Transcript Patau syndrome (trisomy 13)

Heredity by Brainpop
I. Heredity & Genetics
o The passing of traits
from parent to
offspring
o Traits are controlled
by genes
II. ALLELES
o ONE FORM of a gene
o Sex cells have one
o Body cells have two
forms or ALLELES
for a single gene
o One may be dominant
over another.
III. DOMINANT AND RECESSIVE
o Dominant will
always be
expressed and will
“mask” recessive
o A recessive trait
can only be
expressed if there
are no dominant
alleles present.
o Example:
Eyecolor—Brown
color is dominant
and blue is
recessive.
• Dominant alleles
are represented
with a capital
letter, recessive
with a lower case
letter.
IV. GREGOR MENDEL
o “father of genetics”
o Mendel worked with
peas
V. PROBABILITY
o chance something will happen
o Ex: heads or tails on a coin is 50%
(1/2 chances)
o more accurate with more trials
Why is it that if a couple has 2
children, they don’t always have
one boy and one girl?
2 is a really small trial #…so won’t
always “see” the ratio!
VI. Using a Punnett Square
o Used to predict
probability of traits
o trait is given TWO
letters, one for each
allele.
GENOTYPE = Gene
Combinations located on
chromosomes
o “Purebred” =BB or bb.
o “heterozygous”(hybrid).
Bb
o The PHYSICAL trait =PHENOTYPE.
o Blue Eyes.
Incomplete dominance
• Heterozygous
expresses a
different
phenotype
Multiple alleles - Blood type
• 3 alleles,
codominance A,B,o
4 blood types from 3 alleles
•
•
•
•
AA or Ao= type A
BB or Bo= type B
AB = type AB
oo = type O
Polygenic inheritance = many
genes for one character.
SEX-LINKED
and
SEX
INFLUENCED
TRAITS
SEX CHROMOSOMES
CAN CARRY OTHER
GENES TOO
=
SEX
LINKED
TRAITS
_________________
Sex chromosomes can
carry other genes
Y-LINKED GENES:
Genes carried on Y chromosome
EX:
Hairy pinna
males.
Y _______
linked genes only show up in __
Sex chromosomes can
carry other genes
X-LINKED GENES:
Genes carried on
the X chromosome
EX: Hemophilia
_____________
Colorblindness
_____________
Duchenne Muscular Dystrophy
_________________________
SEX INFLUENCED
TRAITS
Genes
not carried on
___________
sex chromosomes
BUT affected by
____________
sex hormones
of individual with
gene
PEDIGREE
CHART
Normal Male =
Normal Female =
Has trait =
CARRIER
Individual with one copy of a
recessive autosomal allele
NORMAL
DEFECTIVE
Carriers DON’T SHOW
the trait themselves
but can pass it on
to their offspring
CHROMOSOMES
DNA
Nucleic acid made of
nucleotide subunits
A
T
G
C
Found in nucleus
Carries the genetic
code in its sequence
DNA can appear in 2
forms
Spread out in
nucleus as
CHROMATIN
_____________
in NON-DIVIDING cells
Scrunched into bundles
CHROMOSOMES in
as ________________
DIVIDING cells
Histone PROTEINS
________
• maintain shape of
chromosome
Cancer cells
• Don’t stop dividing
Carcinogens damage DNA
• ___________
Ex: Radiation, cigarette smoke,
chemicals in environment
CANCER
Chromosome structure
CHROMATIDS
• ____________
2 identical arms
CENTROMERE
• ____________
constricted area holds
chromatids together
HOMOLOGOUS
•__________________
PAIR
2 of each chromosome
(one from mom; one from dad)
CHROMOSOME NUMBERS
• Each species has
a characteristic
number of
chromosomes
• HUMANS have
46 chromosomes
(23 pairs)
DIPLOID & HAPLOID
Cells with 2 copies of each chromosome are
DIPLOID 2n
_______________
(one from mom; one
from dad)
• All body cells
Cells with only one copy of each chromosome
HAPLOID 1n
are ____________________
• Sperm and egg
1n
egg
+
+
1n
sperm
=
2n
new organism
KARYOTYPES
KARYOTYPE
________
= picture of
organism’s
chromosomes
• Chromosomes that determine
the sex of an organism =
Sex chromosomes
_________________________
• All other chromosomes =
_________________
autosomes
Humans have two
sex chromosomes
X
y
A KARYOTYPE can tell
the sex of an organism
In humans XY is a male
In humans XX is a female
Guess who?
XY
You can’t judge a critter
by its chromosomes
This critter has
54 chromosomes
Corn has 10 pair of
chromosomes
Snails have 18
pairs of
chromosomes
A mouse has
40
chromosomes
Nondisjunction
• Chromosomes fail to separate
during meiosis
• gametes may have too few or too
many chromosomes
• Disorders:
– Down Syndrome – three 21st chromosomes
– Turner Syndrome – single X chromosome
– Klinefelter’s Syndrome – XXY
45
chromosomes
Eric has
Down’s
Syndrome
1 in 750 births
Has extra #21
chromosome
Mental
retardation
Down’s syndrome (trisomy 21)
Simian line on palm
Eye fold
Down’s syndrome (trisomy 21)
• Most common
chromosomal
abnormality
• 50% have heart
defects
• Mental retardation
• Risk increases with
age of mom
Patau syndrome (trisomy 13)
Patau syndrome (trisomy 13)
• 1 in 7000 births (rare)
Patau syndrome (trisomy 13)
Cleft lip & palate
Eyes too small or
missing
Patau syndrome (trisomy 13)
Low set ears
Polydactyly
TURNER’s SYNDROME
• XOonly 1 X, no Y
• Short stature
• Immature ovaries
• heart problems
• hearing loss
• decreased mental
ability
Turner Syndrome
Normal uterus, tubes
and ovaries
Non-functional
Ovaries
Kleinfelter syndrome
XXy
Kleinfelter syndrome
• 1 in 1000 births
• Male = XXy
• Aslight decrease in
intelligence
• Small testes/can’t
have children
Xyy syndrome
• Xyy males
• Taller, more
aggressive