Download human genetics ppt - phsdanielewiczscience

KARYOTYPE is a picture of
A __________
an organism’s chromosomes
Chromosomes that determine
the sex of an organism =
_________________
Sex chromosomes
http://www.angelbabygifts.com/
All other chromosomes =
_________________
autosomes
Humans have two sex chromosomes
X
y
and _____
44 autosomes
PEDIGREES
_______________are
diagrams
genes are passed
that show how are ____________
in families
on __________
over several
generations
Drawing a pedigree chart
http://www.beavton.k12.or.us/sunset/academics/genetics.htm
http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope.html
Y-LINKED GENES:
carried on Y
Genes ______________
chromosome
EXAMPLE:
Hairy pinna
ONLY show up _______
in males
Y linked
_________genes
_____
Chapter 14
SEX DETERMINATION
XX = female
Xy = male
Who decides?
Mom can give X
Dad can give
X or y
X
X
X
XX
XX
y
Xy
Xy
Dad determines sex of the baby.
SO ____
If dad gives X with mom’s X = girl
If dad give y with mom’s X = boy
SEX CHROMOSOMES
CAN CARRY OTHER
GENES TOO
= ___________________
SEX LINKED TRAITS
These traits show up in different
_______________
in males and females
percentages
because they move with the sex
chromosomes
X-LINKED GENES:
____________
are carried on the X chromosome
X-linked recessive disorders
MORE frequently
show up _____________
in MALES
______ than females
because males only have
ONE X chromosome.
______
Males ONLY HAVE ONE X
DEFECTIVE
They either
have the
disorder
NORMAL
Or
They are
normal
FEMALES HAVE TWO X CHROMOSOMES
DEFECTIVE
NORMAL
DEFECTIVE
Females have
one normal
gene that works.
need 2
Females __________
defective recessive
alleles to show the
disorder
THOMAS HUNT MORGAN’S
RESULTS
HEMOPHILIA
CAUSE:
Mutation in genes for __________________
Blood clotting proteins
on X chromosome
carried ______
Blood clotting proteins are missing so person
with this disorder can’t stop bleeding when
bleed to death from minor
injured; can ________________
cuts or suffer internal bleeding
from bruises or bumps.
HEMOPHILIA
Treatment:
injections of normal clotting
Need ____________
proteins to stop bleeding
More common in ______
males because it is
_____________
TWO recessive
X-linked, but females with ______
hemophilia alleles will also show the trait.
1 in 10,000 males has hemophilia
COLORBLINDNESS
CAUSE:
Mutation in one of three genes for
_______________
carried on X chromosome
Color vision
Persons with this disorder have trouble
distinguishing colors.
Red-green
_________________
colorblindness is most common
Seen in 1 in 10 males
1 in 100 females
http://gizmodo.com/gadgets/peripherals/samsung-develops-lcd-for-colorblind-036306.php
Duchenne Muscular Dystrophy
CAUSE:
deletion in gene
that codes for a
muscle protein
_______________
Results in
progressive weakening
____________________
and loss of
skeletal
muscle
___________________
http://www.cadenhead.org/workbench/gems/jerry-lewis-telethon.jpg
http://www.tokyo-med.ac.jp/genet/chm/dei.gif
Duchenne Muscular Dystrophy
(DMD)
SYMPTOMS:
1 in 3000 male births
Appears before age 5
Progressive muscle weakening
Most in wheelchair by age 13
Eventually lethal
What’s the pattern:
Y-linked traits show up _______
ONLY in _______
males
________
X-linked recessive traits:
__________________
______________________
more common in males than females.
________________
ONLY FEMALES can be ________.
carriers
AUTOSOMAL RECESSIVE traits:
_______________________
FEMALES can be ________
carriers
BOTH MALES
______ & _________
CHROMOSOMAL Abnormalities
________________
• 1 infant in 200 newborns has a
chromosomal abnormality
• 28% of first trimester miscarriages have
a chromosomal abnormality
• Abnormalities in larger
chromosomes don’t usually survive
CHROMOSOMAL MUTATIONS
____________________________:
structure or
Change in the ______________
number
____________
of chromosomes
Homologous chromosomes
fail to separate during MEIOSIS
________________
NONDISJUNCTION
= _________________________
One cell gets 2 copies of
the chromosome the
other cell gets none.
Normal Meiosis
Nondisjunction
http://web.udl.es/usuaris/e4650869/docencia/gen_etica/meioferti2.html
http://www.tokyo-med.ac.jp/genet/anm/domov.gif
Nondisjunction
Nondisjunction
Since it happens to a
sperm or egg, the new
baby can end up
3 copies
with _____________
of a
chromosome
TRISOMY
= __________________
OR
one copy of a
only ___________
chromosome
= ___________________
MONOSOMY
Human Abnormalities
caused by Non-Disjunction
__________________
Down syndrome
Klinefelter syndrome
__________________
Turner syndrome
__________________
TRISOMY 21
Down syndrome (= ____________)
Down syndrome (Trisomy 21)
• 1 in 800 births
• Similar facial
features
• Slanted eyes
• Protruding tongue
Down syndrome (Trisomy 21)
Simian line on palm
Down syndrome (Trisomy 21)
• Most common chromosomal
abnormality
• 50% have heart defects that
need surgery to repair
• Mild to severe mental
retardation
• Increases susceptibility to
many diseases
• Risk of having a child with
Down syndrome increases
with age of mom
Turner syndrome
XO
Turner syndrome ____
•
•
•
•
•
•
•
•
•
1 in 5000 births
Females have only one X chromosome
Small size
Slightly decreased intelligence
35% have heart abnormalities
Hearing loss common
Broad chest
Reproductive organs don’t develop at puberty
Can’t have children
http://medgen.genetics.utah.edu/photographs/diseases/high/611.gif
Klinefelter syndrome XXy
Klinefelter syndrome
• 1 in 1000 births
• Males have extra X chromosomes
(Can be XXy, XXXy, or XXXXy)
• Average to slight decrease in intelligence
• Small testes/can’t have children
• Usually not discovered until puberty when
don’t mature like peers
Karyotype
(need cells from baby)
Image from: http://members.tripod.com/~yenial/chromosome.html
Can tell __________________
MISSING/EXTRA chromosomes
GENDER
__________
DELETIONS/INSERTIONS
Some _____________________
single gene
Can’t see _______________
mutations
If having extra chromosomes causes
genetic problems, how come having
two X chromosomes in females and
one X in males is not a problem?
X-chromosome Inactivation
ONE X chromosome
In female cells ______
SWITCHED OFF
is randomly ________________
It condenses and forms a dense
region in the nucleus called a
BARR BODY
_____________
http://fig.cox.miami.edu/~cmallery/150/gene/barr.htm
CAT COLOR
http://www.islandstrolling.com/mainland/peloponnes/photo/mystra_cat_white_orange_black.jpg
In cats, a gene that
controls the
SPOT COLOR
_____________
is carried on the
X chromosome
____________________
In some female cells the X with the allele for orange spots
is switched off and in some cells the X with the allele for
black spots is switched off, so cat has different
colored spots.
CAT COLOR
http://ascensionparish.net/forum/messages/14/2493.jpg
Male cats have only
_________
one X chromosome, so they
can only have
____________
one color of spots!
THINK ABOUT IT?
How many colors of spots could a male cat with
Klinefelter syndrome have?