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