What type of cells are these?
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%
A-T-C-A-T-T-C-T-G
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 or letters
ex: TT
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
14. PTC
Punnett Squares- visual tool used to display the
possibilities of a genetic cross
Mom’s Traits
D
a
d’
s
T
r
a
i
t
s
For For the Wisconsin Fast plant, purple stems are dominate
to green stems. After growing several hundred plants, Johnny
realizes that 75% of the offspring have purple stems and 25%
of the offspring have green stems.
Find the genotypes of the parents using a Punnett square.
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