1. How
DNA
Works

2. • DNA is found in
the cells of all
organisms, from
mosquitoes to
bacteria to humans
• Each organism has
a unique set of
DNA, but DNA
functions the same
way in all
organisms.

3. Unraveling DNA
• 1) DNA is often wound around proteins,
coiled into strands, and then bundled up
even more
• 2) In a cell that lacks a nucleus, each
strand of DNA forms a loose loop within
the cell
• 3) In a cell with a nucleus, the strands of
DNA and proteins: are bundled into
chromosomes

4. See the Difference!

5. • 4) The order of the bases on one side of
the molecule is a code that carries
information.
• 5) A gene consists of: a string of
nucleotides that gives cell information

7. Genes and Proteins
1) DNA code reads like a book—from 1
end to the other, in 1 direction
2) Bases form the alphabet of the code.
Groups of 3 bases are the codes for
specific amino acids.
3) Example: 3 bases CCA form proline.
4) A long string of amino acids forms a
protein. Thus, each gene is usually a: set
of instructions for making a protein.

8. Proteins and Traits
1) Proteins are found throughout cells
and cause: most differences you
see.
2) Proteins act as chemical triggers
and messengers.
3) A single organism may have
thousands of genes that code for
thousands of proteins.

9. Help From RNA
1) RNA: ribonucleic acid,
a molecule that is
present in all living
cells and plays role in
protein productions
2) RNA is so similar to DNA
that is can serve as:
temporary copy of a
DNA segment

10. Making of a
Protein (Figure 2):

12. Changes in Genes
1) Mutation: Changes
in the number, type,
or order of bases on
a piece of DNA
1) Deletion: base is
left out
2) Insertion: extra
base added
3) Substitution:
wrong base is
used

13. Do Mutations Matter?
• Three possible consequences to
changes in DNA:
1) An improved trait
2) No change
3) Harmful trait
• When error is found, it is usually fixed
• If the mutation occurs in the sex cells, the
changed gene can be passed from one
generation to the next.

14. How Do Mutations Happen?
1) Mutations happen regularly because of:
random errors when DNA is copied
2) Also, damage to DNA can be caused by
abnormal things that happen to cells
3) Any physical or chemical agent that can
cause a mutation in DNA is called a
mutagen.
4) Examples of mutagens: X-rays, UV
radiation, cigarette smoke

15. Uses of Genetic
Knowledge
• Genetic Engineering
1) Genetic engineering:
when scientists
manipulate individual
genes within an
organism
2) New products created: Genetically
engineered
drugs, food, fabrics peanut plant
3) For example, bacteria may
be used to make the
proteins found in a
spider’s silk

16. • Genetic
Identification
1) Your DNA is
unique, so it can
be used like a
fingerprint to
identify you.
2) DNA fingerprinting
identifies: the
unique patterns
in an individual’s
DNA

17. 1) Identical twins
have truly identical
DNA. Scientists
are now able to
create something
like a twin, called a
clone. A clone is a
new organism that
has an exact copy
of another
organism’s genes.