Chapter 13Chapter 13

Genes and ChromosomesGenes and Chromosomes

Could you be like Mike?Could you be like Mike?

Genetics vs. Environmental factorsGenetics vs. Environmental factors

Genetics

Environment

Everyone is a productEveryone is a productgenes genes andand environmentenvironment– Ex. HeightEx. Height– Siamese Cat furSiamese Cat fur

Hot areas: whiteHot areas: white

Cold areas: blackCold areas: black

Identical versus Fraternal TwinsIdentical versus Fraternal TwinsGenetically identical– Same fertilized egg

splits into two

Different environment– Different food, sleep,

experiences, emotions, sunlight

differing traits=stronger environmental influence

Old Belief: Blending theoryOld Belief: Blending theoryBelief: fertilization Belief: fertilization mixed your parent’s mixed your parent’s genesgenes

You are average of bothYou are average of both

Once mixed, cannot be Once mixed, cannot be separatedseparated

Events Contradicting “blending theoryEvents Contradicting “blending theory

You don’t always look like parentsYou don’t always look like parents

Healthy parents have sick childrenHealthy parents have sick children

Gregor MendelGregor MendelA monk, gardener, A monk, gardener, and high school and high school science teacherscience teacher

1860’s, grew garden 1860’s, grew garden peaspeas

Studied 28,000 pea Studied 28,000 pea plants around 8 yearsplants around 8 years

Pea Plants as SubjectsPea Plants as SubjectsEasy to growEasy to growLittle maintenanceLittle maintenanceSelf-fertilizingSelf-fertilizing– Can be artificially Can be artificially

fertilizedfertilized

Can obtain true-Can obtain true-breeding plantsbreeding plants– If bred to itself, If bred to itself,

always produce always produce offspring identical offspring identical toto

MendelMendelStudied 7 Studied 7 characteristicscharacteristics– Pod shape: inflated or Pod shape: inflated or

constrictedconstricted– Stem length: tall or shortStem length: tall or short– Other 5 are to the rightOther 5 are to the right

GenerationsGenerations

Parental Generation or Parental Generation or Pgen:Pgen:

First filial generation or First filial generation or F1:F1:

Second filial generation or Second filial generation or F2:F2:

Green pods w/ Yellow podsGreen pods w/ Yellow pods

F1 generation: children F1 generation: children are all greenare all green

F2 generation: ¼ is F2 generation: ¼ is yellow, ¾ greenyellow, ¾ green

Defies blending theoryDefies blending theory

Mendel came up with Mendel came up with the concept of a the concept of a inherited unit(inherited unit(gene)gene)

GeneGene

Segment of DNA that encodes a functional Segment of DNA that encodes a functional proteinproteinGene: eye color makes pigment proteinsGene: eye color makes pigment proteins– Alleles: different formsAlleles: different forms– Ex. Brown vs. blue eye colorEx. Brown vs. blue eye color

Most traits are multigenic and environmentalMost traits are multigenic and environmentalEx. Hair colorEx. Hair color

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A

Gene A

Genes vs. allelesGenes vs. allelesGenes are responsible for Genes are responsible for making a proteinmaking a proteinAlleles are different Alleles are different versions of geneversions of gene– Make the same proteinMake the same protein– Slightly different formsSlightly different forms

Gene makes a protein that Gene makes a protein that makes the peas a certain makes the peas a certain colorcolor– One allele makes a certain One allele makes a certain

proteinproteinGives a green colorGives a green color

– Another allele makes Another allele makes another version proteinanother version protein

Yellow colorYellow color

Genes and ChromosomesGenes and Chromosomes

Chromosome: long continuous strands of Chromosome: long continuous strands of DNADNA– Diploid organisms have homologous Diploid organisms have homologous

chromosomeschromosomes– Two very similar chromosomes, one from mom, Two very similar chromosomes, one from mom,

one from dadone from dad

Holds thousands of genes at certain pointsHolds thousands of genes at certain pointsEasy to study when they’re condensedEasy to study when they’re condensed

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Karyotype 1Karyotype 1A picture of an A picture of an organisms organisms chromosomeschromosomes

Each human cell has Each human cell has all 23 pairs of all 23 pairs of chromosomeschromosomes

Can look at picture to Can look at picture to detect abnormalities detect abnormalities and determine genderand determine gender– Amnio test on unborn Amnio test on unborn

babiesbabies

Karyotype 2Karyotype 2White blood cells usedWhite blood cells usedAdd chemicals to stop Add chemicals to stop it in metaphaseit in metaphasePlaced on slide and Placed on slide and treated with watertreated with water– Spread chromosomes Spread chromosomes

outout– Easier to studyEasier to study

Add stain which Add stain which creates unique bandscreates unique bandsTake a pictureTake a picture

Karyotype..continuedKaryotype..continuedThen you take Then you take picture and cut out picture and cut out chromosomeschromosomesPair them up based Pair them up based onon1. size1. size2. banding patterns2. banding patterns3. location of 3. location of centromerecentromere

Lab: Karyotyping ActivityLab: Karyotyping Activity

In pairs, you will learn how In pairs, you will learn how chromosomes are actually organized chromosomes are actually organized into karyotypesinto karyotypes

A picture of a human patient’s A picture of a human patient’s chromosomes were takenchromosomes were taken

Cut out and organize into a Cut out and organize into a karyotypekaryotype