studying human inheritance 12-1 & 12-2. pea characteristics

Studying Human Inheritance12-1 & 12-2

Pea Characteristics

http://mac122.icu.ac.jp/BIOBK/BioBookgenintro.html

GENES are more complicated than MENDEL thought

Some traits have more than two allele choices =

____________________ traits

EX: A,B,O blood typeglycoproteins

MULTIPLE ALLELE


Some traits are determined by more than one gene

=_____________traits

EX: Human height, Intelligence

http://www.bcps.org/offices/lis/models/life/images/grow.JPG

POLYGENIC


POLYGENIC traits have lots of “in-between” phenotypes

http://www.newtonswindow.com/problem-solving.htm

There aren’t just SMART people and DUMB people…. there is a whole rangeof intelligences in-between


Some genes are LINKED TOother genes

_____________ traits arelinked to a sex chromosomeSEX-LINKED

SEX DETERMINATION

XX =

Xy =

female

male

Images from: http://members.tripod.com/~yenial/chromosome.html

Who decides?

Mom can give X

Dad can give X or y

If dad gives X with mom’s X = girlIf dad give y with mom’s X = boy

__________ determines sex of babies.

X

y

X X

X X

X X y y

X X

DAD

Thomas Morgan’s experiments with fruit flies

PURE PURE

RED-EYED WHITE-EYED

FEMALES MALES

http://www.accessexcellence.org/RC/VL/GG/sex.html

X

GOT ALL RED EYED FLIES50% males 50% females

XXRR XXRR XXRr XXRr

XyRR XyRR XyRr XyRr

XyRr XyRr Xyrr Xyrr

XXRr XXRr XXrr XXrr

XR

yR

yr

Xr

XR XR Xr Xr

RED-EYED FEMALESWHITE-EYED MALESRED-EYED MALES

WHITE-EYED FEMALES

MORGAN EXPECTED:

Thomas Morgan’s experiments with fruit flies

ACTUAL RESULTS from cross:RED EYED FEMALES

RED EYED MALES

WHITE EYED MALES

NO WHITE EYED FEMALES!

http://www.accessexcellence.org/RC/VL/GG/sex.html

GENE FOR EYE COLOR in Fruit flies IS CARRIED ON X CHROMOSOME

So it acts as a single gene cross

Image modified from:http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

XRXR XRXR XRXr XRXr

XRXR XRXR XRXr XRXr

XRy XRy Xry Xry

XRy XRy Xry Xry

XR

XR

y

y

XR XR Xr Xr

NO WHITE-EYED FEMALESRESULTS:

When traits do not appear

in expected ratios….

they may be linked.

Genes located on the same chromosome form a ______________ group LINKAGE

X-linked genes are carried on the X CHROMOSOME

X-linked recessive disorders

show up MORE frequently in _________________

X-LINKED RECESSIVE DISORDERSColor blindnessHemophiliaMuscular dystrophy

X* X

X* yMALES

FEMALES CAN BE CARRIERSfor X-linked recessive disorders

Females need 2 copies of the mutant gene to show the disorder

X* X

X*X*

PERSONS that carry a genefor a recessive disorder but DON’T show the disorder themselvesare called __________________CARRIERS

CARRIER

Carriers DON’T SHOW the trait themselvesbut can pass it on to their offspring

DEFECTIVE NORMAL


CARRIERONLY FEMALES can be carriers for

X-linked recessive disorders

Females have TWO X’s.

DEFECTIVE NORMAL


CARRIERMales CAN’T be carriers for

X-LINKED RECESSIVE disorders

Only have one X chromosome

NORMALDEFECTIVE


BOTH MALES and FEMALES can be carriers for _______________________genes.

AUTOSOMAL RECESSIVE

DEFECTIVEGENE

NORMAL

AUTOSOMAL RECESSIVE DISORDERSPhenylketonuria Cystic fibrosis Albinism Image modified from:

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif


GENES can change places

CROSSINGOVER

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

Gametes get different

gene combinations

Image modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

GENES that are _________________ are _________ likely to separate during crossing over in meiosis.

FARTHER APART

MORE


GENES that are _________________ are _________ likely to separate during crossing over in meiosis.

CLOSE TOGETHER

LESS


We can tell where genes are on a chromosome by seeing how often they cross over.

Geneticists use crossing over frequency to make a____________________that shows the location ofgenes along a chromosome

Chromosome map

SEX-LINKED and SEX INFLUENCEDTRAITS http://biology.clc.uc.edu/courses/bio105/geneprob.htm

http://www.people.virginia.edu/~rjh9u/hairears.html

SEX LINKED TRAITS show up in different % in males and

females because they move with the sex chromosomes

Sex chromosomes can carry other genes

X-LINKED GENES:

Genes carried on the X chromosome

EX: __________________________

_________________________

HemophiliaColorblindness Duchenne Muscular Dystrophy

Sex chromosomes can carry other genes

Y-LINKED GENES: Genes carried on Y chromosome

EX:Hairy pinna

_________genes only show up in _______Y linked males.Image from: http://www.people.virginia.edu/~rjh9u/hairears.html

SEX INFLUENCED TRAITS

Genes that are carried on ______________ BUT are affected by the ____________ of the individual that has the gene

AUTOSOMESsex hormones

Male Pattern Baldness

Autosomal dominant gene

http://biology.clc.uc.edu/courses/bio105/geneprob.htm

YOUR SEX CHANGES THE EXPRESSION OF THE GENEB is dominant for baldnessB’ is recessive for not bald

If you are MALE: If you are FEMALE:

BB = BB= BB’ = BB’=B’B’ = B’B’=

BALDBALDNOT bald

NOT baldBALD

NOT bald

PEDIGREES can help show how are genes passed on over

generations

PEDIGREE CHART

Normal Male = Normal Female =

Has trait = Carrier =

Images modified from: http://www.beavton.k12.or.us/sunset/academics/genetics.htm

http://www.beavton.k12.or.us/sunset/academics/genetics.htm

http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope.html

http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/europeanroyalfamily.html

How can we detect disorders?BEFORE BIRTH• Amniocentesis• Chorionic Villi Sampling (CVS)• Karyotype (need to get cells by Amnio/CVS 1st )

• Alpha feto protein (AFP)

AFTER BIRTH• PKU

How can we detect disorders ?Insert needle into sac around baby andwithdraw fluidcontaining baby’s cells

Done at 14-16 weeks

Karyotype can detect:missing/extra chromosomes Other tests can detect: Huntington’s; Cystic Fibrosis

Image from: http://www.fiu.edu/~srose/pregchildbirth.doc

Chorionic Villi Sampling

Done at EARLIER (8-10 weeks)

Greater chance of miscarriage than with amniocentesis

Insert needleand take a sample of sack baby is growing in

Can detect same disorders as amniocentesis but sooner

Image from: http://www.nlm.nih.gov/medlineplus/ency/imagepages/9181.htm

Karyotype-(need cells from baby)

Can tell missing/extra chromosomesGenderSome deletions/additionsCan’t show point/frame shift mutations

Image from: http://members.tripod.com/~yenial/chromosome.html

ALPHA FETO PROTEIN

Test MOTHER’s blood during pregnancy

Measures AFP proteinmade by baby that crossesover into mother’s blood

Low AFP = possible Down/Turner syndrome High AFP = Spina bifida

http://www.androusa.com/Blood%20Tubes.jpg

PKUPhenylketonuria

Blood test givento ALL babies

before leaving hospital

Special diet can prevent mental retardation

http://www.androusa.com/Blood%20Tubes.jpg

http://www2.coca-cola.com/presscenter/img/imagebrands/downloads/lg_dietcoke_can.jpg

studying human inheritance 12-1 & 12-2. pea characteristics

Documents

moms x

x chromosomeso

carriersfor x

x chromosomex

white eyed females

red eyed flies50

recessive disorders

linked toother genes