Download Dioxyribose Nucleic Acid

Dioxyribose Nucleic
Acid
Chapter 8 – Lesson 2
What is DNA?
• DNA is made of nucleic acids.
DNA contains information
that an organism needs to
grow and function. DNA
makes you who you are.
• DNA stands for dioxyribose
nucleic acid.
Discoverers of DNA
• James Watson and Francis
Crick made an accurate
model of DNA in 1953.
• Rosalind Franklin
discovered even more
about DNA, but she died
before she could become
famous .
DNA Structure
• The structure of DNA is similar to a
twisted ladder.
Sugar
Phosphate
– The sides of the ladder are made up
of sugar-phosphate molecules.
– The rungs of the ladder are made
up of nitrogen bases.
Nitrogen
Bases
Nitrogen Bases
•
•
•
•
Adenine – (A)
Guanine – (G)
Thymine – (T)
Cytosine – (C)
• A always pairs with T
• G always pairs with C
NITROGENOUS BASES
A = Adenine
T = Thymine
G = Guanine
C = Cytosine
Genes
• Genes are sections of DNA on a
chromosome.
• Everyone has different
patterns of
A, T, C, G. These different
patters allow for different
genes. Or, a different genetic
code.
Gene 1
Gene 2
Gene 3
Examples
A-T
T-A
G-C
G-C
C-G
A-T
A-T
G-C
G-C
C-G
A-T
T-A
G-C
C-G
C-G
different genes = different traits!
Genes
• Did you know:
- The majority of our DNA is considered “junk”
- 98% of our genetic code is the same as apes
- 50% of our genetic code is the same as a pig
DNA Replication
• Before a cell divides
(MITOSIS!), its DNA
duplicates itself by
unwinding and
separating its sides, then
forming new sides.
RNA
• Think of DNA as a
zipper. When it’s
zipped up, you have
plain DNA. When it’s
unzipped, you have
something known as
RNA!
C
G
T
A
C
T
C
G
A
A
G
G
C
A
U
T
G
A
G
C
U
T
U
T
C
RNA
• In RNA, T (thymine) get
replaced with U (uracil)
RNA
• RNA carries the amino acid codes for
making proteins.
AMINO ACIDS
PROTEINS
 What are amino acids? The building blocks of
proteins. Think legos…
Amino Acids
– All amino acids have their own “three” digit code using
nitrogen bases.
– Amino acids make proteins in your body.
• There are only 20 amino acids.
U A G
C U A
G C U
MRNA
– Messenger RNA (mRNA) carries the amino acid
code from the nucleus to the ribosomes in the
cytoplasm.
– When the ribosomes get the code, they can start
making proteins.
nucleus to…
ribosome
C U A
A
U
G C U
U A G
C
G
A
U
C
G
A
Mutations
• Mutations are any permanent change in
the DNA sequence of a cell’s gene or
chromosome. (DNA is deleted, inverted or
replaced)
– Can be caused by outside factors like x-rays,
sunlight, and some chemicals.
– A change in a gene or chromosome can
change the traits of an organism.
Mutations
• Mutations can be bad, but
they are also responsible
for diversity!
• Example: Giraffe Necks