Human Heredity and BiotechnologyChapter 11.1 & 11.3

with a scattering from Chapter 13

Recessive Genetic Disorders

• Began with the study of alkaptonuria

• Passed like any recessive trait

• Heterozygous condition results in ‘carriers’

• Disorder Table: cystic fibrosis & albinism

• Disorder Table: galactosemia &Tay Sachs

Dominant Genetic Disorders

• Only need one dominant allele to inherit the disease

• No carriers

• Disorder Table: Huntington’s Disease & Achondroplasia

PEDIGREE

chart which shows theinheritance of a trait from one generation

to the next

Allows geneticists to trace the transmission of a trait through a family.

square = malecircle = female

colored shape = has traithalf colored shape = carrier

slash = deceased

Alexandrina Victoria, born May 1819British Monarch

Queen Victoria was a carrier of hemophilia.

She had nine children and passed hemophilia on to several of them.

All of her children married into the royal families of various countries of Europe.

In this way, all of the Royal Families of Europe inherited the gene for hemophilia.

How many generations are represented?How many males? afflicted males? normal males?

How many females? afflicted females? normal females?Any carriers?

Sex-linked or autosomal trait?Dominant or recessive trait?

Any twins? deceased individuals?

HUMAN CHROMOSOMES

Humans contain….

46 individual chromosomes

23 chromosome pairs

SEX CHROMOSOMES (1 pair)

• determine the sex

of an individual

AUTOSOMES (22 pairs)

• do not determine the sex

of an individual

KARYOTYPE

is a photomicrograph of the chromosomes

in a dividing cell

chromosomes are grouped

and placed into pairs

female - 46 XX

male - 46 XY

Telomeresprotective caps on ends on chromosomes

made of protein and DNAmay play a role in cancer and aging

Mutations

• Caused by mutagens (anything that may cause a mutation)

– Virus, chemicals, toxins, UV light, etc.

• 3 types1. Somatic cell mutations: affect body cells

will affect individual, but not offspring

2. Germ cell mutations: affect germ cells Will affect offspring, but not the individual

3. Lethal mutations Will cause death either before or shortly after birth

Chromosome Mutations

• Deletion– A piece of a chromosome is lost

• Inversion– A piece of a chromosome breaks off, flips over, and reattaches

• Translocation– A piece of a chromosome breaks off and reattaches to another

chromosome

• Nondisjunction– Homologues do not separate

Deletion

Inversion

Translocation

NONDISJUNCTION

may arise when chromosomes don’t separate

properly during meiosis, this is called

“not coming apart”

Nondisjunction

• Leads to either monosomy (45) or trisomy (47) in a cell• Trisomy on #21 = Down’s Syndrome• Trisomy on sex chromosomes (#23) can lead to XXY

(Klinefelter’s syndrome) or XYY• Monosomy on sex chromosomes (#23) can lead to XO

(Turner’s Syndrome)

DOWN SYNDROME(also called trisomy 21)

male or female having an extra chromosome in pair #21

(instead of 2 chromosomes in pair there are 3)

47 XX or 47 XY

Nondisjunction on #21 = Trisomy 21 (Down Syndrome)

TURNER SYNDROME female that is missing a sex chromosome -

45 XO

KLINEFELTER SYNDROME

male having an extra sex chromosome

47 XXY or 48 XXXY

Which mutations are shown?

Fetal Testing

• Genetic testing for couples with family history of genetic diseases– pre-pregnancy: DNA testing & genetic counseling– post-pregnancy: PKU testing– during pregnancy:

• Amniocentesis

• Chorionic villi sampling

• Fetal blood sampling

HUMAN GENOME PROJECT

Began in 1990 -

an attempt to sequence

all of the human DNA.

Genome = an organism’s DNA

Mapping of the human

genome completed in 2003.

GENE THERAPY

process in which an absent or faulty gene is replaced by a normal, working gene

various approaches have been taken…

– Bone marrow removed, modified in the laboratory and placed back in the body

– Modified viruses have been used to carry replacement genes into the body

– Inhalation of genetically engineered viruses containing “good” genes has been attempted

up to this point, gene therapy has not been very successful

Manipulating DNA…• Today, we have expanded our use of genetic

information and we are able to use techniques for manipulating (modifying) DNA.

We can…. • extract DNA from cells, • cut it into small pieces, • identify the genes and sequences in DNA• make copies

Cell Transformation….process by which a cell takes in DNA from an

outside source

• the external DNA may become part

of the cell’s DNA

Recombinant DNA – taking DNA from one organism and combining it with another organism

• we have inserted the genes for human insulin and human growth hormone into bacteria

Transgenic Organism…an organism containing genes from

another organism

cow containing genes

for producing

human milk proteins

bacterium containing

recombinant DNA

Cloning…process of producing an identical copy of an organism

• we have successfully cloned frogs, salamanders, mice, sheep and other organisms

DOLLY

What is genetic engineering?it is simply….

genetic modification

Throughout the ages,

man has applied his knowledge

of genetics to the world around him –

especially to plants and animals.

Selective Breeding…the process of breeding animals or plants with

desired characteristics

• Man has used selective breeding to develop plants and animals with “desirable traits”.

• Nearly all domestic animals – dogs, cats, horses, and most crop plants have been produced by selective breeding.

Selective Breeding…of plants

Selective Breeding…of animals

Hybridization…

crossing dissimilar individuals to bring together the best traits of both organisms

hybrids (produced by

such crosses) are

often healthier and

hardier than either

of the parents

Hybridization …

ZEDONK – cross between a zebra and a donkey

Hybridization …

LIGER – cross between a lion and a tiger

Hybridization …

male DONKEY and female HORSE = MULE

Offspring (mules) are almost always sterile. The mule has

greater endurance, is stronger and less excitable than a horse.

Inbreeding…continued breeding of individuals with similar characteristics - used to maintain

characteristics in a breed

Inbreeding…

While selective breeding often limits variation, scientists are also interested in preserving the genetic diversity in organisms.

WHY?

Genetic diversity (variation) in a population

can be increased by inducing mutations.

Mutations may be induced by the

use of chemicals and radiation.