Transcript GENES that are

Studying Human
Inheritance
12-1 & 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 =
MULTIPLE ALLELE traits
____________________
EX: A,B,O blood type
glycoproteins
GENES are more complicated
than MENDEL thought
Some traits are determined by
more than one gene
=_____________traits
POLYGENIC
EX: Human height,
Intelligence
http://www.bcps.org/offices/lis/models/life/images/grow.JPG
GENES are more complicated
than MENDEL thought
POLYGENIC traits have lots of
“in-between” phenotypes
There aren’t just SMART people
and DUMB people….
there is a whole range
of intelligences in-between
http://www.newtonswindow.com/problem-solving.htm
GENES are more complicated
than MENDEL thought
Some genes are LINKED TO
other genes
SEX-LINKED traits are
_____________
linked to a sex chromosome
SEX DETERMINATION
XX = female
Xy = male
Images from:
http://members.tripod.com/~yenial/chromosome.html
Who decides?
Mom can give X
X
Dad can give X or y
y
X
X
XX
XX
Xy
Xy
If dad gives X with mom’s X = girl
If dad give y with mom’s X = boy
DAD determines sex of babies.
__________
Thomas Morgan’s experiments with
fruit flies
PURE
RED-EYED
FEMALES
X
PURE
WHITE-EYED
MALES
GOT ALL RED EYED FLIES
50% males
50% females
http://www.accessexcellence.org/RC/VL/GG/sex.html
XR
XR
Xr
Xr
XXRR
XXRR
XXRr
XXRr
XyRR
XyRR
XyRr
XyRr
yr
XyRr
XyRr
Xyrr
Xyrr
Xr
XXRr
XXRr
XXrr
XXrr
XR
yR
MORGAN EXPECTED:
RED-EYED FEMALES
WHITE-EYED FEMALES
RED-EYED MALES
WHITE-EYED MALES
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
XR
XR
XR
XR
Xr
Xr
XRXR
XRXR
XRXr
XRXr
XRXR
XRXR
XRXr
XRXr
y
XRy
XRy
Xry
y
XRy
XRy
Xry
RESULTS:
Xry
Xry
NO WHITE-EYED FEMALES
Genes located on the same
chromosome form a
______________
LINKAGE group
When traits do not appear
in expected ratios….
they may be linked.
X-linked genes are carried on the
X CHROMOSOME
X-LINKED RECESSIVE DISORDERS
Color blindness
*
Hemophilia
Muscular dystrophy
X X
X-linked recessive disorders
show up MORE frequently in
MALES
_________________
*
X
y
FEMALES CAN BE CARRIERS
for X-linked recessive disorders
X* X*
*
X X
Females need 2 copies of the
mutant gene to show the
disorder
PERSONS that carry a gene
for a recessive disorder
but DON’T show the disorder
themselves
CARRIERS
are called __________________
CARRIER
DEFECTIVE
NORMAL
Carriers DON’T SHOW
the trait themselves
but can pass it on
to their offspring
Image modified from:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
CARRIER
ONLY FEMALES can be carriers for
X-linked recessive disorders
DEFECTIVE
NORMAL
Females have TWO X’s.
Image modified from:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
CARRIER
Males CAN’T be carriers for
X-LINKED RECESSIVE disorders
DEFECTIVE
NORMAL
Only have one
X chromosome
Image modified from:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
BOTH MALES and FEMALES can be
carriers for _______________________
AUTOSOMAL RECESSIVE
genes.
DEFECTIVE
GENE
NORMAL
AUTOSOMAL RECESSIVE DISORDERS
Phenylketonuria
Cystic fibrosis
Image modified from:
Albinism
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
GENES are more complicated
than MENDEL thought
GENES can change places
CROSSING
OVER
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
Image modified from:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
Gametes get different
gene combinations
FARTHER APART
GENES that are _________________
are _________
MORE likely to separate
during crossing over in meiosis.
Image modified from:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
Image modified from:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
CLOSE TOGETHER
GENES that are _________________
are _________
likely to separate
LESS
during crossing over in meiosis.
We can tell where
genes are on a
chromosome by seeing
how often they
cross over.
Geneticists use crossing over
frequency to make a
____________________
Chromosome map
that shows the location of
genes along a chromosome
http://www.people.virginia.edu/~rjh9u/hairears.html
SEX-LINKED
and
SEX
INFLUENCED
TRAITS
http://biology.clc.uc.edu/courses/bio105/geneprob.htm
show up
in different % in males and
females because they move with
the sex chromosomes
SEX LINKED TRAITS
Sex chromosomes can
carry other genes
X-LINKED GENES:
Genes carried on
the X chromosome
EX: _____________
Hemophilia
_____________
Colorblindness
Duchenne Muscular Dystrophy
_________________________
Sex chromosomes can
carry other genes
Y-LINKED GENES:
Genes carried on Y chromosome
EX:
Hairy pinna
Y linked
males.
_________genes
only show up in _______
Image from: http://www.people.virginia.edu/~rjh9u/hairears.html
SEX INFLUENCED
TRAITS
Genes that are carried on
______________
AUTOSOMES BUT are affected by
the ____________
sex hormones of the individual
that has the gene
Male Pattern Baldness
Autosomal
dominant gene
http://biology.clc.uc.edu/courses/bio105/geneprob.htm
YOUR SEX CHANGES THE
EXPRESSION OF THE GENE
B is dominant for baldness
B’ is recessive for not bald
If you are MALE:
BB = BALD
BB’ = BALD
B’B’ = NOT bald
If you are FEMALE:
BB= BALD
BB’= NOT bald
B’B’= NOT bald
PEDIGREES can help show how are
genes passed on over generations
Images modified from: http://www.beavton.k12.or.us/sunset/academics/genetics.htm
PEDIGREE
CHART
Normal Male =
Normal Female =
Has trait =
Carrier =
http://www.beavton.k12.or.us/sunset/academics/genetics.htm
http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope.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 ?
Image from: http://www.fiu.edu/~srose/pregchildbirth.doc
Insert needle
into sac around
baby and
withdraw fluid
containing
baby’s cells
Done at 14-16 weeks
Karyotype can detect:missing/extra chromosomes
Other tests can detect: Huntington’s; Cystic Fibrosis
Chorionic Villi Sampling
Image from: http://www.nlm.nih.gov/medlineplus/ency/imagepages/9181.htm
Insert needle
and take a sample
of sack baby is
growing in
Done at EARLIER
(8-10 weeks)
Greater chance of
miscarriage than with
amniocentesis
Can detect same
disorders as
amniocentesis but sooner
Karyotype(need cells from baby)
Image from: http://members.tripod.com/~yenial/chromosome.html
Can tell missing/extra chromosomes
Gender
Some deletions/additions
Can’t show point/frame shift mutations
ALPHA FETO PROTEIN
Test
MOTHER’s blood
during pregnancy
Measures AFP protein
made by baby that crosses
over into mother’s blood
http://www.androusa.com/Blood%20Tubes.jpg
Low AFP = possible Down/Turner syndrome
High AFP = Spina bifida
PKU
Phenylketonuria
http://www.androusa.com/Blood%20Tubes.jpg
Blood test given
to ALL babies
before leaving
hospital
Special diet can prevent
mental retardation
http://www2.coca-cola.com/presscenter/img/imagebrands/downloads/lg_dietcoke_can.jpg