DNA: The molecule of
Heredity
What controls heredity?
DNA determines an organism’s traits. Chromosomes are made of long DNA molecules.
DNA is the information for life, the complete instructions
for manufacturing all the proteins of an organism.
DNA determines what proteins will be made.
Living things contain proteins. Your skin, muscles, bones.
All actions, eating, running, thinking depend on proteins
called enzymes.
Structure of DNA:
DNA is composed of subunits called nucleotides.
Nucleotides have 3 parts:
A sugar—deoxyribose
A phosphate group
A nitrogenous base (either adenine, guanine, cytosine, or thymine)
The DNA molecule is a double helix, like a spiral
staircase. The backbone or handrails are
phosphate groups and ribose sugars, the rungs are nitrogenous bases paired by
weak hydrogen bonds.
Base Pairing:
Adenine can only bond with Thymine A-T
Guanine can only bond with Cytosine G-C
A cattail, a cat, and a catfish are all different organisms,
composed of different proteins.
Yet they all contain DNA made up of the A, T, G, C.
How can they be so different from each other when their
genetic material is made of the same thing?
Sequence of nucleotides form the unique genetic information
of each organism.
Before a cell can divide, the genetic information must be
copied.
The process of copying DNA is called REPLICATION.
DNA Replication:
DNA replication results in two
identical DNA strands.
Now the genetic
information can be passed on to new cells by mitosis or onto new offspring
through meiosis.
Why are each of you unique?
What are the rules of base pairing?
What is a replication fork?
Why must DNA unzip before it can be copied?
What are the two functions of DNA polymerase?
How does the original DNA molecule compare to the original molecule?