Download Unit 4. Week 2. Meiosis and Reproduction

Warm Up
1. Pick up a slip of paper to write your warmup
2. Explain the difference between Mitosis
and Meiosis. I should see a paragraph
that includes the following information in
your answer:
a. The number of cells that each produces
b. How the number of chromosomes is affected
Agenda
• Objectives: SWBAT: explain how each gene
is made up of two alleles, one coming from
each parent AND explain how cancer
spreads in an organism.
• Pass Back Notebooks
– Explain Grades
• Review
• Brain Pop Video
• Start Genetics
• Short Quiz tomorrow on cellular division
Notebook Grades
•
•
•
•
•
Out of 125 points
Table of Contents: 3 points
Warm-ups: 2 points each = 38 points
Notes: 5 points each= 90 points
Stamps are extra credit 
Review Mitosis and Meiosis
a. Mitosis occurs in body cells.
–
–
Mitosis is how your body grows and repairs its
tissues.
Form of asexual reproduction
b. Meiosis occurs only in sex cells (sperm and
egg cells).
–
–
Meiosis allows people to reproduce.
Form of sexual reproduction
Mitosis vs. Meiosis
Mitosis produces 2 diploid cells
Meiosis produces 4 haploid
cells
COPY THE CHARTS AND DIAGRAMS
Practice Problems
1.
2.
3.
What is an advantage of meiosis?
What is a disadvantage of mitosis?
Is mitosis an asexual or sexual method of
reproduction?
4. A cell has 12 chromosomes.
a. How many chromosomes will it have
after MITOSIS?
b. How many chromosomes will it have
after MEIOSIS?
5. Meiosis makes cells with ______ set(s) of
chromosomes.
Rate of Cell Division
a. Cells only divide through mitosis and
cytokinesis so the body can grow
and repair itself
b. If you get a cut, your skin cells will
divide rapidly to heal the wound.
When you’re almost healed, the cell
division will slow down and then stop.
How can I relate to cell
division?
• Raise your hand if you know someone
that had or has cancer.
Cellular Division and Cancer
a. Cancer is when your body cannot control
the rate of cellular division.
b. Cancer forms in the body when harmful
cells continue to divide and reproduce.
c. The cells reproduce asexually through
mitosis and cytokinesis.
d. Harmful cells form tumors and can also
enter the blood stream.
More on Cancer
• Cancer
• Make sure you’re paying attention
because you may have to answer
some questions from the video!
The Big Picture
• http://www.brainpop.com/science/
cellularlifeandgenetics/genetics/
Exit Ticket
1. What happens to a person’s cells if they
have cancer?
2. A cell has 12 chromosomes.
a. How many chromosomes will it have after
MITOSIS?
b. How many chromosomes will it have after
MEIOSIS?
Study Guide
• Complete study guide
• If everyone is working quietly, I will
consider letting you use your study
guides on the quiz tomorrow
Oh yeah, I said it!
Warm Up
1. How many daughter cells are produced after
a cell goes through meiosis?
2. How many sets of chromosomes are in cells
that are produced by meiosis?
3. What is the name for a cell that has 1 set of
chromosomes?
Practice Questions
1. If a hamster’s body cell has 22
chromosomes how many
chromosomes will the daughter cells
have that are produced by Mitosis?
2. If a organism has 13 chromosomes in
one of its sex cells (gametes), how
many chromosomes are in its body
cells?
Review
1. If a human body cell has 46 chromosomes
in it how many chromosomes are in the
daughter cells that are produced by
meiosis?
2. If a dog has 22 chromosomes and it goes
through mitosis, how many chromosomes
will be in the 2 daughter cells produced?
Meiosis
If an organisms diploid number is 24,
then its haploid number is
a. 6
b. 24
c. 12
d. 48
Warm-Up
1. What do you know about genes
and/or genetics?
2. Where did you get your genes from?
3. Which type of cell division leads to
genetic variability?
Genetics
Why we are the way we are
What is Heredity?
a. Genetics is the study of heredity
b. What is heredity?
-
Heredity is how different genes are passed
down from parents to children.
What is Heredity?
c. Every person has traits that they
inherited from their parents
-
Traits are specific characteristics that vary
from one person to another
Examples include height, eye color, hair
color
What are Genes?
a. Genes are made up of DNA, which
make up chromosomes
-
Comparison: If genes were sentences,
then DNA would be the words and
chromosomes would be the paragraph.
All of your genetic information would be
a book.
What are Genes?
"I have no money," said the tree,
"Just apples, twigs and leaves".
But soon the boy grew older
and one day he came and
said,
"Can you give me some
money, tree, to buy
something I’ve found"?
"I have no money," said the
tree, "Just apples, twigs and
leaves".
"But you can take my apples,
boy, and sell them in the
town".
And so he did and
Oh, the tree was happy.
Oh, the tree was glad
What do genes do?
a. Genes are like an
instruction manual for our
cells. They tell cells what
to do and how to do it.
b. Genes determine things
like what type of
organism you are and
what you look like
“Where do you stand”
activity
• “Activity One: Heredity and
Environment”
• Let’s read the directions together
• Be prepared to discuss what you put
down!
Conclusion
• Not everything about you is
determined by heredity
• Environment can sometimes play a big
role in who you are and what you do
• We’re going to focus in the unit on the
genetic side of the debate
Warm Up
1. What does heredity mean?
2. How many chromosomes do we have?
3. What do genes do?
4. What is an example of a trait?
5. Do you think alcoholism is due to
heredity or the environment? Explain why
Agenda
• Objective:
• Vocabulary Development
– Understanding vocabulary is crucial for
this unit.
– There are a lot of new terms to learn
1. Review of key terms
a. Heredity is how characteristics are
passed from parents to offspring.
b. Genetics is the study of heredity
c. Traits are inherited characteristics that
vary between individuals
c. Genes are sequences of DNA that
code for specific traits
2. Gregor Mendel
a. Gregor Mendel was a
monk that lived in the
1800’s
b. He worked with 2
different kinds of pea
plants that
reproduced in 2
different ways
- Self-pollination
- Cross-pollination
3. Types of Reproduction
a. Self-pollination is when a plant’s
pollen fertilizes egg cells in the
SAME flower
b. Cross-pollination is when pollen
from one flower fertilizes the eggs
in A DIFFERENT flower
Tying concepts together
When offspring are produced by ONE
parent, is it sexual or asexual
reproduction?
Asexual
Is self-pollination asexual or sexual
reproduction?
Asexual
Is cross-pollination asexual or sexual
reproduction?
Sexual
4. Mendel’s Experiments
a. Mendel grew pea plants with different
traits from one another.
– When the plants self-pollinated, their
offspring had the exact same traits
b. Then he crossed different plants with
different characteristics.
– Example: Crossed tall plants with short
plants
– Cross: to breed 2 different individuals that
result in offspring with genetic material
from each parent.
5. First Cross
a. In the first cross or
generation, Mendel
observed only 1 of
the 2 traits in the
offspring
– Ex. When he crossed
tall plants with short
plants, he ALWAYS
got tall plants
5. First Cross
b. One parents’ traits seem to dominate
the other parent’s traits.
c. Traits that always dominate others are
called DOMINANT
6. Second Cross
a. Mendel decided to do another cross to
see if he got the same results
b. In the second cross or generation, both
traits reappeared
-
He saw tall and short plants in the second
generation
He saw the dominant trait as well as the hidden
trait
c. Hidden or masked traits are called
RECESSIVE
• Cross tall plant
and short plant
• First Generation
– Only tall plants
• Second Cross
• Second
Generation
– Tall and short
plants
Exit Ticket
• Define genetics
• What did Gregor Mendel discover
about traits?
• What are dominant traits?
• We now know that the factors that
Mendel studied are alleles, or
alternative forms of a gene.
• One allele for each trait is passed from
each parent to the offspring.
1. Dominant and Recessive
a. Dominant and recessive can refer to
– Traits
– Genes
– Alleles
b. Alleles are the different forms of a gene.
They are represented by one letter (a, D)
c. Genes are represented by two letters (Aa,
DD)
d. Dominant traits are not necessarily more
common
What’s the difference
between…
• Homozygous and Heterozyous
AND
• Genotype and Phenotype
2. Homozygous vs.
Heterozyous
Definition
Homozygous
When a gene has two
identical alleles for the
same trait
Heterozygous
When a gene has two
different alleles for the
same trait
Dominant, Example
recessive
or both?
Practice Set 1
1. Which gene below is homozygous
dominant?
2. Which gene below is heterozygous?
GG, Gg, gg
allele
3.
Gg
4.
Gg
Gene
3. Genotype vs. Phenotype
Definition
Genotype
The ____________
make up of an
organism
Phenotype
The ____________
make up of an
organism
Example
(eye color)
Practice Set 2
5. bb = ____________________
6. Blue eyes = ________________
4. Punnett Squares
a. Punnett Squares: are used to determine the
offspring of a cross.
b. In a Punnett square, the male genotype is
written above the square and the female
genotype is written to the left of the square
A
a
a
A
5. What do we use them for?
a. To find the results of crosses and…
– The probability of an offspring being
heterozygous, homozygous dominant, or
homozygous recessive
– The probability of certain phenotypes
b. A Monohybrid cross shows the possible
genotypes for a single specific trait, like
height.
– “Mono” = one
6. How do you fill in
Punnett Squares
a. Rule of Thumb….
– The male
genotype goes
above the square
– The female
genotype goes
on the left of the
square
6. How do you fill in Punnett
Squares?
b. First, you write the
parents’ genotypes
-
one letter for each
column or row
c. Then you distribute
the letters
Practice Set 3
7. Fill in the Punnett square
8. How many boxes have
homozygous genes?
____ out of 4 = _____ %
9. How many boxes have
heterozygous genes?
____ out of 4= _____ %
10. If brown is the dominant
eye color, what percentage
of children will have brown
eyes?
Let’s try another
• A couple wants to know
the probability that they
will have a that has
dimples.
• Dimples are a dominant
trait
• The man has a genotype
of Dd and the woman has
a genotype of dd.
Thursday Bellwork
1.
2.
3.
4.
5.
6.
An _________ is a form of a
gene that is represented by
one letter
What does homozygous
mean?
What does heterozygous
mean?
What’s the difference
between genotype and
phenotype?
In the Punnett square shown,
is the father heterozygous or
homozygous?
How many squares are
Friday Bellwork
Identify each of the
following as homozygous
dominant, homozygous
recessive or
heterozygous.
1.Hh
2.Kk
PP
Pp
3.ll
4.jj
PP
Pp
5.DD
6. What is the genotype
of the father in this
punnett square?
7. What’s the genotype
of the mother?
8. What’s the probability
of a child being
homozygous
recessive?
• Today
Friday
Agenda and
Announcements
– Turn in Bellwork and Genetics Practice Problems
Sheet
– Review with whiteboards
– Pull Tickets
– Quiz
• Next Week
– Tracking mastery and make-up
– Genetics activity
– Progress reports and projects
Review
Quiz