do now: quietly…….. take a poll of how many of you have the following traits: - brown hair...
TRANSCRIPT
DO NOW: Quietly……..
Take a poll of how many of you have the following traits:
- brown hair -blonde hair -red hair- black hair - blue/green eyes-brown eyes
GENETICS
MAIN IDEA…………
ALIEN ACTIVITY
http://www2.edc.org/weblabs/BabyBoom/babyBoom.html
WHAT IS GENETICS???
Genetics is the scientific study of
heredity.
Heredity is what makes each species
unique.
KEY VOCABULARY Dominant:
inherited characteristic that appear in an organism
Represented with capital letter.Ex: B, X, R
Recessive:
inherited characteristics often masked
Represented with lowercase letter.Ex: b, x, r
KEY VOCABULARY
EXAMPLE:
Brown Eyes: B Blue Eyes: b
Dominant Recessive
Phenotype: physical traits that appear in an individual as a result of its genetic make-up
How to remember…….Phenotype= Physical
Ex: brown eyes, blonde hair
Genotype:
genetic Make Up of an individual
How to remember….GENotype= GENEtic
Ex:B- brown eyesb- blue eyes
having two identical alleles
Ex: BB or bb
having two different alleles for a trait
Ex: Bb
Homozygous Heterozygous
PHENOTYPE VS. GENOTYPE
bb Blue Eyes
Genotype Phenotype
A little girl has blue eyes
Allele different forms of a gene for a
specific trait 2 for each trait
ALLELE
Could code for a PURPLE flower
Could code for a WHITE flower
CHROMOSOME FOR FLOWER COLOR
MAIN IDEA…………
HISTORY
FATHER OF GENETICS: MENDEL
GREGOR MENDELAustrian MonkFamous for his work with pea plantsWHY?????
They weren’t messy Rapid results Many generation
He is known as the father of genetics
MENDEL’S WORK
Mendel used true-breeding plants True Breeding:
When bred with themselves they would produce identical offsprings.
He studied 7 different traits in pea plants.
Trait: is a specific characteristic that
can vary from one individual to another
MORE ON MENDEL’S WORK
Hybrids are offspring from parents with
different traits.
Genes are the chemical factors that
determine a trait.
MENDEL’S EXPERIMENTS: 3 PRINCIPLES
1. Principle of Dominance2. Segregation 3. Independent Assortment
PRINCIPLE 1: THE PRINCIPLE OF DOMINANCE
States that some alleles are dominant and others are recessive.
Dominant alleles are always expressed.
Recessive alleles are only expressed if both alleles are recessive.
PRINCIPLE 2: SEGREGATION
The two alleles for a trait separateHELP……
Segregate means to separate
Happens during meiosis
form gametes (sex cells)
PRINCIPLE 3: INDEPENDENT ASSORTMENT
states that genes for different traits separate independently during the formation of gametes.
EX:the color of the flower has
nothing to do with the lengthThey separate INDEPENDENTLY
SUMMARIZE MENDEL’S PRINCIPLES The inheritance of biological characteristics
are determined by genes.
For two or more forms of a gene, dominance and recessive forms may exist (Principle #1).
Most sexually reproductive organisms have two sets of genes that separate during gamete formation (Principle #2).
Alleles segregate independently (Principle #3).
MAIN IDEA…………
PROBABILITY AND PUNNETT SQUARES
PROBABILITY & GENETICS
Probability is the likelihood that an event
will happen.
The principle of probability can be used to predict the outcomes of genetic crosses.
PUNNETT SQUARESDiagram used to predict genetic
crosses.
REVIEW: Homozygous individuals with
identical allelesHeterozygous individuals with
different alleles are calledPhenotype physical characteristicGenotype genetic makeup
HOW TO USE PUNNETT SQUARES……
1. Choose a letter to represent the alleles in the cross.
2. Write the genotypes of the parents.3. Enter the possible gamete at the top and
side of the Punnett square.4. Complete the Punnett square by writing
the alleles from the gametes in the appropriate boxes.
5. Determine the phenotypes of the offspring.
6. Using the results of step 4. write down the genotypic and phenotypic ratios.
EXAMPLE PUNNETT SQUARE
WHAT IS THE PROBABILITY THAT TWO HETEROZYGOUS PURPLE FLOWERS WILL PRODUCE A WHITE FLOWER? 1. Choose a letter to represent the
alleles in the cross.
2. Write the genotypes of the parents.
3. Enter the possible gamete at the top and side of the Punnett square.
WHAT IS THE PROBABILITY THAT TWO HETEROZYGOUS PURPLE FLOWERS WILL PRODUCE A WHITE FLOWER?
4. Complete the Punnett square by writing the alleles from the gametes in the appropriate boxes.
5. Determine the phenotypes of the offspring.
6. Using the results of step 4. write down the genotypic and phenotypic ratios
REVIEW QUIZ ON PROBABLITY AND PUNNETT SQUARES
http://anthro.palomar.edu/mendel/quizzes/mendqui2.htm
MAIN IDEA…………
TEST CROSSES
WHAT IS A TEST CROSS?????
Test that is conducted to determine if the genotype of an organism HOMOZYGOUS
DOMINANT for a trait
HETEROZYGOUS for a trait
5 KEY POINTS……
1. The organism with the dominant trait is always crossed with an organism that is HOMOZYGOUS RECESSIVE
2. If ANY offspring shows the recessive trait than the unknown genotype is heterozygous.
1. Recessive trait seen heterozygous
3. If ALL offspring have the dominant trait, the unknown is homozygous dominant.
1. Dominate trait homozygous
4. Large numbers of offspring are needed for reliable results
5. Start by making a key and writing down what you know.
EXAMPLE: If fire breathing is dominant to not fire breathing in Gregorous Dragon, how can we determine if Mendelia is homozygous dominant or heterozygous?????
SO WHAT DO WE KNOW………….
Let’s say F= fire breathing f= can’t fire breathe.
Set up a two different Punnett squares Both with a homozygous recessive ff
Then as the other parent place a: FF in one Punnett square Ff is another
Essentially, your two Punnett squares will have:Ff crossed with ffFF crossed with ff
INTERPRETATION
If all of the Gregorous dragon babies can firebreathe we can assume that Mendelia is HOMOZYGOUS DOMINANT
If any of the babies DO NOT fire breathe than Mendelia is HETEROZYGOUS
DIFFERENT TYPES OF INHERITANCE
DIHYBRID CROSSES
DIHYBRID CROSSES
Cross that involves two traits
Gives 16 offspringsExample: Pea
color and wrinkles
STEPS FOR A DIHYBRID CROSS
1. Make a key for the two traits that you are crossing
2. Write out the different genotypes of the parents
3. Figure out the possible gametes 1. similar to FOIL2. there are four for each parent3. each gamete must have one allele
from each trait4. Set up and Solve the Punnett Square
EXAMPLE PROBLEM: A MOTHER IS HETEROZYGOUS BROWN HAIR AND BLUE EYES. THE FATHER HAS BLONDE HAIR AND IS HETEROZYGOUS FOR BROWN EYES. WHAT ARE THE POSSIBLE GENOTYPES AND PHENOTYPES OF THEIR OFFSPRINGS?
Step 1 Make a key for the traits
Brown Hair (B) vs Blonde Hair ( b) Brown Eyes (E) vs Blue eyes (e)
Step 2 Genotypes of the parents
Mother Bbee Father bbEe
Step 3 Figure out the possible gamete
Mother Gamete’s Be, Be, be, be Father’s Gamete’s bE, be, bE, be
STEP 4 SET UP AND SOLVE PUNNET SQUARE
Be Be be be
bE
be
bE
be
BbEe
Bbee
BbEe
Bbee
BbEe
Bbee
BbEe
Bbee
bbEe
bbee
bbEe
bbee
bbEe
bbee
bbEe
bbee
COUNT UP THE POSSIBLE GENOTYPES AND PHENOTYPES THAT YOU HAVE FROM YOUR PUNNETT SQUARE
BbEe 4/16
Bbee 4/16
bbEe 4/16
bbee 4/16
Brown Hair; Brown eyes
Brown Hair; Blue eyes
Blonde Hair; Brown eyes
Blonde Hair; Blue eyes
Genotypes Phenotypes
SEX LINKED
SEX LINKED
sex is determined by the X and Y chromosomes.
Females XX
Males XY
SEX DETERMINATION
Sons: get their X chromosome from their mothers
only. Get Their Y chromosome for their fathers
Daughters: fathers must pass their X chromosomes
SEX LINKED TRAITS Traits found on the SEX chromosomes
Genes that are found on the X chromosome follow a have a special pattern of inheritance: X linked traits are only passed to sons from
the mother
Males are much more likely to be affected than females
If trait is recessive, daughters have a second X chromosome so they
can be heterozygous.
Sons only have one X chromosome therefore more likely to express the trait
Females can be carriers and pass the trait onto their son.
Example: Baldness Colorbindness
COLORBLINDNESS
TRY THIS……
A woman is not colorblind but her husband is. Construct a punnett square to determine what is the chance that their children will be colorblind. What is the percentage of children with colorblindness?
A woman who is a carrier for hemophilia marries an unaffected male. What is the % chance that their children will be affected?
INCOMPLETE DOMINANCE
INCOMPLETE DOMINANCE
when one trait is not completely dominant over another
Results heterozygous form being blended together
Example: Pink flower
SOLVING INCOMPLETE DOMINANCE:
Same as performing a regular monohybrid Punnett square
Only difference heterozygous offspring will be mixture of two
trait Ex:
red + white = PINK
Example Problem: Black fur color are not completely dominant to white white fur color. The mother is a homozgygous for black fur color and the father is homozygous for white fur color. Perform a punnett square.
B B
b
b
Bb Bb
Bb Bb
CODOMINANCE
CODOMINANCE Two different alleles are present and both
are expressed
Basically…….. Both alleles contribute to the phenotype.
Example: Red cow X White Cow = Roan Cow Blood types
BLOOD TYPES: Red blood cells are coated with different protein
markers. Person can have either
A B A and B neither protein.
Blood Types are: A B AB O
Genotype Phenotype
IAIA
IAIO
A Blood
IBIB
IBIOB Blood
IAIB AB Blood
IOIO O Blood
EXAMPLE PROBLEM #1
Melissa has type AB blood. Joe has type AB blood as well. If Melissa and Joe have a baby girl, what are the possible blood types the baby can have? HINT: Draw a Punnet Square!!!!!!
EXAMPLE PROBLEM #2
David has blood type AB. Jessica has blood type O. They have a son that has blood type A? Since neither David nor Jessica have this blood type, was their a mistake in the hospital?
HINT: Draw a Punnett Square to help!!!!!!!!!