Transcript Part 4

Nucleic Acids
• Nucleic acids provide the
directions for building
proteins.
• Two main types…
 DNA – deoxyribonucleic
acid
 Genetic material (genes)
that are passed on from
parent to offspring
 Codes the amino acids
sequence to create a
protein
 RNA – ribonucleic acid
 Helps translate the genetic
code to make proteins
•
•
Nucleic acids are
polymers made from the
monomers called
nucleotides
3 parts of a nucleotide –
1.
2.
3.
Sugar (either deoxyribose
or ribose)
Phosphate group
(phosphorus atom bonded
to oxygen atoms)
Nitrogenous base

DNA bases


Adenine, Guanine,
Cytosine, Thymine
RNA bases

Adenine, Guanine,
Cytosine, Uracil
NUCLEOTIDES
DNA Strands
• DNA is many nucleotides
chemically bonded in a
specific sequence into a
polymer by using
dehydration synthesis.
• DNA is composed of two
strands wrapped around each
other in a Double helix.
• In the center of the helix, the
nucleotide bases are held
together by hydrogen bonds.
• This base-pairing is specific
– Adenine bonds with Thymine
– Guanine bonds with Cytosine
DNA Replication
Before a cell can divide the DNA must copy itself in DNA
Replication.
It uses a semi-conservative model by having each strand used as
a template for the new strand.
This ensures that
the DNA of the
offspring is identical
to the parent.
Evolutionary Link
DNA and Protein