Transcript mendel and mex

Mendel and ME
Reading and activities
Read Vignette 1 (first page) and
answer these questions
How did Mendel deal with failure or struggle?
How does Mendel’s story Relate to Science?
What do you have in common with Mendel?
(Work on your own for this ?)
USE TEXTUAL EVIDENCE TO SUPPORT YOUR ANSWERS
TO THE FIRST TWO QUESTIONS.
Apples
Mendel wandered why there were differences between peas. Think
about an apple. Have you ever noticed that some apples are sweet and
some are bitter?
 What characteristics make these apples similar or different?
Create a Venn-Diagram
 Hypothesize (choose one below)
Why do you think the red delicious apples are sweeter than the
granny smiths?
Why do you think one is red and one is green?
Read Vignette 2 (second page) once you
finish answer the question and complete
the task.
What do you think Mendel wanted to
learn more about? Use evidence from the
reading to support your answer.
Come up with a research question
Mendel would have wanted to study
and test.
Class Traits
Work in groups of 2 to complete the inventory of
traits. You should mark yes or no for your own
personal traits “An Inventory of My Traits-Survey”
Work with the other group at your table (4
people). Flip the page over and add up the
totals for your 4 person group. “Data Table”
Once you have the totals for your larger group
send a representative to the front and record
them on the class sheet under the document
camera.
Class Traits “Graph”
Create a graph
showing how many
people in your class
answered yes or no
for each trait. Be sure
to label each trait
type on the x axis.
Traits Questions
1.
2.
Why do you think one form of each trait is
more common (has a higher frequency) than
the other.
Traits are controlled by factors called genes.
You get one gene from your mother and one
from your father. For each trait there is a
dominant form and a recessive form. Based
on the class results for dimples and cleft chin.
Which form of each trait is dominant for
each? Explain your answer.
Traits Questions
3.Does a traits dominance play a
role in how much it will show up in
a population of organisms?
Genetics
 Allele: Different versions of the same trait represented by letters
 most living thing gets one set of chromosomes from biological
mother and one set from biological father (this does not include
cloning)
 2 alleles for each trait
 Phenotype: what an organism looks like - what you see
 Genotype: the genes that make up the genetics
 Dominant trait: a trait that shows up no matter what it is paired
with
 Recessive trait: a trait that is masked or hidden unless it is paired
with another recessive trait
Homozygous vs. Heterozygous
 Homozygous: pair of genes controlling the characteristic has identical
alleles, TT or tt
 Heterozygous: pair of genes controlling the characteristic are different
alleles, Tt
 Punnett Squares/Genetic Crosses:
When working on genetic crosses the capital letter represents
the
dominant allele and the small letter represents the recessive allele
Punnett Squares
Using the Punnett Squares
 STEPS:
1. determine the genotypes of the parent organisms
2. write down your "cross" (mating)
3. draw a p-square
4. "split" the letters of the genotype for each parent & put them
"outside" the Punnett-square
5. determine the possible genotypes of the offspring by filling in the
Punnett-square
6. summarize results (genotypes & phenotypes of offspring)
Using the Punnett Squares
Step #1: Determine the genotypes of the parent organisms.
Sometimes this is done for you, “Cross two organism with
the following genotype: Tt & tt", it's all right there in the
question already.
Sometimes you need to use key words from the questions
to figure out the genotypes of the parents. “Cross a short
pea plant with one that is heterozygous for tallness.”
Genotypes: short pea plant (tt) x heterozygous tall pea
plant (Tt)
Using the Punnett Squares
Step 2: Write down your "cross" (mating). Write the
genotypes of the parents in the form of letters (ex:
Tt x tt)
Step #3: Draw a Punnett-square.
Using the Punnett Squares
 Step #4: "Split" the letters of the genotype for each parent & put them "outside" the
punnett-square.
Use these parental genotypes: Tt x tt.
Take the genotype letters of one parent, split them and put
them on the left, outside the rows of the punnett-square.
Now take the two letters of the second
parent's genotype, split them up, and place
them above each of the two columns of the
punnett-square
Using the Punnett Squares
 Step #5: Determine the possible genotype of the offspring by filling in the
punnett-square.
 To determine the outcome, fill-in the the boxes of the punnettsquare. Again we do this be taking
a letter from the left & matching it
with a letter from the top. Like so:
Using the Punnett Squares
Step 6: summarize results (genotypes & phenotypes of offspring).
Phenotypes of Offspring:
2 heterozygous tall
2 short
Genotypes of Offspring:
2 Tt
2 tt
Ratio and Percentage:
Percent of tall offspring 2/4 or 50%
Percent of short offspring 2/4 or 50%
Practice
A species of flamingo's has been discovered
that have 2 different colored feathers, red or
blue.
A is a dominant trait a is a recessive trait
A represents red a represents blue
AA and Aa are red aa is blue
A homozygous red bird (AA) is crossed with a
homozygous blue bird (aa).
Practice
A is a dominant trait a is a recessive trait
A represents red a represents blue
AA and Aa are red aa is blue
A heterozygous red bird is crossed with a
heterozygous red bird. (remember step
2!)
Codominance
This is where two alleles combine and neither is
masked they are equal in “power”. Combined
An example of this is human blood type. ABO are
the alleles which make up the human blood types.
A and B are equal in dominance (codominance)
both over O (recessive).
Lets look at what happens when we cross a parent
who has a blood type of A (AO) with a parent with
blood type B (BO).
Codominance Practice
Roses are co-dominant for color.
A blue rose has BB
A green rose has GG
When crossed they produce spotted offspring (BG)
If a blue knockout rose (BB) is crossed with a green
knockout rose (GG) what % of their offspring will be
spotted?
If two spotted roses are crossed how many of their
offspring will be green, blue, spotted?
Incomplete Dominance: A third
phenotype is created
Roses are incomplete dominant for color.
A red rose has RR
A white rose has WW
When crossed they produce pink offspring (RW)
If a red knockout rose (RR) is crossed with a white
knockout rose (WW) what % of their offspring will be
pink?
If two pink roses are crossed how many of their
offspring will be pink, white, red?
Dihybrid Crosses
This type of cross requires a 16 box Punnett square.