Name: _________________________________ Date: _____________ Per. ______

Meiosis Card ActivityInstructions:Match the pictures with the descriptions for the steps of MeiosisDraw the phases below with a brief description and answer the following questions.

Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase II

Cytokinesis

1. How many times does the cell divide during meiosis? _________________2. How many cells are made during meiosis? _____________________3. If humans have 46 chromosomes, how many chromosomes are found in each cell at

the end of meiosis? _________________4. What type of cells do you think go through meiosis? ___________ Why? _________

_____________________________________________________________________5. How do you think meiosis is different in boys then girls? ______________________

_____________________________________________________________________6. List three ways you think Meiosis is different than Mitosis.

a. _______________________________________________________________b. ______________________________________________________________c. _______________________________________________________________

Name: __________________________ Per. __________ Genetics is the Study of _________________

Unit 8- Meiosis & Mendelian GeneticsAlthough the resemblance between generations of organisms had been noted for thousands of years, it wasn’t until the 1800s that scientific studies were carried out to develop an explanation for this. Today we know that we resemble our parents because of heredity, which is the set of characteristics we receive from our parents. The study of heredity is known as genetics.

I. SEXUAL REPRODUCTION & MEIOSIS (270-276) In sexual reproduction, an egg and sperm cell fuse together to create a fertilized egg or

zygote. Egg and sperm cells are known as gametes. Gametes are created through a special process of cell division called meiosis which halves

the chromosome number. Meiosis only occurs in the ovaries of females and the testes of males

A. Chromosome Number1. Somatic Cells: (body cells)

Human Somatic cells contain 46 chromosomes and are diploid or 2n because they have a double set of chromosomes. 23 from mom and 23 from dad.

These “matching” chromosomes are known as homologous pairs

Homologous pairs- same pair of chromosomes- one from each parent, with the same type of characteristics or genes.

2. Gametes: (sex cells) Egg & Sperm- contain 23 chromosomes and are haploid or n. These contain ½ the total number of chromosomes or single set of chromosomes. Fertilization – when gametes fuse together- egg + sperm = zygote (n + n= 2n)

B. Formation of Gametes

Formed in Meiosis Occurs in ovaries of females and testes of males In Meiosis, DNA is replicated once in S of interphase, but the cell goes through 2 divisions,

resulting in 4 daughter cells with ½ the original chromosome number.

Meiosis occurs in 2 stages:1. Meiosis 1-

Before meiosis I - DNA is replicated in S of interphase. End up with chromosomes, each consisting of 2 sister chromatids.

Prophase I- pairing of homologous chromosomes & Crossing Over- produces exchange of genetic info (so siblings look different from each other)

Metaphase I- Sister chromatids line up in the middle of the cell in homologous pairs Anaphase I & Telophase I- the homologous pairs separate, but the sister chromatids are still

connected at the centromere Two cells are formed with 23 pairs of Sister Chromatids = 23 chromosomes, but there are no

longer any homologous pairs so the cells are haploid or n. 2. Meiosis II-

The two cells Do NOT go through interphase (DNA does NOT replicate again)!!! Prophase II- Chromosomes condense (again) & spindles form Metaphase II- Chromosomes align in the middle Anaphase II- Sister chromatids are pulled apart Telophase II- Four nuclei form around chromosomes

Genetics is the Study of _________________

What is the end result of Meiosis?

What would happen if the sister chromatids of one pair did not separate during anaphase II?

4 new cells are formed, each with ½ the original number of chromosomes as the original.

C. Crossing Over: Occurs during prophase I when homologous

pairs of chromosomes come together. Part of one sister chromatid breaks off and

exchanges with the corresponding portion of a sister chromatid of the homologous chromosome.

Very common and Increases the genetic variability in offspring.

II. Meiosis in Men and Women: During Spermatogenesis (the production of

sperm), Men will produce 4 sperm cells for each somatic cell.

During Oogenesis (the production of ovum or egg cell), the woman will produce 1 egg and 3 polar bodies (non-viable cells that get “flushed” out) for each somatic cell

III. Comparison of Mitosis & Meiosis (pg. 275)Mitosis Meiosis

Definition: Definition:

Cells where process occurs: Cells where process occurs:

What is the end result of Meiosis?

What would happen if the sister chromatids of one pair did not separate during anaphase II?

Number of DNA Replications: Number of DNA Replications:

Number of Cell divisions: Number of Cell divisions:

Number of Resulting Daughter cells: Number of Resulting Daughter cells:

Chromosome number in Original Cell: Chromosome number in Original Cell:

Chromosome number in Daughter cell: Chromosome number in Daughter cell:

Purpose for cell division: Purpose for cell division:

Illustration: Label each cell as n or 2n and describe each step using pg. 275 in book:

Illustration: Label each cell as n or 2n and describe each step using pg. 275 in book:

Rules for InheritanceEvidence

DescriptionWhat do you notice? Questions you have What your

learned so far1.

2.

3.

4.

5.

6.

Based on the evidence presented, What Are the Basic Rules for Inheritance?

IV. History of Genetics (pg. 277-285)A. Gregor Mendel-

“Father of Genetics” Did experiments on pea plants Studied 7 traits: plant height, seed color,

follower color ect.. Used true-breeding (purebred, prueline)

which means the characteristics always show.

Generation of true-breeding plants is known as P generation.

Trait- an inherited characteristic Cross-pollinated – pollen from one plant

fertilizes an egg from another. Self-pollinate- pollen can fertilize egg from

same plant. Mendel did experiments by controlling cross-pollination and preventing self-

pollination.

B. Mendel’s Results:1. P generation:- Cross a purebred with one trait with a purebred with another trait.

Example: Tall plant x short plant

2. F1 generation- offspring produced from P x P. In F1, one trait disappearsExample: Tall plant x short plant = all tall plants (Tt)

3. F2 generation- Offspring produced from F1 x F1. In F2 the trait that disappeared in F1

comes back in ¼ of the offspring; the other ¾ shows the trait seen in F1

C. Mendel’s Principles- 1. Law of Dominance- For each gene, an organism inherits two alleles, one from each parent. Alleles are

different forms or possibilities of a gene. The dominant trait is the trait shown and is represented by a capital letter. T=

tall The recessive trait is the trait that is hidden and is represented by a lower case

letter, t = short. Homozygous= same TT = tall or tt= short

Homozygous Dominant- TT = Tall or RR= Round or BB= Brown Homozygous Recessive- tt= short or rr= wrinkled or bb = blond

Heterozygous= (hybrid) different Tt the plant will be tall, but they carry the recessive trait

2. Genotype and Phenotype- Phenotype- the physical description of the trait. Ex: tall, short, brown, blond Genotype- The genetic make-up of the organism’s alleles. Ex: TT, Tt, tt

3. Mendel’s law of segregation- In meiosis the two alleles for a trait segregate (separate). Each egg or sperm

receives a copy of one of the two alleles. There is a 50% chance that a copy of that allele will end up in the gamete.

Why is Mendel known as the Father of Genetics?

What does P generation mean? ________________

Explain what true-breeding means:

If you cross a true-breeding plant with yellow flowers with a true-breeding plant that also has yellow flowers, what are you going to get?

If you cross a golden retriever with a golden retriever what are you going to get?

P =F1 =F2 =

Pure Tall= TTPure short = ttCross a TT x tt

What do you get?

Cross the offspring from the problem above:

Genotype: ____________(Homo Dom : Hetero: Homo rec)

Phenotype: ___________ (Dom : Rec)

B=Black, b= greyCross a Homozygous black rabbit with a heterozygous rabbit.

During fertilization the two alleles (one from mom and one from dad) will unite.

4. Mendel’s Law of Independent assortment- Random distribution of alleles occur during gamete formation Genes on separate chromosomes sort independently during meiosis.

Homework Practice Problems:Write examples of the following: using long hair (L) and short hair (l) : Long hair is dominant

1. Two dominant alleles ________2. Two recessive alleles ________3. Homozygous alleles ________ & _________4. Heterozygous alleles _______

B=Black, b= greyCross a Homozygous black rabbit with a heterozygous rabbit.

Give the phenotype for the following plants T=tall t=short5. TT _________________6. Tt __________________7. tt ___________________

Which guinea pigs are black? B= black b= white8. BB __________________9. bb ___________________10. Bb ___________________

What is the phenotype of the morning glories? B=blue b= white11. BB __________________12. bb ___________________13. Bb __________________

Given the 3 genotypes: ll, LL & Ll with L= long hair in dogs & l = short hair. In the space below tell which genotype is homozygous recessive, which is heterozygous and which is homozygous dominant

14. Ll _____________________________________15. LL _____________________________________16. ll ______________________________________

V. Analyzing InheritanceA. Probability

Due to the law of segregation if you know the genotype of the parents, you can predict the outcome of the offspring.

Probability can be written 3 ways: The probability of a coin coming up heads:1. Fraction: ½ 2. Ratio: 1:23. Percent: 50%

B. Punnett Squares Used to predict the possible outcomes of meiosis and fertilization. Predict the probability of certain traits appearing in offspring

VI. Punnett Practice:A. Monohybrid Cross- (Cross one trait at a time)

1. Construct a Punnett square to determine the probability of white flowers if a heterozygous purple (Pp) flower is crossed with a homozygous white (pp) flower.

Key: ____________________________

Cross: _________________________

Genotype ratio: = ___________________Phenotype ratio:= ___________________Percentage of white flowers: _______________

2. Construct a Punnett square to determine the probability of short pea plants if a homozygous tall (TT)plant is crossed with a heterozygous tall (Tt) plant.

Key: ____________________________

Cross: _________________________

Genotype ratio: = ___________________Phenotype ratio:= ___________________Fraction of plants that will be heterozygous: ____________________

In purple people eaters the color Purple is dominant over red.P= purpleP = red

Cross a Hetero with a red purple people eater:

Give the probability of:Geno: _____________Pheno: _____________

What terminology would be described if I said “The dog was black”?

What terminology would be descried if I said “The dog was BB”?

3. In Flowers Red is dominant over white. One flower is heterozygous red and it is crossed with a homozygous white plant.

Key: ____________________________

Cross: _________________________

Genotype ratio: = ___________________Phenotype ratio:= ___________________

4. In certain species of pine trees, short needles are dominant (S) to long needles (s). What is the probability of the offspring having long needles if you cross a heterozygous with a long needle plant?

Key: ____________________________

Cross: _________________________

Genotype ratio: = ___________________Phenotype ratio:= ___________________

Homework Practice Problems:1. . In flies, red eyes (R) are dominant to brown eyes (r). A heterozygote fly is crossed with homozygous recessive fly. a. What percentage of offspring will have brown eyes? ___________

b. What fraction of offspring will be heterozygotes? ___________

2. In a plant species, long stems (L) are dominant to short stems (l). A heterozygous plant is crossed with a homozygous dominant plant.

a. What percentage of offspring will have short stems? ___________

b. What will be the ratio of genotypes in the offspring? _________________

3. In a species of mammals, gray fur (G) is dominant to white fur (g).Two heterozygous mammals are mated together and produce offspring.

a. What fraction of offspring will have gray fur? ___________

b. What percentage of the offspring will be white fur? ___________

4. In plants, being short (t) is recessive to the tall allele (T).A heterozygous plant is crossed with a short plant.

a. What will be the ratio of tall plants to short plants? _______________

b. What fraction of offspring will be homozygous recessive? ___________

5. In a certain animal, green eyes (B) are dominant and blue eyes (b) are recessive. A heterozygote is mated with a blue eyed animal.a. What fraction of offspring will have blue eyes? ___________

b. What percentage of the offspring will be heterozygotes? ___________

B. Dihybrid Cross- (Cross two traits at a time)

1. If a pea plant with genotype RRYy (round, yellow peas) is crossed with a pea plant with genotype rrYy (wrinkled, yellow peas), what would the results be?

Key: R = round, r = wrinkled; Y = yellow, y = green

Cross: ________________________________________How many Round and Yellow _____How many Round and green _____

How many wrinkled and Yellow ______How many are wrinkled and green ______

2. Cross a GgRr x GgRrKey: G = gray body R = red eyes g = black body r = black eyes

Cross: ___________________________________How many Gray and Red eyes __________How many Gray and black eyes _________How many black and Red eyes _________How many black and black eyes ________

3. In Purple People Eaters Having horns is dominant to no horns and being purple is dominant to being red. If you cross a heterozygous for horned red monster with a no horned heterozygous purple monster what would you get?

Key: __________________________________________________________________Cross: ___________________________________

How many Horned Purple monsters ______How many Horned red monsters ________How many no horned purple monsters _________How many no horned red monsters ________

The other way to do this:Using the same cross as above:What fraction of offspring will have the genotype of HhPp ____________

Homework Practice ProblemsIn flies, red eyes (R) are dominant to brown eyes (r) and brown bodies (B) are dominant to yellowbodies (b). A fly with genotype RrBb is mated with a fly with genotype rrbb.

a. What percentage of offspring will genotype RRbb? ___________

b. What fraction of offspring will have red eyes and brown bodies? ____________

Show your math:

2. In pea plants, smooth peas (S) are dominant to wrinkled peas (s) and purple flowers (P) are dominantto white flowers (p). Two plants that are heterozygous for both traits (SsPp) are crossed.

a. How many different genotypes will appear in the offspring? ___________

b. What percentage of the offspring will have smooth peas and purple flowers? ____________

Show your math:

3. In certain birds, yellow feathers (g) are recessive to green feathers (G) and short beaks (l) arerecessive to long beaks (L). A bird with genotype (ggLl) is crossed with a bird with genotype (GgLl).

a. How many different combinations of phenotypes will be in the offspring? ___________

b. What fraction of offspring will yellow feathers and long beaks? ____________

Show your math:

4. In a certain species of mammals, gray fur (G) is dominant to white fur (g) and brown eyes (B) are dominant to blue eyes (b). An animal with white fur and blue eyes is crossed with an animal that hasgray fur and brown eyes (GGBb).

a. What trait will appear in all of the offspring of this mating? _________________________

b. What fraction of offspring will have genotype GgBb? ____________

Show your math:

6. In plants, being tall (T) is dominant to being short (t), and smooth peas (S) are dominant to wrinkledpeas (s). A tall plant with smooth peas (TtSs) is crossed with a short plant with wrinkled peas.

a. What percentage of offspring will be short with smooth peas? ___________

b. What fraction of the offspring will have the genotype TtSs? ___________

c. What fraction of offspring will be tall with wrinkled peas? ____________

Show your math:

VII. A Closer Look at HeredityA. Incomplete Dominance

Neither allele has “complete” dominance over the other - heterozygous phenotype is a blend of the two colors

For example, in snapdragons if you cross a Red snapdragon (R) with a White snapdragon (R’) you will get a Pink snapdragon (RR’)

1. Cross a red snapdragon with a pink snapdragonKey: ____________________________

Cross: _________________________

Genotype ratio: = ___________________Phenotype ratio:= ___________________

2. In some breeds of rabbits if you cross a black bunny with a white bunny you can get a grey bunny. What will you get if you cross two grey bunnies together?

Key: ____________________________

Cross: _________________________

Genotype ratio: = ___________________Phenotype ratio:= ___________________

B. Co-dominance Both alleles of a gene are dominant and both are seen For example in some breeds of chickens if you cross a black chicken (B) with a

white chicken (W) you will get a checkered (BW) chicken1. Cross a checkered chicken with a white chicken

Key: ____________________________

Cross: _________________________

Genotype ratio: = ___________________Phenotype ratio:= ___________________

2. In some breeds of cows and horses if you cross a red animal (R) with a white (W) animal you can get a Roan (RW) animal. What will you get if you cross two roan animals?

Key: ____________________________

Cross: _________________________

Genotype ratio: = ___________________Phenotype ratio:= ___________________

C. Polygenic Traits- “Many genes” Many traits are controlled by more than one gene. Examples include: hair color, eye color and skin color

D. Multiple Alleles Many genes have options for more than two alleles, although an individual can

only express two alleles, one from mom and one from dad. Example: blood type. There are 3 possible alleles for this: A, B & O (AB is co-

dominant so someone can be blood type AB)

Homework Practice Problems

Use the tables to answer the following questions about incomplete dominance.1. A plant with pink flowers is crossed with a flower that has white flowers. What percentage of the offspring will have white flowers?

2. Two plants that both have heterozygous genotypes (Rr) and pink flowers are crossed to produce offspring. What will be the ratio of phenotypes in the offspring they produce?

4. A dark brown horse is mated with a palomino horse to produce offspring. What percentage of the offspring from this mating would be expected to be palomino horses?

5. A palomino horse (Dd) is mated with a cream colored horse (dd) and they produce offspring. What would be the expected ratio of phenotypes from the offspring of these horses?

Use the tables to answer the following questions about Co-dominanceIn humans, there is a disorder known as sickle cell anemia which is caused by a point mutation. This disorder changes the shape of the red blood cells to where they cannot carry oxygen. Persons of African descent are more likely to be affected with this disorder.

Cross two people who are resistant to malaria and give the fractions for each of the following:1. Malaria Resistant: ____________2. Normal _____________3. Sickle Cell ______________

Cross a man who has sickle cell anemia with a woman who is resistant to malaria and give the percentage of the following:

4. Malaria Resistant: ____________5. Normal _____________6. Sickle Cell ______________

Genotype PhenotypeHH Normal red blood cellsHh Resistance to malaria

Have both normal and sickle red blood cells

hh Sickle Cell Anemia