Slides cover Meiosis and Mendelian/ Nonmendelian outlines

Interphase

.

Propase

Duplicated chromosome(two sister chromatids)

Chromosomereplication

2n = 6

Parent cell(before chromosome replication)

Chromosomereplication

MITOSIS MEIOSIS

Chiasma (site ofcrossing over) MEIOSIS I

Prophase I

Tetrad formed bysynapsis of homologouschromosomes

Tetradspositioned at themetaphase plate

Metaphase IChromosomes positioned at themetaphase plate

Metaphase

AnaphaseTelophase

Homologuesseparateduringanaphase I;sisterchromatidsremain together

Sister chromatidsseparate duringanaphase

Daughtercells of

meiosis I

Haploidn = 3

Anaphase ITelophase I

MEIOSIS IIDaughter cells

of mitosis

2n2n

n

Sister chromatids separate during anaphase II

n n nDaughter cells of meiosis II

TWO Divisions (easy version – meiosis)

(First Division)

(Second Division)

Spermatogenesis

Spermatogonium

Primary spermatocyte(in prophase of meiosis I)

Mitotic division, producinglarge numbers of spermatogonia

Meiosis I completed

Differentiation and onset of meiosis I

Secondary spermatocyte

Meiosis II

Earlyspermatids

Spermatids(at two stages ofdifferentiation)

Differentiation

Sperm cells Neck

Head Midpiece TailPlasma membrane

MitochondriaAcrosome Nucleus

Sertoli cellnucleus

Lumen ofSeminiferous tubule

Cross sectionof seminiferoustubule

Testis

EpididymisSeminiferous tubule

Oogenesis in the ovaries

Primary germ cellin embryo

Mitoticdivision

Primaryoocyte

Ovary

Oogonium

DifferentiationOogoniumin ovary

Primaryoocytewithinfollicle

Growingfollicle

Secondaryoocyte

Completion of meiosis Iand onset of meiosis II

Ovulation

First polar body

Mature follicleEntry of spermtriggerscompletionof meiosis IISecond polar body

Ovum

Rupturedfollicle

Ovulatedsecondary oocyte

Corpus luteum

Degen-erating corpus luteum

Crossover in Prophase I

Mitosis vs. Meiosis

Propase

Duplicated chromosome(two sister chromatids)

Chromosomereplication

2n = 6

Parent cell(before chromosome replication)

Chromosomereplication

MITOSIS MEIOSIS

Chiasma (site ofcrossing over) MEIOSIS I

Prophase I

Tetrad formed bysynapsis of homologouschromosomes

Tetradspositioned at themetaphase plate

Metaphase IChromosomes positioned at themetaphase plate

Metaphase

AnaphaseTelophase

Homologuesseparateduringanaphase I;sisterchromatidsremain together

Sister chromatidsseparate duringanaphase

Daughtercells of

meiosis I

Haploidn = 3

Anaphase ITelophase I

MEIOSIS IIDaughter cells

of mitosis

2n2n

n

Sister chromatids separate during anaphase II

n n nDaughter cells of meiosis II

Independent Assortment

Key

Maternal set ofchromosomes

Paternal set ofchromosomes

Possibility 1 Possibility 2

Combination 2Combination 1 Combination 3 Combination 4

Daughtercells

Metaphase II

Two equally probablearrangements ofchromosomes at

metaphase I

Locus(Gene locations on chromosomes)

Alleles for a gene

True breeds & Hybrids

Phenotype vs. GenotypePhysical Trait vs. Gene allele type

Test Cross

Dominant phenotype,unknown genotype:

PP or Pp?

If PP,then all offspring

purple:

p p

P

P

Pp Pp

Pp Pp

If Pp,then 1

2 offspring purpleand 1

2 offspring white:

p p

P

Ppp pp

Pp Pp

Recessive phenotype,known genotype:

pp

Monohybrid

Dihybrid

Dihybrid – Normal 9:3:3:1 ratio

Law of Segregation - Anaphase

Independent Assortment

Key

Maternal set ofchromosomes

Paternal set ofchromosomes

Possibility 1 Possibility 2

Combination 2Combination 1 Combination 3 Combination 4

Daughtercells

Metaphase II

Two equally probablearrangements ofchromosomes at

metaphase I

Complete Dominance

Incomplete Dominance

Codominance (AB) & Multiple Alleles

Pleiotropy (Sickle Cell)

Epistasis

Sperm

BC bC Bc bc

BbCcBBCcBbCCBBCC

BbCC bbCC BbCc bbCc

BbccBBccBbCcBBCc

BbCc bbCc Bbcc bbcc

BC

bC

Bc

bc

BbCc BbCc

14

14

14

14

14

14

14

14

916

316

416

Polygenic Inheritance&

Norm of the Reaction

aabbcc Aabbcc AaBbcc AaBbCc AABbCc AABBCc AABBCC

AaBbCcAaBbCc

20/64

15/64

6/64

1/64

Frac

tion

of p

roge

ny

Multifactorial example(Acid in soil changes the color)

.

Ww ww ww Ww

Ww wwWwwwwwWw

WW wwor

Ww

No widow’s peak

Thirdgeneration

(two sisters)

Widow’s peak

Second generation(parents plus aunts

and uncles)

First generation(grandparents)

Dominant trait (widow’s peak)

.

First generation(grandparents) Ff Ff

FF or Ff ff ff Ff Ff

ff

ff

Ff

Second generation(parents plus aunts

and uncles)

Thirdgeneration

(two sisters)

Attached earlobe Free earlobe

ff FForFf

Recessive trait (attached earlobe)

Genes on Chromosomes

Female (XX) Karyotype(Remember… “kary” means “nucleus”)

Autosomes and linked genes

Linkage Map based on Crossover

frequency

Recombinationfrequencies

9% 9.5%

17%

b cn vg

Chromosome

Locus Gene Maps

Sex –Linked Female – TWO Xs

Sex-Linked Male – ONE X

One from EACH parentSperm AND Egg

Pedigree of Color Blindness

Pedigree of Hemophila

Non-Disjunction

Trisomy 21

Chromosome Structure Errors

Extranuclear DNA(This DNA CAN can affect an organism)