Download Genetics Unit Class Power Point

Chapter 9 Lab Bio
Chapter 12 Honors Bio
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Brainstorm:
- define genetics
- define heredity
Anticipatory Set:
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How important is it to be able to find your own
answers to questions you may face?
Does education and learning end with your high
school or college years?
How do you plan to develop the skills to become a
life long learner?
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The study of how characteristics
are transmitted from parent to
offspring
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The transmission of
characteristics from parent to
offspring
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Chromosome: structure within nucleus, made
of DNA
Gene: unit of heredity found in DNA molecule
(words)
Allele: symbols (letter) used to represent genes
ex: T=tall, t=short
Dominant: trait/characteristic that are
expressed – represented with capital letter
Recessive: trait/characteristic that may not be
expressed (always lower case) ex: t=short
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Homozygous/pure: both alleles are alike ex:
TT or tt
Heterozygous/hybrid: alleles differ ex: Tt
Genotype: genetic make up ex: (pure
homozygous) tall, hybrid (hetero.) tall
Phenotype: what you see (physical appearance)
ex: tall, short
Cross: symbolic of reproduction ____ X _____
P: parent generation
F1: first generation
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A GENE is the segment of DNA on a
chromosome that controls a particular trait.
Chromosomes are in pairs i.e.
Genes occur in pairs (each of several alternative
forms of a gene is called an ALLELE
MENDEL’S FACTORS ARE NOW KNOW AS
ALLELES!!!!!!
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CAPITAL = Dominant alleles
Lower case = recessive alleles
Example: P = purple color (dom.)
p = white color (rec.)
When gametes combine in fertilization
offspring receive ONE ALLELE for a given trait
from EACH PARENT!
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Helps us predict the likely outcome of
offspring!!
1. genotype: genetic make-up, consists of
alleles
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Ex: P=purple,
Pp = purple
PP = purple
White = pp
p=white
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2. Phenotype = appearance of an
offspring (what you see)
 Ex: purple flowers, white
flowers, hair color
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3. Homozygous = when both
alleles of a pair are alike
 Ex:
tt, TT, PP, pp
 Homozygouse recessive = pp
 Homozygouse dominant = PP
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4. Heterozygous = two alleles in
a pair are different
 Ex:
Pp or Tt
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Do you think that we could make as many
discoveries in science if we didn’t use animals?
Explain…..
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!
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Austrian Monk
Studied garden pea plants (Pisum
sativum)
1842 he entered the monastery in
Austria
1851 enetered Univ. of Vienna to
study science and mathematics
(statistics)
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Observed 7 characteristics each in 2 contrasting
traits:
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Long  short stems
Axial  terminal (flower position)
Green  yellow (pod color)
Inflated  constricted (pod appearance)
Smooth  wrinkled (seed texture)
Yellow  green (seed color)
Purple  white (flower color)
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He controlled how pea plants were
POLLINATED!!!
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SELF POLLINATION=pollen is transferred from
anthers (male) of a flower to stigma (female) of same
flower or flower on the same plant
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CROSS POLLINATION=involves flowers of 2
separate plants
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1. remove anthers from a flower
2. manually transfer the anther of a
flower on one plant to stigma of a
flower on another plant
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P1 (cross) pure Purple x pure White
Law of Dominance
F1
ALL came out PURPLE
F1 (cross)
Purple x Purple
Law of Segregation
F2
¾ PURPLE, ¼ WHITE
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Mendel hypothesized that the trait appearing
in the F1 generation was controlled by a
DOMINANT FACTOR (allele) because it
masked, or dominated, the other factor for a
specific characteristic.
RECESSIVE is the trait that did not appear in
the F1 generation but reappeared in the F2
generation.
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A pair of factors (alleles) is segregated (or
separated) during the formation of gametes
Each reproductive cell (gamete) receives only
one factor (allele) of each pair.
Crossed two heterozygous purple plants!
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Is the purple plant
homozygous or
heterozygous ?
Perform a test cross!
Always! Cross the
unknown with a
homozygous
recessive
Test Cross
? x gg
P
g
Key:
G=green
g= yellow
G g
G g
F1
g
Gg
Phenotype:
100% green
Gg
Genotype:
100%
heterozygous
P
? x gg
Key:
G=green
g= yellow
F1
Phenotype:
50% green
50% yellow
Genotype:
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Neither allele is dominant
In some cases, an intermediate phenotype is
shown
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In snapdragons, flower color can be red,
pink, or white. The heterozygous
condition results in pink flowers
rr
RR
Rr
Key:
R= Red
r= White
F1 Phenotype:
100% pink
F1 Genotype:
100% heterozygous
Rr
Key:
R= Red
r= White
Phenotype: 1:2:1
25% Red
25% White
50% Pink
Genotype: 1:2:1
25% homozygous RR
25% homozygous rr
50% heterozygous Rr
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Both alleles are expressed equally
Neither allele is more dominant than the
other
Erminette
chickens
Roan Cows
Key:
B =Black
B1 = White
B
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B
B1
B B1
B B1
B1
B B1
B
B1
P generation
Black chicken X White chicken
F1 generation = erminette
(checkered patterned)
Phenotype: 4:0 or 1:0
100% erminette
Genotype: 4:0 or 1:0
100% heterozygous
Key:
BB =Black
BW = White
Key:
B= Black
W= White
BB
B1
B2
B1
B1 B1
B1 B2
B2
B1 B2
B2 B2
BW
BB
BB BB
BB BW
BW
BB BW
BW BW
Key:
B1 =Black
B2 = White
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1. What does recombination mean?
2. Do you know of any traits that seems to be
inherited together?
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Ex: red hair and fair skin……
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Does anyone here look “nothing” like their
parents?
If not do you know someone who looks
nothing like their family members?
Can we explain this genetically?
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Traits are inherited independently of each
other unless they are linked.
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Random Assortment
Genetically Unique
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Independent Assortment is the random
assortment of chromosomes during the
production of gametes, the result are
genetically unique individual gametes.
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He also crossed plants with 2 different
characteristics
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Ex: flower color & seed color
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FACTORS FOR DIFFERENT CHARACTERISTICS
ARE DISTRIBUTED TO GAMETES
INDEPENDENTLY.
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Ex: Pure tall yellow x pure short green
TTYY
x
ttyy
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XX= female
Female karyotype
Xy = male
Male karyotype
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Nondisjunction: failure of chromosomes to separate
during meiosis 1 or 2
 Results in an extra chromosome or a missing chromosome
 http://glencoe.mcgraw-
hill.com/olcweb/cgi/pluginpop.cgi?it=swf::550::400::/sites/dl/
free/0078757134/383925/Chapter11_NGS_VisualizingNondisju
nction_10_10_06.swf::Visualizing%20Nondisjunction
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XO- Turner Syndrome
XXX- Trisomy X
XXY- Klinefelter Syndrome
XYY- Jacob Syndrome
Very often, symptoms are slight due to X-inactivation
and the small amount of genes found on the Y
chromosome
SEX LINKED TRAITS
X-LINKED GENES:
Genes carried
on the X
chromosome
Hemophilia
Color blindness
Baldness
Muscular Dystrophy
Mother
H H
Without hemophilia = X X
H
Without hemophilia = X X
h
With hemophilia = X X
h
Father
H
Without hemophilia = X y
h
With hemophilia = X y
h
CARRIER
How common is your blood type?
46.1%
38.8%
11.1%
3.9%
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Human blood type is determined by co-dominant
alleles
Antigens-proteins-exist on the surface of all of your
red blood cells.
Blood types
For
simplicity
IA
A
IB
B
i
O
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Found in the plasma
Specific to a single kind of antigen
Attack and kill that specific kind of
antigen
•There are 3 alleles for blood type: A, B, O
•Since we have 2 genes: 6 possible combinations
http://learn.genetics.utah.edu/units/basics/blood/types.cfm
Blood Types
AA or AO = Type A
BB or BO = Type B
OO = Type O
AB = Type AB
Antibody B- protects the body by
attacking foreign B antigen blood
RBC= Red Blood Cell
= antibody
Blood Transfusions
Blood transfusions – used to replace blood lost during surgery or a serious injury
or if the body can't make blood properly because of an illness.
Who can give you blood?
TYPE O -Universal Donors
Universal Donor
can give blood to any blood type
•No antigens present on RBC
TYPE AB- Universal Recipients
can receive any blood type
• No antibodies present in plasma
Universal Recipient
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Rhesus monkeys –contain certain
similarities with humans
A blood protein was discovered and present
in the blood of some people
The presence of the protein, or lack of it, is
referred to as the Rh (for Rhesus) factor.
Rh positive (Rh+) - contain the protein
Rh negative (Rh-)- NOT contain the protein
Rh factor
Rh+
http://www.fi.edu/biosci/blood/rh.html
Rh-
Possible
genotypes
Rh+/Rh+
Rh+/RhRh-/Rh-
A+ AB+ BAB+ ABO+ O-
Pedigree of Queen Victoria
Have you ever seen a family tree… do you have one??
Graphic representation of family inheritance.
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Shows a pattern of inheritance in a family for a
specific trait (phenotype)
Genotypes can usually be determined
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Track the occurrence of diseases such as:
 Huntington’s – simple dominant – lethal allele – causes
breakdown of the brain
 Cystic fibrosis – 1/2500 – mucus accumulates (white
North Amer.)
 Tay-Sachs disease – lipids accumulate in CNS (Jewish)
 Phenylketonuria – missing enzyme causes problems in
CNS (Nordic/Swedish)
•generations are numbered with Roman Numerals
•oldest offspring are on the left
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Autosomal dominant:
The disease is passed from the
father (II-3) to the son (III-5), this
never happens with X-linked traits.
The disease occurs in three
consecutive generations, this is
rare with recessive traits.
Males and females are affected,
with roughly the same probability.
–Examples: Polydactyly
–Huntington’s disease
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Autosomal recessive
Males and females are equally likely to be
affected.
The trait is characteristically found in
siblings, not parents of affected or the
offspring of affected.
Parents of affected children may be
related. The rarer the trait in the general
population, the more likely a
consanguineous mating is involved.
–Cystic fibrosis
–Tay-Sach’s disease
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Sex-linked recessive conditions
The disease is never passed from
father to son.
Males are much more likely to be
affected than females.
•All affected males in a family are
related through their mothers.
–Examples:
–Color-blindness
Trait or disease is typically passed
from an affected grandfather,
through his carrier daughters, to half
of his grandsons.
–Duchenne Muscular Dystrophy
•X-linked recessive
•Autosomal dominant
•Autosomal recessive
•X-linked recessive
•Autosomal dominant
•Autosomal recessive
•X-linked recessive
•Autosomal dominant
•Autosomal recessive
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Law of Dominance
Law of Segregation
Test Cross
MENDEL’S RULES DO NOT APPLY TO:
Incomplete dominance
Multiple alleles
Codominmanmce
Polygenic inheritance
Pleiotyropy
Environmental influence
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Law of dominance
Law of segregation
Test cross
Incomplete dominance
Codominance
Independent assortment
Sex determination
Sex linkage
Multiple alleles