Mendelian Genetics

Figure 14.1

Figure 14.3-1

P Generation

EXPERIMENT

(true-breedingparents) Purple

flowersWhite

flowers

Figure 14.3-2

P Generation

EXPERIMENT

(true-breedingparents)

F1 Generation(hybrids)

Purpleflowers

Whiteflowers

All plants had purple flowers

Self- or cross-pollination

Figure 14.3-3

P Generation

EXPERIMENT

(true-breedingparents)

F1 Generation(hybrids)

F2 Generation

Purpleflowers

Whiteflowers

All plants had purple flowers

Self- or cross-pollination

705 purple-flowered

plants

224 whiteflowered

plants

Table 14.1

Figure 14.4

Allele for purple flowers

Locus for flower-color gene

Allele for white flowers

Pair ofhomologouschromosomes

Figure 14.5-3

P Generation

F1 Generation

F2 Generation

Appearance:Genetic makeup:

Gametes:

Appearance:Genetic makeup:

Gametes:

Purple flowers White flowers

Purple flowers

Sperm from F1 (Pp) plant

Pp

PP pp

P

P

P

P

p

p

p

p

Eggs from F1 (Pp) plant

PP

ppPp

Pp

1/21/2

3 : 1

Phenotype

Purple

Purple

Purple

White

3

1

1

1

2

Ratio 3:1 Ratio 1:2:1

Genotype

PP(homozygous)

Pp(heterozygous)

Pp(heterozygous)

pp(homozygous)

Figure 14.6

Figure 14.7

Dominant phenotype,unknown genotype:

PP or Pp?

Recessive phenotype,known genotype:

pp

PredictionsIf purple-floweredparent is PP

If purple-floweredparent is Pp

or

Sperm Sperm

Eggs Eggs

or

All offspring purple 1/2 offspring purple and 1/2 offspring white

Pp Pp

Pp Pp

Pp Pp

pp pp

p p p p

P

P

P

p

TECHNIQUE

RESULTS

Figure 14.10-1

P Generation

Red White

Gametes

CWCWCRCR

CR CW

Figure 14.10-2

P Generation

F1 Generation

1/21/2

Red White

Gametes

Pink

Gametes

CWCWCRCR

CR CW

CRCW

CR CW

Figure 14.10-3

P Generation

F1 Generation

F2 Generation

1/21/2

1/21/2

1/2

1/2

Red White

Gametes

Pink

Gametes

Sperm

Eggs

CWCWCRCR

CR CW

CRCW

CR CW

CWCR

CR

CW

CRCR CRCW

CRCW CWCW

Figure 14.11

Carbohydrate

Allele

(a) The three alleles for the ABO blood groups and their carbohydrates

(b) Blood group genotypes and phenotypes

Genotype

Red blood cellappearance

Phenotype(blood group)

A

A

B

B AB

none

O

IA IB i

iiIAIBIAIA or IAi IBIB or IBi

Figure 14.14

Figure 14.13

Eggs

Sperm

Phenotypes:

Number ofdark-skin alleles: 0 1 2 3 4 5 6

1/81/8

1/81/8

1/81/8

1/81/8

1/8

1/8

1/8

1/8

1/8

1/8

1/8

1/8

1/646/64

15/6420/64

15/646/64

1/64

AaBbCc AaBbCc

Figure 14.12

Sperm

Eggs

9 : 3 : 4

1/41/4

1/41/4

1/4

1/4

1/4

1/4

BbEe BbEe

BE

BE

bE

bE

Be

Be

be

be

BBEE BbEE BBEe BbEe

BbEE bbEE BbEe bbEe

BBEe BbEe BBee Bbee

BbEe bbEe Bbee bbee

Figure 14.9

Segregation ofalleles into eggs

Segregation ofalleles into sperm

Sperm

Eggs

1/2

1/2

1/21/2

1/41/4

1/41/4

Rr Rr

R

R

RR

R

R

r

r

r

r r

r

Figure 14.8

P Generation

F1 Generation

Predictions

Gametes

EXPERIMENT

RESULTS

YYRR yyrr

yrYR

YyRr

Hypothesis ofdependent assortment

Hypothesis ofindependent assortment

Predictedoffspring ofF2 generation

Sperm

Spermor

EggsEggs

Phenotypic ratio 3:1

Phenotypic ratio 9:3:3:1

Phenotypic ratio approximately 9:3:3:1315 108 101 32

1/21/2

1/2

1/2

1/41/4

1/41/4

1/4

1/4

1/4

1/4

9/163/16

3/161/16

YR

YR

YR

YRyr

yr

yr

yr

1/43/4

Yr

Yr

yR

yR

YYRR YyRr

YyRr yyrr

YYRR YYRr YyRR YyRr

YYRr YYrr YyRr Yyrr

YyRR YyRr yyRR yyRr

YyRr Yyrr yyRr yyrr

Figure 14.UN01

Probability of YYRR

Probability of YyRR

1/4 (probability of YY)

1/2 (Yy)

1/4 (RR)

1/4 (RR)

1/16

1/8

Figure 14.UN02

Chance of at least two recessive traits

ppyyRr

ppYyrr

Ppyyrr

PPyyrrppyyrr

1/4 (probability of pp) 1/2 (yy) 1/2 (Rr) 1/4 1/2 1/2 1/2 1/2 1/2 1/4 1/2 1/2 1/4 1/2 1/2

1/16

1/16 2/16

1/16

1/16

6/16 or 3/8

Figure 15.6

Parents

orSperm

or

Egg

Zygotes (offspring)

44 XY

44 XX

22 X

22 Y

22 X

44 XX

44 XY

22 XX

22 X

76 ZW

76 ZZ

32 (Diploid)

16 (Haploid)

(a) The X-Y system

(b) The X-0 system

(c) The Z-W system

(d) The haplo-diploid system

Figure 15.8

Early embryo:

X chromosomesAllele fororange fur

Allele forblack fur

Two cellpopulationsin adult cat:

Cell division andX chromosomeinactivation

Active XInactive X

Active X

Black fur Orange fur

Figure 15.7

Eggs Eggs Eggs

Sperm Sperm Sperm

(a) (b) (c)

XNXN XnY XNXn XNY XNXn XnY

Xn Y XN Y YXn

Xn Xn

XN

XN

XN XNXNXn XNY

XNY

XNY XNY

XnY XnYXNXn XNXn

XNXnXNXN

XnXn

Figure 14.15

Key

Male Female Affectedmale

Affected female

Mating Offspring

1stgeneration

2ndgeneration

3rdgeneration

1stgeneration

2ndgeneration

3rdgeneration

Is a widow’s peak a dominant orrecessive trait?

(a) Is an attached earlobe a dominantor recessive trait?

b)

Widow’speak

No widow’speak

Attachedearlobe

Freeearlobe

FForFfWW

orWw

Ww ww ww Ww

Ww Ww Wwww ww ww

ww

Ff Ff Ff

Ff Ff

ff

ffffffFF or Ff

ff

Figure 15.3

Figure 15.4a

All offspringhad red eyes.

PGeneration

F1

Generation

F2

Generation

RESULTS

EXPERIMENT

Figure 15.4b

F2

Generation

PGeneration

Eggs

Eggs

Sperm

Sperm

Xw

CONCLUSION

XX Y

w

ww w

w

ww w

w

w

w

w

w

ww w

F1

Generation

Figure 15.9-1P Generation (homozygous)

Wild type(gray body, normal wings)

b b vg vg b b vg vg

Double mutant(black body,vestigial wings)

EXPERIMENT

Figure 15.9-2P Generation (homozygous)

Wild type(gray body, normal wings)

F1 dihybrid(wild type)

TESTCROSS

b b vg vg

b b vg vg

b b vg vg

b b vg vg

Double mutant(black body,vestigial wings)

Double mutant

EXPERIMENT

Figure 15.9-3P Generation (homozygous)

Wild type(gray body, normal wings)

F1 dihybrid(wild type)

Testcrossoffspring

TESTCROSS

b b vg vg

b b vg vg

b b vg vg

b b vg vg

Double mutant(black body,vestigial wings)

Double mutant

Eggs

Sperm

EXPERIMENT

Wild type(gray-normal)

Black-vestigial

Gray-vestigial

Black-normal

b vg b vg b vg b vg

b b vg vg b b vg vg b b vg vg b b vg vg

b vg

Figure 15.9-4P Generation (homozygous)

Wild type(gray body, normal wings)

F1 dihybrid(wild type)

Testcrossoffspring

TESTCROSS

b b vg vg

b b vg vg

b b vg vg

b b vg vg

Double mutant(black body,vestigial wings)

Double mutant

Eggs

Sperm

EXPERIMENT

RESULTS

PREDICTED RATIOS

Wild type(gray-normal)

Black-vestigial

Gray-vestigial

Black-normal

b vg b vg b vg b vg

b b vg vg b b vg vg b b vg vg b b vg vg

965 944 206 185

1

1

1

1

1

0

1

0

If genes are located on different chromosomes:

If genes are located on the same chromosome andparental alleles are always inherited together:

:

:

:

:

:

:

:

:

:

b vg

Figure 15.10a

Testcrossparents

Replicationof chromosomes

Gray body, normal wings(F1 dihybrid)

Black body, vestigial wings(double mutant)

Replicationof chromosomes

Meiosis I

Meiosis II

Meiosis I and II

Recombinantchromosomes

Eggs

b vg

b vg

b vg

b vg

b vg

b vg

b vg

b vg

b vg

b vg

b vg

b vg

b vg

b vgb vg

b vg

bvg b vgb vg

b vg

Spermb vg

Figure 15.10b

Testcrossoffspring

965Wild type

(gray-normal)

944Black-

vestigial

206Gray-

vestigial

185Black-normal

Sperm

Parental-type offspring Recombinant offspring

Recombinationfrequency

391 recombinants2,300 total offspring

100 17%

b vg b vgb vgb vg

b vg b vg b vg b vg

b vg

Eggs

Recombinantchromosomes

bvg b vg b vg b vg

Figure 15.11

Chromosome

Recombinationfrequencies

9% 9.5%

17%

b cn vg

RESULTS

Figure 15.12

Mutant phenotypes

Shortaristae

Blackbody

Cinnabareyes

Vestigialwings

Browneyes

Long aristae(appendageson head)

Gray body

Red eyes

Normalwings

Redeyes

Wild-type phenotypes

104.567.057.548.50

Meiosis I

Nondisjunction

Figure 15.13-1

Meiosis I

Meiosis II

Nondisjunction

Non-disjunction

Figure 15.13-2

Meiosis I

Meiosis II

Nondisjunction

Non-disjunction

Gametes

Number of chromosomes

Nondisjunction of homo-logous chromosomes inmeiosis I

(a) Nondisjunction of sisterchromatids in meiosis II

(b)

n 1 n 1n 1 n 1 n 1n 1 n n

Figure 15.13-3

“Normal”Which phase of meiosis is this?

Nondisjunction

Figure 15.15

Figure 15.15b

Figure 14.19

(a) Amniocentesis (b) Chorionic villus sampling (CVS)

Ultrasound monitor

Amnioticfluidwithdrawn

FetusPlacentaUterus Cervix

Centrifugation

Fluid

Fetal cells

Several hours

Severalweeks

Several weeks

Biochemicaland genetic

tests

Karyotyping

Ultrasoundmonitor

Fetus

Placenta

Chorionic villi

Uterus

Cervix

Suctiontubeinsertedthroughcervix

Several hours

Fetal cells

Several hours

1

1

2

2

3

Edward’s Syndrome

Clenched fists, small jaw, severe mental handicap, unlikely to survive past 3 months

What causes Edward’s Syndrome?

Turner’s Syndrome • Short female, most often sterile (infertile), no female development at puberty, no mental retardation

• Treatment with growth hormone (increase height) and estrogen replacement (promote female development)

• No treatment for sterility

What causes Turner’s Syndrome?

Klinefelter’s SyndromeMale with female secondary sex characteristics (wide hips, breasts, etc…)

Usually tall and slender, no retardation

Usually sterile (cannot reproduce)

What causes Klinefelter’s Syndrome?

Figure 15.14a

(a) Deletion

(b) Duplication

A deletion removes a chromosomal segment.

A duplication repeats a segment.

BA C D E F G H

A B C D E F G H

A B C D E F G H B C

A B C E F G H

Figure 15.14b

(c) Inversion

(d) Translocation

An inversion reverses a segment within a chromosome.

A translocation moves a segment from onechromosome to a nonhomologous chromosome.

A B C D E F G H

A D C B E F G H

A B C D E F G H M N O P Q R

GM N O C H FED A B P Q R

Figure 15.16

Normal chromosome 9

Normal chromosome 22

Reciprocal translocation

Translocated chromosome 9

Translocated chromosome 22(Philadelphia chromosome)

Cri du Chat Syndrome

Larynx (voicebox) malformed, high pitched voice (cry of the cat), mental handicap

What causes Cri du Chat?

Living S cells(control)

Living R cells(control)

Heat-killedS cells(control)

Mixture ofheat-killedS cells andliving R cells

Mouse dies Mouse diesMouse healthy Mouse healthy

Living S cells

EXPERIMENT

RESULTS

Figure 16.2

Figure 16.4-1

Bacterial cell

Phage

Batch 1:Radioactivesulfur(35S)

DNA

Batch 2:Radioactivephosphorus(32P)

RadioactiveDNA

EXPERIMENTRadioactiveprotein

Figure 16.4-2

Bacterial cell

Phage

Batch 1:Radioactivesulfur(35S)

Radioactiveprotein

DNA

Batch 2:Radioactivephosphorus(32P)

RadioactiveDNA

Emptyproteinshell

PhageDNA

EXPERIMENT

Figure 16.4-3

Bacterial cell

Phage

Batch 1:Radioactivesulfur(35S)

Radioactiveprotein

DNA

Batch 2:Radioactivephosphorus(32P)

RadioactiveDNA

Emptyproteinshell

PhageDNA

Centrifuge

Centrifuge

Radioactivity(phage protein)in liquid

Pellet (bacterialcells and contents)

PelletRadioactivity(phage DNA)in pellet

EXPERIMENT

Figure 16.UN04

Figure 16.6

(a) Rosalind Franklin (b) Franklin’s X-ray diffractionphotograph of DNA

Figure 16.1

Figure 16.7b

(c) Space-filling model

3.4 nm

1 nm

0.34 nm

Hydrogen bond

(a) Key features ofDNA structure

(b) Partial chemical structure

3 end

5 end

3 end

5 end

T

T

A

A

G

G

C

C

C

C

C

C

C

C

C

C

C

G

G

G

G

G

G

G

G

G

T

T

T

T

T

T

A

A

A

A

A

A

Figure 16.7a

Figure 16.UN01

Purine purine: too wide

Pyrimidine pyrimidine: too narrow

Purine pyrimidine: widthconsistent with X-ray data

Figure 16.8

Sugar

Sugar

Sugar

Sugar

Adenine (A) Thymine (T)

Guanine (G) Cytosine (C)

Figure 16.9-3

(a) Parent molecule (b) Separation ofstrands

(c)“Daughter” DNA molecules,each consisting of oneparental strand and onenew strand

A

A

A

A

A

A

A

A

A

A

A

A

T

T

T

T

T

T

T

T

T

T

T

T

C

C

C

C

C

C

C

C

G

G

G

G

G

G

G

G

Figure 16.10

(a) Conservativemodel

(b) Semiconservativemodel

(c) Dispersive model

Parentcell

Firstreplication

Secondreplication

Figure 16.11a

Bacteriacultured inmedium with15N (heavyisotope)

Bacteriatransferred tomedium with14N (lighterisotope)

DNA samplecentrifugedafter firstreplication

DNA samplecentrifugedafter secondreplication

Less dense

More dense

21

3 4

EXPERIMENT

RESULTS

Figure 16.11b

Predictions: First replication Second replication

Conservativemodel

Semiconservativemodel

Dispersivemodel

CONCLUSION

Figure 16.12a

(a) Origin of replication in an E. coli cell

Origin ofreplication Parental (template) strand

Double-strandedDNA molecule

Daughter (new) strand

Replication forkReplicationbubble

Two daughterDNA molecules

0.5 m

Figure 16.12b

(b) Origins of replication in a eukaryotic cell

Origin of replicationDouble-strandedDNA molecule

Parental (template)strand

Daughter (new)strand

Bubble Replication fork

Two daughter DNA molecules0.25 m

Figure 16.13

Topoisomerase

Primase

RNAprimer

Helicase

Single-strand bindingproteins

5

3

5

53

3

Figure 16.15a

Leadingstrand

Laggingstrand

Overview

Origin of replication Laggingstrand

Leadingstrand

Primer

Overall directionsof replication

Origin of replication

RNA primer

Sliding clamp

DNA pol IIIParental DNA

3

5

5

33

5

3

5

3

5

3

5

Figure 16.15b

Figure 16.16a

Origin of replication

Overview

Leadingstrand

Leadingstrand

Laggingstrand

Lagging strand

Overall directionsof replication

12

Figure 16.16b-1

Templatestrand

3

35

5

Figure 16.16b-2

Templatestrand

RNA primerfor fragment 1

3

3

3

3

5

5

5

51

Figure 16.16b-3

Templatestrand

RNA primerfor fragment 1

Okazakifragment 1

3

3

3

3

3

3

5

5

5

5

5

5

1

1

Figure 16.16b-4

Templatestrand

RNA primerfor fragment 1

Okazakifragment 1

RNA primerfor fragment 2

Okazakifragment 2

3

3

3

3

3

3

3

3

5

5

5

5

5

55

5

2

1

1

1

Figure 16.16b-5

Templatestrand

RNA primerfor fragment 1

Okazakifragment 1

RNA primerfor fragment 2

Okazakifragment 2

3

3

3

3

3

3

3

3

3

3

3

5

5

5

5

5

55

55

55

2

21

1

1

1

Figure 16.16b-6

Templatestrand

RNA primerfor fragment 1

Okazakifragment 1

RNA primerfor fragment 2

Okazakifragment 2

Overall direction of replication

3

3

3

3

3

3

3

3

3

3

3

3

5

5

5

5

5

55

55

55

5

2

2

21

1

1

1

1

Figure 16.17

Overview

Leadingstrand

Origin of replication Lagging

strand

LeadingstrandLagging

strand Overall directionsof replicationLeading strand

DNA pol III

DNA pol III Lagging strand

DNA pol I DNA ligase

PrimerPrimase

ParentalDNA

5

5

5

5

5

33

3

333 2 1

4

Figure 16.22a

DNA double helix(2 nm in diameter)

DNA, the double helix

Nucleosome(10 nm in diameter)

Histones

Histones

Histonetail

H1

Nucleosomes, or “beads ona string” (10-nm fiber)

Figure 16.22b

30-nm fiber

30-nm fiber

Loops Scaffold

300-nm fiber

Chromatid(700 nm)

Replicatedchromosome(1,400 nm)

Looped domains(300-nm fiber) Metaphase

chromosome