Chapter 14: Human Genetics

Human Chromosomes Autosome - any

chromosome other than the X & Y

Sex chromosomes–

23rd pair of determine sex in organism

Karyotype

A picture of chromosomes arranged based on size and shape.

Karyotypes can identify abnormal number of chromosomes due to mistakes during meiosis.

Nondisjunction: the failure of chromosomes to separate properly during Anaphase I or II.

Anaphase 1Anaphase 2

As a result of nondisjunction:

Can lead to a number of disorders in the baby. Trisomy (extra chromosome) or Monosomy (one less chromosome).

• Down’s syndrome• Klinefelter’s syndrome• Turner’s syndrome• Edward’s syndrome

Karyotyping & Disease

Sex: Female # of

chromosomes=46

Diagnosis: healthy

Karyotyping & Disease

46 Male Healthy

Karyotyping & Disease

Male 47 Klinefelters

Klinefelter’s Syndrome

Karyotyping & Disease

Female 45 Turners

Turner’s Syndrome

Karyotyping & Disease

Female 47 Downs Syndrome

Down’s syndrome

Karyotyping & Disease

Male 47 Edward’s

syndrome

Edward’s syndrome

Pedigree A chart that shows the relationships within a

family that can be used to trace inheritance.

How to draw a pedigree

A

c

i

r

c

l

e

r

e

p

r

e

s

e

n

t

s

a

f

e

m

a

l

e

.

A circle represents a female

A square represents a male

A horizontal line connecting a male and female represents a marriage

A vertical line and a bracket connect the parents to their children.

A shaded circle or square indicates that a person expresses the trait.

A circle or square that is not shaded indicates that a person does not express the trait.

http://www.google.com/url?sa=i&rct=j&q=pedigree&source=images&cd=&cad=rja&docid=ESiTE8zW2tmVNM&tbnid=pZWEx_2BFdPIAM:&ved=0CAUQjRw&url=http://carrier.pbworks.com/w/page/15282807/Biology%202%20Genetics&ei=iD59Uf-UNoPT0wHUuoFA&bvm=bv.45645796,d.dmQ&psig=AFQjCNGGRwn9vKO-8Wx652g47ZGaeUoNvA&ust=1367248874382993

Ms. Pitt’s pedigree:

Laura Tom Arlene Tom Joann Chuck Diane Jack

TammyNicole Tom Jeff Matt Jess Jodie Ms. PittMonica Candice Kayla

Mae Tom

X-Chromosomes Inactivation

In female cells, one X chromosome is randomly switched off.

The turned off X chromosome forms a dense region in the nucleus called a Barr body.

Human Genome Project An ongoing effort to analyze the

human DNA sequence.

End of their Notes

Slide 23-38 I will do when I return.

Autosomal Recessive DisordersTay - Sachs Disease More common

among Jewish populations

Young children begin showing signs of slowed development

Severe impairment and death

Build up of lipids in the body – lysosomes do not function properly

Autosomal Recessive Disorders

Cystic Fibrosis More common in

Caucasians Mucus in

respiratory tract, difficulty breathing

Extreme salty sweat

Mucus may cause secondary infections

Autosomal Recessive Disorders

Phenylketonuria (PKU) Lack enzyme for

normal metabolism Phenylalanine builds

up and causes brain damage

Newborns are routinely tested

Changes in diet lead to normal life

PKU

Can be managed if caught early

Autosomal Recessive Disorders

Sickle Cell Disease More common

in Africans (African-Americans)

Causes blood to be sickle shaped

Affects oxygen flow to organs, causing weakness, pain, anemia, etc

Heterozygotes are resistant to malaria

Sickle-Cell Anemia

Autosomal Dominant Disorders

Affected children usually have an affected parent

Heterozygotes are effected

Two heterozygotes (Hh x Hh) can produce a normal (hh) child

Autosomal Dominant DisordersHuntington Disease Neurological disorder, progressive

degeneration of the brain Symptoms appear later in life (40s,

50s)

Huntington’s Disease

Huntington’s Disease

Autosomal Dominant Disorders

Achondroplasia Common form of Dwarfism Short arms and legs, normal

torso Homozygotes (AA) do not

survive

Achondroplasia

HDLs vs. LDLs

Autosomal Dominant DisorderHypercholesterolemia Incomplete dominance Caused by a recessive allele, however in

the heterozygous form (Hh), individuals have 2x the normal blood cholesterol levels

Can lead to Atherosclerosis