Download Tt (tall) - Amazon Web Services

INTRO TO
GENETICS
GENETICS
the study of how
traits are passed from
one generation to the
next
TRAIT
a characteristic
Examples:
Plant size, seed color, pod shape
GENES
Each feature of the pea plants is controlled by a
gene. It may have a gene that controls its
color, another for size and another for shape.
GENE
the factors that
control traits
(found in the DNA)
Above you see chromosomes. The circled
area is a gene on chromosome #22. The
absence of this gene causes velo-cardiofacial syndrome (VCFS) which may
cause ADD and mental illness
ALLELES
Each gene comes in different forms called
alleles, so the gene that controls flower color
may come in two alleles: purple and white.
ALLELES
different forms
of a gene
GREGOR MENDEL
•
•
•
•
The “father” of genetics
Lived from 1822-1884
Austrian Monk
Published his work in
1866, but no one took him
seriously until 1900.
• Studied Pea Plants!
MENDEL’S
EXPERIMENTS
Mendel experimented with 7
different characteristics
Mendel Got Lucky for 2 Big Reasons
1. First, he had a lot of time…he
was a monk. This let him do
LOTS of experiments with the
peas!
2. Each trait had 2 options. This
was key because he could tell if it
was one way or the other.
HOMOZYGOUS
organism with two
identical alleles for
the same trait
(TT or tt)
HETEROZYGOUS
organism with two
different alleles for
the same trait
(Tt)
DOMINANT
allele that is expressed
when in the presence
of a recessive allele
(TT or Tt = tall)
RECESSIVE
allele that is expressed
only when
homozygous
(tt = short)
PHENOTYPE
physical
characteristics
(Tall, Brown)
GENOTYPE
the genetic makeup
(TT, TtHh)
GENE = Height
ALLELE = Tall, Short
Gene is represented by the letter “t”
Dominant = T
Recessive = t
Remember you need 2 copies of every gene!!!
How can we
determine what the
offspring are going
to be?
PUNNETT
SQUARES
Reginald C. Punnett
• Inventor of the
Punnett Square
PUNNETT
SQUARES
chart showing the
possible combination
of alleles in a cross
Punnett Squares
show the
probability of
getting a certain
type of offspring
THE PARENTS
GENOTYPES
• DAD = Tt (heterozygous)
• MOM = Tt (heterozygous)
PHENOTYPES
• DAD = Tall
• MOM = Tall
PUNNETT SQUARES
THE OFFSPRING
GENOTYPES
1TT:2Tt:1tt (1:2:1)
• TT (homozygous dominant)
• Tt (heterozygous)
• Tt (heterozygous)
• tt (homozygous recessive)
THE OFFSPRING
PHENOTYPES
3 Tall :1 Short (3:1)
• TT (tall)
• Tt (tall)
• Tt (tall)
• tt (short)
Cross a homozygous
dominant with a recessive
(for height where T is
dominant and tall).
Find the genotype and the
phenotype
Cross a heterozygote with a
recessive (for height where T
is dominant and tall).
Find the genotype and the
phenotype
Cross a heterozygote with
another heterozygote (for
skin color where Black is B,
b = white).
Find the genotype and the
phenotype
Cross a heterozygote with
another heterozygote (for
nose size where big nose is N
and small nose is n).
Find the genotype and the
phenotype
Independent
Assortment
each trait is inherited
independent of other
traits (chance)
Segregation
in meiosis two alleles
separate so that each gamete
(sex cell) receives only one
form of the gene from each
parent
Mendel’s Principles of Inheritance
• Inherited traits are transmitted by genes which occur
in alternate forms called alleles
• Principle of Dominance - when 2 forms of the same
gene are present the dominant allele is expressed
• Principle of Segregation - in meiosis two alleles
separate so that each gamete receives only one form
of the gene
• Principle of Independent Assortment - each trait is
inherited independent of other traits (chance)
If we saw an organism
that had round seeds
(round is dominant),
how could we figure out
what its genotype is?
Test Cross
A cross between an
unknown and a
homozygous recessive
Example of a Test Cross
Unknown
Incomplete Dominance
When a combination of the
dominant and recessive creates
a new phenotype. RR = red,
rr = white, and Rr = pink
Incomplete Dominance
RR
Rr
rr
Incomplete Dominance
Cross
Incomplete Dominance
Cross
Co-dominance
When an intermediate between
the dominant and recessive is
expressed. TT = tall, Tt =
medium, and tt = short
Sex Linked Trait
a trait that is found
on either the X or Y
chromosome
Hemophilia is an
example of a sex
linked trait.
Hemophilia
a disease where your
blood doesn’t clot.
Hemophilia only
occurs when all of the
X chromosomes have
a copy of the recessive
gene.
H
h
X X :female carrier
h
h
X X :female hemophiliac
H
X Y:normal male
h
X Y:hemophiliac male
SICKLE CELL
ANEMIA
Difference between normal
cells & sickle cells
Sickle Cell
SS =
normal
Ss = carrier
(SC trait)
ss = sickle
cells
(lethal)
Sickle Cells tend to get stuck
easily in the circulatory system.
Why would African
American’s be so
much more likely to
have Sickle Cell?
Regular red blood cells
infected by malaria
PEDIGREE
chart that shows
the relationships
within a family
Sample Pedigree
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Sample Pedigree
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Pedigree Basics
• Males are squares, females are circles, and
unborn babies are triangles or octagons
• Shaded figures represent individuals with
the trait, a carrier could be 1/2 shaded
• Generations are numbered with roman
numerals (I, II, II, IV) from top to bottom
• People within generations are numbered
(1,2,3) from left to right
ANTIBODY
a protein produced by white
blood cells in the body in
response to the presence of an
antigen, for example, a
bacterium or virus
ANTIGEN
a substance, usually a
protein, on the surface of a
cell or bacterium that
stimulates the production of
an antibody
Blood Groups
Quic kT i me™ and a
T IFF (Unc ompres s ed) dec ompres s or
are needed t o s ee thi s pi c ture.
Quic kT i me™ and a
T IFF (Unc ompres s ed) dec ompres s or
are needed t o s ee thi s pi c ture.
Blood group A
You have A antigens on the
surface of your red blood cells
and B antibodies in your blood
plasma.
Blood group B
You have B antigens on the
surface of your red blood
cells and A antibodies in
your blood plasma.
Blood Groups
Quic kT i me™ and a
T IFF (Unc ompres s ed) dec ompres s or
are needed t o s ee thi s pi c ture.
Blood group AB
You have both A and B antigens
on the surface of your red blood
cells and no A or B antibodies at
all in your blood plasma.
Blood group 0
Quic kT i me™ and a
T IFF (Unc ompres s ed) dec ompres s or
are needed t o s ee thi s pi c ture.
You have neither A or B
antigens on the surface of your
red blood cells but you have
both A and B antibodies in your
blood plasma.
Rh Factors
Quic kT i me™ and a
T IFF (Unc ompres s ed) dec ompres s or
are needed t o s ee thi s pi c ture.
Quic kT i me™ and a
T IFF (Unc ompres s ed) dec ompres s or
are needed t o s ee thi s pi c ture.
Many people have a
Rh factor on the
surface of their red
blood cells. This is
also an antigen and
those who have it are
called Rh+. Those
who haven't are called
Rh-.
Possible Blood Groups
You can belong to either of
following 8 blood groups:
A Rh+
B Rh+
AB Rh+
0 Rh+
A RhB RhAB Rh0 Rh-
Transfusions
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
The transfusion will work if a person who is
going to receive blood has a blood group
that doesn't have any antibodies against the
donor blood's antigens.
QuickTi me™ and a
T IFF (Uncom pressed) decom pressor
are needed to see t his pict ure.
People with blood
group 0 are called
"universal donors"
and people with
blood group AB
are called
"universal
receivers.
PRACTICE TRANSFUSIONS
http://www.nobel.se/medicine/ed
ucational/landsteiner/index.html
200 B.C.
Humans “clone” trees by cuttings
1950
Humans clone frogs
1980’s
Humans clone mice!
1997
HUMANS CLONE SHEEP!!!
1998
Humans clone 8 copies of a cow!!!
20??
GENETIC
ENGINEERING
moving genes from one
chromosome of one
organism to the
chromosome of another
“Fat” Gene
CLONING
making an exact
copy of another cell
/ organism
Dolly—the first cloned sheep
Ian Wilmut,
the dude that
did it
Check out this short
movie that talks about
cloning…
A dividing cell
Read NYTimes Article
"Despite Warnings, 3 Vow to Go Ahead on Human Cloning"
a. What did three proponents of human cloning
announce on August 7, 2001?
b. Where did they make this announcement?
c. Why did some scientists at the symposium object
to the proponents' announcement?
d. Why did Dr. Alan Colman object to the research
by these proponents being done in secret?
e. According to the article, what was the consensus
among the panel and most of those who
testified before it?
Read NYTimes Article
"Despite Warnings, 3 Vow to Go Ahead on Human Cloning"
f. Who was "Dolly"?
g. What animals have been successfully cloned?
h. According to the article, what is involved in
cloning a human?
i. How did the three proponents say they would
address the possibility of genetic
abnormalities?
j. How did other experts at the symposium respond
to this statement?
k. Why do the proponents need to conduct their
research secretly?
•http://www.biology.arizona.edu/human_bio/activities/karyot
yping/karyotyping.html
•http://www.pathology.washington.edu/galleries/Cytogaller
y/cytogallery.html
•http://www.biology.iupui.edu/biocourses/N100/2k2humancs
omaldisorders.html
•http://www.biology.washington.edu/bsa/karyotypeS.html
•http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html
AMNIOCENTESIS
A technique used to
determine the genetic
traits of a baby before
it is born
Klinefelter Syndrome
• Have male genitalia and internal ducts, but
underdeveloped testes
• Do not produce sperm
• Slight enlargement of the breasts
• 47,XXY
• 1 out of every 500 male births
Turner Syndrome
•
•
•
•
•
•
•
Has female external genitalia
Underdeveloped ovaries
Short (under 5 feed)
Webbed Neck
Broad, Shield-like chest
45,X
1 out of every 3000 female births
Cri-du-Chat Syndrome
• Partial monosomy (part of 1 chromosome is lost)
• Loss of about 1/3 of the short arm of chromosome
5
• Anatomical malfomrations (gastrointestinal and
cardiac complications)
• Mentally retarded
• Abnormal development of the larynx which makes
the baby’s cry sound like a cat’s cry
• 1 in 50,000 live births
Down Syndrome
•
•
•
•
•
•
•
•
•
BKA trisomy 21 (47, 21+); 3 copies of the 21st chromosome
Short
Small round heads
Protruding, furrowed tongues which cause mouth to remain partially
open
Retarded (IQ below 70)
Shortened life expectancy (<50)
Prone to reparatory disease and heart malformations
Have 15x higher chance of getting leukemia
Chance of having a baby with Down syndrome goes up as the mother
gets older