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What makes you….you!
What type of cells are these?
What is the arrow pointing to?
1800’s – with discovery of microscope, scientists realized
something [DNA] existed in the nucleus
1950’s – Rosalind Franklin- using X-ray discovered a stand
of DNA consists of a “double helix” or spiral
shaped ladder
- Watson and Crick- “ sides of ladder” consists of
sugars and phosphates and “steps of ladders” are
nitrogen base pairs
Video: Cracking the Code of Life |
Watch NOVA Online | PBS Video
phosphate
DNA- [Deoxyribonucleic Acid]
threads of chromatin
Sugar
Shape - like a spiral ladder
Nitrogen
base
1. Rungs = Pairs of Nitrogen Bases
A-T = Adenine - Thymine
G-C = Guanine - Cytosine
2. Handrails = Alternating Phosphate
and Deoxyribose Sugar
* Base pairs always attached to sugar
Inside the Nucleus
The Human Genome
Project, 3D Animation YouTube
Gene - a section of DNA coil, determines traits
of organism
Heredity- passing of genes from parent > offspring
Alleles - different forms a gene may
have for a trait
Genetics- study of how alleles affect generations of
offspring
Total Base
Pairs =
3.2 billion
Total
Genes =
30,000
To read all
3.2 billion
base pairs
aloud -it
would take
9.5 years
Chromosome
Number of Base Pairs [millions]
1
279
2
251
3
221
4
197
5
198
6
176
7
163
8
148
9
140
10
143
11
148
12
142
13
118
14
107
15
100
16
104
17
88
18
86
19
72
20
66
21
45
22
48
X/Y
163 / 51
98% of genes
for Humans
& Chimps
are alike
Genes
between
Humans
only differ
by 0.01%
The Human
Genome Project,
3D Animation YouTube
A-T-C-A-T-G-G-C-T
Isoleucine
Substitution
Methionine
Alanine
A-T-G-A-T-G-G-C-T
Methionine
Insertion
A-T-C-A-A-T-G-G-C-T
Deletion
A-T-C-T-G-G-C-T
http://app.discoveryeducation.com/search?Ntt=mutations
http://app.discoveryeducation.com/search?Ntt=mutations
http://www.youtube.com/watch?v=RjsU_rJpTWg
http://www.youtube.com/watch?v=-EwtyO16dFg
One comes from mom, one from Dad
Dad
Mom
Eye color
Genetic Cross- random pairing of one gene from
each parent
Gregor Mendel = Father of Genetics
Dominant- “what is seen” [Capital letter]
Recessive- “what is hidden”
[Lower case letter]
Phenotype- physical trait that appears
ex: Tall
Genotype- genetic make-up represented
by letters
ex: TT
What would all the possible
genotypes be for the trait of
tallness in a pea plant?
Homozygous [homo means same, zygous means pair] = TT,
tt
Heterozygous [hetero means different, zygous means pair] = Tt
Dominant Traits
1. Tongue roller
2. Hand clasp
3. Unattached earlobe
4. Straight Pinky
5. Hairy finger- 2nd section
6. Dimples
7. Cleft Chin
8. Straight hair line
9. Freckles
10. Hitch hiker thumb
11.Brown eyes
12. Second toe longer
than big toe
13. Finger divide- 2 vs 1
Yes
No
Genetics in Harry Potter?
• What types of inherited genetic traits are
described in the Harry Potter series?
17
Inherited Physical Traits
in Harry Potter
"All the Weasleys have red hair, freckles, and
more children than they can afford."
-- Draco Malfoy (Sorcerers Stone, Ch.6)
He was almost twice as tall as a normal
man and at least five times as wide.
(Sorcerer’s Stone, Ch.1)
Harry had a thin face, knobby knees,
black hair, and bright green eyes.
(Sorcerer’s Stone, Ch.1)
A pale boy with a pointed face and whiteblond hair, Draco greatly resembled his
father. His mother was blonde too...
(Goblet of Fire, Ch.8)
18
Applying Genetics to
the Harry Potter Characters
• What are some phenotypes (observable traits)
described in the four excerpts from the Harry
Potter books?
19
Applying Genetics to
the Harry Potter Characters
• What are some phenotypes (observable traits)
described in the four excerpts from the Harry
Potter books?
– Freckles
– Hair color
– Eye color
– Height
20
Applying Genetics to
the Harry Potter Characters
• A genetic trait can be described in two ways:
– Phenotypes are observable traits resulting from
how one’s genes are expressed. Ex., hair color, a
talent, sickle cell disease, etc.
– A Genotype consists of two letters that represent
a gene’s allele pair that results in a phenotype.
21
Example: Freckles
• Two possible phenotypes for freckles are:
– Has Freckles (observable)
– No freckles (observable)
• A genotype for freckles is indicated by two alleles in
the freckle gene. The possible alleles using the first
letter of the trait “f” are:
– F (dominant) = Has Freckles
– f (recessive) = No freckles
22
Freckles: Genotypes & Phenotypes
Question: Using F and f, what are possible
genotypes of the allele pair for freckles?
Genotype
Phenotype
(alleles inherited from parents)
(physical appearance)
FF
======
has freckles
Ff
======
has freckles
ff
======
no freckles
One dominant allele (F) is sufficient for its trait (has
freckles) to be observable, but both alleles have to be
recessive (f) for the recessive trait (no freckles) to be
observable.
23
Punnett Squares- visual tool used to display the
possibilities of a genetic cross
The parents’
homozygous
genotypes are:
Mom = F F
Dad =
ff
Mom’s Traits
FF
D
a
d’
s
T
r
a
i
t
s
ff
F
F
f
F
F
F
f
f
Example: Red Hair
• Red hair color is recessive to brown color. One way
to describe the hair color alleles are:
– Red hair = r (notes recessive red color)
– Brown hair = R (notes dominant brown color)
Question: Using r (red hair) and R (brown hair) alleles,
what possible genotypes of the allele pair are there?
Genotype (allele pair)
Phenotype (appearance)
RR
Rr
rr
======
======
======
brown hair
brown hair
red hair
Punnet Square: Weasley Family
All Weasley children have freckles and red hair. Use
the Punnett Square to predict the most likely
genotypes of Molly and Arthur Weasley for the two
traits.
Use the following allele possibilities that we
identified previously:
–
–
–
–
r (notes recessive red color) = Red hair
R (notes dominant brown color) = Brown hair
F (dominant) = Has Freckles
f (recessive) = No freckles
27
Punnett Square: Weasley Family
All Weasley children have freckles and red hair—100%
probability. Possible genotypes for their red hair (recessive
trait) and freckles (dominant trait) are: rr only for red hair
and Ff or FF for freckles. Create Punnett squares to find out
more about their parents Molly and Arthur:
rr
rr
Ff/FF
Ff/FF
rr
rr
Ff/FF
Ff/FF
Both parents have rr.
At least one parent has FF.
Punnet Square: The Potters
Question 1: Harry has dark/brown hair like his
father, but his mom had red hair. Using the
genotypes of rr, Rr, and RR, what possible
genotypes does each of the Potters have?
The phenotypes of the Potters are:
James Potter (dad)—dark/brown hair
Lily Potter (mom)—red hair
Harry Potter—dark/brown hair
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Punnet Square: The Potters
Using the genotypes of rr, Rr, and RR, what are
possible genotypes for Harry’s parents?
– Mom-Lily (red hair) = rr
– Dad-James (dark hair) = Rr or RR
r
r
r
R
R
r
R
r
The parents’ genotypes lead to 2 Punnett Squares.
30
Punnet Square: The Potters
Given Harry’s parents’ possible genotypes, the two
Punnett Squares can be completed as follows:
r
r
r
r
R Rr
Rr
R Rr
Rr
r rr
rr
R Rr
Rr
The only possible genotype for Harry’s dark hair is Rr.
31
Punnet Square: The Potters
Questions : Harry marries Ginny who has red hair.
What are possible genotypes of their children’s hair
colors?
Punnet Square: Harry & Ginny
Harry marries Ginny who has red hair. What are
possible genotypes of their children’s hair colors?
First, what are the genotypes for Harry and Ginny’s
hair colors?
Harry’s genotype = Rr
Ginny’s genotype = rr
33
Punnet Square: Harry & Ginny
Harry marries Ginny who has red hair. What are
possible genotypes of their children’s hair colors?
Given Harry and Ginny’s genotypes, Rr and rr, we
can fill in the Punnett Square for their children’s
genotypes.
Their children have a 50%
chance of having red or
dark hair colors.
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1. What are the steps of the DNA ladder made of?
Nitrogen Base Pairs : A-T, G-C
2. What are the sides of the ladder made of?
Phosphates and sugars
3. What are base pairs always attached to?
Sugar
4. Where are genes located?
On chromosomes
5. Different forms of the same genes are called?
Alleles
6. Physical appearance of a trait is called?
Phenotype
7. Genetic make up of an organism?
Genotype
8. What does the term heterozygous mean? Homozygous?
Different gene combinations, dominant and recessive
Same gene pairs
9.What is a mutation? Are they always harmful?
Permanent change to an organism
No create variety
10. What is the purpose of using a Punnett square?
Determine probability of traits that can be inherited
11. What is the process that involves one cell dividing two times to
create four new cells with half the number of chromosomes?
Meiosis
12. What type of cells undergo meiosis?
Sperm and Egg
13. How many chromosomes are in a human
egg cell?
23 ----- Why not 46?
14. What is it called when many genes create ONE trait?
polygenic inheritance
15. What is the term for more than two possibilities of a trait?
multiple alleles
16. When both genes are expressed equally for a trait it is called?
incomplete dominance
Creation of Proteins
Base pairs form amino acids which link together
to form proteins