1 dec opener: what does a karyotype show us? agenda review karyotypes meiosis meiosis puzzle ...

1 Dec

Opener: What does a

karyotype show us?

Agenda Review

Karyotypes Meiosis Meiosis puzzle Meiosis drawing

Homework none

Human female karyotype

46 chromosomes23 pairs

XX

diploid = 2 copies2n

46 chromosomes23 pairs

XY

Human male karyotypediploid = 2 copies2n

Do we make egg & sperm by mitosis?

46 46+ 92

egg sperm zygote

What if we did, then….

Doesn’t work!

No!

Meiosis 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

gametes

How do we make sperm & eggs? Must reduce 46 chromosomes 23

must halve the number of chromosomes haploid

23

2346

egg

sperm

46

meiosis 46

fertilization

23

23

zygote

Meiosis makes sperm & eggs

46 chromosomes to 23 chromosomes halve the number of chromosomes

23

2346

egg

sperm

46

meiosis

haploiddiploid

Steps of meiosis

1. Cell copies its DNA2. Chromosomes that code for the same

information pair-up and some of their information is transferred (crossing-over)

3. Cell divides once, yielding 2 cells4. 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

Genetics Discussion Questions

1. Where do you get your traits?2. How do you get your traits?3. Are your traits just a blend of your

parents’?4. Is it possible to have a trait that neither of

your parents have?5. Besides function, what is the difference

between sex cells (sperm & egg) and body cells (skin, liver, brain)?

6. Can humans reproduce asexually?

Pedigree basics

Male/female Marriage line Offspring line Generations Shading Questions:

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

Pedigree basics

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

Pedigree Class Regroup

Does this disease affect malesmore 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?

3 Dec

Opener: Agenda Finish Pedigree

worksheet Homework

4 Dec

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

Meiosis Review

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

Crossing over-

Crossing over

Asexual vs. Sexual reproduction

Asexual Reproduction Sexual ReproductionAdvantages:- Can reproduce very quickly- No need to look for mate- If well suited to environment, no

changes are made

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

5 Dec

Opener Agenda Generation of

Variation Meiosis Review

Pop Beads White Board

Participation Quiz

Homework

Natural selection 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 adaptationsCharles Darwin

Where does the Variation come from?

Generation of variation

Where does that variation in offspring come from?

Mutations & Epigenetics Crossing over Independent assortment of

chromosomes into gametes Random fertilization or combination

of gametes

On your whiteboard…

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

Participation Quiz

1. What is the main advantage of sexual reproduction over asexual reproduction?

2. What type of cells are produced via meiosis?

3. In meerkats, a diploid cell contains 36 chromosomes. How many chromosomes does a meerkat egg contain?

4. T/F: All the gametes produced from meiosis are genetically identical to one another.

5. How many chromosomes did you get from your mother?

8 Dec

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

Genetics vocabulary

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

Genetics Vocab (cont.)

Genotype- an organism’s genetic make-up ex. Tt, rr, Qq

Phenotype- the physical trait- “what is seen” Ex. Attached earlobes, blood type, eye

color

You can’t always tell a genotype by looking at the phenotype

Solving genetic problems

1. Write out genotypes

2. Write out cross

3. Make a Punnett square

4. Answer the question

Gregor Mendel

In pea plants, Yellow seeds (E) are dominant over green (e) seeds.

What are the possible genotypes for a yellow- seeded plant?

green-seeded? If two heterozygotes were crossed, what

could be the possible outcomes?

EE or Eeee

Use a Punnett Square

Punnett square : a chart that shows the predicted outcomes of a genetic cross

Punnett squaresEe x Ee

male / sperm

fem

ale

/ e

gg

s EE

Ee ee

EeE

e

E eNow try:

EE x ee

Ee x ee

Let’s try a problem…

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.

Rr rr

Rr rr

R r

r

r

4. 2/4= 50%

9 Dec

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

Participation Quiz

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 problem2. Show the cross3. Draw the Punnett square.4. 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 2nd toe-

dominant

Polydactyly (D)

Freckles (D)

Breaking the Law of DominanceAccording 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 F1 generation should be red but...

Incomplete Dominance

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.

The same is true in cows!

Multiple Alleles

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 typeAlleles: A gene B gene O gene

Polygenic inheritance 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

Example of a polygenic trait

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)

Sex-linked inheritance

Alleles carried on sex chromosomes (usually “X” chromosome)

Gender influences phenotype

Examples:

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.

XH = Normal (dominant allele)

Xh = hemophilia (recessive allele)

Y = no allele for this trait XHXh x XHY

XH Y

XH XHXH XHY

Xh XHXh XhYFem

al

eMale

Environmental Effects

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

Soil acidity and hydrangea