1. Gregor Mendel conducted experiments with pea plants in the 19th century that laid the foundations for genetics by establishing basic genetic concepts like dominant and recessive traits, true-breeding organisms, and the inheritance of traits from parents to offspring. 2. DNA technology like genetic engineering allows scientists to cut and splice genes from one organism into another, creating recombinant DNA and transgenic organisms. This has applications in producing human insulin and growth hormones in bacteria. 3. Issues around genetic engineering include safety concerns about creating new pathogens, the ethics of modifying human genes or eliminating genetic defects, and who has access to gene therapies.

1. III. Genetics & Genetic
Engineering
Presentation # 3 Ch. 11, 13, & 14
• Gregor Mendel - the ―Father of
Genetics‖
• Was an Austrian monk
• Worked in a monastery garden
• Cross-pollinated plants, studied
traits (characteristics) of offspring
• Looked at true-breeding pea
plants - if pollinated produced
offspring identical to themself
• Looked at hybrids - the offspring
of crosses between parents of
different traits

2. Some of Mendel’s crosses:
Section 11-1
Seed Seed Seed Coat Pod Pod Flower Plant
Shape Color Color Shape Color Position Height
Round Yellow Gray Smooth Green Axial Tall
Wrinkled Green White Constricted Yellow Terminal Short
Round Yellow Gray Smooth Green Axial Tall

3. III. Genetics
– A . Terms to Memorize:
• 1. Gene - units of DNA passed from parent to offspring. Each adult
has two copies of each gene - 1 from each parent
• 2. Allele - a specific form or expression of a gene trait
– Example - brown eyes, Curly hair.
• 3. Dominant - an allele that is always expressed or seen
– Dark pigments are usually dominant
• 4. Recessive - an allele that is can be hidden, it will not be
expressed if present with a dominant allele
• 5. Phenotype - actual gene expression - what is physically seen
• 6. Genotype - the actual pair of alleles present
– Homozygous = same 2 alleles in gene pair BB, bb (purebred)
– Heterozygous= = different alleles present in gene pair Bb, Tt (Hybrid)
• 7. Probability - the likelihood that a particular event will occur
- Q:If you flip a coin 4 times in a row, what is the probability that it will
land
on tails every time?
- A: 1/2 x 1//2 x 1/2 x 1/2 = 1/16 Each coin flip is an independent
event.
- Q: What is the probability of having 3 girls in a row?

4. III. Genetics
Probability can help us predict the outcomes of genetic crosses.
– B. Genetic Crosses
• 1. Monohybrid - 1 trait crosses
– Studies 1 set of alleles from both parents
– a) identify the trait and letters to be used - brown hair (B) or blond (b)
– b) write the genotypes - i.e. Bb or BB or bb for both parents
– c) separate the alleles into possible gametes b , B for each parent
– d) draw a Punnett square and write one allele by each row and
column
– Join gametes together
– Determine ratios
of phenotypes and
genotypes
B B
B
b

5. III. Genetics
– B. Genetic Crosses
• 2.Dihybrid - 2 trait crosses
– Studies 2 sets of alleles from both parents
– Steps are the same but more complex because of more combinations
– To identify # of possible gametes - look at how many different alleles
there are for each trait then multiply.
– Example - BbFf - 2 different b’s and 2 different f’s 2x2=4
– Use foil to get possible gametes f-firsts, 0-outer, i-inner, l-lasts
– Use punnett square to determine offspring

6. Dihybrid Cross
BF Bf bF bf
BF BBF BBFf BbFF BbFf
F
Bf BBFf BBff BbFf Bbff
bF BbFf bbFF bbFf
BbFF
bf BbFf Bbff bbFf bbff

7. An example of a
Dihybrid cross

8. Another Dihybrid cross:
Section 11-3

9. III. Genetics
– B. Genetic Crosses
• 3. Incomplete Dominance
– Two alleles are neither dominant or recessive
– The two show a blending of their phenotypes
– Example: red carnations crossed with white carnations produce all pink
carnations
– CRCR= red CW CW = white CRCW = pink
• 4. Co dominance
– Two alleles are both dominant or expressed at the same time
– Example: hair color in cattle Red and White hair crossed = Roan
– HRHR = red hair HWHW = white HRHW = roan (red and white hair)

10. Incomplete
Dominance:

11. III. Genetics
– B. Genetic Crosses
• 5. Polygenic traits
– More than one gene will determine phenotype
– Hair color in humans is controlled by more than one gene
– Eye color in humans also is polygenic
– Epistatic traits - one gene exerts control over another gene
expression.
- Ex: More than 12 pairs of alleles interact in various ways to
produce coat
color in rabbits.
- Ex: 2 gene pairs interact together to produce 8 types of combs in
roosters.
• 6. Multiple Alleles
– More than two alleles are possible for one gene
– Example: Blood type
» Type A = ―A‖ antigen on the blood cell IA = A allele
» Type B = ―B‖ antigen on the blood cell IB = B allele

12. Multiple alleles- Blood Typing

13. Polygene inheritance

14. III. Genetics
– C. Genetic Disorders/Diseases
• 1. Detection - obtaining fetal cells to do karyotyping and biochemical tests
– A) amniocentesis (see next slide)
– B) Chorionic villus sampling (see next slide)
• 2. Sex-linked traits - genes only found on the X or Y chromosomes
– A) colorblindness
– B) hemophilia
– C) muscular dystrophy
– Do a Punnett Square example:
• Question: XC Xc
•Can 2 normal parents have
a colorblind child? If so, what is
the sex of that child? XC XCXC XCXc
• A: Yes (If mom is a carrier). Male.
Y XCY XcY

16. III. Genetics
– C. Genetic Disorders/Diseases
• 4. Gene mutations - changes in DNA sequence caused by exposure to
radiation or chemicals, crossing over or genetic errors
– Sickle-celled anemia - blood cells are misshaped due conditions of low
oxygen
» Recessive trait, no known cure
– Cystic fibrosis - recessive allele, causes thick mucous build up in the
lungs and intestines, can cause liver disease, diabetes
» Recessive trait, no know cure
– Tay-Sachs - slow degenerative disease of optic and mental function in
young children
» Recessive trait carried on chromosome 15, no known cure

17. D. How have humans created new breeds?
• Selective Breeding - allowing
only those animals with desired
characteristics to produce the
next generation.
• Ex: breeds of dogs, horses, cats,
farm animals, crops.
• Hybridization - crossing
dissimilar individuals to bring
together the best of both
organisms. Ex: daisies, crops
• Inbreeding - continued breeding
of individuals with similar
characteristics.
• Ex: Golden retrievers, German
www.vwgs.com/ shepherds
• All of the above have been done
for years, without altering the
genetic code.

18. IV. DNA Technology
– A. Genetic Engineering-making changes in the DNA code
• Restriction Enzymes- proteins that ―cut‖ DNA at specific locations,
looks for a certain nucleotide (base) sequence
• DNA recombination
– Cutting and splicing pieces of DNA into other strands of DNA
» Plasmids - circular DNA molecules found in bacteria, separate
from other bacterial DNA
» Sticky ends - matching or complimentary segments of DNA that are
produced by restriction enzymes
» Human genes can be inserted into bacterial plasmids so the
bacteria can produce human enzymes or proteins = recombinant
DNA

19. How restriction enzymes are used to edit DNA:
• Enzymes cut the DNA molecule at a certain site.
• Different restriction enzymes recognize and cut different sequences of
DNA.
• The cut ends are called sticky ends because they may ―stick‖ to other
complementary bases by means of H bonds.
• Can then take a gene from one organism and attach it to the DNA of
another organism = Recombinant DNA.
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.

20. Overview: Making a
Recombinant DNA
molecule.

21. • Ex: Genetically
Engineered Insulin -
Produced by splicing the
human gene for making
insulin into the plasmid of
E.coli host cells.
• The genetically modified
bacteria then produces
insulin; it is collected and
used for diabetics.
• Was 1st recombinant DNA
drug approved for use in
humans.
• Another Ex: Human
Growth Hormone

22. Example: Steps in producing Human Growth Hormone

23. Example of Using DNA Technology:
DNA Fingerprinting:
Process of cutting apart DNA from two
sources and comparing the results
from gel electrophoresis.
Utilized in criminal investigations and
paternity/maternity cases. (No
individual is exactly alike.)
Weblink
http://www.pbs.org/wgbh/nova/sheppard/labwave.html

24. DNA Fingerprinting Procedure:
• A small sample of DNA is cut with13-6 Gel enzyme.
Figure a restriction Electrophoresis
(From sperm, blood, hair, or other material.)
Section 13-2
• The DNA fragments are separated by size using gel electrophoresis.
• The shorter fragments move faster toward the + charge.
• Patterns of bands are compared to see if suspect’s band pattern is the same as that of the
crime scene material.
DNA plus restriction Power
enzyme source
Longer
fragments
Shorter
fragments
Mixture of DNA Gel
fragments

25. Applications of Genetic Engineering:
• Transgenic Organisms - they
contain genes from another
species
• Examples:
• tobacco plant which glows in
the dark (see top photo)
www.mun.ca/.../Luciferase_ reporter_gene.htm • corn which produces a natural
pesticide
• mice with similar immune
systems as humans - are used
study effects of diseases
• sheep which carry a gene for a
human blood protein. They
secrete it in their milk - helps
patients with cystic fibrosis.
(See GM sheep, bottom photo)

26. More applications of Genetic Engineering: Cloning.
Section 13-4 Steps of cloning:
A donor cell is taken from
a sheep’s udder. Donor
Nucleus
These two cells are fused
using an electric shock.
Fused Cell
Egg Cell
The nucleus of the
egg cell is removed.
An egg cell is taken The fused cell
from an adult begins dividing
female sheep. normally.
Cloned Lamb Embryo
The embryo The embryo is placed
develops normally in the uterus of a foster
into a lamb—Dolly
Foster mother.
Mother

27. Decision Making - Safety and Ethical Issues of
DNA Technology:
• Can DNA technology create
hazardous new pathogens? Could
they escape from the lab?
• Is genetically modified food safe to
eat?
• Can transgenic plants pass their
new genes to other plants in wild
areas?
• Who should be allowed to take
Human Growth Hormone?
• Should we try to eliminate genetic
defects in our children?
• Should everyone get a DNA
fingerprint ID?
• Can the Human Genome Project
result in human health

28. Chromosomal Abnormalities and
Nondisjunction
• Nondisjunction in meiosis results in gametes with
abnormal chromosome number
• Most cases produce gametes that are not viable

29. Down Syndrome – Trisomy 21
• Extra 21st
chromosome
• Causes physical
and mental
abnormalities

30. Trisomy 18 Trisomy 13
Edward’s Patau’s
Syndrome Syndrome

31. Turner’s Syndrome
• Female with only one X
chromosome (XO)
• Sterile

32. Klinefelter’s Syndrome
• Male XXY, XXXY, or XXXXY
• Sterile

33. Jacob’s Syndrome (XYY)
• Men are mostly
normal
• Increased
aggression and
learning disabilities