Question of the DAY DEC 6 Which cells are responsible for the passing on of genetic information from parent to offspring? A. Somatic cells B. Diploid cells.

Question of the DAY DEC 6

• Which cells are responsible for the passing on of genetic information from parent to offspring?

• A. Somatic cells• B. Diploid cells• C. Gametes• D. Cancer cells

DO NOW DEC 6• Work in groups of 3 to complete the DO NOW

• Create a list of physical characteristics you have in common with your group.

• Consider things like eye and hair color, style/texture of hair, shape of nose/ears, and so on.

• Why do we all look different from each other?

DO NOW ANSWERED

• We all have different parents.

• Our parents have their own physical characteristics that are expressed.

• These characteristics have been inherited from their parents as you have inherited characteristics from your parents.

Chapter 11: Introduction to Genetics

11-1: The Work of Gregor Mendel

• heredity: set of characteristics an organism receives from its parents • genetics: study of

heredity

Gregor Mendel

• born in 1822• studied pea

plants and how they reproduced

Reproduction in Pea Plants• pollen is the male sex cell• eggs are the female sex cell• reproduce by self

pollination: process in which pollen fertilizes an egg from the same plant

• reproduces by cross pollination: process in which pollen from one plant fertilizes an egg from another plant

Mendel’s First Experiment• prevented flowers from self

pollinating• controlled cross pollination• cut off male parts of flowers and

dusted flowers with pollen from another flower

• was able to cross plants with different characteristics

• used purebreds: an organism that only produces offspring with only one form of a trait– A specific characteristic such as seed

color or plant height

QUESTION of the Day Dec 9

• Which of the following are not examples of heredity?

• A. the stripes of a zebra• B. the rows of teeth in the mouth of a Great

White Shark• C. speaking a foreign language• D. a tiger hunting prey

DO NOW DEC 9

• If you crossed a Tall pea plant with a short pea plant, how would you predict the offspring produced?

DO NOW ANSWERED

• You would need to know which trait, Tall or short, was the dominant one.

• It is also necessary to identify the alleles from each parent that may be passed down to an offspring.

• This dominant trait will most likely be expressed.

True-Breeding

• True-breeding plants are plants that only carry one allele for a trait.

• If these plants are allowed to self-pollinate, they will produce offspring identical to themselves.– TALL plants produce TALL plants– Green seeded plants produce Green seeded plants

Pea Plant Traits• studied only seven traits

with only two options• decided to cross pea

plants with different characteristics for the same trait

• tall with short, green seeds with yellow seeds, round seeds with wrinkled seeds, and so on

• alleles: different forms of a gene

Mendel’s Results

• offspring were hybrids: organisms produced by crossing parents with differing characteristics

• all hybrids had the characteristics of only one parent

Mendel’s Conclusions

• 1. individual factors, called genes, control each trait

• 2. principle of dominance: some factors or alleles are dominant whereas others are recessive

Mendel’s Second Experiment• allowed hybrid plants to

reproduce among themselves

• kept groups in order– P generation: purebred

group– F1 generation: hybrid

group– F2 generation: offspring

of hybrids

• in F2 plants, the recessive traits reappeared

Mendel’s Results• in his F2 generations, the recessive

trait showed up in ¼ of the offspring

• phenotype: physical characteristics

• genotype: genetic makeup• homozygous: two identical alleles

for a particular trait– TT, homozygous dominant– tt, homozygous recessive

• heterozygous: having two different alleles for the same trait– Tt

Question of the Day DEC 11

• An organism with a genotype of bb is called

• A. Heterozygous recessive• B. Homozygous dominant• C. Heterozygous dominant• D. Homozygous recessive

DO NOW DEC 11

• Determine the possible genotypes of a pea plant that is Tall and has white flowers.

• Tall is dominant over short• Purple is dominant over white flowers

DO NOW ANSWERED

• Possible Genotypes

• TT pp where T = Tall P = Purple t = short p = white

• Tt pp

Genes and Alleles• genes: unit that

determines traits• alleles: different forms

of a gene– have two alleles for

each trait – one from each

parent– sex cells contain one

allele– when sex cells

combine, create cells with two sets of genes

11-2: Probability and Punnett Squares

• probability applies to genetics because the formation of gametes depends on random events

Probability and Punnett Squares• probability: the likelihood that a

particular event will occur• probability = the number of times a

particular event occurs ÷ the number of opportunities for the event to occur

• Punnett squares analyze the results of an experimental cross

• determines the probability of getting certain genotypes and phenotypes

Predicting Averages

• Consider our class and the test we have recently taken.

• If the test average was a 70, explain how this average is possible having only 2 test scores.

• With 3 Test Scores?• These results will depend on the individual

students and courses.

Predicting Averages• Probabilities predict the average outcome of a large

number of events.

• Cannot predict the precise outcome of an single event.

• Also true for genetics.• Larger numbers of offspring will produce results closer

to the expected values/ratios.– In the F1 Gen of Mendel’s pea plants, only 3 or 4 offspring

may not the predicted offspring.– However, hundreds or thousands of these offspring will

produce ratios very close to expectations of Mendel’s results.

Question of the Day Dec 12

• Which ratio did Mendel find in his F2 Generation of pea plants?

• A. 3:1• B. 1:3:1• C. 1:9• D. 4:3

DO NOW DEC 12

• Solve the following problem…

• Cross a Heterozygous Long-clawed panther with a short-clawed panther.

• List all of the possible genotypes and their phenotypes.

• What ratio of panther cubs with short claws?

DO NOW ANSWERED Dec 12

• L = LONG CLAW DOMINANT • l = short claw

L l

l LL ll

l Ll ll

AGENDA DEC 12• BIG Question: How do geneticts use the principle

of probability?

• 1. Question of the Day and DO NOW• 2. Section 11-1/11-2 QUIZ• 3. Principles of Segregation and Independent

Assortment• 4. Inheriting Traits Lab Investigation• 5. Review and Homework– Inheriting Traits Lab Packet DUE FRIDAY

Segregation

• the separation of alleles during gamete formation

• when gametes, or sex cells, come together, new combinations occur

• gene combinations can be represented in a chart using Punnett squares

• monohybrid cross: crossing one trait

Segregation

• F1 plants each have one dominant and one recessive allele.

• When the F1 plants are crossed with each other, the recessive allele reappears in the offspring (F2 Gen)

Independent Assortment• process by which genes

segregate independently• if a plant has a round seed, it

does not mean it will always have a yellow seed

• can cross two traits, called a dihybrid cross, and have independent assortment

• get all sort of genotypes

A Summary of Mendel’s Work

1. genes control heredity2. genes are inherited from each parent3. some forms of the gene may be dominant

and others may be recessive4. segregation occurs during the formation of

reproductive cells5. genes for different traits may sort

independently of one another

Dihybrid Crosses

• Solving for two different traits.• Parents --- RrYy and RrYy• R = Wrinkled seed Y = Yellow seed• Capital Letters = DOMINANT TRAITS

• Use the FOIL method to determine all of the possible genotypes of the parents.

• F=first O=outer I=inner L=last

Dihybrid Crosses

• Parent Genotypes – RrYy

• Use FOIL Method to find possible allele combinations.

• F – RY O – Ry I – rY L – ry

• Allele Combinations – RY Ry rY ry

Dihybrid Crosses

RY Ry rY ry

RY RRYY RRYy RrYY RrYy

Ry RRYy RRyy RrYy Rryy

rY RrYY RrYy rrYY rrYy

ry RrYy Rryy rrYy rryy

Agenda Apr 12

• Big Question: What is meiosis?

• 1. Hand in your Dihybrid Crosses Homework.• 2. DO NOW• 3. The Phases of Meiosis• 4. Chapter 9 Test• 5. Homework --- Read Chapter 13 Section 1– Intro to Evolution

DO NOW Apr 12

• We will review problem #2 from the homework.

• 1. Identify the genotypes of the parents.• 2. Use the foil method to determine all of the

possible allele combinations.• 3. Solve your Punnett Square

Problem #2

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he HhEe Hhee HhEe Hhee

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