1. How DNA Works
section 2

2. Unraveling DNA
DNA is often wound around proteins, coiled
into strands and bundled up
in prokaryotic cells- loose loop
in eukaryotic cells - bundled into
chromosomes

3. Allows it to hold information
Structure of DNA
Allows it to hold information
The order of the bases on one side is the
code for the information carried
Genes- string of nucleotides that give a cell
information on how to make a
specific trait
There is an enormous amount of DNA, so
there is a variety of genes to hold it
Human DNA contains 3 billion base pairs
If you could print a book containing all
the genetic information found in one cell,
it would be 500,000 pages long ou

4. Genes and Proteins
DNA code is read like a book
one end to the other
bases form an alphabet
3 bases = code for a specific amino acid
CCA = proline
AGC = serine
long strings of amino acids make proteins
so each gene is instruction to make a
specific protein

5. Proteins and Traits
proteins are found throughout the cell and
cause most differences we see
proteins act as chemical triggers and
messengers for many processes with
in the cell
proteins help determine height, colors we
see, curly or straight hair, etc
proteins exist in an almost limitless variety
thousands of genes = thousands of code
for proteins

6. Help from RNA
RNA = ribonucleic acid
helps the proteins
similar to DNA
serves as a temporary copy of DNA
several forms to help transform DNA
into proteins
tRNA - transfer RNA
mRNA - messenger RNA

7. Making a protein
copy one side of a DNA segment with RNA
copy is called mRNA; it moves out of the
nucleus into the cytoplasm
mRNA is fed through the protein assembly
line in the ribosomes
mRNA is fed in 3 bases at a time
tRNA translates the 3 bases of the mRNA
tRNA matches an animo acid to the bases
animo acids become linked in chain
chain leaves the ribosome and folds into a
new protein molecule

9. Changes in Genes
Changes in the number, types or order of bases in a piece of DNA is a mutation
3 types of mutations
deletion - base is left out
insertion - base is added
substitution - when the wrong base is
used ( most common)

10. Do mutations matter?
There are 3 possible consequences to changing DNA
can improve a trait
no change at all
can create a harmful trait
Cells can make proteins to detect and fix errors, but repairs are not accurate and become part of the genetic code
If the mutation is in the sex cells, the change can be passed down to the next generation

11. How do mutations happen?
Happens regularly because of errors when
the DNA is copied
Can happen when something abnormal
happens to the cell
Any physical or chemical agent that causes
a mutation is called a mutagen
Mutagens include
high energy radiation- x-rays, UV rays
asbestos
chemical in cigarettes

12. An Example of a Substitution
A mutation, like substitution, can be harmful
because it can cause a gene to make the
wrong protein
example - GAA (glutamic acid)
if copied as GTA ( valine acid)
This change can cause sickle cell disease
When valine is substituted for glutamic acid in the blood protein, the red blood cells are changed into a sickle shape
sickle cells :
not good oxygen carriers
get stuck in blood vessels
cause painful and dangerous blood clots

13. An Example of Substitution
Chain of amino acids forming normal hemoglobin
Normal red blood cell
Mutated
DNA
Complementary
copy
Chain of amino acids forming mutated hemoglobin
Sickled red blood cell

14. Uses of Genetic Knowledge
Since Watson and Crick made their model,
scientists have learned a lot about DNA
used to benefit humans
has also caused ethical and scientific
debates

15. Scientists can manipulate individual genes within an organism
Genetic engineering
Scientists can manipulate individual genes
within an organism
called genetic engineering
transfer genes from one organism to another
ex. transfer biochemical from firefly to
plant produced a glowing plant
scientists may use genetic engineering to
create new products
drugs, food, fabrics
bacteria producing proteins found in spider's silk
cow proteins used to create human proteins
produce proteins needed for a human with a
genetic disease
scientists also worry about creating
genetically engineered organisms

16. (drag & drop into wells)
Elapsed
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DNA Gel Electrophoresis
DNA Gel Electrophoresis
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Negative
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wells:
Kilobases
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Agarose Gel
STOP A
Samples C D
1kb Ladder B
Infinite Cloner
(drag & drop into wells)

17. Genetic Identification
DNA is unique, like fingerprints
DNA fingerprinting is used to identify patterns
in a human's DNA
DNA fingerprinting is used as evidence in
criminal investigations
Also can be used to help identify individuals
like World Trade Center victims
Can be used to show family relationships or
hereditary diseases

18. Cloning
A clone is a new organism that has an exact
copy of another organisms genes
this has done with small mammals
cloning humans is being debated