Download Non-Mendelian Genetics (powerpoint view)

Robert Wadlow
8’ 11.1 in.
Zeng Jinlian
8 ft 1.75 in
 Many
traits are inherited just as the rule of dominance
predicts.


1 dominant allele inherited from one parent is all that is
needed for a person to show the dominant trait.
2 recessive alleles must be inherited (1from each parent)
for a person to show the recessive phenotype.
Most
genetic disorders are caused by
recessive alleles.
Most of these alleles are rare, but a few
are common in certain ethnic groups.
Albinism: condition where individuals produce
little or no melanin (skin pigment)
alligator
fawn
gorilla
peacock
chimpanzee
penguin
Squirrel
bat
Lion
bear
cobra
giraffe
hedgehog
Lion
Rattler
Cystic Fibrosis: a build up of excessive, thick mucus in
the lungs and digestive tract


~4% of people of European descent carry the gene for
cystic Fibrosis
Life expectancy is ~37 years
Sickle Cell Anemia: Disorder in which the red blood
cells take on an abnormal shape, resulting in anemia.

More common in black Americans whose families
originated in areas of high malaria incidence.
Tay-Sach’s: Disorder of the central nervous system
due to the absence of an enzyme that
breaks down a lipid.



The lipid accumulates in nerve cells & leads to blindness,
loss of movement, & mental decline.
Most common in Ashkenazi Jews (1 in 27 are carriers of
the recessive gene)
Life expectancy is ~3-5 years
Phenylketonuria (PKU): Disorder in which the
amino acid phenylanlanine found in dairy
products, meats, nuts & diet drinks cannot
be converted to the amino acid tyrosine.
 Phenylalanine
builds up in nerve cells and causes
damage resulting in mental retardation and other
disorders involving the nervous system.
Require
only one allele from one of
the parents for the phenotype to be
visible.
 Attached
earlobes are recessive to freely
hanging earlobes.
ATTACHED: recessive
UNATTACHED: dominant
Dimples – dominant to Freckles - dominant
no dimples
HITCHHIKER’S: dominant
STRAIGHT: recessive
Polydactyly
 Having
more than five fingers or toes, is dominant to
the allele that produces only five digits.
 Cleft
chin
 Almond shaped eyes
 Thick lips
 Hair on middle section of fingers
Huntington’s disease: Rare, lethal genetic disorder caused
by a mutation of a dominant allele.
If 1 parent has the allele (and thus the disease) their children
have a 50% chance of the disorder.
 The nervous system degenerates, resulting in uncontrolled,
jerky movements of the head and limbs and mental
deterioration.
 Life expectancy is ~20 years after symptoms appear

Polygenic Inheritance: A condition in which two or
more sets of genes produce more or less similar
effects on the same trait.

Eye Color, like skin color, is determined by polygenic
inheritance.
 Eye
color is controlled by 3 genes, each on a
different chromosome.
 Each gene has 2 alleles (1 dominant & 1
recessive)
gene 1: B & b
 gene 2: G & g
 gene 3: Y & y

Number of dominant alleles
Eye color
6-5
4-3
2-1
0
dark brown
brown
green
blue
BGY
bgy
Bgy
BbGgYy Bbggyy
brown
green
BgY Bgy
bGY bGy bgY bgy
BbggYy Bbggyy bbGgYy bbGgyy bbggYy
bbggyy
green
blue
green
green
green
green
 Some
traits are expressed differently in males and
females (e.g. male pattern baldness)
FEMALE
MALE
B’B’
Thin hair
bald
BB’ or B’B
Normal
Bald
BB
normal
normal
Incomplete Dominance: Pattern where the
phenotype of a heterozygote is in between
those of the two homozygotes

neither allele is dominant over the other
RR = red flower
 R’R’ = white flower
 RR’ = pink flower (blend of red & white)

F1
P1
F1
F2
Codominance: Pattern where the phenotype of both
homozygotes are produced in heterozygous
offspring so that both alleles are equally expressed.
 Example



BB = black feathers
WW = white feathers
BW = checkered
Multiple Alleles: Presence of more than
2 alleles for a trait.
 Human
blood types are determined by the
presence or absence of certain molecules on the
surface of red blood cells. This gene, I, has three
alleles, IA, IB, & i.
Genotypes
Surface Molecules
Phenotypes
IAIA or IA i
A
A
IBIB or IB i
B
B
IAIB
A&B
AB
ii
none
O
Type A
Type B
Type AB
Type O
 Determining
blood types is necessary before
a person can receive a blood transfusion b/c
incompatible blood types could clump
together, causing death. (type O is the only
one that can donate to anyone)
Blood
Type
Distribution
in USA (%)
Antigen on
RBC
Antibody in
Serum
Plasma
Will Clot with
Blood From
These Donors
Anti-A
A, B, AB
Anti-B
Can
Receive
From
Can Give to:
O
All
O
48
None
A
42
A
Anti-B
B, AB
A&O
A & AB
B
7
B
Anti-A
A, AB
B&O
B & AB
AB
2
A&B
None
None
All
AB
 Blood
typing can also be helpful in cases of
disputed parentage. For example, if a child
has type AB blood and its mom has type A, a
man with type O blood could not be the
father. This is not the best way to determine
parentage (A DNA test is).
 (1)
cross a man heterozygous for type B blood & a
woman heterozygous for type A blood
 (2) cross a man with type AB blood & a woman
with type O blood.
1.
Phenotypic ratio:__________
2.
Phenotypic ratio:_________
MULTIPLE ALLELES & CODOMINANCE11.04
Sex chromosomes: control the inheritance
of sex-linked traits
 are
indicated by the letters X & Y.
 Female: XX (23rd pair of chromosomes look
alike).
 Male: XY (23rd pair of chromosomes look
different)
Males
produce two
kinds of gametes, X &
Y, by meiosis.
Females produce
only X gametes.
After fertilization there
will always be a 1:1
ratio of males to
females.
Sex-Linked Traits: Traits determined by genes that are
carried on the sex chromosomes.


Males, XY, pass an X chromosome to their daughters and a
Y chromosome to their son.
Females, XX, pass an X chromosome to each child.
 With
an X-linked trait
males pass the allele to
all of their daughters
and to none of their
sons.
 Y-linked traits are passed
from father to son.
Heterozygous
females have a
50 percent of
passing on a
recessive Xlinked allele to
each child.
Red-Green colorblindness: disorder that
causes the inability to differentiate
between red and green.
4.03
Normal – 8
Normal & color blind see a
12
Color blind - 3
Normal – 5
Colorblind - 2
Normal – 29
Colorblind - 70
Normal – 74
Normal – 7
Colorblind - 21
Colorblind - nothing
Normal – 45
Normal – 2
Colorblind - nothing
Colorblind - nothing
Normal – nothing
Normal – 16
Colorblind - 2
Colorblind - nothing
Normal – traceable line
Colorblind - nothing
Adrenoleukodystrophy (ALD): disorder in
which a certain fatty acid builds up causing
myelin (nerve cover) to deteriorate causing
the nerve signals to not reach their destination.
Hemophilia: Disorder in which blood
does not clot
1
in 10,000 males has it
 1 in 100,000,000 females inherits it
Duchennes muscular dystrophy: Disorder that
results in the loss of muscle control
 Children
seldom survive to adulthood
= males, Circles = females
 Pedigree:
A visual chart showing how a trait is passed
from generation to generation
 Roman numerals represent a generation (I, II, III, etc.)
 Arabic numbers represent an individual (1, 2, 3, etc.)
 A horizontal line represents a marriage
 A vertical line extends from a marriage line shows the
children produced in order of birth.

Affected male
Unaffected male

Affected female
Unaffected female
 Carrier: A person that is heterozygous for a trait.
Represented by a half shaded shape
 Environment
expressed.

Coat color: temperature can affect what color is
expressed


can play a role in how certain genes are
Color point cats, winter and summer color coats
Plant color: the acidity or alkalinity of the soil can influence
the color of a plant

Red / purple cabbage (acidic) or green (alkaline)
Selective breeeding: Involves selecting the organisms
with the desired traits and breeding them to
produce more organisms with desirable traits
Inbreeding: Mating between closely related individuals
to eliminate undesirable traits


Results in offspring that are homozygous most traits
May bring out harmful recessive traits
Hybridization: Crossing of two purebred organisms to
produce a hybrid

Results in organisms that are larger & stronger than either
parent
Goat x sheep
geep
Cow x buffalo
beefalo
liger
 Used
to determine the genotype of an organism
that exhibits the dominant trait
 Involves crossing the individual with the
unknown genotype with one that expresses the
recessive phenotype
Involves cutting or
cleaving DNA from one
organism into small
fragments and inserting
the fragments into a host
organism of the same or
different species.
 DNA is cut or cleaved
with restriction enzymes
(bacterial proteins – they
are specific)
 Referred to as
recombinant DNA
technology

 Organism
that contains functional recombinant
DNA (foreign DNA) from an organism of a
different genus
 Means
by which DNA from another
species can be carried (transferred) into
the host cell
 Vectors may be biological (viruses or
plasmids – small rings of DNA found in a
bacterial cell) or mechanical
(micropipette or microscopic metal bullet
coated with DNA that is shot into the cell
from a gene gun)
Crime forensics:
Paternity :
Which DNA belongs to
identical twins?
Maternal “identical twins” scenarios (1,2,3)
1
2
3
Fraternal
If Maternal, mark A.
If fraternal, mark B.
1)
2)
3)
4)
5)
6)
What type of twins are
identical?
What type were formed from
two different eggs and sperm?
What type are considered
clones?
Which have identical DNA?
If a brother and sister are twins,
what type are they?
What typed are from one egg
and one sperm?