Human GeneticsHuman Genetics

Genetic Genetic

Experiment 626Experiment 626

Karyotyping:Karyotyping:

technique for examining the technique for examining the chromosomechromosome make up of an make up of an organism organism shows chromosomes arranged shows chromosomes arranged by by sizesize: : – homogulous pairshomogulous pairsa way of detecting a way of detecting abnormalitiesabnormalities

Karyotyping:Karyotyping:

chromosomes pairedchromosomes paired

–Total of Total of 4646 chromosomes chromosomes

–Or 23 pair:Or 23 pair: 22 autosomes, somatic cells, body cells 22 autosomes, somatic cells, body cells &&

1 1 pair of sex chromosomes pair of sex chromosomes

XX = XX = femalefemale

XYXY = male = male

Sex- Linkage:Sex- Linkage:

Genes located on the sex Genes located on the sex chromosomes:chromosomes:–genes found on the x genes found on the x

chromosome = x linkedchromosome = x linked–genes found on thegenes found on the

y chromosome = y linkedy chromosome = y linked

a gene found on either the x or y a gene found on either the x or y chromosomes = sex linked chromosomes = sex linked

STOP!!!STOP!!! CK POINT!! CK POINT!!

Topic: Intro to Human GeneticsTopic: Intro to Human GeneticsIdentify the following:Identify the following:

What is/are:What is/are:

1.1. KaryotypesKaryotypes2.2. Sex- linked traitsSex- linked traits

Mutations:Mutations:

any change in the genetic any change in the genetic hereditary material of the cellhereditary material of the cell

2 forms:2 forms:–inheritable mutations – occur in the inheritable mutations – occur in the

sex cellssex cells

–non inheritable mutations – occur in non inheritable mutations – occur in the somatic cells (autosomes, body the somatic cells (autosomes, body cells)cells)

2 Types of inheritable mutations:2 Types of inheritable mutations:

ADD TO YOUR NOTES!!ADD TO YOUR NOTES!!1.1. Chromosomal Mutations Chromosomal Mutations

And And

2. Gene mutations2. Gene mutations

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Topic: Mutations 1Topic: Mutations 1

What is a mutation?What is a mutation?

What are the 2 types of What are the 2 types of inheritable mutations?inheritable mutations?

Chromosomal Mutations:Chromosomal Mutations:

change in the structure of a change in the structure of a chromosome chromosome

the loss of an entire chromosome the loss of an entire chromosome or addition of a chromosomeor addition of a chromosome

– Examples Include: Examples Include:

a. Nondisjunctiona. Nondisjunction

Chromosome Mutation Cont.Chromosome Mutation Cont.

A.A. Nondisjunction: Nondisjunction:

failure of chromosomes to failure of chromosomes to separate during meiosisseparate during meiosis

–ex. Down syndrome – extra ex. Down syndrome – extra chromosome # 21 chromosome # 21

–Ex .trisomy 18, trisomy 13Ex .trisomy 18, trisomy 13

Nondisjunction:Nondisjunction:

NondisjunctionNondisjunctionDown syndromeDown syndrome (trisomy 21):(trisomy 21):

Nondisjunction: Nondisjunction: Patau syndrome (trisomy 13):Patau syndrome (trisomy 13):

serious eye, brain, circulatory defects as serious eye, brain, circulatory defects as well as cleft palate. 1:5000 live births. well as cleft palate. 1:5000 live births. Children rarely live more than a few Children rarely live more than a few months.months.

NondisjunctionNondisjunctionEdward's syndrome (trisomy 18):Edward's syndrome (trisomy 18):

almost every organ system affected Children almost every organ system affected Children rarely live more than a few months.rarely live more than a few months.

Other Examples of Nondisjunction: Other Examples of Nondisjunction: Sex chromosome :Sex chromosome :

Sex chromosome aneuploidsSex chromosome aneuploids

1.1. XO = XO = Turners SyndromeTurners Syndrome

2.2. XXY = XXY = KlinefelterKlinefelter Syndrome Syndrome

3.3. XXX = XXX = TriploTriplo-X Syndrome-X Syndrome

4.4. XYY =XYY =Jacob SyndromeJacob Syndrome

Turners Syndrome:Turners Syndrome:XO individuals are genetically female, however, they do not mature sexually during puberty and are sterile. Short stature and normal intelligence. (98% die before birth)

XXY = XXY = KlinefelterKlinefelter Syndrome SyndromeMale sex organs; unusually small testes, sterile. Male sex organs; unusually small testes, sterile. Breast enlargement and other feminine body Breast enlargement and other feminine body characteristics. Normal intelligence. characteristics. Normal intelligence.

XXX = XXX = TriploTriplo-X Syndrome-X Syndrome

XXXXXX females. 1:1000 live births - healthy females. 1:1000 live births - healthy and fertile - cannot be distinguished from and fertile - cannot be distinguished from normal female except by karyotypenormal female except by karyotype

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Topic: NondisjunctionTopic: Nondisjunction

What is Nondisjunction?What is Nondisjunction?

When does it occur? ( Be Specific)When does it occur? ( Be Specific)

Identify 3 genetic mutations Identify 3 genetic mutations resulting from nondisjunction.resulting from nondisjunction.

– What is the cause for each?What is the cause for each?

CChromosome mutationshromosome mutations (structure): (structure):

translocation – a section of one chromosome is transferred to a nonhomogulous chromosome

addition – a portion of a chromosome is added

Chromosome mutations (structure):Chromosome mutations (structure):

deletion – a portion of a chromosome is deleted

Cri-du-Chat Syndrome (segmental deletion)

inversion – order of genes on a chromosome is changed

Chromosomal mutation-Chromosomal mutation-Deletion:Deletion:

Example - Example - Cri du Cri du

chat (cry of the cat):chat (cry of the cat):

A deletion of a small A deletion of a small

portion of portion of

chromosome 5; chromosome 5;

these children have these children have

severe mental severe mental

retardation, a small retardation, a small

head with unusual head with unusual

facial features, and facial features, and

a cry that soundsa cry that sounds like a like a distressed cat.distressed cat.

In summaryIn summaryChromosomal Mutations:Chromosomal Mutations:

Chromosomal Chromosomal abnormalities can cause abnormalities can cause serious mental or serious mental or physical physical disabilitiesdisabilities, , Structure of the Structure of the chromosome has been chromosome has been compromisedcompromisedThe number of The number of chromosomes is incorrectchromosomes is incorrect

STOP!!!STOP!!! CK POINT!! CK POINT!!

Topic: Mutations 2Topic: Mutations 2

1. Identify 4 structural chromosomal 1. Identify 4 structural chromosomal mutations.mutations.

2.2. How are each of the 4 How are each of the 4 chromosomes mutated?chromosomes mutated?

3. What is Turners Syndrome?3. What is Turners Syndrome?

Gene MutationsGene Mutations

Point Mutation – the substitution, addition, Point Mutation – the substitution, addition, or removal of a or removal of a single nucleotidesingle nucleotide

– substitutions, substitutions, 1 nucleotide in a codon 1 nucleotide in a codon is replaced with a different nucleotide, is replaced with a different nucleotide, resulting in a new codon.resulting in a new codon.

sickle cell anemiasickle cell anemia (also called sickle (also called sickle cell disease) is a point mutation cell disease) is a point mutation substituting Adenine for Thymine in a substituting Adenine for Thymine in a single DNA codon,single DNA codon,

Gene Mutations Cont.Gene Mutations Cont.

Frame Shift Mutation -the addition Frame Shift Mutation -the addition or deletion of a single nucleotide or deletion of a single nucleotide causes the remaining codons to causes the remaining codons to be incorrectly groupedbe incorrectly grouped–Addition/removal – a single Addition/removal – a single

nucleotide is added or removednucleotide is added or removed– Addition and Deletion MutationsAddition and Deletion Mutations

sickle cellsickle cell

Welcome to Discovery Education PlayerWelcome to Discovery Education Player

Characteristics of Mutations:Characteristics of Mutations:

1.1.most are harmful to the most are harmful to the organismorganism

2.2. they are randomthey are random3.3.most are recessive traitsmost are recessive traits4.4.Can be beneficial to the Can be beneficial to the

organism when the mutation organism when the mutation helps the organism to adapt to helps the organism to adapt to the environment.the environment.

Mutagenic Agents:Mutagenic Agents:

radiation - x-rays, radioactive radiation - x-rays, radioactive isotopes, cosmic rays, ultraviolet isotopes, cosmic rays, ultraviolet raysrays

chemicals – saccharin, nitrates, chemicals – saccharin, nitrates, carcinogens carcinogens

Human Genetic Traits & DisordersHuman Genetic Traits & DisordersX- linked Traits:X- linked Traits:

traits controlled by traits controlled by the female sex the female sex chromosomechromosomesymbolized by a character on 1 of symbolized by a character on 1 of the chromosomesthe chromosomes–XX’ XX’ X’ carries the traitX’ carries the trait–The female = the carrierThe female = the carrier–The trait is not visible in the femaleThe trait is not visible in the female

Examples of Sex linked traits:Examples of Sex linked traits: X- linked X- linked

Ex. Hemophilia –blood disorder Ex. Hemophilia –blood disorder in which blood does not clot in which blood does not clot properlyproperly

Ex. Color blindness – cannot Ex. Color blindness – cannot distinguish between red and distinguish between red and greengreen

X-linked traits cont.X-linked traits cont.

Symbols for constructing a Punnett Symbols for constructing a Punnett square (sex-linked trait)square (sex-linked trait)– XX normal femaleXX normal female

– XY normal maleXY normal male

– X’X carrier femaleX’X carrier female

– X’Y male with hemophiliaX’Y male with hemophilia

http://www.macmed.ttuhsc.edu/Morgan/http://www.macmed.ttuhsc.edu/Morgan/bleedingdisorders/pages/newpage26.htmbleedingdisorders/pages/newpage26.htm

Know These!!!!

Ex. HemophiliaEx. Hemophilia

Hemophiliac male x carrier femaleHemophiliac male x carrier female

GenotypeGenotype

PhenotypePhenotype

Hemophilia cont.Hemophilia cont.

Normal male x female carrierNormal male x female carrier

GenotypeGenotype

PhenotypePhenotype

Multiple Alleles:Multiple Alleles:

2 or more alleles for a 2 or more alleles for a particular traitparticular trait

alleles are expressed as alleles are expressed as codominantcodominant

ex. Blood typesex. Blood types

Human Blood Types:Human Blood Types:

PhenotypePhenotype GenotypeGenotype A A I IAAIIAA, I, IAAii

BB I IBBIIBB, I, IBBii

ABAB AB AB

OO iiii

Blood Types & Punnett Squares;Blood Types & Punnett Squares;What are the What are the possible outcomes possible outcomes for a heterozygous for a heterozygous A blood type A blood type crossing crossing with a homozygous with a homozygous B blood type?B blood type?Genotypes Genotypes

PhenotypesPhenotypes

Blood Type Cont.Blood Type Cont.Construct a punnett square showing a Construct a punnett square showing a

cross b/w a blood type O person with a cross b/w a blood type O person with a

heterozygous B blood type personheterozygous B blood type person

GenotypeGenotype

PhenotypePhenotype

Why?Why?THINK!THINK!

Raise your hand to answer…Raise your hand to answer…

WHY Blood typing WHY Blood typing important?important?

RBCRBC

agglutinationagglutination

Put your skills to the test!Put your skills to the test!

Look at the handout provided:Look at the handout provided:

““Using Blood tests Using Blood tests

to Identify Babies”to Identify Babies”

Polygenic Traits:Polygenic Traits:

traits controlled by 2 or more allelestraits controlled by 2 or more alleles

expressed as incomplete dominanceexpressed as incomplete dominance

ex. Eye color, height, and skin color ex. Eye color, height, and skin color

This pattern of inheritance is This pattern of inheritance is identified has a wide range of identified has a wide range of phenotypes (skin & hair color).phenotypes (skin & hair color).

THINK…THINK…

How is multiple alleles How is multiple alleles different from polygenic different from polygenic traits? (look in your traits? (look in your

notes!)notes!)

Go SU!!Go SU!!

Genetic Disorders:Genetic Disorders:– Genetic screening or studying Karyotypes can Genetic screening or studying Karyotypes can

show possible genetic disordersshow possible genetic disorders

Amniocentesis – Karyotyping and analyzing Amniocentesis – Karyotyping and analyzing amniotic fluid for fetal cells amniotic fluid for fetal cells

Chorionic villi sampling – piece of the placenta Chorionic villi sampling – piece of the placenta that is studied for genetic abnormalitiesthat is studied for genetic abnormalities–Ex. PKU: a genetic disorder that does not allow Ex. PKU: a genetic disorder that does not allow

the baby to breakdown phenylalanine , can cause the baby to breakdown phenylalanine , can cause severe brain damagesevere brain damage

–Can be detected and eliminated with special Can be detected and eliminated with special diets diets

STOP!!!STOP!!! CK POINT!! CK POINT!!

Topic: Genetic DisordersTopic: Genetic Disorders

1.1. What is the difference among:What is the difference among: Multiple AllelesMultiple Alleles

Sex-Linked TraitsSex-Linked Traits

Polygenic TraitsPolygenic Traits

2.2. What is amniocentesis? What is amniocentesis?

Disorders associated with Disorders associated with Genetics:Genetics:

Cystic FibrosisCystic Fibrosis

Tay - Sacs DiseaseTay - Sacs Disease

Phenylketonuria (PKU)Phenylketonuria (PKU)

Huntington’s diseaseHuntington’s disease

Albinism Albinism

Cystic FibrosisCystic Fibrosis

SymptomsSymptoms–Mucous clogs the lungs and Mucous clogs the lungs and

pancreaspancreas

–Usually do not survive into Usually do not survive into adulthoodadulthood

–White population most effectedWhite population most effected

Tay-SachsTay-Sachs

Symptoms:Symptoms:–Deterioration of the nervous Deterioration of the nervous

systemsystem

–Usually do not survive adulthoodUsually do not survive adulthood

–European descents most European descents most effectedeffected

PKUPKU

Failure of the brain to Failure of the brain to develop during infancydevelop during infancy

If untreated, death in early If untreated, death in early childhoodchildhood

Controlled by diet!!Controlled by diet!!

Huntington’s DiseaseHuntington’s DiseaseCarried on an autosome (Dom)Carried on an autosome (Dom)

Symptoms:Symptoms:–ForgetfulnessForgetfulness–Appears in 30’s-40’sAppears in 30’s-40’s–Loss of muscle controlLoss of muscle control–Uncontrollable muscle spasmsUncontrollable muscle spasms–Mental illnessMental illness–deathdeath

In your pkt:In your pkt:

Get into your groups: Get into your groups:

> 1 min. > 1 min.

Get owl text booksGet owl text books

Same place as yesterday Same place as yesterday

Turn to pg 91-92 Turn to pg 91-92 – Begin answering questionsBegin answering questions– Popsicle sticks!!Popsicle sticks!!