Transcript the child with green hair

Genetics Notes
Who is Gregor Mendel?
“___________________”
Principle of _____________________– Inheritance of one
trait has _________________on the inheritance of
another trait
Traits
• Genetics – study of how _________ are passed from
__________ to ______________
• Traits are determined by the __________on the
______________________. A gene is a segment of
_________that determines a _______________.
• Chromosomes come in _________________pairs, thus
____________come in pairs.
Homologous pairs – _________________ genes – one
from female parent and one from male parent
• Example: Humans have 46 chromosomes or ____ pairs.
One set from dad – 23 in __________
One set from mom – 23 in _________
• One pair of Homologous Chromosomes:
Gene for ________
______ (blue eyes)
Homologous pair
of chromosomes
Gene for ____________
(brown eyes)
_______– different _____(possibilities) for the same _____
– ex: blue eyes or brown eyes
Dominant and Recessive Genes
• Gene that ___________________the other gene from
“showing” – ________________
• Gene that _________________“show” even though it is
____________– _________________
• Symbol – Dominant gene – ________case letter – ____
Recessive gene – ________case letter – ____
Dominant
color
Recessive
color
Example: Straight thumb is ______________ to hitchhiker
thumb
___= straight thumb __= hitchhikers thumb
(Always use the same letter for the same alleles—
No S = straight, h = hitchhiker’s)
Straight thumb = TT
Straight thumb = Tt
Hitchhikers thumb = tt * Must have __ recessive _______
for a recessive trait to “______”
• Both genes of a pair are the same –
____________ or _______________
TT – homozygous _____________
tt – homozygous _____________
• One dominant and one recessive gene –
_________________or _________________
Tt – heterozygous
BB – Black
Bb – Black w/
white gene
bb – White
Genotype and Phenotype
• Combination of genes an organism has (_____________
____________) – ______________
Ex: TT, Tt, tt
• ___________________________resulting from gene
make-up – _________________
Ex: hitchhiker’s thumb or straight thumb
Punnett Square and Probability
• Used to __________the _________ gene makeup of
____________– Punnett Square
• Example: Black fur (B) is dominant to white fur (b) in mice
1. Cross a ______________male with a ______________________
female.
Black fur (B)
Heterozygous
male
White fur (b)
White fur (b)
Homozygous
recessive female
White fur (b)
Male = Bb X Female = bb
b
Male gametes - N
(One gene in
sperm)
B
b
b
Bb
Bb
bb
bb
Female gametes – N
(One gene in egg)
Possible offspring – 2N
Write the ratios in the following orders:
Genotypic ratio = 2 Bb : 2 bb
50% Bb : 50% bb
Genotypic ratio
homozygous : heterozygous : homozygous
dominant
recessive
Phenotypic ratio = 2 black : 2 white
50% black : 50% white Phenotypic ratio
dominant : recessive
Cross 2 hybrid mice and give the genotypic ratio and
phenotypic ratio.
B
b
B
BB
Bb
b
Bb
bb
Bb X Bb
Genotypic ratio = 1 BB : 2 Bb : 1 bb
25% BB : 50% Bb : 25% bb
Phenotypic ratio = 3 black : 1 white
75% black : 25% white
Example: A man and woman, both with brown eyes (B)
marry and have a blue eyed (b) child. What are the
genotypes of the man, woman and child?
Bb X Bb
Man = Bb
B
b
B
BB
Bb
b
Bb
bb
Woman = Bb
Sex Determination
• People – _______chromosomes or _____pairs
• 22 pairs are ___________________(look alike) – called
_______________-– determine body traits
1 pair is the ______chromosomes – determines sex (male or female)
• Females – sex chromosomes are ___________(look alike) – label __
Males – sex chromosomes are different – label ____
• What is the probability of a couple having a boy? Or a girl?
Chance of having female baby? 50%
male baby? 50%
X
X
X
XX
XX
Y
XY
XY
Who determines the sex of the child? father
Incomplete dominance and Codominance
• When one allele is NOT completely _____________ over
another (they _________) – _______________________
Example: In carnations the color red (R) is incompletely
dominant over white (W). The ________ color is
_________. Give the genotypic and phenotypic ratio
from a cross between _____________________.
RW X RW
R
W
R
RR RW
W RW WW
Genotypic = 1 RR : 2 RW : 1 WW
Phenotypic = 1 red : 2 pink : 1 white
• When _________ alleles are _______________–
____________________
Example: In certain chickens black feathers are
codominant with white feathers.
Heterozygous chickens have black and white speckled
feathers.
Sex – linked Traits
• _________for these ______
are located _______ on the
___chromosome (NOT on
the Y chromosome)
• X linked alleles __________
show up in _______ whether
___________ or
_____________ because
males have only _____ X
chromosome
• Examples of ________________sex-linked disorders:
1. _____________________ – inability to distinguish
between certain colors
You should see 58
(upper left), 18
(upper right), E
(lower left) and 17
(lower right).
Color blindness is the inability to distinguish the differences between certain colors. The most
common type is red-green color blindness, where red and green are seen as the same color.
2. ________________– blood won’t clot
• Example: A female that has normal vision but is a ______
______________ marries a male with ______________.
Give the expected phenotypes of their children.
N = normal vision
n = colorblindness
XN Xn X XN Y
XN
Xn
XN XNXN
XNXn
XNY
XnY
Y
Phenotype: 2 normal vision females
1 normal vision male
1 colorblind male
Multiple Alleles
• _____________________of the __________gene that code for
a ____________trait
• In humans, ____________________is determined by 3 alleles
– ___, ____, and _____
BUT each human can only _____________ alleles
1. Dominant – A and B (codominance)
Recessive – O
2. Blood type – A = AA or AO
B = BB or BO
AB = AB
O = OO
Example: What would be the possible blood types of
children born to a female with type AB blood and
a male with type O blood?
AB X OO
A
O AO
B
BO
O AO
BO
Children would be type A or B only
Mutations
• Mutation – sudden _____________________(change in
_________ pair sequence of __________)
• Can be :
_____________ mutations – organism ____________ to
survive:
genetic disorders, cancer, death
________mutations – allows organism to ____________
______: provides _______________
__________ mutations – ________
harmful nor helpful to organism
• Mutations can occur in 2 ways:
__________________ mutation or
__________________ mutation
Chromosomal mutation:
• ________________________than a gene mutation
• more ________– affects entire ____________, so affects
___________________ rather than just one
• caused by failure of the _____________ chromosomes
to _________________ normally during meiosis
• _________________no longer look the same – too few
or too many genes, different shape
• Examples:
__________syndrome – (Trisomy 21) ___chromosomes,
extra chromosome at pair _______
_________________syndrome – only ______
chromosomes, missing a ________ chromosome (X)
_______ affected – short, slow growth, heart
problems
_________________ syndrome – ____chromosomes,
_______ chromosomes (XXY)
_________________affected – low testosterone levels,
underdeveloped muscles, sparse facial hair
• Having an ____________of chromosomes is ________
in ____________, but in ___________ it makes them
___________and ______________.
Hardier
Gene or Point Mutation
• _______________ and __________________
• only _____________ is altered
• Examples:
Recessive gene mutations:
_____________________–
____________________
are sickle shaped instead of
round and cannot carry
enough _____________ to
the body tissues –
heterozygous condition
protects people from
_____________
____________________–
______________ builds up in the
_____________
___________________________–
deterioration of the ____________
________________ – early death
Mutated genes produce enzymes that are less
effective than normal at breaking down fatty
cell products known as gangliosides. As a
result, gangliosides build up in the lysosomes
and overload cells. Their buildup ultimately
causes damage to nerve cells.
_____________________(PKU) – an
__________________ common in
___________ cannot be broken
down and as it builds up it causes
____________________ – newborns
are tested for this
Dominant gene mutations:
_____________________– gradual
_______________ of
__________________, shows up in
_____________and is _________
___________________ – variety of
_________________ abnormalities
Detecting Genetic Disorders
• picture of an individual’s chromosomes – ___________
• amniotic fluid surrounding the embryo is removed for
analysis – _________________________
Female with _______ syndrome