Download Gene

Heredity
Outline
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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
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 are
characteristics that can be passed
from parents to their offspring
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
• 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
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
Mendel’s Work
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 have a certain part (location) of a
chromosome where they are found
• Everyone has different combinations of
traits, but…
– The genes for those traits are on the same
parts (locations) of chromosomes in everyone.
Human Genome Project
• Major science project that mapped out
all of the genes on the human
chromosomes
– Identified the location of our genes
Our Genes
• How many genes do
humans have?
http://web.ornl.gov/sci/t
echresources/Human_
Genome/posters/chro
mosome/
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
Our Genes
• We have 2 copies of each
gene.
• 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
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
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
• When the sperm and egg
cell combine they form 1
cell with 46 single
chromosomes (23 pairs).
– All humans have started as 1
cell just like that
Inheritance
• The characteristics seen in us depend on 2
things.
1. the combination of gene variations we get
from our parents
2. how those gene variations 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 or
observed if it is present
– Recessive: the trait/characteristic that is only seen or
observed when the dominant variation is not present
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
Inheritance Terms
• Homozygous Dominant: 2 dominant genes
• Homozygous Recessive: 2 recessive
genes
• Heterozygous: 1 dominant and 1 recessive
gene
Predicting Inheritance
• Punnett Square: a tool to
predict the
characteristics a child
can inherit from its
parents
W = dominant
w = recessive
– Use the alleles each parent
has to determine the
possible combinations that
can be passed to offspring
– Capital letters represent
dominant allele
– Lowercase letters
represent recessive allele
Punnett Square Example
• Example using hairline
– Mother has the following
combination – Ww
– Father has the following
combination – ww
– They each pass 1 variation
(letter) on to their
offspring
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Draw a Punnett Square
Label sides
Add parent variations
Fill in the square
MOTHER
W
F
A
T
H
E
R
w
w
Ww
Ww
w
ww
ww
Punnett Square Example
• What does this show us?
– Ww would have a widow’s
peak
– ww would have 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
W
F
A
T
H
E
R
w
w
Ww
Ww
w
ww
ww
Modern uses of DNA Technology
• Selective Breeding
– Breeding plants or animals for specific traits
– 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
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?
Forensic Science Pictures
Forensic Science Pictures
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
– Transgenic organism: an organism that has had
it’s DNA altered by genetic engineering.
Modern uses of DNA Technology
• Gene Therapy
– A type of genetic engineering in which
damaged genes are replaced by normal genes
Genetic Engineering Movies
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
Cloning
Cloning Movies
Cloning Movies
Cloning Movies
Modern uses of DNA Technology
• Stem Cell Research
– Taking an undifferentiated cell (one that
hasn’t changed into a specific type of cell)
and making it turn into the type of cell you
want it to
– Can be used for:
• Creating new organs to replace damaged ones
• Replace damaged nerve cells in a spinal cord
• Replace damaged brain cells
Stem Cells