chapter 11: genetics. 1. asexual reproduction a. a single celled organism undergoes ______________...

Chapter 11: Genetics

1. Asexual Reproduction

a. a single celled organism undergoes ______________ to create 2 identical offspring

b. prokaryotes undergo ______________ to create 2 identical offspring

2. Sexual Reproduction

a. ______________ must occur between 2 specialized

reproductive cells (gametes).

b. ______________ - the division of a cell to create gametes with __ the genetic information of a normal cell

______________ – the passing of characteristics or traits from one generation to the next.

binary fission

Heredity

fertilization

mitosis

Meiosis

1/2

identical

Genetically Different

11-4 Meiosis A Purpose of Meiosis

a ________ gametes – ____________ divisionb genetic ______________

1 crossing over2 independent assortment

Chromosome # Somatic Cell Gamete

DiploidHomologous Pairs

Diploid HaploidNo Homologous Pairs

Homo sapianHumans

DrosophilaFruit Fly

Pisum sativumCommon Pea

reduction

variation

2n 2n n

46 46 23

8 8 4

12 12 6

B. Phases of Meiosis – Interphase Meiosis 1Meoisis II

1. Interphase – a. G phases (G1 & G2) - cell growth, protein

synthesis organelle productionb. S phase - DNA replication

2. Meiosis I – segregation of __________

PROPHASE I•homologous pairs form _________

•nucleus and nucleolus _________•_______________ occurs•2n, duplicated

Prophase I

tetrads

disappearcrossing over

Homologous pairs

Interphase I

Metaphase I

METAPHASE I•spindle fibers attach•tetrads____________

*Independent Assortment

ANAPHASE I•homologous pairs (alleles) _____________ (segregate)

*Principle of Segregation

Anaphase IProphase I

line up

separate

Interphase I

TELOPHASE I (with cytokinesis)•nuclear membrane reforms•2 ______________ daughter cells

•______________ •1n, duplicated

Prophase I Metaphase I Anaphase I

Telophase I

(with cytokinesis)

haploidnot identical

Interphase I

Prophase II Metaphase II Anaphase II Telophase II (and Cytokinesis)

o nucleus and nucleolus disappear

o 1n, duplicated

o sister __________line up

o spindle fibers attach

o sister chromatids ____________

o nucleus reforms o ______________ daughter cells (__________) o 1n, unduplicated o genetically unique

3. Meiosis II – separation of _________________ sister chromatids

chromatidsseparate

4 haploidgametes

C. Formation of Gametes

1. Female – ______________

a.____ haploid cells are produced

1 1 viable cell (gamete) = ___________

2 3 __________ due to unequal distribution of cytoplasm and organelles

2. Male – Spermatogenesis

a. 4 viable cells (gametes) = ______________

oogenesis4

eggpolar bodies

sperm

http://wps.prenhall.com/esm_freeman_biosci_1/7/1957/501052.cw/index.html

The human life cycle

Room for sketch in notes

Com

parison of Mitosis

and Meiosis

*Handout

http://biologyinmotion.com/cell_division/

 Mitosis Meiosis

Number of daughter cells

Type of cells produced    

Number of divisions    

Number of DNA replications

Purpose of division    

2 diploid cells

1

1

Growth, repair, asexual reproduction

gametes

2

1

4 haploid cells

Sexual reproduction, genetic variation

Somatic Cells/Body cells

11-1 The Work of Gregor Mendel

A. Gregor Mendel’s Peas1. Mendel (1822-1884)

a. a priest, mathematician, scientist and teacher

b.experiments with ________laid the foundation for the science of genetics

pea plants

2. The Common Pea (Pisum Sativum)

a. Monoecious – a plant have both male and female sexual parts (________________)b. Self Pollinating – The sperm cells pollinate the eggs cells of the ______________ c. True- breeding – the plants produced offspring ______________ to themselvesd. Mendel ___________ these flowers to see what would happen

stamen/pistil

same plant

identicalcross pollinated

B. Mendel’s Discoveries

1. Mendel crossed plants with contrasting traits to study the outcome (yellow seed x green seed)

2. P – parental (true breeding) yellow seed x green seed

F1 – filial (hybrid) the result of a P cross

all offspring came out yellow

Mendel’s Traits

Seed Shape

Flower Position

Seed CoatColor

Seed Color

Pod Color

Plant Height

PodShape

Round

Wrinkled

Round

Yellow

Green

Gray

White

Smooth

Constricted

Green

Yellow

Axial

Terminal

Tall

Short

Yellow Gray Smooth Green Axial Tall

2 CONCLUSIONS:

1. Factors (genes) have different forms (alleles)

ex. seed color – gene; green and yellow - alleles

2. ________________________: a. Some alleles are dominant and others are

recessive

b. Dominant, Y (capital letter), Recessive, y

(lower case)

Principle of Dominance

3. Were the recessive alleles gone forever?

a. Mendel crossed the hybrid plants of all 7 crosses F1 x F1 to produce the F2 generation.a. F1 Yellow x F1 Yellow = F2 about ¼ of the

plants were ____________ and the rest were yellow

b. The trait reappears. c. ____________________________:

a. At some point the allele for yellow seeds and the allele for green seeds are segregated

b. ______________: This occurs during the formation of gametes, every gamete carries only ______________ of the gene

Principle of Segregation

green

Meiosis I

one copy

(one allele)

11-2 Probability and Punnett Squares

A. Genetics and Probability

1. Probability can be used to predict genetic crosses.2. When alleles segregate, it is random much like

the toss of a coin. 3. Past outcomes cannot predict future outcomes.

1. Every time you flip a coin you have a ½ chance of getting heads.

2. What is the probability of flipping heads twice in a row? three times?

½ x ½ = ____ ½ x ½ x ½ = ______

4. The larger the number of tries (offspring), the more likely the predicted numbers are accurate

1/4 1/8

B. Punnett Squares1. A way to determine the probable outcomes of genetic crosses.2. Punnett Square Vocabulary:

(using attached and free earlobes) Homozygous (true breeding) – both alleles are the

same ex. ______________ Heterozygous – having 2 different alleles ex. ______________ Genotype – the actual genes, alleles carried ex. ______________ Phenotype – the physical characteristic ex. __________________________

FF, ff

Ff

FF, Ff, ff

free or attached

True Breeding Cross:

Two true breeding plants are crossed (P), a yellow seed (YY)with a green seed (yy). Show the probable offspring (F1)using a Punnett square. Parents:_________ Possible Gametes: _______ x ________

F1:

YY x yyY, Y y, y

Y

Yy

Yy

Yy

Yy

yy

Y

Genotype:

100% Yy

Phenotype:

Yellow Seeds

Gamete

s

Hybrid Cross: Two F1 hybrid yellow seed plants are

crossed. Show the probable offspring (F2) using a Punnett square.

F1: ___________ Possilble Gametes:______x _______

F2:

Yy x YyY, y Y, y

Y

y

Y y

YY Yy

Yy yy

G 1:2:1

YY - 25% - yellowYy - 50% - yellowyy - 25% - green

P 3:1

11-3 Exploring Mendelian Genetics

A. Independent Assortment1. Mendel wondered if one gene or pair

of alleles had an affect on another pair. ex. Does seed shape affect the color

of the plant?

2. To illustrate what Mendel was attempting a ______________is used.Dihybrid Cross

True Breeding Dihybrid Cross (2 Factor Cross)

A homozygous round, yellow seed plant is crossed with a homozygous wrinkled, green seed plant.

P: ______________1. Make possible gametes FOIL method2. ______________ x ______________

1. Place gametes on the axis of the Punnett Square1. Cross the gametes

F1: _________

genotype: _____________ phenotype: _____________

RRYY x rryy

RY, RY, RY, RY ry, ry, ry, ry

RY

RY

RY

RY

ry ry ry ry

RrYy100% RrYy

RrYy

Round, yellow

RrYy RrYy RrYy

F1 Dihybrid Cross (2 Factor Cross)

Cross the F1 generation from the true breeding dihybrid cross.

F1: ______________1. Make possible gametes FOIL method2. ___________x________3. Place gametes on the axis of the Punnett Square4. Cross the gametes

RrYy x RrYy

RY, Ry, rY, ry RY, Ry, rY, ry

RY

Ry

rY

ry

RY Ry rY ry

F1 Dihybrid Cross (2 Factor Cross)

RRYY RRYy RrYY RrYy

RRYy RRyy RrYy Rryy

RrYY RrYy rrYY rrYy

RrYy Rryy rrYy rryy

RY

Ry

rY

ry

RY Ry rY ry

genotype phenotype1RRYY, 2RrYY, 4RrYy, 2RRYy = ____ round yellow1RRyy, 2Rryy = ____ round green2rrYy, 1rrYY = ____ wrinkled yellow1rryy = ____wrinkled green

F2: 9:3:3:1_______________Phenotypic ratio

9

331

Mendel’s actual F2 generation had a ____________________.

Did they sort independently? _____. Seed color and texture were not

connected to each other. All of the traits that Mendel worked with

were on different _______________. They illustrate the idea of

______________________________. What happens if two genes are on the

same chromosome? They can be _______________. the _______________ out the gene is on the

chromosome, the higher chance it can be switched ______________________.

the _______________ genes are to each other, the more likely they are to be linked

similar ratio

YES

chromosomes

Independent Assortment

linkedfarther

during crossing overcloser 2

OVERVIEW: Principle of Dominance

One allele will be _______________ over another allele

FF, ff, Ff Law of Segregation

The different traits/alleles from each parent are _______________ from each other (homologous pairs)*

_______________ Independent Assortment

Different genes located on different chromosomes sort independently from one another.

_______________ Ex. _________________________

________________

expressed

separated

Anaphase I

Metaphase IYellow seeds are not always smooth

B. Beyond Dominant and Recessive

1. Incomplete Dominance – the phenotype of heterozygous individuals are a _______________ of the 2 alleles

ex. 4 o’clock flowers

blending

Incomplete Dominance in Four O’clock Flowers

Incomplete Dominance in Four O’clock Flowers

2. Codominance – both alleles are_______________but not blended

ex. chicken feathers, human blood types and cholesterol

expressed

3. Multiple Alleles – there are more than _______________for 1 gene

ex. rabbit coat color, human blood type

2 alleles

4. Polygenic Traits – ________________________ gene contributes to a characteristic

ex. skin color, eye color, weight and hair color in humans

More than 1

**Usually associated with a characteristic that has a range of phenotypes

Karyotype

http://www.genomenewsnetwork.org/resources/whats_a_genome/Chp1_2_1.shtml

Crossing Over

Section 11-4

Crossing-Over

Go to Section:

Crossing Over: exchange of genetic material between homologous pairs of chromosomes

Section 11-4

Crossing-Over

Go to Section:

Crossing Over

Section 11-4

Crossing-Over

Go to Section:

Crossing Over

Free and Attached Earlobes