2. The Vocabulary of DNA
Genetics—The study of
genes & heredity
Trait-- inherited
characteristic
determined by the
presence and
expression of dominant
and/or recessive alleles.
Gene-- a segment of
DNA that codes for a
protein, which in turn
codes for a trait (skin
3. DNA Facts
Chromosomes are made of DNA
Deoxyribonucleic Acid (DNA)
Molecule that stores genetic information in cells
Copies itself exactly for new cells
4. DNA-Deoxyribonucleic Acid
DNA is often called the
blueprint of life.
In simple terms, DNA
contains the instructions for
making proteins within the
cell.
5. Proteins
Responsible for all cell
structures and functions
Made of long chains of
amino acids
There are 20 amino acids in the
body
Proteins are responsible for:
Hair, skin, hormones, muscle
movement, antibodies, chemical
reactions, oxygenation of cells.
6. When Watson, Crick
and Wilkins got their
Nobel prize awards in
1962, Rosalind
Franklin was cheated
of deserved
recognition in part by
her early death from
cancer in 1958.
Rosalind Franklin and Maurice
Wilkins took DNA X-ray photos that
were essential to the discovery of the
double helix of DNA by James
Watson and Francis Crick in 1953.
7. Why is the Study of DNA
Important?
It’s essential to all life on earth
Medical Benefits—disease detection,
treatment, prevention
Development of Crops
Forensics
8. DNA Structure
DNA is a polymer (composed of
repeating subunits called nucleotides)
2 long strands
Each a chain of nucleotides
10. Adenine and Guanine are PURINES
Adenine and guanine each have two rings
of carbon and nitrogen atoms.
C
C
C
C
N
N
N
Adenine N
N
C
C
C
C
C
N
N
O
N
Guanine N
N
C
11. Thymine and Cytosine are PYRIDAMINES
Thymine and cytosine each have one ring
of carbon and nitrogen atoms.
C
C
C
C
N
N
O
N
cytosine
C
C
C
C
N
N
O
O
thymine
C
12. Types of Nitrogenous Bases
A = adenine
T = thymine
C = cytosine
G = guanine
13. DNA Strand
Each nucleotide bonds
to the next one to form a
strand.
The two strands twist
around a central axis to
form a double helix.
Sides of the ladder
alternate phosphate and
sugar (deoxyribose)
Rungs are held together
by Hydrogen bonds
14. Base Pair Rule
Adenine can bond
only with Thymine
A-T or T-A (2 H
bonds)
Cytosine can bond
only with Guanine
C-G or G-C (3 H
bonds)
This is called the
BASE PAIR RULE
15. Nitrogenous Bases
Those 4 bases
(ATCG) have endless
combinations
Just like the letters of
the alphabet can
combine to make an
infinite number of
words.
The two strands are
said to be
complimentary
That means that if you have
GAATAC on one side you
16. Replication
The process by which DNA
makes a copy of itself
Why does DNA need to copy?
Cells divide for an organism to
grow or reproduce
Every new cell needs a copy of
DNA
In DNA replication enzymes
work to unwind and separate
the double helix and add
complimentary nucleotides to
the exposed strands
17. Replication
DNA replication is semi-conservative.
When it makes a copy, one half of the old
strand is ALWAYS kept in the new strand
This helps reduce the number of copy errors.
18. DNA Replication
DNA helicases—
break H-bonds
linking bases
DNA
polymerases—
move along each of
the strands, adding
nucleotides,
according to base
pairing rules.
19. DNA Replication
The result is two
exact copies of the
original DNA
Each new double
helix is composed of
one original DNA
strand and one new
strand.
Semi-conservative
20. Translation
DNA is in the nucleus
To make proteins,
DNA must get its
instructions to the
ribosomes who make
proteins.
To transport its
instructions, it uses
Messenger RNA
(mRNA)
21. RNA
Ribonucleic Acid
Consists only of
one strand of
nucleotides
Has ribose (a 5C
sugar) NOT
deoxyribose
Has uracil (U) as
a nitrogenous
base NOT
thymine
22. DNA by the Numbers
Each cell has about 3
meters of DNA.
The average human has
300 trillion cells.
The average human has
enough DNA to go from
the earth to the sun more
than 400 times.
DNA has a diameter of
only 0.000000002 meters.
The earth is 150 billion meters
or 93 million miles from
the sun.
