Transcript Sexual Reproduction and Meiosis

Sexual Reproduction:
• The reproductive process that involves
two parents who combine their genetic
material to produce an offspring that is
not identical to either parent.
• So, what are the important parts?
Sexual Reproduction:
•The reproductive process that involves
two parents who combine their genetic
information to produce offspring that is
not identical to either parent.
•What are some examples of organisms
that are able to reproduce this way?
What is the advantage of having
two parents?
Advantage of two parents:
• You get more genetic variation:
Which means…
Because half of the DNA comes from
the female and half from the male…
You get a mix of traits—more variety!
How do you get so many
differences in traits?
• Well, let’s start at the very beginning…a
very good place to start!
• If you look at the DNA of any cell, you
will find that each strand of DNA has a
pair or partner.
How do you get so many
differences in traits?
• Well, let’s start at the very beginning…a
very good place to start.
• If you look at the DNA of any cell, you
will find that each strand has a pair or
partner.
• These are called homologous pairs
• One of the chromosomes from a pair
comes from mom, and one comes from
dad.
• They code for the same type of traits
• All organisms that reproduce sexually
have the ability to make special cells
called GAMETES.
• Gametes: special cells that only have half
of the DNA that all the other cells have
• Gametes are AKA: sperm/egg cells
• How do gametes end up with only half of
the DNA?
MEIOSIS:
The making of GAMETE CELLS
Before we do this, let’s review
MITOSIS!
Remember PMAT?
Differences between MEIOSIS and
MITOSIS:
Meiosis:
• End up with four cells instead of two
– Four cells are called GAMETES
• Each gamete only has HALF the DNA
• How does meiosis get four cells with half
the DNA?
• Goes through PMAT TWICE!!
Meiosis Video
• http://www.youtube.com/watch?v=D1_mQS_FZ0#t=57
Gamete Fusion
• Gametes are AKA:
Gamete Fusion
• Gametes are AKA: sperm/egg cells
• Gamete fusion:
Gamete Fusion
• Gametes are AKA: sperm/egg cells
• Gamete fusion: when a sperm fuses with
an egg
• Gamete fusion is AKA:
Gamete Fusion
• Gametes are AKA: sperm/egg cells
• Gamete fusion: when a sperm fuses with
an egg
• Gamete fusion is AKA: fertilization
• Zygote:
Gamete Fusion
• Gametes are AKA: sperm/egg cells
• Gamete fusion: when a sperm fuses with
an egg
• Gamete fusion is AKA: fertilization
• Zygote: sperm + egg cell = new “baby” cell
Gamete Fusion
________ Twins
Dominant vs. Recessive
Dominant trait:
Dominant vs. Recessive
Dominant trait: the stronger trait
- Use an uppercase letter
Ex: Free earlobe =
Dominant vs. Recessive
Dominant trait: the stronger trait
- Use an uppercase letter
Ex: Free earlobe = F
Recessive trait:
Dominant vs. Recessive
Dominant trait: the stronger trait
- use an uppercase letter
Ex: Free earlobe = F
Recessive trait: the weaker trait
- use a lowercase letter
Ex: Attached earlobes =
Dominant vs. Recessive
Dominant trait: the stronger trait
- use an uppercase letter
Ex: Free earlobe = F
Recessive trait: the weaker trait
- use a lowercase letter
Ex: Attached earlobes = f
Letter
Dominant
Free Earlobes
Number Letter
Recessive
Attached Earlobes
Number
Letter
Dominant
Number Letter
Recessive
Free Earlobes
Attached Earlobes
Farsightedness
Normal Vision
Number
Letter
Dominant
Number Letter
Recessive
Free Earlobes
Attached Earlobes
Farsightedness
Normal Vision
Brown/Dark Hair
Blond, light, red hair
Number
Letter
Dominant
Number Letter
Recessive
Free Earlobes
Attached Earlobes
Farsightedness
Normal Vision
Brown/Dark Hair
Dimples
Blond, light, red hair
No Dimples
Number
Letter
Dominant
Number Letter
Recessive
Free Earlobes
Attached Earlobes
Farsightedness
Normal Vision
Brown/Dark Hair
Blond, light, red hair
Dimples
No dimples
Widow Peak
No Widows Peak
Number
Letter
Dominant
Number Letter
Recessive
Free Earlobes
Attached Earlobes
Farsightedness
Normal Vision
Brown/Dark Hair
Blond, light, red hair
Dimples
No dimples
Widow Peak
No Widows Peak
Extra Digits
Normal Number
Digits
Number
Letter
Dominant
Number Letter
Recessive
Free Earlobes
Attached Earlobes
Farsightedness
Normal Vision
Brown/Dark Hair
Blond, light, red hair
Dimples
No dimples
Widow Peak
No Widows Peak
Extra Digits
Normal Number
Digits
Double-jointedness
Normal joints
Number
Letter
Dominant
Number Letter
Recessive
Free Earlobes
Attached Earlobes
Farsightedness
Normal Vision
Brown/Dark Hair
Blond, light, red hair
Dimples
No dimples
Widow Peak
No Widows Peak
Extra Digits
Normal Number
Digits
Double-jointedness
Normal joints
Normal blood
clotting
Hemophilia
Number
Dominant vs. Recessive
Genotype:
Dominant vs. Recessive
Genotype: genetic make-up of your cells,
Represented by two letters
i.e. what your genes “say”
Homozygus:
Heterozygus:
Phenotype:
Dominant vs. Recessive
Genotype: what your GENES say
Homozygus: FF or ff
Heterozygus:
Phenotype: What you PHYSICALLY show
Dominant vs. Recessive
Genotype: what your GENES say
Homozygus: FF or ff
Heterozygus: Ff
Phenotype: What you PHYSICALLY show
Homologus pair of chromosomes:
Dominant vs. Recessive
Genotype: what your GENES say
Homozygus: FF or ff
Heterozygus: Ff
Phenotype: What you PHYSICALLY show
Homologus pair of chromosomes: one came
from mom, one from dad
Ex: genotype: mom =
dad =
Dominant vs. Recessive
Genotype: what your GENES say
Homozygus: FF or ff
Heterozygus: Ff
Phenotype: What you PHYSICALLY show
Homologus pair of chromosomes: one came
from mom, one from dad
Ex: genotype: mom =
dad =
Dominant vs. Recessive
Genotype: what your GENES say
Homozygus: FF or ff
Heterozygus: Ff
Phenotype: What you PHYSICALLY show
Homologus pair of chromosomes: one came
from mom, one from dad
Ex: genotype: mom =
dad =
phenotype: mom =
dad =
Dominant vs. Recessive
Genotype: what your GENES say
Homozygus: FF or ff
Heterozygus: Ff
Phenotype: What you PHYSICALLY show
Homologus pair of chromosomes: one came
from mom, one from dad
Ex: genotype: mom = FF dad = ff
phenotype: mom = Free dad = Attached
Dominant vs. Recessive
Genotype: what your GENES say
Homozygus: FF or ff
Heterozygus: Ff
Phenotype: What you PHYSICALLY show
Homologus pair of chromosomes: one came
from mom, one from dad
Ex: genotype: mom = FF dad = ff
Punnett square or hybrid cross
Mom =
Dad =
Dominant vs. Recessive
Hidden trait:
Dominant vs. Recessive
Hidden trait: gene that someone has but
doesn’t express
Carrier:
Dominant vs. Recessive
Hidden trait: trait that someone has but
doesn’t show
Carrier: someone that carries a hidden trait,
meaning they have a heterozygous
genotype and the recessive gene will not be
expressed or shown
Dihybrid cross
• Curly hair and widow’s
peak are both dominant
traits. If a mom was
heterozygous for curly hair
and homozygous recessive
for widow’s peak. What is
her genotype?
Dihybrid cross
• What is the genotype of a
man who is homozygous
dominant for curly hair and
heterozygous for widow’s
peak?
Dihybrid cross
Dad’s genotype:
Mom’s genotype::
Chromosome Pair #23
Gender:
Chromosome Pair #23
Gender: coded for by chromosome pair #23
Girl =
Boy =
Chromosome Pair #23
Gender: coded for by chromosome pair #23
Girl = XX
Boy = Xy
Chromosome Pair #23
Gender: coded for by chromosome pair #23
Girl = XX
Boy = Xy
X Linked Traits: Traits that are coded for on
the 23rd chromosome
Anastasia
Romanov Family
Tzar Nicholas Romanov
(1868-1918)
Males & Females have Different
Inheritance Patterns
– ALL of a male’s X-linked
genes are expressed.
– Males have no second
copies of X chromosome
– Because of this, males
can NEVER be “carriers”
of X-linked traits or
disorders.
– Ex: Colorblindness,
Hemophilia, Muscular
dystrophy
67
More punnett square practice
More punnett square practice
• Will baby Lyla
be color blind?
• Lets do a
punnett square
and see
Pedigree Charts
(How to interpret)
Girl =
Boy =
Married = line between circle and square
Divorced = ----- dashed line between circle
and square
Children = vertical line down from parents
Adopted = ---- dashed vertical line from
parents
Has trait = filled in
Carries trait= half filled in
Pedigree Charts
• Go back to the dominant vs. recessive
chart. Pick on trait and make a list of all
your family members and write by their
name whether they have the dominant trait
or the recessive trait.
• Remember: Blond and Red hair are recessive traits,
brown is dominant
• Blue/green eyes are recessive, brown eyes are dominant
Make your own
• Make a pedigree chart of your family using
the dominant/recessive traits of your family
you just listed
• Be sure to label each individual of your
family
• Include as many extended family
members as possible
• List the GENOTYPES of each individual
Mammals
Amphibians, Reptiles,
and Fish
Insects