paper bag project

Paper Bag Project

1. Make Paper Bag according to guidelines for traits

2. Fill in phenotype column of table

3. Fill in genotype column of table

4. Fill in alleles on chromosomes

5. Act out meiosis to create gametes

6. Mate animals (fertilization)

7. Use Punnet squares to predict traits of baby

8. Give birth and decorate baby to match inherited genotype

Paper Bag Project• Genetic Traits – inherited characteristics of a living organism

(examples: hair color, number of limbs, ability to make insulin)

• Phenotype – the observable version of a trait expressed (examples: brown hair, four limbs, diabetic)

• Allele – the genetic sequence that codes for each distinct possible phenotype for a trait (examples: the alleles for hair color are brown, black, red, and blonde; the alleles for insulin would be all of the different variations of insulin that exist in the human genome, some of which have mutations that make it not work as well or at all)

• Genotype – in humans, the pair of alleles that determine each trait, because humans get one set of genes from mom and one set from dad – with the exception of the genes on the X and Y chromosomes (example: if you have black hair, your genotype may include the black allele from one parent and a brown allele from the other parent)

• Dominant Allele – the allele that is expressed as the phenotype of an organism when paired with a “competing” allele (in the example above, black is dominant over brown)

• Recessive Allele – the allele that is NOT expressed as the phenotype of an organism when paired with a “competing” allele that is dominant over it (in the example above, brown is recessive to black)

InheritanceGregor Mendel – “Father of Genetics”

• Did experiments with pea plants in mid-late 1800’s to show basic patterns of inheritance

• Genetic Traits – inherited characteristics of a living organism

• Allele – the genetic sequence that codes for each distinct possible phenotype for a trait

Traits Alleles (genes)

Seed Shape (round or wrinkled) Seed Color (yellow or green) Seed Coat color (gray or white) Pod Shape (smooth or constricted) Pod Color (green or yellow) Flower Position (axial or terminal) Plant Height (tall or short)

Traits Alleles (genes)

InheritanceGregor Mendel – “Father of Genetics”

• Phenotype – the observable version of a trait expressed • Found that when two plants with different alleles are crossed, the

offspring look like one of the parents, rather than a blending of both parents Principle of Dominance: Some alleles are dominant and others are recessive

Dominant Alleles

Recessive Alleles

Seed Shape (round or wrinkled) round wrinkled Seed Color (yellow or green) yellow green Seed Coat color (gray or white) gray white Pod Shape (smooth or constricted) smooth constricted Pod Color (green or yellow) green yellow Flower Position (axial or terminal) axial terminal Plant Height (tall or short) tall short

Phenotypes

Homozygous dominantor Heterozygous

Homozygous recessive

genotypes

Inheritance

Gregor Mendel – “Father of Genetics”• Phenotype - The observable physical characteristic of a trait

• Genotype - The genetic combination of alleles for a trait

• Letters are used to represent the alleles (usually correspond to the dominant phenotype – Example: “P” for purple if purple flowers are dominant over white)

Upper Case Letters = Dominant Allele

Lower Case Letters = Recessive Allele

Seed Shape: round (R) or wrinkled (r) RR = round rr = wrinkled Rr = round Seed Color: yellow (Y) or green (y) YY = yy = Yy = Pod Shape: smooth (S) or constricted (s) SS = ss = Ss = Pod Color: green (G) or yellow (g) GG = gg = Gg = Plant Height tall (T) or short (t) TT = tt = Tt =

traits alleles genotypes = phenotypes homozygous homozygous

dominant recessive heterozygous

1. Which of the following are genotypes and which are phenotypes: Brown hair Heterozygous Bb Webbed Fingers Homozygous recessive Down Syndrome

For each statement below, underline any genotypes and put a box around any phenotypes.

2. Robert and his wife are both carriers for Tay Sach’s disease.

3. Maria inherited an allele for brown hair from her mother and an allele for black hair from her father; and now she has black hair.

4. My mother has brown hair and I had blonde hair until I was ten.

5. Ron’s parents both have brown eyes, but they are both heterozygous for eye color. As a result, Ron has blue eyes.

6. If you have a widow’s peak, you are homozygous recessive for this trait.

7. People with Type O blood are homozygous for the recessive O allele. People with type AB blood have the A allele and the B allele.

Practice Questions

Practice Questions

AllelesTraits

Paper Bag Project• Which of the following are traits

and which are alleles?

Gender male (XY) or female (XX) Eye Shape oval (E) or slit (e) Eye Color brown (B), blue (b),

green (g), yellow (y) Hair Color black (H), brown (h),

yellow(y) Eyelashes present (L), not present (l)

(X-linked) Tail (Y-linked) present (T), not present (t) Ear Shape round (R), pointed (r) Nose Shape triangle (N), circle (n)

Paper Bag Project• Which of the following are traits

and which are alleles?

Gender male (XY) or female (XX) Eye Shape oval (E) or slit (e) Eye Color brown (B), blue (b),

green (g), yellow (y) Hair Color black (H), brown (h),

yellow(y) Eyelashes present (L), not present (l)

(X-linked) Tail (Y-linked) present (T), not present (t) Ear Shape round (R), pointed (r) Nose Shape triangle (N), circle (n)

Inheritance

Most Dominant

Most Recessive

Genotype Phenotype EE Ee Bg bg nn hy lY LY Xt

Meiosis

Cell division that results in production of gametes (sex cells)

• Eggs (females) – occurs in ovaries

• Sperm (males) – occurs in testes (singular = testis)

Fertilization (enables mixing of genes from two different individuals which helps create genetic variation among individuals)

https://www.youtube.com/watch?v=_5OvgQW6FG4

MeiosisMeiosis is similar to mitosis, but results in the formation of gametes: four cells each having only one set of chromosomes (a total of 23 chromosomes)

• Recall that “normal” cells are diploid, they have two sets of 23 chromosomes (one set from mom, one set from dad) for a total of 46 chromosomes

• Gametes are haploid, they have one copy of each chromosome – either from mom or dad (the other copy ended up in the sister gamete)

These cells have two sets of 3 chromosomes, humans have 2 sets of 23 chromosomes

These cells have one set of 3 chromosomes, human gametes have one set of 23 chromosomes

Meiosis• Homologous chromatids or homologous chromosomes have the same

genes but are not identical

• Sister chromatids are exact copies of one another

homologous chromatids homologous chromosomes

sister chromatids

Review of MitosisInterphase DNA Replication

1. Prophase• Chromatin condenses to

form chromosomes

• Mitotic spindle begins to form

3. Anaphase• Centromeres replicate• Mitotic spindle pulls chromatids

apart to opposite sides of cell

2. Metaphase

• Mitotic spindle attaches to chromatid pairs and pulls them into alignment at center of cell

4. Telophase• The cell membrane invaginates and

pinches off between the two daughter cells

MeiosisSimilar to mitosis, but results in four cells each having only one copy of each chromosome (a total of 23 chromosomes)

• Recall that “normal” cells have 23 sets of chromosomes (one from mom, one from dad) for a total of 46 chromosomes

1. DNA replication during interphase2. DNA condenses to form 92 chromatids3. Homologous chromatids from mom and dad

pair up and crossing over occurs4. 46 homologous chromatid pairs line up at

center of cell5. Homologous chromatid pairs are separated

into two halves of cell (random assortment)6. Cytokinesis divides cell into two cells

(each daughter cell gets 23 pairs, 46 chromatids total, each chromatid pair is either derived from mom or dad)

http://www.johnkyrk.com/meiosis.htmlhttp://www.pbs.org/wgbh/nova/baby/divi_flash.htmlhttp://www.cellsalive.com/meiosis.htm

http://www.johnkyrk.com/meiosis.html

http://www.pbs.org/wgbh/nova/baby/divi_flash.html


http://www.cellsalive.com/meiosis.htm


MeiosisSimilar to mitosis, but results in four cells each having only one copy of each chromosome (a total of 23 chromosomes)

• Recall that “normal” cells have 23 sets of chromosomes (one from mom, one from dad) for a total of 46 chromosomes

1. DNA replication during interphase2. DNA condenses to form 92 chromatids3. Homologous chromatids from mom and dad

pair up and crossing over occurs4. 46 homologous chromatid pairs line up at

center of cell5. Homologous chromatid pairs are separated

into two halves of cell (random assortment)6. Cytokinesis divides cell into two cells

(each daughter cell gets 23 pairs, 46 chromatids total, each chromatid pair is either derived from mom or dad)

7. 23 chromatid pairs line up at center of each daughter cell (46 chromatids total)

8. Centromeres divide and 46 chromosomes are separated into two halves of cell

9. Cytokinesis divides two cells into four cells (each gamete gets 23 chromosomes)

http://www.johnkyrk.com/meiosis.htmlhttp://www.pbs.org/wgbh/nova/baby/divi_flash.htmlhttp://www.cellsalive.com/meiosis.htm

http://www.johnkyrk.com/meiosis.html





Mitosis vs. Meiosis• Mitosis results in two daughter cells that are both genetically identical to the

original cell

• Meiosis results in four gamete cells that are each genetically identical due to crossing over and random assortment

23 chromosomes (haploid cells = gametes)

46 chromosomes (one set of 23 from

each parent)

92 chromatids

Diploid cells (identical to original cell)

46 chromosomes

46 chromosomes

92 chromatids (crossing over occurs between

homologous chromosomes)

46 chromosomes (random assortment divides mom and dad chromosomes)

Meiosis

Genetic variation comes from• Mutations

• Crossing Over

• Random Assortment

Results in four genetically unique haploid cells (gametes)

Predicting Inheritance

Phenotype: White

Genotype: pp

(homozygous recessive)

Phenotype: Purple

Genotype: PP

(homozygous dominant)

Gregor Mendel – “Father of Genetics”• Found that alleles show up in predictable patterns and that

some alleles show up more often than others• Punnett Square – tool used to predict probability of a

particular phenotype

Learn Biology: How to Draw a Punnett Square:https://www.youtube.com/watch?v=prkHKjfUmMs

Mr. Anderson: Mendelian Geneticshttps://www.youtube.com/watch?v=NWqgZUnJdAY

Pure-Breed Dominant Crosses result in: 100% chance dominant phenotype

Predicting Inheritance• Homozygous (Pure-Breeds) - both alleles are the same

Pure-Breed Recessive Crosses result in: 100% chance recessive phenotype

Hybrid Crosses result in: 75% chance dominant phenotype25% chance recessive phenotype

Predicting Inheritance• Heterozygous (Hybrids) - both alleles are different• Carriers – heterozygous for a recessive trait

Both parents have the dominant phenotype but are carriers for the recessive allele

Inheritance

Gregor Mendel – “Father of Genetics”• Found that alleles can be tracked through multiple

generations and probabilities determined

First Generation: 100% chance dominant phenotype

Second Generation: 75% chance dominant phenotype

Third Generation: 63% chance dominant phenotype

100% chance 75% chance 75% chance 0% chance

Linked genes (genes that occur very close to one another on a chromosome) are the exception (for example, freckles and the gene for red hair are close together on the same chromosome)

Summary of Mendel’s Principles

Gregor Mendel’s work forms the basis of modern genetics:

• Genes are passed from parent to offspring

• Some forms of genes (alleles) are dominant while others are recessive

• Genes randomly segregate (random assortment) when gametes are formed= Law of Segregation

• The alleles for different genes usually segregate independently of one another = Law of Independent Assortment

Solving Punnett SquaresIf a round pea plant (AA) is crossed with a wrinkled pea plant (aa), what percent of the offspring will be:

• Round?

• Wrinkled?

If two heterozygous round pea plants are crossed, what percent of the offspring will be:

• Round?

• Wrinkled?

If a heterozygous round pea plant is crossed with a homozygous wrinkled pea plant, what percent of the offspring will be:

• Round?

• Wrinkled?

Solving Punnett Squares

Depending on how the chromosomes independently assort determines the genotype, and thus phenotype, of the resulting progeny (offspring)

Parents

Offspring

Predicting phenotype gets more complicated when you look at more than one trait at a time

Honors

Solving Punnett Squares

If a round, yellow pea plant (AABB) is crossed with a wrinkled, green pea plant (aabb), what percent of the offspring will be:

• Round and yellow?

• Round and green?

• Wrinkled and yellow?

• Wrinkled and green?

Honors

• Complete Dominance (what we have been studying): Homozygous dominant genotype dominant phenotype

Heterozygous genotype dominant phenotype

Homozygous recessive genotype recessive phenotype

Other Types of Inheritance

• Complete Dominance

• Codominance Homozygous genotype one phenotype

Heterozygous genotype both phenotypes

R1 R1

R2 R1R2 R1R2

R2 R1R2 R1R2

R R

W RW RW

W RW RW



• Codominance Homozygous genotype one phenotype

Heterozygous genotype both phenotypes



• Codominance

• Incomplete Dominance Homozygous genotype one phenotype

Heterozygous genotype new phenotype(usually an intermediary between both)

C = curly CS = wavy S = straight

C C

S

S

CS

CS

CS

CS



• Codominance

• Incomplete Dominance Homozygous genotype one phenotype

Heterozygous genotype new phenotype(usually an intermediary between both)

Pink = new genotype



• Codominance

• Incomplete Dominance

• Sex-Linked X-linked: gene lies on X

chromosome (males only have one copy of the gene)

Y-linked: gene lies on Y chromosome (only males have the gene)

Contributes to slightly younger mortality rate in males – males are more likely to have a genetic disease

Hemophilia



• Codominance


• Sex-Linked X-linked: gene lies on X

chromosome (males only have one copy of the gene)

Y-linked: gene lies on Y chromosome (only males have the gene)

Contributes to slightly younger mortality rate in males – males are more likely to have a genetic disease

Phenotypic Expression Varies

Hemophilia


• Codominance


• Sex-Linked X-inactivation disables one

x-chromosome in each cell (females and males each only use one x-chromosome)

can lead to unique phenotypes in females


• Polygenic Traits

Controlled by more than one gene

Most common type ofexpression


There are two layers to the iris, the anterior and the external, or front and back layers. To produce blue eyes, there is no pigment found in the front layer. The brown pigment melanin is deposited in the back layer only. It appears blue because of reflection and diffraction of light. In green eyes, a small amount of melanin is deposited in the front layer of the iris along with the melanin found in the back layer. The additional pigment to the amount needed for blue eyes, causes the eye to appear green. To produce gray eyes, the dark pigment is distributed in the front layer of the iris and over the blue background it appears gray. In brown eyes there is so much pigment in the front layer, that the blue behind is completely covered up. Some people have so much pigment in the front layer that their eyes appear very dark brown or black. Hazel, blue-green, gray-blue eye colors are produced by different amounts of pigmentation and the pattern in which the pigment is placed. Albino eyes are have no pigment at all in either layer of the iris. The iris appears pink or red because of the reflection of blood vessels in the back of the eye. The pattern in which the pigment is deposited is also determined by genetics. The pigment may be deposited in rings, clouds, radial stripes, or spread over the entire iris. (from http://www.sewanee.edu/)

There are three known gene pairs that control eye color. The bey 2 gene on chromosome 15 contains a brown and blue allele, the bey 1 gene on chromosome 15 contains a brown gene, and the gey gene on chromosome 19 contains a green allele and a blue allele. All four alleles must be blue to produce a blue eyed person.

https://www.youtube.com/watch?v=Zf2hnFhyJFI

Sources of Genetic Diversity

During Interphase (DNA Replication)

• Mutations – create new alleles

During Meiosis

• Random Assortment (law of segregation) – mixes up chromosomes inherited from mother and father

• Crossing Over – mixes up genes that occur on the same chromosome

(“Linked genes” occur adjacent or very close to one another on the same chromosome and so are almost always inherited together)

During Sex

• Fertilization – mixes up genes from two different partners

Inherited(from mom or dad or both)

New Mutations (“De Novo”)(new point mutations or chromosomal)

Genetic Disorders

Gametes(egg / sperm)

meiosis

Complete Dominance

Incomplete Dominance

Codominance

Sex-Linked

Polygenic Traits

Tay Sachs (one wrong letter)http://www.pbs.org/wgbh/nova/genome/program.html

How do mutations during meiosis affect an organism differently than mutations during mitosis?

http://www.pbs.org/wgbh/nova/genome/program.html

http://www.pbs.org/wgbh/nova/genome/program.html

Pedigrees

Autosomal Dominant PedigreeHow can we tell?

• Graphically shows the lineage of a disorder in a particular family

• Be able to tell if disorder is dominant, recessive, or sex-linked from a pedigree

• Be able to predict the chance that an indicated couple will have a child with the disorder

Autosomal Recessive PedigreeHow can we tell?

PedigreesSex-Linked Pedigrees

How can we tell?

Which is X-linked and which is Y-linked?

Is the X-linked dominant or recessive?

Honors

Practice Problems1. What are gametes? Where are they made in the body? How are they made?

2. What are the eight phases of meiosis? What occurs during each phase? How does meiosis differ from mitosis?

3. How do crossing over and random assortment “mix up” genes so that children are genetically different from their parents?

4. At each step of meiosis, is the cell haploid or diploid?

5. If an allele is dominant and two heterozygous individuals mate, what is the chance that their child will have the dominant phenotype?

6. If two alleles are codominant and two heterozygous individuals mate, what is the chance that their child will have both phenotypes?

7. If two individuals mate and their child has a phenotype completely different from both parents, what was the genotype of the parents?

8. If a disorder is X-linked and a normal man mates with a woman who is a carrier, what is the chance that they will have a boy with the disorder? What is the chance that they will have a girl with the disorder?

paper bag project

Documents