Transcript DNA

DNA
Chapter 8 Section 3
p. 224- 229
A. DNA
• A Chemical that contains the
information that an organism
needs to grow and function
A. DNA
• 1. Watson and Crick made the
first accurate model of DNA in
1953.
A. DNA
• 2. The Structure of DNA is
similar to a Twisted Ladder (a
double helix)
A. DNA 2.The Structure of DNA is similar
to a Twisted Ladder (a double helix)
• a. The sides of
the ladder are
made up of
sugar-phosphate
molecules
A. DNA 2.The Structure of DNA is similar
to a Twisted Ladder (a double helix)
a. The sides of the
ladder are made
up of sugarphosphate
molecules
• b. The rungs of
the ladder are
made up of
nitrogen bases
A. DNA 2.The Structure of DNA is similar
to a Twisted Ladder (a double helix)
• There are 4
Nitrogen Bases
that make the
Rungs (steps) of
the ladder –
– IN DNA,
– Adenine always
bonds to Thymine
– Guanine always
bonds to Cytosine
A. DNA 2.The Structure of DNA is similar
to a Twisted Ladder (a double helix)
• 3. Before a Cell
divides, its DNA
duplicates itself by
unwinding and
separating its sides,
then forming new
sides.
B. Genes
• Sections of DNA on a
chromosome
B. Genes
• 1. Contain instructions for
making specific proteins
B2. RNA
• Carries the codes for
making proteins from the
nucleus to the ribosomes
in the cytoplasm
Three types:
– Messenger RNA
(mRNA)
– Transfer RNA (tRNA)
– Ribosomal RNA
(rRNA)
B2. RNA
•There are 4 Nitrogen
Bases that make the
Rungs (steps) of the
ladder –
–IN RNA,
–Adenine always bonds to
Uracil
–Guanine always bonds
to Cytosine
B2. RNA
• 2a. Messenger
RNA (mRNA)
carries the code
that directs the
order in which
the Amino acids
bond
B2. RNA
• 2b. Ribosomal RNA makes up
the ribosomes where the
proteins are built
B2. RNA
• 2c. Transfer RNA brings amino
acids to the ribosomes to build
the proteins
B. Genes
• 3. Cells use only the genes that
direct the making of proteins
needed by that cell
A theatrical example:
• DNA is like letters that make up
• Genes which are like words or
sentences which make up
• Chromosomes like paragraphs or
chapters which work together with
• All the Chromosomes which makes
the script of the play that is YOU!
C. Mutations
• Any permanent change in the
DNA sequence of a cell’s genes
or chromosomes
C. Mutations
• 1. Can be caused by outside
factors like x-rays, Sunlight, and
some chemicals.
C. Mutations
• 2. A change in a gene or
chromosome can change the
traits of an organism.