
Opener:

What does a karyotype show us?

Agenda

Review Karyotypes

Meiosis

Meiosis puzzle

Meiosis drawing

Homework
 none

diploid = 2 copies 2n Human female karyotype
46 chromosomes
23 pairs
XX

diploid = 2 copies 2n
46 chromosomes
23 pairs
Human male karyotype
XY


Do we make egg & sperm by mitosis?
No!
What if we did, then….
46 egg
+ 46 sperm
92 zygote
Doesn’t work!


Meiosis
 special cell division in sexually reproducing organisms
 reduce number of chromosomes

Diploid (2 sets of chromosomes  haploid or monoploid (1 set )
 makes gametes- sex cells
 sperm, eggs


Must reduce 46 chromosomes  23

 must halve the number of chromosomes haploid
46
23
23 meiosis egg
23
46 23 zygote fertilization
46 sperm gametes


46 chromosomes to 23 chromosomes
 halve the number of chromosomes
46
23 egg meiosis
46 23 diploid sperm haploid

1.
2.
3.
4.
Cell copies its DNA
Chromosomes that code for the same information pair-up and some of their information is transferred
(crossing-over)
Cell divides once, yielding 2 cells
Each of the 2 cells divide again, yielding 4 gametes.

2 Dec

Opening question

If neither parent has a genetic disease, can a child have it?

Agenda:

Hand back work

Fire drill/lock down procedures

Genetics discussion questions

Pedigree Basics

Class activity

HW: none

1.
2.
3.
4.
5.
6.
Where do you get your traits?
How do you get your traits?
Are your traits just a blend of your parents’?
Is it possible to have a trait that neither of your parents have?
Besides function, what is the difference between sex cells (sperm & egg) and body cells (skin, liver, brain)?
Can humans reproduce asexually?







Male/female
Marriage line
Offspring line
Generations
Shading
Questions:






How many males?
How many matings?
How many generations?
How many kids were made from 2 nd generation?
How many people with the disease?
Does the disease have a pattern?


Questions:

How many males?





How many matings?
How many generations?
How many kids were made from 2 nd generation?
How many people with the disease?
Does the disease have a pattern?


Does this disease affect males more than females?

If the parent has this disease, does that mean the kids are going to have it?


If the parents don’t have it, can their kids have it?
Any ideas on how this disease is passed on through families by their genes?


Opener:

Agenda

Finish Pedigree worksheet

Homework


Opener

Think about the pedigrees from yesterday. When can we tell someone’s genetic make-up by observing them?

Agenda:



Review Meiosis
Why sex?
Sources of variation

Homework


Meiosis Review

 http://media.pearsoncmg.com/bc/bc_0media_bio/ bioflix/bioflix.htm?8apmeiosis


Crossing over-

Asexual vs. Sexual reproduction
Asexual Reproduction
Advantages:
- Can reproduce very quickly
- No need to look for mate
- If well suited to environment, no changes are made
Sexual Reproduction
Advantages:
- Increases genetic variation
- Easier for population to adapt to changing environmental conditions
Disadvantages:
- No variation generated
- Difficult for population to adapt to changing environment
Disadvantages:
- Energy expended looking for mates
- No mates = no reproduction


Opener

Agenda

Generation of
Variation

Meiosis Review

Pop Beads
 White Board

Participation Quiz

Homework


There is heritable variation within populations

More offspring are born than can survive

This leads to a competition for limited resources

Some survive/reproduce based on favorable adaptations
Charles Darwin
Where does the Variation come from?

Where does that variation in offspring come from?

Mutations & Epigenetics

Crossing over

Independent assortment of chromosomes into gametes

Random fertilization or combination of gametes





Show the complete process of meiosis from parent cell to gamete.
Pretend your organism’s diploid number of chromosomes is six.
Be sure to have a small, medium and large set of homologous chromosomes.
Make sure to include the following terms:





Diploid
Haploid
Gamete
Crossing over
Homologous pair

2.
3.
1.
4.
5.
What is the main advantage of sexual reproduction over asexual reproduction?
What type of cells are produced via meiosis?
In meerkats, a diploid cell contains 36 chromosomes.
How many chromosomes does a meerkat egg contain?
T/F: All the gametes produced from meiosis are genetically identical to one another.
How many chromosomes did you get from your mother?


Opener:

If a couple (of humans) were going to have a baby, what are the chances of them having a girl? How do you know?

Agenda


Genetics Vocab
Punnett Squares

Homework

Punnett Square Problems






Allele - different versions of a gene
Dominant - an allele that masks the effects of another.
Only need one copy to show the trait. Usually represented as a capital letter
Recessive - need two copies to show the trait. Usually represented with a lower case letter
Homozygous - two copies of the same allele (dominant or recessive)

Ex. RR, tt, EE, qq
Heterozygous - one copy of each allele. Also, called carriers

Ex. Rr, Tt, Ee, Qq


Genotypean organism’s genetic make-up
 ex. Tt, rr, Qq

Phenotypethe physical trait- “what is seen”

Ex. Attached earlobes, blood type, eye color
You can’t always tell a genotype by looking at the phenotype

1.
Write out genotypes
2.
Write out cross
3.
Make a Punnett square
4.
Answer the question

In pea plants, Yellow seeds (E) are dominant over green (e) seeds.



What are the possible genotypes for a yellowseeded plant? 
EE or Ee green-seeded?  ee
If two heterozygotes were crossed, what could be the possible outcomes?  Use a Punnett Square
Punnett square : a chart that shows the predicted outcomes of a genetic cross

Now try:
EE x ee
Ee x ee
E
Ee x Ee
E male / sperm e
EE Ee e Ee ee


In a certain species of daisy, purple flowers are dominant to white flowers. A heterozygote and a homozygous recessive plant are crossed. What percent of their offspring would you expect to be white?
1. R= purple flowers r= white
2. Rr x rr
3. r r
R
R r
R r r rr rr
4. 2/4= 50%


Opener: In lynx, striped fur is dominant over solid fur. If you were presented with a striped lynx, how could you determine its genotype
(without doing a genetic test)?

Agenda

Participation quiz

Non-Mendelian
Genetics

Homework
 none


In a certain species of daisy, purple flowers are dominant to white flowers. A heterozygote and a homozygous recessive plant are crossed.
1.
Write a key for this problem
2.
3.
4.
Show the cross
Draw the Punnett square.
If 36 offspring are produced from this cross, how many of their offspring are expected to be purple?

What traits in humans obey Mendel’s
Law of Dominance?

Tongue curling- dominant

Free Ear lobe- dominant

Widow’s peak- dominant

Hitchhiker’s thumb- recessive

Shorter big toe than 2 nd toe- dominant

According to the law of dominance what should happen when you cross a purebred/homozygous white snapdragon plant with a purebred/homozygous red snapdragon?

All the F
1 generation should be red but...


Heterozygotes show a blending of the two parental traits

Red is incompletely dominant over white so pink snapdragons are produced

According to the Law of Dominance what should happen when you cross a red and white horse?

All red or all white horses should be produced, but…

CODOMINANCE-
Both parental phenotypes are shown in heterozygotes
White and red color in horses are codominant so a white and red horse is produced.


Many genes have more than just two alleles

If there are three or more alleles for a trait, it is called multiple alleles

Example: Human Blood type
Alleles:

A gene


B gene
O gene


Some phenotypes determined by additive effects of 2 or more genes on a single character
 phenotypes on a continuum
 human traits
 skin color
 height
 weight
 intelligence
 behaviors


Eye color

There are genes for
 Tone of pigment (what color it is)
 The amount of pigment
 Position of pigments (look at people’s eyes- there are many different patterns in the iris)


Alleles carried on sex chromosomes (usually “X” chromosome)

Gender influences phenotype


Hemophilia

Red-green color-blindedness

Male pattern baldness

A woman who is a carrier for hemophilia mates with a man who does not have hemophilia.

X H = Normal (dominant allele)
X h = hemophilia (recessive allele)
Y = no allele for this trait

X H X h x X H Y
X H
Male
Y
X H X H X H X H Y
X h X H X h X h Y


The environment can influence the expression of genes

Remember Epigenetics?

Example of effect of temperature

Ptarmigan in the tundra- change color depending on the temperature and weather