pedigrees, karyotypes, and genetic disorders cle 3210.4.4 compare different modes of inheritance:...
TRANSCRIPT
Pedigrees, karyotypes, and genetic disorders
CLE 3210.4.4 Compare different modes of inheritance: sex linkage, co-dominance,
incomplete dominance, multiple alleles, and polygenic traits.
CLE 3210.4.6 Describe the connection between mutations and human genetic disorders.
Overview
• Review karyotypes and chromosome type
• Discuss mutations and various genetic disorders
• Compare these with sex-linked inheritance
• Apply the use of karyotypes and pedigrees to better understand inheritance
Karyotypes• A karyotype is an organized profile of an individual’s
chromosomes. In a karyotype, chromosomes are arranged and numbered by size, from largest to smallest.
• Humans have 46 chromosomes or 23 pairs.
• 22 of these pairs are autosomes.
• 1 pair are sex chromosomes, X and Y.
• Which chromsomes do females have? Males?
3
Normal Karyotype
Autosomes
(44)
Sex chromosomes
(2)
Abnormal Karyotype
*3 Chromosomes instead of 2
Autosomes
(44)
Sex chromosomes
(2)
Mutations that produce changes in a single gene = _________________
Mutations that produce changes in whole chromosomes = _____________________
KINDS OF MUTATIONS
GENE MUTATIONS
CHROMOSOMAL MUTATIONS
Images from: http://www.bbc.co.uk/scotland/education/bitesize/higher/img/biology/genetics_adaptation/mutations/02gene_mutation.gif
KINDS OF MUTATIONS________ CELLS = ___________ CELLS
Somatic cell mutations can: ______________________
______________________
_____________
BODY
Cause cancer
Make cell not able to function
Kill cell
BUT _________ passed on to offspring
WON’T BE
SOMATIC
Kinds of Mutations
___________ = _________cells(sperm & eggs)
GAMETES
Germ cell mutations ________ passed on to offspring
CAN BE
http://anthro.palomar.edu/biobasis/images/meiosis.gif
GERM
MANY HUMAN GENES HAVE BECOME
KNOWN THROUGH THE STUDY OF GENETIC DISORDERS
Many genetic ___________ result fromchanges in the DNA code so
_________________ proteins are produced.
DISORDERS
NON-FUNCTIONING
http://patentdocs.typepad.com/photos/uncategorized/2007/05/28/dna1.gif
What do I need to know about each disorder?
• Which specific type of disorder it is:– Autosomal Recessive– Autosomal Dominant– Sex-Linked– Nondisjunction– Codominant
• What causes it• Characteristics of it
Autosomal Recessive Disorders
• A mutation that creates a disfunctional protein that appears RECESSIVE to the working allele.
• Includes:– Albinism– Cystic Fibrosis– Phenylketonuria (PKU)– Tay-Sach’s disease– Sickle-cell disease
• Example: Albinism:– AA = no albinism– Aa = carrier for
albinism– aa = albino
Autosomal Recessive Disorders
• Albinism– Characterized by lack of pigment in the
skin, hair, and eyes.
Albinism
Autosomal recessive: CYSTIC FIBROSIS CAUSE:
Loss of 3 DNA bases in a gene for the _____________ that transports _________ so salt balance is upset
Causes a build up of _________________ in lungs and digestive organs
.
thick mucous
protein
Image from: BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006
Cl- ions
Phenylketonuria (PKU)
CAUSE: Mutation in gene for an ___________ that __________ an ___________ called phenylalanine
Build up causes ________________________MENTAL RETARDATION
ENZYME
http://biology.clc.uc.edu/courses/bio104/protein.htm
breaks down amino acid
X
X
Phenylketonuria (PKU)
____ babies are ________for PKU before they leave the hospital.
Treatment: Need a diet _____________________ to extend life and ______________ mental retardation
If phenylalanine is an _____________, what type of foods should PKU patients avoid? __________________
amino acid
PROTEINS !
LOW in phenylalaninePREVENT
ALL tested
TAY-SACHS DISEASE___________________
CAUSE: Mutation in gene for an ___________ that breaks down a kind of _________in the developing _________
Build up of lipids in brain cells leads to:mental retardation, blindness, and DEATH in early childhood
Found more frequently in people with _______ _____________ ______________, ancestry
BRAIN
ENZYME
Jewish
Image from: http://www.djsfoundation.org/images/Steeler%20pics%20Dylan.jpg
AUTOSOMAL RECESSIVE
Mediterranean Middle Eastern
LIPID
Tay-Sachs
http://www.biochem.arizona.edu/classes/bioc460/spring/rlm/RLM36.1.html
A __________ person who carries a _________ allele for a genetic disorder, but ______________ the disorder themselves is called a_____________CARRIER
heterozygous
doesn’t show
recessive
A male who is a heterozygous carrier for an autosomal recessive disease marries a homozygous unaffected female. What is the chance of having an affected child? A child who is a carrier?
A. 50 %; 50%
B. 0%; 50%
C. 50%; 0%
D. 25%; 50%
20
A mutation that codes for a new proteinwhose action masks the normal alleleappears as a ______________ mutation.
Examples of _________________________ GENETIC DISORDERS:
____________________
____________________
DOMINANT
Huntington’s disease
Achondroplasia
AUTOSOMAL DOMINANT
HUNTINGTON’S DISEASE______________________
CAUSE: Extra 40-100 ______________ at end of gene on chromosome 4
The _____________ . . . the more __________ the symptoms.
severe
CAG repeats
http://www.healthsystem.virginia.edu/internet/huntdisease/images/cag.gif
more repeats
AUTOSOMAL DOMINANT
HUNTINGTON’S DISEASE
Causes progressive _____ of ________________ and ___________function
loss
muscle control
mental
1 in 10,000 people in U.S. have Huntington’s disease
http://www.scielo.br/img/revistas/bjmbr/v39n8/html/6233i01.htm
Huntington’s brain
Normal brain
A person with Huntington’s disease has a _____ chance of passing the disorder on totheir offspring.
Problem:Symptoms of disorder usually don’t show until ____________ . . .
so you don’t know you have it until ________ you have had children.
50%
MIDDLE AGE
AFTER
ACHONDROPLASIA(One kind of Dwarfism)
CAUSE: ___________________________ gene
200,000 “little people” worldwide
AUTOSOMAL DOMINANT
1 in 20,000 births
Mother has achondroplasia
Father has diastrophic displasia, a recessive disorder
Autosomal Dominant Disorders
• Achondroplasia– 99.96% of all the people in the world are
homozygous recessive for this trait (aa).– Interesting fact: The AA (homozygous
dominant) genotype of this trait is lethal and will result in a spontaneous abortion of the fetus.
• The only viable genotype is Aa.
Activity 1: With a partner
• Take 5 minutes and draw a two-circle Venn Diagram to compare and contrast:
• Autosomal recessive Vs. autosomal dominant
DISORDERS CAUSED BY ____________________
____________________SICKLE CELL DISEASE
CAUSE: T changed to A in gene for
__________________ (protein in red blood cells that carries oxygen in blood)
HEMOGLOBIN
AUTOSOMAL CODOMINANT ALLELES
SICKLE CELL DISEASE
SYMPTOMS:_____________ become sickle shaped in persons with ______ sickle cell ________
RED BLOOD CELLS
TWOALLELES
SICKLE CELL DISEASE
Circulatory problemsCells stick in capillariesLoss of blood cells (anemia)Organ damage (brain, heart, spleen)Can lead to DEATH
SICKLE CELL DISEASEMore common in _________________ 1 in 500 = have sickle cell disease 1 in 10 = carriers for allele
Also affects persons of _______________ and _________________ descent
Why do so many African Americans carry the sickle cell allele?
AFRICAN AMERICANS
MEDITERRANEANMIDDLE EASTERN
SICKLE CELL DISEASEMany can trace their ancestry to
westcentral Africa where ___________,a serious parasitic disease thatinfects red blood cells is common.
Images from: http://en.wikipedia.org/wiki/Malaria
MALARIA
A person who is __________________ for the ____________allele (ss) will have _______________
A person who is _________________ for normal hemoglobin alleles will have normal blood cells, but can become infected with __________ (SS)
A _________________ person (Ss)(with one normal/one sickle cell allele) isgenerally healthy and has the benefit ofbeing _________ to malaria
HOMOZYGOUSsickle cell
sickle disease
HOMOZYGOUS
malaria
HETEROZYGOUS
resistant
Chromosomes that determine the sex of an organism = _________________
All other chromosomes = _________________
Sex chromosomes
autosomes
Humans have two sex chromosomes
and _____ autosomes
X y44
http://www.angelbabygifts.com/
SEX DETERMINATIONXX =
Xy =
female
male
Who decides?
Mom can give X
Dad can give X or y
SO ____ determines sex of the baby.
If dad gives X with mom’s X = girlIf dad give y with mom’s X = boy
X X
X
y
X X X X
X y X y
Dad
Sex linked genes• In addition to their role in
determining sex of an organism, X and Y chromosomes have many other genes that are unrelated to sex.
• A gene on either sex chromosome is call a sex-linked gene.
• Congenital generalized hypertrichosis (CGH), the type that Danny Gomez has, is X-linked dominant; the gene that is mutated is found on the X chromosome.
• Sex-linked mutations can be either dominant or recessive.
37
X-linked inheritance pattern from a
heterozygote mother and unaffected father
_______________are diagrams that show how are ____________ on __________ over several generations
PEDIGREESgenes are passed
in families
Drawing a pedigree chart
http://www.beavton.k12.or.us/sunset/academics/genetics.htm
Genes carried on X or Y chromsomes= ___________________SEX LINKED TRAITS
These traits show up in different _______________ in males and females because they move with the sex chromosomes
percentages
Y-LINKED GENES: Genes ______________ chromosome
EXAMPLE:Hairy pinna
_________genes _____ show up _______Y linked in males
carried on Y
ONLY
____________ GENES: are carried on the X chromosome
X-linked recessive disorders show up _____________in ______ than femalesbecause males only have______ X chromosome.
MALES
X-LINKED
ONE
MORE frequently
Males ONLY HAVE ONE X
They eitherhave the disorder
DEFECTIVE NORMAL
They are normal
Or
FEMALES HAVE TWO X CHROMOSOMES
Females have one normalgene that works.
NORMAL DEFECTIVEDEFECTIVE
Females __________defective recessivealleles to show the disorder
need 2
Examples of ________________________ DISORDERS:
____________________
____________________
____________________
HEMOPHILIA
COLORBLINDNESS
DUCHENNE MUSCULAR DYSTROPHY
X-LINKED RECESSIVE
HEMOPHILIA CAUSE:
Mutation in genes for __________________ carried ______ chromosome
Blood clotting proteins are missing so person with this disorder can’t stop bleeding when injured; can ________________ from minor cuts or suffer internal bleedingfrom bruises or bumps.
bleed to death
Blood clotting proteinson X
COLORBLINDNESS CAUSE:
Mutation in one of three genes for _______________ carried on X chromosome
Persons with this disorder have trouble distinguishing colors.
_________________ colorblindness is most common
Seen in 1 in 10 males 1 in 100 females
Red-green
Color vision
http://gizmodo.com/gadgets/peripherals/samsung-develops-lcd-for-colorblind-036306.php
Duchenne Muscular DystrophyCAUSE: deletion in genethat codes for a_______________
Results in ____________________and loss of
___________________
http://www.cadenhead.org/workbench/gems/jerry-lewis-telethon.jpghttp://www.tokyo-med.ac.jp/genet/chm/dei.gif
muscle protein
progressive weakeningskeletal muscle
What’s the pattern: ________ traits show up _______ in _______
__________________ traits: ______________________ than females. ________________ can be ________.
_______________________ traits:BOTH ______ & _________ can be ________
Y-linked ONLY males
X-linked recessivemore common in males
AUTOSOMAL RECESSIVE
ONLY FEMALES carriers
MALES FEMALES carriers
Activity 2 (group): Interpreting pedigrees
• Using your pedigree reference sheet, try to identify the inheritance pattern for each pedigree on the handout.
• Is it:– Sex-linked dominant?– Autosomal dominant?– Autosomal recessive?
____________________________:Change in the ______________ or ____________ of chromosomes
CHROMOSOMAL MUTATIONS
structurenumber
Homologous chromosomes ________________ during MEIOSIS
= _________________________
One cell gets 2 copies of the chromosome the other cell gets none.
NONDISJUNCTION
fail to separate
Normal Meiosis Nondisjunction
http://www.tokyo-med.ac.jp/genet/anm/domov.gif
http://web.udl.es/usuaris/e4650869/docencia/gen_etica/meioferti2.html
Human Abnormalities caused by Non-Disjunction______________________________________________________
Down syndrome
Klinefelter syndrome
Turner syndrome
Down syndrome (= ____________)TRISOMY 21
Non-Disjunction Disorders• Down Syndrome (1:700)
– Characterized by obvious physical features and mild to profound mental disabilities.
• Short stature, heart defects, short lifespan, often sexually underdeveloped and sterile.
– Caused by a duplication of the 21st chromosome (47 TOTAL) = TRISOMY 21.
Turner syndrome – “monosomy”
Non-Disjunction Disorders• Turner’s Syndrome (1:5,000)
– THIS SYNDROME IS THE ONLY VIABLE MONOSOMY WHICH EXISTS IN HUMANS.
• 98% of these fetuses die prior to birth– Individuals affected with this disorder develop as
females only.– Occurs when all or part of one of the X chromosomes
is missing (45 TOTAL) =MONOSOMY X.– Characterized by short stature, webbed neck, stocky
build and absence of sexual development; normal intelligence.
Klinefelter syndrome XXy
Non-Disjunction Disorders• Klinefelter’s Syndrome
– A condition which occurs in males only.– Individuals with this disorder have an extra
X sex chromosome (47 TOTAL) = TRISOMY XXY.
– This disorder can affect the stages of language, physical, and social development.
– Characteristics include small testes, breast enlargement and other feminine body attributes; normal intelligence.
Which disorder is this?
Which disorder is this?
Which disorder is this?
Polygenic traits – Eye color
Compare and contrast
• Complete dominance
• Incomplete dominance
• Co-dominance
• Sex-linked