Transcript Genetics Powerpoint

Do Now:






1. Certain acquired characteristics, such as
mechanical or mathematical skill may be inherited.
2. Certain thoughts or experiences of a mother
mark or alter the hereditary makeup of an unborn
child.
3. Color blindness is more common in males than in
females.
4. A person may transmit characteristics to offspring
which he/she does not show.
5. Certain inherited traits may be altered by the
stars, planets or moon early in development.
6. The total number of male births exceeds female
births each year.
Objectives:



To distinguish between
heredity and inheritance
To describe Mendel’s
experiments in heredity
To compare
heterozygous vs.
homozygous and
dominant vs. recessive.
Genetics
Chapter 4
Basic Genetics
The
Father
of
Genetics
Gregor Mendel
1866- Gregor Mendel
•Austrian Monk
•Worked with Pea Plants
•Pure breeds
•Self-fertilization
•Discovered how traits were inherited in a
population
Heredity – transmission of
traits from parents to their
offspring
Inheritance
passing of
traits by
heredity
Mendel’s experiments
used pea plants
Pollination – transfer of pollen from
anthers to stigma in flowers
1) self pollination
occurs within the
same flower or
same plant
2) cross pollination
occurs between
different plants
Mendel’s Crosses with Pea Plants
P
parental
1 generation
Pure tall
plants
X
Cross
F1
F2
first filial
generation
Pollination
All Tall plants
Self
second filial
generation
Pure short
plants
Pollination
787 tall plants, 277 short plants
3 to 1 ratio
Definitions
Genetics – study of heredity
Gene – segment of DNA on a
chromosome that codes for a
particular protein

genes
occur in
pairs
Allele – alternative form of a gene
T = tall
t = short
Recessive
Lowercase
letter (usually
hidden)
Dominant
capital
letter (shields
recessive trait)
G = green
pods
g = yellow
pods
Phenotype –
physical
characteristics
of an organism
(Ex: Blue eyes or Brown Eyes)
Genotype – genetic makeup
of an organism (genes)
(internal information
Ex: BB, Bb, bb)
Where do Phenotypes come from?
Example of Genotype and
Phenotype
TT
genotype
Tall
phenotype
DO NOW
A man with a widow’s peak marries a woman with
no widow’s peak. Widow’s peak is a dominant
trait. Identify the following:
1. Man’s geneotype:
2. Woman’s genotype:
3. Man’s phenotype:
4. Woman’s phenotype:
Use the letter W or w.
Homozygous – when both alleles
of a pair are the
same
homozygous
dominant
homozygous
recessive
TT
tt
Heterozygous – when both alleles
of a pair are not
the same
heterozygous
(tall)
Tt
In rabbits, black fur color is
dominant over brown fur color
B = black fur
b = brown fur
bb
BB or Bb
Think – Pair - Share



If Fred Flintstone is heterozygous for black hair.
(B=Black, b=blonde)

What is Fred’s genotype?

What is Fred’s phenotype?
Tweety bird is YY. (Y= yellow feathers, y=brown
feathers)

1. What is his genotype?

2. What is his phenotype?

3. Is he heterozygous or homozygous? Explain.
Think – Pair - Share
Worksheet on
homozygous/heterozygous and
dominant and recessive.


Due Tomorrow (or next time I see
you!)
Homework

Create flashcards with the definition
and an example









Heterozygous
Homozygous
Genotype
Phenotype
Dominant
Recessive
Allele
Gene
Genetics
Do Now


Sponge Bob Square pants is heterozygous
for brown eyes. Sandy is also
heterozygous for brown eyes. Create a
punnett square to determine the possible
outcomes of their children.
Show phenotype and genotype ratios.
Objective:

To describe Mendel’s 3 laws
of inheritance

Complete a Monohybrid
cross
**Take Out your Homework!!!
1) Law of Dominance

Each trait is controlled by 2
factors, one factor (dominant ) may
mask the other factor (recessive )
preventing it from having an effect.
P1
F1
F2
2) Law of Segregation


Each allele a
person has
separates into
different gametes
Ex. Ww – one W
goes in one sperm
and the other w
goes into another
sperm
http://highered.mcgrawhill.com/sites/0072495855/student_view0/
chapter28/animation__random_orientation
_of_chromosomes_during_meiosis.html
w W
w
W
Sperm
3) Law of Independent
Assortment

Gene pairs
(homologous)
will separate
randomly into
gametes
(metaphase I
of meiosis)
Monohybrid Cross


R= Can roll your tongue
r= Can’t roll your tongue
R

Genotype Ratio:
R
r

Phenotype Ratio:
r
Genotypic vs. Phenotypic
Ratios

Phenotype Ratio:



Ratio of different physical traits
Ex) Brown eyes ¼ or 25%
Genotype Ratio:


Ratio of the different possible alleles
Ex) Tt = ¼ or 25%
Lets Try a Monohybrid together!
1) Daffy Duck is heterozygous for black feathers.
Daisy Duck is homozygous for yellow feathers. Set
up a punnett square and determine probabilities of
their potential offspring. (Both genotype and
phenotype ratios!)
2) B = Black
b = yellow
Practice!

Get with a partner and work on the
sample problems!
DO NOW:
Sleeping Beauty has freckles. Her
prince charming is heterozygous
for no freckles. What are the
chances of her children having
freckles? Please show your work.
Do Now



Being able to roll your tongue is a
dominant trait.
1. Write down your phenotype and
genotype.
2. Are you positive that’s your genotype?
Test cross – an individual with
unknown genotype is crossed
with a homozygous recessive
individual

used to determine
the genotype of
any individual
whose
phenotype is
dominant
Lets Try a Test Cross

Spongebob squarepants doesn’t know
whether or not he is Homozygous
Dominant or Heterozygous for his yellow
color. The recessive trait is a white
sponge. Let’s say that we perform a “test
cross” on spongebob (spongebob + a
white female sponge) and all of the baby
sponges are yellow. What would
spongebob’s genotype be?
Objectives:

To set up and complete a
dihybrid cross.
What is a dihybrid Cross?

A dihybrid cross allows us to predict
possible outcomes of offspring that will
have 2 traits simultaneously.

Ex: what would you get if you crossed a
Brown-haired brown-eyed male with a blondehaired blue-eyed female? How many of the
children would have brown hair and brown
eyes? Brown hair and blue eyes? Blonde hair
and brown eyes? Blonde hair and blue eyes?
Example
Setting up Dihybrid Crosses




1.
2.
3.
4.


Determine parent genotypes
Determine alleles to be passed down
Set up punnet square
Determine outcome
Phenotype Ratio
Genotype Ratio
More Practice

Mickey Mouse is heterozygous for Round
ears and homozygous for Black eyes.
Minnie Mouse also is homozygous for
Floppy ears and heterozygous for Black
eyes. Determine genotype and phenotype
ratios. (B=black, b=brown, R=round, r=
floppy.)
Dihybrid Crosses

Looking at two different traits







Ex. Hair color and eye color
B=brown eyes
b=blue eyes
R=Brown hair
r=blonde hair
Mother is heterozygous for both traits
Father is heterozygous for eye color and homozygous
dominant for hair color
What could the phenotypes and
genotypes be of their children?
Objectives:


To define gene
linkage and
polypoidy.
To understand
pedigrees and figure
out how to use one.
Pedigree


Shows history of a trait in a family
Allows researchers to analyze traits within
a family
Symbols for Pedigree
Lets try to figure out their
genotypes!
Dominant or Recessive

Pedigrees can depict both dominant and
recessive traits…
Homework

Pedigree Lab! Due next lab day!
Do Now



Fill in the genotypes for the following
pedigree
B=brown eyes
b = blue eyes
Objectives


To be able to solve for the genotypes of
pedigrees.
To be able to practice monohybrid and
dihybrid crosses.
Practice!

It’s Harry Potter time!! Get with a partner
and work on the sample problems
involving some of my favorite fictional
characters!
Do Now
Dominant or Recessive Trait?
Objectives


To understand incomplete dominance and
be able to do incomplete dominance
monohybrid crosses.
To explain codominance, multiple alleles,
sex-linked traits, and polygenic
inheritence.
11.2 Incomplete Dominance:




Heterozygous phenotype is an
intermediate phenotype between the two
homozygous phenotypes.
Two alleles are blended
Ex) Four O’clock Flowers
Red + White = Pink
Incomplete Dominance
Codominance



Neither trait is dominant instead, both
traits are shown (No Blending)
Ex) Roan Cows
Red + White = RED AND WHITE
Roan Coat
Sickle Cell Disease

Affects red blood cells and ability to
transport oxygen.

Homozygous recessive alleles=

Heterozygous=

Homozygous dominant alleles=
Sickle Cell and Malaria

People who are
heterozygous for sickle
cell, have a higher
resistance to malaria.
Do Now

A man who is a breeder of roan cows wants
to cross two roan cows to produce more
roan cows. After the two cows mate, the
offspring are one red cow and one white
cow. He is very disappointed. Explain why
this happened. Provide a punnet square.
Multiple alleles – 3 or more alleles
that control a trait

Example – blood type (IA,IB,io)
GENOTYPES
IA IA
IAio
IB IB
IBio
IAIB
ioio
RESULTING PHENOTYPES
Type A
Type A
Type
Type
Type
Type
B
B
AB
O
Universal Donor?
Sample Problem




Determine the possible offspring of the
following crosses
1. AB and O
2. AA and BO
3. AB and AB
Coat Color of Rabbits







Rabbits have a hierarchy of coat color
4 alleles (C, cch, ch, and c)
Dominant C > cch> ch > c
Recessive
C Full color
cch Chinchilla
ch Himalayan
c albino
Coat Color of Rabbits
Chinchilla
Albino
Full Color
Himalayan
Let’s try a sample problem

cc x Ccch
 Genotype and phenotype ratios
What do you see?
What do you see?
Sex Linked Traits



Traits located on the sex chromosomes
(X or Y)
X linked: gene is located on the X
chromosomes
Y linked: gene is located on the Y
chromosome
What are the chances of having a
girl?

How would you go about solving it?
Sex-Linked Traits

A woman who is color blind marries a man
that does NOT have color blindness. What
is the chance of having a color blind boy?
Polygenic Traits
 Polygenic traits arise from the interaction
of multiple pairs of genes.
Objectives:



To define test cross
To define incomplete
dominance
To define codominance
Objectives:

To predict the results of
dihybrid crosses by using
a Punnett square
Do Now: Matching
Quiz Review Question 1
 A man that is a carrier for albinism marries a
woman what is also a carrier. Set up a
punnet square to determine the chance of
having a child with albinism.
Quiz Review Question 2
 A heterozygous man with achondroplasia
marries a woman that is the normal. Set up a
punnet square to determine the chance of
having a child with achondroplasia.
Quiz Review Question 3
**CHALLENGE**
 A man who has hemophilia marries a woman
who is normal and not a carrier. What is the
chance of having a child with hemophilia?