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Genetics
Genetics-___________________
 Heredity-passing of traits from
__________________________
 Trait- ____________________
that can be passed on to offspring
ex: hair color, eye color, etc

What Determines Traits?


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Genes!
Genes- _____________________
___________________________
__________________________ .
There are _________ of
genes on each chromosome.
DNA chromosome  gene
 protein  trait
Genes
protein

Some traits are coded for by one gene which codes
for one protein causing a trait.
 i.e. freckles, earlobe attachment, etc
Polygenic
– When a Single Trait is Influenced by
PolygenicInheritance
traits – ______________________________
Many Genes
_____________________________________________.
More than one gene = more than one protein that
causes the trait so complex variation in that trait
Hand span, height, eye color, etc.

Height is a
polygenic trait
Chromosomes
homologous chromosomes

Homologous chromosomes__________________________
__________________________
__________________________
__________________________



One of each pair from Mom and
one from Dad
Each human somatic (body) cell
has _________ of homologous
chromosomes
Other species have different
numbers.
Passing of One Gene



Remember that during meiosis when we make gametes
(egg and sperm) the genetic material is cut in half.
Egg and sperm each only have ________________
because these gametes only get ONE copy of every
chromosome (haploid).
When gametes come together during fertilization, it
forms the baby with a complete set of chromosomes and
________________________ (_________).
Homologous Chromosomes



_____ contributed one and
_____ contributed other of
each pair of homologous
chromosomes in our
somatic cells.
Therefore, we received
_______________ from
each of our parents
This means each somatic
cell has ________________
____, and therefore,
______________.
Alleles

Alleles - ________________________________
 F  allele codes for freckles
 f  allele codes for no freckles
Allele for freckles--F
Position on chromosomes
where freckle presence
gene is located
Allele for no freckles—f
Genotype vs. Phenotype
Genotype- ______________________________________
 Written as _________-one copy from each parent
 _________________
 Phenotype- ________________
____________________________
 Written as _______________
 Freckles or no freckles

***Phenotype = Genotype + Environment
Genotypes


_______________________ - (purebred) receiving two
identical alleles for a particular trait from your parents.
 i.e. Freckle presence gene
 Alleles F=freckles and f=none
 Homozygous: FF or ff
______________________ - (hybrid) receiving two different
alleles for a particular trait from your parents
 Heterozygous: ________?
F
F
F
f
f
f
Mom Dad
Mom Dad
Mom Dad
Possibility #1
Possibility #2
Possibility #3
What About the
Heterozygous Genotype?




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FF genotype = ____________ phenotype?
ff genotype = _____________phenotype?
What about Ff phenotype?
As it turns out, the allele coding for freckles, F,
___________________ the alleles coding for no freckles, f.
The heterozygous genotype, Ff, results in ________________
____________
F
Mom Dad
F
F
f
Mom Dad
f
f
Mom Dad
_________________– form of trait that overcomes others and
written as a ___________________
_________________- of trait that is hidden in the presence of a
dominant one and written as a __________________
Genotype
Homozygous
Dominant
Example
Phenotype
Freckles
No freckles
Heterozygous
So What?



How can we use this information on meiosis and
genetics?
If we know parents’ genotypes, we can figure out
the genotype possibilities of their children.
It can be used to determine how likely you and your
spouse are to have children with freckles, their blood
type, or the possibility of passing on a disease to
them among other things.
Genetics Predictions

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To determine possible genotypes
of offspring, we use
______________________
Punnett squares -figures used to
determine ___________________
___________________________
based on the parents’ genotypes.
For example, if you crossed two
heterozygous parents who have
freckles, would their kids all have
freckles, just some, or none at all?
Parent #1
gametes
Parent #2
gametes
How To Make a Punnett Square for a
One-Factor Cross or Monohybrid Cross
Write the genotypes of the two organisms that will serve as parents in a cross.
In this example we will cross a male and female osprey that are heterozygous
for large beaks.
They each have genotypes of Bb.
1
3
2
4
Practice
Trait: Number of fingers
Alleles: F or f
____________: F codes for polydactyly so
person has more than 5 fingers or toes.
_____________: f codes for normal five
fingers or toes
Genotype
Example
Homozygous
Dominant
Homozygous
Recessive
Heterozygous
FF
Phenotype
Five fingers
Use a Punnett square to cross a normal parent with a
heterozygous parent.
What are their chances of having a child with polydactyly?
Rules of Genetics
Early Ideas - Heredity
►We know about genetics
because an Austrian monk
named _______________
decided to run experiments
on pea plants.
►Father of genetics
►It was originally believed a
child’s traits were result of
“blending” between
parent’s traits
►Nothing was known about
DNA!
Mendel’s Pea Plants
Why did Mendel
use pea plants?
1. Peas ________________
___________________
___________________
he could observe easily
2. He understood
their method of
reproduction
3. They reproduced quickly
Characters
investigated by
Mendel
Reproduction in Plants
• Plant cells undergo
meiosis, just like
animals, to create
plant gametes
– Plant sperm =pollen
– Plant egg = ovule
Reproduction in Plants
• ____________
– Pollen released
– Pollen fertilizes the
ovules
– ____________________
___________.
• Mendel could control
how plants were
fertilized because he
understood this process
• Pollination Animation
Genotype vs. Phenotype
►One trait Mendel followed
through many crossed of peas
was peas shape.
►Alleles:
– ______________
– ______________
Mendel’s Experiments
►____________________(P) “original” group mated
►________________(F1) offspring of the parental cross
►_________________(F2) offspring of crossing two F1
plants
Mendel’s First Experiment
• Wanted to know what would
happen if cross 2 plants with
different forms of a trait.
• The 1st thing Mendel did was
cross 2 _____________
(homozygous) plants as the
_______________________(P).
?
Results of the Cross?
►In F1 generation _____________
resulted.
►What happened?
►Round _____________ over wrinkled
►Do a Punnett square to show the
results he should have gotten.
ALL ROUND F1
Principle of Dominance
►Round allele (R) dominated over
wrinkled form of the gene (r)
►Rule #1:
one allele can dominate so trait
coded by other allele hidden.
.
– i.e. R dominates over r when both present
– Because we know this, we
represent the round allele with a capital R.
Mendel’s 2nd Experiment
►Mendel extended his
experiment and crossed two
of his F1 plants…
►Do a Punnett square to show
what results he should have
gotten.
?
Results?
►After crossing two F1 plants,
_________________, some
F2 generation offspring
showed recessive trait,
some the dominant trait
►________(round: wrinkled)
►25% wrinkled, 75% round
►The wrinkle trait showed up
again.
Mendel’s Conclusions
•
- when gametes form, the
two copies of our genes are separated so each parent
gives only one in their egg or sperm
• This gave us the idea of meiosis and how gametes are
formed!
Pea Parent 1:
Rr
meiosis
R
or
gametes
Pea Parent 2:
Rr
meiosis
r
R or
gametes
r
Mendels Conclusions cont.
►Does everyone with brown hair have blue eyes?
►Does everyone with freckles have a big nose?
►NO!
►Mendel’s
- inheritance of
one trait will not affect inheritance of another. Traits
most of the time are not “_______” together!
►He saw pea plants with round peas and purple flowers,
and pea plants with round peas and white flowers.
Mendel Video:
Independent Assortment
Mendel wondered if the _____________________
______________another pair.
Mendel performed an experiment that followed two
different genes as they passed from one generation to
the next.
Because it involves two different genes, Mendel’s
experiment is known as a _____________________.
Single-gene crosses are ___________________.
The Two-Factor Cross: F1
Mendel crossed truebreeding plants that
produced only round yellow
peas with plants that
produced wrinkled green
peas.
The round yellow peas had
the genotype RRYY, which
is homozygous dominant.
The wrinkled green peas had
the genotype rryy, which is
homozygous recessive.
All of the F1 offspring
produced round yellow peas.
These results showed that
the alleles for yellow and
round peas are dominant
over the alleles for green and
wrinkled peas.
The Punnett square shows that the genotype
of each F1 offspring was RrYy, ____________
___________________________.
The Two-Factor Cross: F2
Mendel then crossed the F1 plants to produce F2 offspring.
Mendel observed that 315 of the F2 seeds were round and yellow, while another
32 seeds were wrinkled and green—the two parental phenotypes.
But 209 seeds had combinations of phenotypes, and therefore combinations of
alleles, that were not found in either parent.
The alleles for seed shape segregated independently of those for seed color.
Genes that segregate independently—such as the genes for seed shape and seed
color in pea plants—do not influence each other’s inheritance.
Mendel had discovered the principle of independent assortment.
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
Genetics Rules
►Rule #1:
Dominance
►Rule #2:
dominance -some alleles aren’t
completely dominant so they BLEND
►Rule #3:
-some alleles dominate
together so BOTH ARE SEEN
►Rule #4:
-ALL alleles on a male’s X
chromosome (X-linked) are expressed.
Complete Dominance
►Rule #1: Some alleles
_________________
over others:
– B= brown eyes
– b=blue eyes
– Bb= brown eyes, so B is
completely dominant.
– One allele capital, the
other lower case
Incomplete Dominance
►Rule #2: Some alleles
_______________________,
so they ____________:
–
–
–
–
R= red flowers
R = white flowers
Rr = pink flowers
One allele capital, the other
lower case
PINK FLOWERS!!!
BLENDING!!!
Codominance
►Rule #3: Some alleles __________________ so they
BOTH are shown
– H = brown hair on horses
– H’ = white hair on horses
– HH’ = both brown and white hairs, so the horse is roan
color.
– Blood types are like this, too.
Blood Types
Antigens-markers on cells
Blood type determined by your
markers on your red blood cells
4 blood group phenotypes:
Type A has A antigens
Type B has B antigens
Type AB has A and B antigens
Type O has no antigens
Multiple Alleles
 Multiple alleles- 3 different
forms of the gene code for
blood types IA, IB, and i
– Allele IA codes for “A”
antigen
– IB codes for “B” antigen
– i codes for none
Multiple Alleles
• 6 blood group genotypes
• ___________________IA and IB dominate over i
• ____________- IAIB
genotype shows BOTH A
and B antigens
• Both alleles that
codominate are written
with capital letters!
Blood Types
►Your body’s immune systems creates antibodies
against anything foreign
– Antibodies-proteins produced by your immune system
to fight off things that look “foreign.”
►Type A--makes anti-B antibodies
►Type B--makes anti-A antibodies
►Type AB--makes NO antibodies— universal receiver
►Type O--makes anti-A and anti-B antibodies—
universal donor
Sex-Linked Genes
►Rule #4: sex-linked genes: ALL
alleles on a male’s X
chromosome (X-linked) are
expressed.
– Male sex
chromosomes?_________
– Female sex
chromosomes?_________
– We also call sex-linked genes by
another name, X-linked, because
the X chromosome has the
majority of the genes.
Sex-Linked Genes
Genes:
_____
_____
_____ ___
► In males, EVERY gene on their X chromosome is expressed. The Y
doesn’t have the same genes.
► In females this is not the case because they have another copy on
their other X chromosome to overcome it.
Sex-Linked Genes
X-linked recessive disorder
►Examples of sex-linked
disorders:
–
–
–
–
–
–
–
–
Colorblindness
Hemophilia
Fragile X Syndrome
Duchene Muscular Dystrophy
Cleft Palate
Vitamin D Resistant Ricketts
3 types of deafness
Male Pattern Baldness
Sex-Linked Genes
►Genes that occur on sex
chromosomes are written with
X’s and Y’s to show this special
situation.
– I.e. red-green colorblindness is a
recessive trait. It is found on the X
chromosome, not the Y.
– We write the alleles this way:
►X¢ = colorblindness
►XC = normal
The slash indicates it is a lower case
letter so there is no confusion
Sex-Linked Genes
►Try to complete this table:
Phenotypes
Normal Male
Colorblind Male
Normal Female
Normal “carrier”
Female
Colorblind female
Genotypes
What is a Karyotype?


Karyotype- __________
____________________
in a somatic cell.
46 chromosomes in a
normal, human karyotype
 23 pairs of homologous
chromosomes – pairs of
chromosomes with
similar structure and
function
Amniocentesis
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Method for obtaining fetal cells
from fluid surrounding fetus.
Chromosomes can be obtained
from these cells for a
karyotype.
This is a “risky” procedure.
Should ONLY be performed on
women who:
a) Are in their mid 30’s or
older.
b) Have had a previous child
with a chromosomal defect.
What can be determined from
looking at a karyotype?
_____________________
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Autosomes-all
chromosomes except sex
chromosomes
Sex chromosomes -either
XX (female) or XY (male)
_____________________
Two Types of Mutations
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Gene mutation- ___________________________________
Chromosomal mutation- ____________________________
__________________________________________
Either type of mutation can involve autosomes
(chromosomes 1-22) or sex chromosomes (X & Y)
Gene Mutations

Gene mutation- single gene defective
 _____________
 _____________
 _____________
Insertion
Deletion
Subtitution
Chromosomal Mutations

Chromosomal mutation- missing or extra entire
chromosome and ALL its genes
 ___________—having one less chromosome (45)
 ___________—having an extra chromosome (47)
 ___________—missing part of a chromosome
Autosomal Disorders


_________________- disease involving the 22 pairs
of chromosomes that are NOT sex chromosomes
(X,Y) and any genes on them.
Can result from
 Gene mutation: defective gene
on autosome
 Chromosomal mutation: loss
or gain of autosome
Aa
AA
Aa
Aa
Aa
aa
Autosomal Disorders
Gene Mutations
1- Cystic Fibrosis
 Recessive disorder
 Mutated gene on chromosome 17.
 Characterized by excessive, THICK
secretion of the mucus in the
body.
Autosomal Disorders
Chromosomal Mutations
Down Syndrome
 1 in 1,000 live births.
 Trisomy-extra Chromosome 21
 Risk increases with mom’s age
 Mild to severe mental
retardation
Sex-Linked Disorders
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
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Sex-linked disorder – _________________________________
__________________________________________________.
Recessive gene on the X chromosome is ____________ to be
expressed in males
***Y chromosome has no 2nd allele that might counteract the
gene on the X chromosome!
Sex-Linked Disorders
Gene Mutations
1- Color Blindness
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X-linked recessive disorder
Gene mutation on X
chromosome
1 of 10 males
2- Hemophilia
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X-linked recessive disorder
Gene mutation on X
chromosome.
1 of 5,000 males
Interfere with normal blood
clotting
ONLY THE SEX
CHROMOSOMES
ARE INVOLVED
Sex-Linked Disorders
Chromosomal Mutations
1- Klinefelter Syndrome (XXY)


1 of 1,000 males.
Trisomy- extra X chromosome
Sex-linked Disorders
Chromosomal Mutations
2- Turner’s Syndrome (XO)

1 of 10,000 females

Monosomy- one of X chromosomes is
either missing or inactive
 Have immature female appearance and
lack internal reproductive organs.
GENETIC DISORDERS
________________
Chromosomes 1-22
Gene Mutations
_______________
_______________
_______________
_____________________
Sex Chromosomes X and Y
Chromosomal
Mutations
___________________
___________________
_______________
1 gene mutated
on X chromosome
EXAMPLES?
_______________
_______________
Extra or missing
Sex chromosome
How Do We Know About Our
Genes?


Human Genome Project
 Began in 1990; complete 2003
Goals:
 Determine complete sequence of the 3 billion DNA
bases in human DNA
 Identify all human genes for further biological
study
The Unknown
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________________, exact locations and functions
Gene ______________
_______________ organization
Chromosomal structure and organization
Ethical, Legal
and Social Issues

Fears

Genetic information used to harm or
discriminate

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

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Deny access to health insurance
Deny employment
Deny education
Deny loans?
Cloning?
DNA Databases
Cloning
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
_____________ -creating many
genetically identical cells
from one cell.
Creation of genetically
identical organisms
Why Clone Animals?
Five genetically identical cloned pigs.
To answer questions of basic Biology
For pharmaceutical production.
For herd improvement.
To satisfy our desires (i.e. pet cloning)
Is Animal Cloning Ethical?
The first cloned horse and her surrogate
mother/genetic twin.
As with many important questions, the answer is
beyond the scope of science.
Biotechnology
Dolly and
surrogate Mom
Embryonic stem cells and
gene therapy
Genetically modified rice.