurs when a gene at one locus changes the

phenotypic expression of a gene at a ____________ locus.Example: Mice and Coat Color

A black coat (B) is dominant to a brown coat (b). In order to have a brown coat, the mouse must have _______ recessive alleles (bb).

In addition, there is a second gene that determines whether the pigment will be ___________ the hair (therefore seen). This will be ____ (color).

If the mouse is homozygous recessive for the c gene (____), it will not have a color coat but instead be _________.

The gene for depositing color (C or c) is _______________ to gene for pigment color (B or b). If cc, then the color will not show.

Dihybrid cross ratio: 9 black :3 brown : 4 (3+1) (still a form of 9:3:3:1 ratio)

DIFFERENT

TWO

PUT INTOC

ccALBINOEPISTATIC

_______________InheritanceFor many characters, an either-or classification is

impossible as some characters have varying _______________of characteristics. These are _______________ characters.

Quantitative variation indicates polygenic inheritance: an effect of two or more genes on a single _______________ character.Example: Skin _______________: Assume that it is

controlled by three separate genes A, B, CEach _______________ allele will contribute to the

darkness of skin.AABBCC genotype will result in

_______________skin, AaBbCc and aaBbCC will result in an ________________ shade while aabbcc will be very light in skin color.

Fig 14.12 pg 263

POLYGENIC

LEVELSQUANTITATIVE

PHENOTYPIC

COLOR

DOMINANT

VERY DARKINTERMEDIATE

Graphic Display of Polygenic Inheritance

Nature vs. Nurture: The Environmental Impact on _______________Not all characteristics are based on _______________. Example: humans can affect their height by

_______________, skin pigment by _________________, and time/experience can impact _______________.

Norm of _______________: a genotype does not give a ________ phenotype but instead has a ________ of phenotypic possibilities due to __________________ influences.

Norms of reaction are largest with polygenic characters as we have seen with skin color.

PHENOTYPE

GENETICSNUTRITION

SUN EXPOSUREINTELLIGENCE

REACTIONRIGID RANGE

ENVIRONMENTAL

Environment influences Phenotype: “Nature vs Nurture”

Siamese cats and Himalayan rabbits have dark colored fur on their extremities

Allele that controls pigment production is only able to function at the lower temperatures of those extremities. Ms. Aronson’s cat, Ping Pong

• Color of hydrangea flowers variesdepending on pH of soil

Images from: http://www.gardensablaze.com/Shrubs/ShrubsHydrangea.htm

PedigreesFor humans, geneticists analyze the results of

_______________ that have already occurred by collecting family history for a specific trait.

Pedigree- a display showing the ________________________ of parents and children across the generations for a particular trait.

MATINGS

INTERRELATIONSHIPS

Example:

Which allele is dominant?Recessive?

Individuals III-6 and III-7 have two children and are expecting a third child. Their two children have flat feet. What is the chance that the third child will have _____________________?

NORMAL ARCHES

FLAT FEET

NORMAL ARCHES 3/4

Recessively Inherited Disorders A recessively inherited disorder only shows up in

the _______________ recessive individuals. Heterozygotes are _______________ in phenotype

because one allele can produce enough of the protein to not display the disorder.

Heterozygotes are known as _______________ as they can pass on the recessive allele to their offspring. (Carriers are individuals who are normal in phenotype but carry a recessive allele and can pass it on).

Example: A cross between two __________________ will result in a ¼ chance of passing the disorder to the offspring. Three of the offspring will be _______________.

Incidence of genetic disorders is not _______________ distributed. Geographic location often factors into distribution.

HOMOZYGOUS

NORMAL

CARRIERS

HETEROZYGOTES

CARRIERS

EVENLY

Cystic Fibrosis Most common _______________ genetic disorder in

the U.S. 1 of every 2,500 people of European descent (rarer in other groups). 1/25 people of European descent is a _______________.

Normal allele codes for a membrane protein that is active in transport of _______________ ions between cells.

Cause: If the normal allele is ___________ (for both), these transport channels may be defective or missing in the membrane.

LETHAL

CARRIER

CHLORIDE

MISSING

Effect: High concentrations of extracellular chloride which causes _______________ to become thicker and stickier than normal.Mucus can build up in _______________ (pancreas,

lungs, digestive tract, etc) which lead to multiple effects (_______________ example).

Effects include poor absorption of _______________, chronic bronchitis, and bacterial infections.

If untreated, children may _______ before the age of five.

Treatment: Gentle pounding on the chest (clear mucus from _______________), daily antibiotics (prevent _______________), other preventative treatments can _______________ life.

MUCUS

ORGANS

PLEIOTROPICNUTRIENTS

DIE

AIRWAYSINFECTIONPROLONG

Sickle-Cell disease Most common inherited disorder among people of

African descent and affects 1 of ____ African-Americans.

It is caused by a __________________ of a single amino acid of hemoglobin in red blood cells.

For someone with the disease, at low oxygen levels in the blood, the sickle-cell hemoglobin molecules _______________ into long rods that deform the red cells into a _______________ shape.

Sickled cells will clump and _______________ small blood vessels, which may lead to other symptoms: physical weakness, pain, organ damage, paralysis.

Multiple effects: example of _______________. Treatment: regular blood __________________ can

“prevent” brain damage in children. New drugs can lessen the impact of other problems but there is no _________.

400

SUBSTITUTION

AGGREGATESICKLE

CLOG

PLEIOTROPY

TRANSFUSIONS

CURE

PLEIOTROPYMost genes have multiple phenotypic effects

Image from Biology; Campbell and Reece; Pearson Prentice Hall publishing as Benjamin Cummings © 2005

Dominance of Sickle Cell Disease Homozygous _______________: full sickle cell

disease Heterozygous- presence of one allele can affect

the phenotype. (organism level: _______________ dominance)

They have sickle cell trait and are usually healthy.

May suffer some symptoms from prolonged reduced blood oxygen.

Molecular level, sickle cell anemia is _______________ as both normal and sickle cell hemoglobins are made in __________________.

RECESSIVE

INCOMPLETE

CODOMINANT

HETEROZYGOTES

Other effects1 in 10 African-Americans has a sickle-cell trait

which is very frequent.Explanation: A single copy of the sickle-cell

allele can protect against _______________. It reduces the frequency and severity of attacks (especially in children).

Heterozygotes _______________ while homozygous recessive suffer from the disease. Homozygous dominant genotype effect?

MALARIA

BENEFIT

Mating of Close Relatives (Or why not to marry your cousin, other than the “ick” factor)

When an allele that causes a disorder is rare, the chances that two ____________ of the harmful allele will meet and mate is low.

Close relatives have the probability of passing on recessive traits increase. Consanguineous matings- “_______________” matings (indicated by double lines in pedigrees).

Why? People with recent common ancestors are more likely to carry the same recessive alleles than _______________ people, which means a “same blood” mating increases the chance that offspring will be _______________ for recessive traits.

For these reasons, most societies and cultures have laws against consanguineous marriages.

CARRIERS

SAME BLOOD

UNRELATED

HOMOZYGOUS

Dominantly Inherited Disorders Achondroplasia- a form of _______________. 1 in

25,000 people. __________________ have the dwarf phenotype. 99.9% of the population are homozygous for the

recessive allele and do not have achondroplasia.

DWARFISM

HETEROZYGOTES

Huntington’s disease: Dominant alleles that cause lethal diseases are

much less _______________ than recessive alleles. These lethal alleles arise by _______________ in sperm or egg.

Why? If those with lethal dominant phenotypes die before they reproduce, the allele cannot be passed down.

The lethal recessive alleles can still be passed down by _______________.

COMMONMUTATIONS

CARRIERS

Huntington’s is a degenerative disease of the _______________ system caused by a dominant allele.No symptoms or phenotypic effects until the age

of _______________.Problem: individuals may have _______________

by that age.Once the nervous system deteriorates, the

process is _______________ and inevitably fatal.Children with parents who have Huntington’s

have a ____% chance of inheriting the allele (and _______________). Affects 1 in 10,000 people.

Testing: recent advancements allow DNA testing for the Huntington’s allele (on chromosome 4)Do you want to know if you have inherited a fatal

disease with no cure?

NERVOUS

35-40

CHILDREN

IRREVERSIBLE

50

DISORDER

__________________ Disorders Many of the disorders we have talked about are

called “_______________ disorders” because they result from abnormalities in alleles from one locus.

Many diseases are multifactorial: _______________ component and ___________________ influence

Examples: heart disease, _______________, cancer, alcoholism, bipolar disorder, schizophrenia, etc.

The hereditary component is often _______________.

___________________ health is affected by many genes: some are more susceptible to heart attacks and strokes.

However, _______________ has a large influence between genotype and phenotype for multifactorial characters.

Exercise, a _______________ diet, drug-free lifestyle, and ability to deal with stress _______________ risks for heart disease and some cancer.

MULTIFACTORIAL

MENDELIAN

GENETICENVIRONMENTAL

DIABETES

POLYGENIC

CARDIOVASCULAR

LIFESTYLE

HEALTHFULREDUCE

Genetic Testing Bob and Suzy each have a sibling that has died

from a recessive genetic disorder. They themselves do not have the genetic disorder. What is the probability that Bob and Suzy’s child will have the genetic disorder?

There are now tests to identify whether individuals are carriers for alleles for recessive disorders. Is this a good thing?

Amniocentisis A technique used during the 14th-16th week of

pregnancy that can be used to determine whether the fetus has ________________ abnormalities and/or genetic disorders.

Procedure: a needle is inserted into the ____________ and extracts about 10 mL of amniotic fluid (fluid around fetus)

The fluid itself can be tested for some genetic disorders.

Cells in fluid can be used for _______________ for chromosome analysis.

CHROMOSOMAL

UTERUS

KARYOTYPING

Chorionic Villus Sampling (______) A technique used between the 8th to tenth week

of pregnancy. Procedure: a narrow tube is inserted through the

cervix into the uterus and suctions out a small sample of tissue from the _______________. The ________ of the chorionic villi of the placenta can be used to determine the fetus’ genotype.

The cells divide quickly and can be used for karyotyping (_______________ analysis than amniocentesis).

Disadvantage: cannot be done with tests that require amniotic fluid and is less available.

CVS

PLACENTA CELLS

FASTER

Fetoscopy Thin tube containing a viewing scope and fiber

optics is inserted into the fetus used to view major anatomical abnormalities.

Ultrasound Imaging technique that uses _________ waves to

produce an image of the fetus through _______________ procedure used to view major anatomical abnormalities.

Benefits: no known risk to mother or fetus.

SOUNDNONINVASIVE

RisksAmniocentesis and fetoscopy can have risks such

as maternal bleeding or fetal death (1%).Because of these risks, these are not performed

unless there is a high _______________ of genetic disorder or birth defect.

PROBABILITY

Newborn Screening Phenylketonuria (_______) 1 in 10,000-15,000

births (U.S.) This is commonly screened for in newborns Cause: children with PKU cannot break down

___________________ Effect: Phenylalanine and phenyl pyruvate can

build up to toxic levels in the blood which can cause _______________ retardation.

Treatment: Diet low in phenylalanine can result in normal development and _______________ mental retardation.

PKU

PHENYLALANINE

MENTAL

PREVENT