Karyotype Chromosome Abnormalities Pedigree. A __________ is a picture of an organism’s...
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Transcript of Karyotype Chromosome Abnormalities Pedigree. A __________ is a picture of an organism’s...
Human GeneticsKaryotype
Chromosome AbnormalitiesPedigree
A __________ is a picture of an organism’s chromosomes
KARYOTYPE
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/
KaryotypeKaryotype- an
organized profile of a person’s chromosomes Chromosome are
arranged and numbered by size, from largest to smallest
The two chromosomes in each pair are called homologous chromosomes or homologs
Creating a Karyotype
Scientists take a picture of someone’s chromosomes, cut them out, and match them up using: Size Banding pattern Centromere position as guides
Fig. 13-3a
APPLICATION
Why create a Karyotype?
Determine abnormalities or defective chromosomes that could possibly be passed to offspring
Help determine proper treatment for some types of cancer
Identify the sex of a person, if unclear at birth
________________ Abnormalities
• 1 infant in 200 newborns has a chromosomal abnormality • 28% of first trimester miscarriages have a chromosomal abnormality
• Abnormalities in larger chromosomes don’t usually survive
CHROMOSOMAL
____________________________: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
Nondisjunction
NondisjunctionSince it happens to a
sperm or egg, the new
baby can end up
with _____________ of a
chromosome
= __________________
OR
only ___________ of a
chromosome
= ___________________
TRISOMY
MONOSOMY
3 copies
one copy
Human Abnormalities caused by Non-Disjunction______________________________________________________
Down syndrome
Klinefelter syndrome
Turner syndrome
Down syndrome (= ____________)TRISOMY 21
Down syndrome (Trisomy 21)
• 1 in 800 births
• Similar facial features
• Slanted eyes
• Protruding tongue
Down syndrome (Trisomy 21)
Simian line on palm
Down syndrome (Trisomy 21)• Most common chromosomal
abnormality
• 50% have heart defects that need surgery to repair
• Mild to severe mental retardation
• Increases susceptibility to many diseases
• Risk of having a child with Down syndrome increases with age of mom
Down syndrome (Trisomy 21)• Risk of having a child
with Down syndrome related to age of mom
• More common in women UNDER 16 or OVER 35
Cells that make eggs start meiosis in embryoStop in PROPHASE I (synapsis)One egg restarts & finishs division each monthSo an egg released at age 40 has been in synapsis for 40 years . . . chromosomes more likely to “stick”
Turner syndrome
Turner syndrome ____ • 1 in 5000 births• Females have only one X chromosome• Small size• Slightly decreased intelligence• 35% have heart abnormalities• Hearing loss common• Broad chest• Reproductive organs don’t develop at puberty• Can’t have children
http://medgen.genetics.utah.edu/photographs/diseases/high/611.gif
XO
Klinefelter syndrome XXy
Klinefelter syndrome
• 1 in 1000 births• Males have extra X chromosomes
(Can be XXy, XXXy, or XXXXy)• Average to slight decrease in intelligence• Small testes/can’t have children• Usually not discovered until puberty when
don’t mature like peers
Karyotype(need cells from baby)
Can tell __________________ chromosomes__________Some _____________________Can’t see _______________ mutations
Image from: http://members.tripod.com/~yenial/chromosome.html
MISSING/EXTRAGENDER
DELETIONS/INSERTIONSsingle gene
Difficulties with human genetics: Takes a long time to reach reproductive maturity Relatively few offspring Unethical to “arrange” matings between
individuals with desired genotypes
Pedigree – a graphic representation of genetic inheritance, a families phenotypic history Made up of set of symbols
Human Genetics
_______________are diagrams that show how are ____________ on __________ over several generations
PEDIGREESgenes are passed
in families
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
Pedigree Analysis
male
female
affected male
affected female
carrier
mating twins
fraternal identical
parents
siblings
deceased
offspring
Symbols
Pedigree Analysis
Family Trees Generations are numbered on the left with roman
numerals Siblings are numbered in birth order
http://www.beavton.k12.or.us/sunset/academics/genetics.htm
http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope.html
Complex Inheritance and Human Heredity
Inferring Genotypes Knowing physical traits can determine
what genes an individual is most likely to have.
Predicting Disorders Record keeping helps scientists use
pedigree analysis to study inheritance patterns, determine phenotypes, and ascertain genotypes.
Pedigree Analysis