Karyotype Chromosome Abnormalities Pedigree Human Genetics Karyotype Chromosome Abnormalities Pedigree

A __________ is a picture of an organism’s chromosomes KARYOTYPE

Chromosomes that determine the sex of an organism = _________________ All other chromosomes = _________________ http://www.angelbabygifts.com/ Sex chromosomes autosomes Humans have two sex chromosomes and _____ autosomes X y 44

Karyotype Karyotype- 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 Karyotype

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 Figure 13.3 Preparing a karyotype 6

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 CHROMOSOMAL 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

____________________________: Change in the ______________ or CHROMOSOMAL MUTATIONS ____________________________: Change in the ______________ or ____________ of chromosomes structure number

Homologous chromosomes ________________ during MEIOSIS = _________________________ One cell gets 2 copies of the chromosome the other cell gets none. fail to separate NONDISJUNCTION

Nondisjunction

Nondisjunction Since it happens to a sperm or egg, the new baby can end up with _____________ of a chromosome = __________________ OR only ___________ of a = ___________________ 3 copies TRISOMY one copy MONOSOMY

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 embryo Stop in PROPHASE I (synapsis) One egg restarts & finishs division each month So an egg released at age 40 has been in synapsis for 40 years . . . chromosomes more likely to “stick”

Turner syndrome

Turner syndrome ____ XO 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

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) Image from: http://members.tripod.com/~yenial/chromosome.html Can tell __________________ chromosomes __________ Some _____________________ Can’t see _______________ mutations MISSING/EXTRA GENDER DELETIONS/INSERTIONS single gene

Human Genetics 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

PEDIGREES _______________are diagrams that show how are ____________ on __________ over several generations genes are passed in families

CARRIER heterozygous A __________ person who carries a _________ allele for a genetic disorder, but ______________ the disorder themselves is called a _____________ heterozygous recessive doesn’t show CARRIER http://www.biochem.arizona.edu/classes/bioc460/spring/rlm/RLM36.1.html

Pedigree Analysis 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 http://www.ikm.jmu.edu/Buttsjl/ISAT493/Hemophilia/hemophiliaeurope.html

Pedigree Analysis Inferring Genotypes Predicting Disorders 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.