2. Outline
• What are genes?
• Gregor Mendel
• Where can we find our genes?
• What do our genes do?
• Our Genes
• Genetic Trait Tree
• Where do we get our genes from?
• Inheritance
• Predicting Inheritance
• Modern uses of DNA technology
3. What are genes?
• Heredity: the passing of genes
from parents to offspring
(children)
• Gene: a specific part of DNA
that controls a hereditary trait
• Hereditary traits: characteristics
that can be passed from parents
to their offspring
4. Inherited vs. Acquired
Characteristics
• Inherited characteristics: characteristics
that are controlled by genes/DNA passed
from parents to their offspring
– Examples -> height, natural hair color, eye
color
5. Inherited vs. Acquired
Characteristics
• Acquired characteristics: characteristics
that can be developed or altered during a
person’s lifetime
– Examples -> tattoo, learning to play a sport,
learning to play a musical instrument
6. Gregor Mendel
• Austrian monk
• Considered to be the
father of modern
Genetics
• Used pea plants to
demonstrate how
certain characteristics
were passed through
generations
– Seed shape, seed color,
flower color, pod shape,
pod color, and stem
height
8. Where can we find our genes?
• We have 1000’s of genes and each one is
found at a specific location on a specific
chromosome
– What does that mean?
• All genes are found in specific places
• Everyone has different combinations of
traits, but…
– The genes for those traits are found on the
same parts of chromosomes in everyone
9. What do our genes do?
• Genes determine the traits
that we have
– We are most familiar with
physical traits
– So basically our genes
determine what we look like
• Physical traits are
observable characteristics
– Things that we can see
– examples: hair color, eye
color, tongue rolling, ear
lobes, hairline
10. Genetic Trait Tree
• We are going to be
creating a Genetic Trait
Tree to examine certain
characteristics (traits)
within our class
• For this activity we will
be examining 3 traits
– Free or attached ear
lobes
– Widow’s peak
– Tongue rolling
11. Our Genes
• How many genes do
humans have?
– http://web.ornl.gov/sci/te
chresources/Human_Ge
nome/posters/chromoso
me/
12. Our Genes
• We have 2 copies of each
gene (1 from each parent)
• Each gene has 2 or more
variations for what we see
– We can inherit the same or
different variations
– examples:
• Hair color – brown, black, red,
blonde
• Tongue rolling – can do it,
can’t do it
13. Where do we get our genes from?
• ½ comes from mother
– 23 single chromosomes
in the egg cell
• ½ comes from father
– 23 single chromosomes
in sperm cell
14. Where do we get our genes from?
• When the sperm and
egg cells combine they
form 1 cell with 46
single chromosomes (23
pairs).
– All humans have started
as 1 cell just like that
15. Inheritance
• The characteristics seen in us depend on 2
things.
1. the combination of genes we get from our parents
2. how those genes interact with each other
• The different variations of genes are called
alleles
• 2 basic alleles (gene variations)
– Dominant: the trait/characteristic that is always seen if it
is present
– Recessive: the trait/characteristic that is only seen when
the dominant variation is not present
16. Dominant and Recessive Traits
• Example of dominant and
recessive alleles
– A person can have a widow’s
peak (dominant) or a
straight hairline (recessive)
– 2 dominant alleles = a
person with a widow’s peak
– 1 dominant and 1 recessive
allele = a person with a
widow’s peak
– 2 recessive alleles = a
person with a straight
hairline
18. Predicting Inheritance
• Punnett Square: a tool to
predict the
characteristics a child
can inherit from its
parents
– Use the alleles each parent
has to determine the
possible gene combinations
that can be passed to
offspring
– Capital letters = dominant
allele
– Lowercase letters =
recessive allele
W = dominant
w = recessive
19. Punnett Square Example
• Example using hairline
– Mother has the following
combination – Ww
– Father has the following
combination – ww
– They each pass 1 gene
variation (letter) to their
offspring
• Draw a Punnett Square
• Label sides
• Add parent variations
• Fill in the square
MOTHER
F
A
T
H
E
R
W w
w
w
W w
W w
w w
w w
20. Punnett Square Example
• What does this show us?
– Dominant = widow’s peak
– Recessive = straight
hairline
– Genotype: genetic makeup
• 2 of 4 children have Ww
and 2 have ww
– Phenotype: physical
appearance
• 50% chance of having a
child with a widow’s peak
• 50% chance of having a
child with straight hairline
MOTHER
F
A
T
H
E
R
W w
w
w
W w
W w
w w
w w
21. Modern uses of DNA Technology
• Selective Breeding
– Breeding plants or animals for specific traits (making
them look the way we want)
– Has been used to create all of the different breeds
of dogs that we currently have
• Bred to make them better hunters, or nicer temper, or
better for protection
22. Modern uses of DNA Technology
• Forensic Science
– DNA Fingerprinting: identifying people based
on their DNA
– What shows on TV have you seen that use
this?
25. Modern uses of DNA Technology
• Genetic engineering
– Changing the DNA of an organism to alter it in
some way
– Has been used to alter plants and vegetables
• Grow bigger, faster, in tougher conditions, and
resistant to insects
26. Modern uses of DNA Technology
• Gene Therapy
– A type of genetic engineering in which
damaged genes are replaced by normal genes
28. Modern Uses of DNA Technology
• Cloning
– Creating an exact copy of an existing
organism
– Dolly (a sheep) was the first cloned animal
to survive the process
• Happened in 1997
– How is it done?
– There are problems with it though
