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Human
Heredity and
Biotechnology
Chapter 11.1 & 11.3
with a scattering from
Chapter 13
Recessive Genetic Disorders
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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 the
inheritance of a trait
from one generation
to the next
Allows geneticists to trace
the transmission of a trait
through a family.
square = male
circle = female
colored shape = has trait
half colored shape = carrier
slash = deceased
Alexandrina Victoria, born May 1819
British 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
Telomeres
protective caps on ends on chromosomes
made of protein and DNA
may play a role in cancer and aging
Mutations
•
Caused by mutagens (anything that may cause a
mutation)
–
•
Virus, chemicals, toxins, UV light, etc.
3 types
1.
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
bacterium containing
recombinant DNA
cow containing genes
for producing
human milk proteins
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.