What is a Gene? Gene = a segment of DNA that codes for a protein that controls a trait. Humans have approximately 30,000 genes We have 2 copies of.

What is a Gene?What is a Gene? Gene = Gene = a segment of DNA that codes for a a segment of DNA that codes for a

protein that controls a trait.protein that controls a trait. Humans have approximately 30,000 genesHumans have approximately 30,000 genes We have 2 copies of We have 2 copies of

each gene (one on each chromosome each gene (one on each chromosome

we inherited from our parents).we inherited from our parents).

Each gene has different forms . . . Each gene has different forms . . . Allele –one of the many forms of a gene.Allele –one of the many forms of a gene.

Examples of Genes and Alleles in Pea Examples of Genes and Alleles in Pea PlantsPlants

Gene – Seed ShapeGene – Seed ShapeAlleles: Alleles: __________________________

__________________________ Gene – seed colorGene – seed colorAlleles: Alleles: __________________________

__________________________ Gene – flower colorGene – flower colorAlleles: Alleles: __________________________

__________________________

Chromosomes occur in pairs Chromosomes occur in pairs because offspring inherit because offspring inherit one from each parentone from each parent

*We have 46 Chromosomes *We have 46 Chromosomes (23 pairs of chromosomes)(23 pairs of chromosomes)

Chromosomes are made of genesChromosomes are made of genes Circle one gene.Circle one gene.

What are the 2 alleles for that gene?What are the 2 alleles for that gene?

*Each chromosome is made up of DNA that contains hundreds to *Each chromosome is made up of DNA that contains hundreds to thousands of GENES.thousands of GENES.

*HIERARCHY: CHROMOSOMES *HIERARCHY: CHROMOSOMES CONTAIN DNA CONTAIN DNA MADE MADE OF GENES OF GENES CODE FOR A PROTEIN CODE FOR A PROTEIN MAKE TRAITS MAKE TRAITS

Dominant vs. RecessiveDominant vs. Recessive NOT ALL ALLELES ARE EXPRESSED! NOT ALL ALLELES ARE EXPRESSED!

Some alleles are dominant, while others Some alleles are dominant, while others are recessiveare recessive

Description More Info Examples

DominantAlleles

This trait always shows up in an organism if it is present

*These usually code for a protein so they are the “normal” form of a gene.

-Widows Peak-free earlobes

REPRESENTED WITH CAPITAL LETTER

Recessive Alleles

This trait only shows up if there is no dominant allele present

*These usually code for a different protein, or deactivate the “normal” protein.

-No widow’s peak-attached earlobes REPRESENTED WITH LOWERCASE LETTER

WHAT HAPPENS IF WE WHAT HAPPENS IF WE CHANGE OUR DNA?CHANGE OUR DNA?

Don’t let this happen to you!!

MUTATIONSMUTATIONS

Changes in Changes in DNADNA that affect genetic that affect genetic informationinformation

Gene MutationsGene Mutations

Point Mutations – changes Point Mutations – changes in in one or a fewone or a few nucleotides nucleotides SubstitutionSubstitution

THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT THE FAT HAT ATE THE RATTHE FAT HAT ATE THE RAT

InsertionInsertion THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT THE FAT CAT XLW ATE THE RATTHE FAT CAT XLW ATE THE RAT

DeletionDeletion THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT THE FAT ATE THE RATTHE FAT ATE THE RAT

Gene MutationsGene Mutations Frameshift Mutations – shifts Frameshift Mutations – shifts

the the reading framereading frame of the genetic of the genetic message so that the message so that the protein protein may not be able to perform its may not be able to perform its function.function. InsertionInsertion

THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT THE FAT HCA TAT ETH ERA TTHE FAT HCA TAT ETH ERA T

DeletionDeletion THE FAT CAT ATE THE RATTHE FAT CAT ATE THE RAT TEF ATC ATA TET GER ATTEF ATC ATA TET GER AT

H

H

Chromosome MutationsChromosome Mutations Changes in number and structure of entire Changes in number and structure of entire

chromosomes chromosomes What do scientists use to identify these What do scientists use to identify these

type of mutations?type of mutations?

Original Chromosome Original Chromosome ABC * DEFABC * DEF DeletionDeletion AC * DEFAC * DEF DuplicationDuplication ABBC * DEFABBC * DEF InversionInversion AED * CBFAED * CBF TranslocationTranslocation ABC * JKLABC * JKL

GHI * DEFGHI * DEF

• Your body cells have 23 pairs of chromosomes.– Homologous pairs of

chromosomes have the same structure.

– For each homologous pair, one chromosome comes from each parent.

• Chromosome pairs 1-22 are autosomes.

• Sex chromosomes, X and Y, determine gender in mammals.

Your cells have autosomes Your cells have autosomes and sex chromosomes.and sex chromosomes.

•By investigating body tissue, scientists can detect problems.

•Genetic problems can be identified by defective proteins/enzymes or a negative affect on the bodies metabolism.

•Genes can be studied directly

Electrophoresis Electrophoresis (DNA (DNA fingerprinting)fingerprinting)

KaryotypesKaryotypes a set of photographs of chromosomes grouped a set of photographs of chromosomes grouped

in order in pairs from one cell. in order in pairs from one cell.

What are some observations we could make What are some observations we could make from this karyotype?from this karyotype?

Male vs. FemaleMale vs. Female

Males have Males have XYXY sex chromosomes. sex chromosomes. Females have Females have XXXX sex chromosomes sex chromosomes The Y chromosome carries very few genes The Y chromosome carries very few genes

essential for life. essential for life. The X chromosome is a much longer DNA The X chromosome is a much longer DNA

molecule and contains many, many genes molecule and contains many, many genes that are needed for cells to function. that are needed for cells to function.

Karyotype NotationKaryotype Notation A A short-handshort-hand way to write a person’s way to write a person’s

karyotype.karyotype. Total # of chromosomes, sex chromosomes, Total # of chromosomes, sex chromosomes,

extra or missing chromosomesextra or missing chromosomes Normal FemaleNormal Female 46XX46XX Normal MaleNormal Male 46XY46XY

Karyotype NotationKaryotype Notation

Significance of MutationsSignificance of Mutations1. Most are neutral1. Most are neutral

• Eye colorEye color• Birth marksBirth marks

2. Some are harmful2. Some are harmful• Sickle Cell AnemiaSickle Cell Anemia• Down SyndromeDown Syndrome

3. Some are beneficial3. Some are beneficial• Sickle Cell Anemia to MalariaSickle Cell Anemia to Malaria• Immunity to HIVImmunity to HIV

What Causes Mutations?What Causes Mutations? There are two ways in which DNA can There are two ways in which DNA can

become mutated:become mutated:1. Mutations can be inherited. 1. Mutations can be inherited.

Parent to childParent to child

2. Mutations can be acquired.2. Mutations can be acquired. Environmental damageEnvironmental damage Mistakes when DNA is copiedMistakes when DNA is copied

Non-disjunctionNon-disjunction-failure of chromosomes to separate -failure of chromosomes to separate properly during Meiosis. properly during Meiosis.

What are we making during Meiosis?What are we making during Meiosis? In your own words what is a non-disjunction?In your own words what is a non-disjunction?

Genetic DisordersGenetic Disorders an illness caused by one or more abnormalities in an illness caused by one or more abnormalities in

the genome, especially a condition that is present the genome, especially a condition that is present from birth.from birth.

Conditions may or may not be inherited.Conditions may or may not be inherited.

Mutations occur all the time in every cell in the body. Mutations occur all the time in every cell in the body. Each cell, however, has the remarkable ability to recognize Each cell, however, has the remarkable ability to recognize

mistakes and fix them before it passes them along to its mistakes and fix them before it passes them along to its descendants. descendants.

But a cell's DNA repair mechanisms can fail, or be overwhelmed, But a cell's DNA repair mechanisms can fail, or be overwhelmed, or become less efficient with age.or become less efficient with age.

Turners Turners SyndromeSyndrome

• Affects1 in 2,500 newborns

• 45 chromosomes; have only 1 X chromosome

•#23 Monosomy• girls fail to go thru

puberty

Caused by a nondisjunction, if a pair of sex chromosomes fails to separate during the formation of an egg or sperm

Turners SyndromeTurners Syndrome

•96-98% do not survive to birth•stocky appearance•short webbed neckOther medical symptoms include: •lymphedema (swelling of hands and feet) •heart and/or kidney defects •high blood pressure•infertility (inability to have children)

Cri-Du-Chat Cri-Du-Chat SyndromeSyndrome

•Estimated 1 in 20,000-50,000 newborns•Found in ALL ethnic backgrounds•Not inherited•Can be XY or XX•#5 Deletion

•These children have a deleted portion of chromosome number 5.

Cri-Du-Chat SyndromeCri-Du-Chat Syndrome

•Cry that is high-pitched and sounds like a cat•Downward slant to the eyes•Low birth weight and slow growth•Low-set or abnormally shaped ears•Mental handicap (intellectual disability)•Partial webbing or fusing of fingers or toes•Slow or incomplete development of motor skills•Small head (microcephaly)•Small jaw (micrognathia)•Wide-set eyes

WAGR SyndromeWAGR Syndrome

1 in 500,000 children under age 15

7 in 1000 cases have Wilms Tumor46 chromosomesXY or XX

#11 Deletion of upper arm

•The condition results from a deletion on chromosome 11 resulting in the loss of several genes

Aniridia-Wilms Tumor SyndromeAniridia-Wilms Tumor Syndrome

•Predisposed to Wilms kidney tumor•Mentally handicapped•Severe childhood obesity•Growth retardation•Blindness•Tumors on kidneys•Short lifespan•Missing the iris of the eye

Thirteen Q Deletion Thirteen Q Deletion SyndromeSyndrome

600 cases worldwide

1st diagnosed 20 years ago

46 chromosomes

Affects XY or XX

#13 Deletion of lower arm

Thirteen Q Deletion SyndromeThirteen Q Deletion Syndrome

Mentally retardedDeformed faceNo thumbsHeart diseaseShort lifespan

Prader-Willi Prader-Willi SyndromeSyndrome

1 in 15,000 live births

46 chromosomesXY=97% XX=3%

#15 Deletion of lower arm

Prader-Willi syndrome is caused by a gene missing on part of chromosome 15. Normally, your parents each pass down a copy of this chromosome. Most patients with Prader-Willi syndrome are missing the genetic material on part of the father's chromosome.

Prader-Willi SyndromePrader-Willi Syndrome

Low muscle toneShort statureIncomplete sexual developmentCognitive disabilitiesProblem behaviorsChronic feeling of hungerObesityShorter lifespan

Eighteen Q Deletion Eighteen Q Deletion SyndromeSyndrome

1 in 40,000 newborns

Estimated 100 babies per year

46 chromosomesXY or XX

#18 Deletion of lower arm

Eighteen Q Deletion SyndromeEighteen Q Deletion SyndromeSymptoms correlate with the size of the deletionMentally handicappedHeart diseaseAbnormal hands and feetLarge eyesLarge earsNormal lifespan

Cat-Eye SyndromeCat-Eye Syndrome

1 in 1,000,000 births

46 chromosomes

Affects XY or XX

#22 Deletion of bottom arm

Cat-Eye SyndromeCat-Eye Syndrome•Normal to severe malformations•Fused fingers and toes•Mentally handicapped•Small jaw•Heart problems•Normal lifespan

Four-Ring SyndromeFour-Ring Syndrome

1 in 10,000,000 births

46 chromosomesXY or XX

#4 Inversion

Four-Ring SyndromeFour-Ring Syndrome

Cleft palateClub feetTestes don’t descendShort lifespan

Down SyndromeDown Syndrome1 in 31,000 births

46 chromosomesXY=97%

XX=3%

#14/21 Translocation

1 in 850 newborns

Estimated 250,000 people are affected in the US

47 chromosomesXY or XX

#21 Trisomy Nondisjunction

Trisomy 21Down Syndrome

Down SyndromeDown Syndrome

•Short, broad hands •Stubby fingers•Rough skin•Impotency in males•Mentally handicapped•Cognitive delays•Small round face•Protruding tongue•Short lifespan•Increased risk of developing Alzheimer disease

Patau’s Trisomy Patau’s Trisomy SyndromeSyndrome

1 in 14,000 births

47 chromosomesXY or XX

#13 Trisomy Nondisjunction

Patau’s Trisomy SyndromePatau’s Trisomy Syndrome

Small headSmall or missing eyesHeart defectsExtra fingersMentally handicappedCleft palateMost die a few weeks after birth

Edward’s Trisomy Edward’s Trisomy SyndromeSyndrome

1 in 4,400 births

47 chromosomesXX=80%

XY=20%

#18 Trisomy Nondisjunction

Edward’s Trisomy SyndromeEdward’s Trisomy Syndrome

Small headMentally handicappedInternal organ abnormalities90% die before 5 months of age

Jacob’s SyndromeJacob’s Syndrome

1 in 1,800 births

47 chromosomesXYY only

#23 Trisomy Nondisjunction

Jacob’s SyndromeJacob’s Syndrome

Normal physicallyNormal mentallyIncrease in testosteroneMore aggressiveNormal lifespan

?

Klinefelter SyndromeKlinefelter Syndrome

1 in 1,100 births

47 chromosomesXXY only

#23 Trisomy Nondisjunction

Klinefelter SyndromeKlinefelter Syndrome

Scarce beardLonger fingers and armsSterileDelicate skinLow mental abilityNormal lifespan

Triple X SyndromeTriple X Syndrome

1 in 2,500 births

47 chromosomesXXX only

#23 TrisomyNondisjunction

Triple X SyndromeTriple X Syndrome

Normally physically Normal mentallyFertileShort lifespan

Cystic Fibrosis (CF)Cystic Fibrosis (CF)

Clogs the lungs and leads to life-threatening Clogs the lungs and leads to life-threatening lung infections.lung infections.

Obstructs the pancreas and stops natural Obstructs the pancreas and stops natural enzymes from helping the body break down enzymes from helping the body break down food and absorb vital nutrientsfood and absorb vital nutrients

Fluid in lungs, potential respiratory failureFluid in lungs, potential respiratory failure Common among CaucasiansCommon among Caucasians 1 in 20 are carriers1 in 20 are carriers

Therefore is it dominant or recessive?Therefore is it dominant or recessive?

Cystic Fibrosis (CF)Cystic Fibrosis (CF)

MonogenicMonogenic Cause: Cause: deletion of only 3 deletion of only 3

bases on chromosome 7bases on chromosome 7 Estimated in 30,000 Estimated in 30,000

children and adults in children and adults in the U.S.the U.S.

70,000 people 70,000 people worldwideworldwide

Muscular DystrophyMuscular Dystrophy X-linked or autosomal

genetic disorder. Muscular dystrophy is

a disease in which the muscles of the body get weaker because of a lack of a certain protein

Can be passed on by one or both parents, depending on the form of MD

Symptoms: •Muscle weakness that slowly gets worse•Delayed development of muscle motor skills•Difficulty using one or more muscle groups•Eyelid drooping (ptosis)•Loss of strength in a muscle or group of muscles as an adult•Loss in muscle size•Problems walking (delayed walking)

Huntington’s DiseaseHuntington’s Disease

Huntington's disease Huntington's disease (HD) is an inherited, (HD) is an inherited, degenerative brain degenerative brain disorder which results in disorder which results in an eventual loss of both an eventual loss of both mental and physical mental and physical control. control.

The disease is also The disease is also known as Huntington's known as Huntington's chorea. Chorea means chorea. Chorea means "dance-like movements" "dance-like movements" and refers to the and refers to the uncontrolled motions uncontrolled motions often associated with often associated with the disease. the disease.

Hemophilia, the royal Hemophilia, the royal diseasedisease Hemophilia is the oldest Hemophilia is the oldest

known hereditary known hereditary bleeding disorder.bleeding disorder.

Caused by a recessive Caused by a recessive gene on the X gene on the X chromosome.chromosome.

There are about 20,000 There are about 20,000 hemophilia patients in hemophilia patients in the United States.the United States.

One can bleed to death One can bleed to death with small cuts.with small cuts.

The severity of The severity of hemophilia is related to hemophilia is related to the amount of the the amount of the clotting factor in the clotting factor in the blood. About 70% of blood. About 70% of hemophilia patients hemophilia patients have less than one have less than one percent of the normal percent of the normal amount and, thus, have amount and, thus, have severe hemophilia. severe hemophilia.

ALS ALS (Amyotrophic Lateral (Amyotrophic Lateral Sclerosis, or Lou Gehrig’s Sclerosis, or Lou Gehrig’s disease)disease)

the disease strikes people between the the disease strikes people between the ages of 40 and 70, and as many as ages of 40 and 70, and as many as 30,000 Americans have the disease at 30,000 Americans have the disease at any given time any given time

This monogenic mutation is believed to This monogenic mutation is believed to make a defective protein that is toxic to make a defective protein that is toxic to motor nerve cells. motor nerve cells.

A common first symptom is a painless A common first symptom is a painless weakness in a hand, foot, arm or leg, weakness in a hand, foot, arm or leg, other early symptoms include speech other early symptoms include speech swallowing or walking difficulty swallowing or walking difficulty

Designer BabyDesigner Baby

http://www.cbsnews.com/2100-500165_162-4840346.html

Chromosome MutationsChromosome Mutations

Cri-du-chatCri-du-chat Deletion of material on 5Deletion of material on 5thth

chromosomechromosome Characterized by the cat-like Characterized by the cat-like

cry made by cri-du-chat cry made by cri-du-chat babiesbabies

Varied levels of metal Varied levels of metal handicapshandicaps

Sex Chromosome Sex Chromosome AbnormalitiesAbnormalities Klinefelter’s Klinefelter’s

SyndromeSyndrome XXY, XXYY, XXXYXXY, XXYY, XXXY MaleMale SterilitySterility Small testiclesSmall testicles Breast enlargementBreast enlargement

Sex Chromosome Sex Chromosome AbnormalitiesAbnormalities

XYY SyndromeXYY Syndrome Normal male traitsNormal male traits Often tall and thinOften tall and thin Associated with antisocial and behavioral Associated with antisocial and behavioral

problemsproblems

Sex Chromosome Sex Chromosome MutationsMutations

Turner’s SyndromeTurner’s Syndrome XX FemaleFemale sex organs don't sex organs don't

mature at mature at adolescenceadolescence

sterilitysterility short stature short stature

Sex Chromosome Sex Chromosome MutationsMutations

XXXXXX Trisomy XTrisomy X FemaleFemale Little or no visible differencesLittle or no visible differences tall staturetall stature learning disabilitieslearning disabilities limited fertility limited fertility

What’s an Autosome?What’s an Autosome? Autosome: refers to chromosomes 1-22Autosome: refers to chromosomes 1-22

Ex: Autosomal disorders: gene for the disease is found on Ex: Autosomal disorders: gene for the disease is found on chromosomes 1-22chromosomes 1-22

Autosomal Recessive InheritanceAutosomal Recessive Inheritance Must inherit two copies of the disorder to be affectedMust inherit two copies of the disorder to be affected Healthy is dominant (HH or Hh)Healthy is dominant (HH or Hh) Disease is recessive (hh)Disease is recessive (hh) Ex: Cystic fibrosis, PKU, Albinism, Sickle cell anemiaEx: Cystic fibrosis, PKU, Albinism, Sickle cell anemia

Autosomal Dominance InheritanceAutosomal Dominance Inheritance Only need to inherit one copy of the disorder to be affectedOnly need to inherit one copy of the disorder to be affected Disease is dominant (HH or Hh)Disease is dominant (HH or Hh) Healthy is recessive (hh)Healthy is recessive (hh) Ex: Familial hypercholesterolemia (also called FH), Ex: Familial hypercholesterolemia (also called FH),

Huntington’s disease, NeurofibromatosisHuntington’s disease, Neurofibromatosis

Autosomal Dominance InheritanceAutosomal Dominance Inheritance

Disease is dominant (FF or Ff)Disease is dominant (FF or Ff) Homozygous dominant: early death and don’t survive to reproduceHomozygous dominant: early death and don’t survive to reproduce Heterozygous live into adulthoodHeterozygous live into adulthood

Healthy is recessive (ff)Healthy is recessive (ff) ex: Paul has familial hypercholesterolemia and Stacy is healthy. ex: Paul has familial hypercholesterolemia and Stacy is healthy.

The two have 3 children. After testing, the middle child is the The two have 3 children. After testing, the middle child is the only healthy child.only healthy child.

Key

F = FH disease

f = healthy

disease disease

healthy healthy

Autosomal Dominance Autosomal Dominance InheritanceInheritance

Huntington’s disease is a dominant disorder found on Huntington’s disease is a dominant disorder found on chromosome 4. Betty and Marcus met at a support clinic they chromosome 4. Betty and Marcus met at a support clinic they have been attending to help them cope with the knowledge of have been attending to help them cope with the knowledge of their illness with Huntington’s disease. They would like to know their illness with Huntington’s disease. They would like to know the risk of having a healthy child, now that Betty is pregnant.the risk of having a healthy child, now that Betty is pregnant.

Key

H = Huntington’s disease

h = healthy

disease disease

disease healthy