Biology CP
Name________________________________________
DNA
PART 1-DNA Structure & Replication
http://youtu.be/KHgkAy7GgX0
(Textbook pages 344-357)
HISTORY OF DNA- Bozeman - http://youtu.be/qoERVSWKmGk
AVERY – _______________________________________________________________________________________
HERSHEY AND CHASE – ________________________________________________________________________
MAURICE WILKINS - ___________________________________________________________________________
ROSALIND FRANKLIN - _________________________________________________________________________
ERWIN CHARGAFF - ____________________________________________________________________________
WATSON AND CRICK –__________________________________________________________________________
Last video – around 10:00 – it discusses chromosomes in Eukaryotes vs Prokaryotes
WHAT IS DNA?
 What do the letters DNA stand for?__________________________________________________________

Where is DNA located? Prokaryotic cells ____________________________________________________
Eukaryotic cells _____________________________________________________

How many pieces of DNA are in cells? Prokaryotic cells ________________________________________
Eukaryotic cells _____________________________________________________

What is a chromosome? __________________________________________________________________
______________________________________________________________________________________

What does a chromosome look like?_________________________________________________________
STRUCTURAL FORMS OF DNA
- http://youtu.be/J1HcQCG8cmA (stop at 1:35)
A. Prokaryotic cells:_______________________________________________________________________
B. Eukaryotic cells: DNA can be found in two different structural forms:
1) chromosome: ________________________________
_______________________________________________
_______________________________________________
_______________________________________________

You have ________ chromosomes in your body cells. Each piece is about _________ cm long.

What is the total length of DNA in one body cell? _______________ meters!

How does that much DNA fit inside each of your cells? ______________________________________________
Histones are proteins which act like thread spools. DNA is wound around the histones in order to fit inside a cell.
2) chromatin: __________________________________
_______________________________________________
_______________________________________________
_______________________________________________

Why have 2 different forms of DNA in your cells?
a) The advantage of chromosomes is _________________________________________________
______________________________________________________________________________
b) The advantage of chromatin is ____________________________________________________
______________________________________________________________________________

Each one of your body cells has an exact copy of DNA. That includes toe cells and nose cells, ear cells and eye cells!
DNA vs RNA- Bozeman - http://youtu.be/W4mYwsr9gGE
DNA
RNA
# of strands
Name of sugar
Names of 4 bases found
Location in the cell
2
3
Gene:
_______________________________________________________________________________
CHROMOSOME NUMBER
 Every species of eukaryotic organisms have a specific number of chromosomes in each
cell:
Organism
goldfish
chicken
horse
sand dollar
chimpanzee
dog
human
brown bat
corn plant
housefly
fruit fly
Number of
Chromosomes in
each cell.
94
78
64
52
48
48
Why are these numbers so different?
1) _____________________________________________
2) _____________________________________________
44
20
12
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WHAT IS A GENE?

Gene: 1) A unit of hereditary information which can be passed on to future generations.
2) ______________________________________________________________________________
______________________________________________________________________________
3) Genes hold the code for synthesis of
a) proteins ________________________________________________________________
b) polypeptides ____________________________________________________________
c) traits or parts of a trait ___________________________________________________
________________________________________________________________________

Review of the amino acid structure of proteins:

How many different amino acids could be used to form a single protein or polypeptide? ______________
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THE STRUCTURE OF DNA

Which group of organic compounds does DNA belong to?_______________________________________

Considering that DNA is a long molecule that must periodically be copied, it must be composed of simple units that
fit together easily.
1) DNA is made of repeating subunits called _________________________________
2) Each nucleotide is made up of 3 parts:
a) ____________________ b) ________________________ c) _____________________
3) The sugar and the phosphate groups are identical in all DNA nucleotides but there are four different
types of nitrogen bases:
c) ___________________________
a) ___________________________
d) ___________________________
b) ___________________________ and
STRUCTURES OF THE MOLECULES THAT MAKE UP A NUCLEOTIDE:
1) Deoxyribose sugar:
(ribose sugar minus an oxygen molecule)
Ribose sugar
(found in RNA)
O
2) Phosphoric Acid (Phosphate group):
HO
P
OH
OH
3) One of four different nitrogen bases:
PURINES – DOUBLE RING
1) adenine
2) guanine
PYRIMIDINES- SINGLE RING
3) cytosine
4) thymine
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
NUCLEOTIDE: A nitrogen base bonded to a sugar and a phosphate group.
Here is an example of a nucleotide:
As you can see, the chemical structure of a nucleotide is difficult to draw so we normally
draw a nucleotide using symbols/letters to represent the parts.
In the diagram above, what does the "A" stand for?______________________________
What other letters could be used in that position?___________________________
In the diagram above, what does the "S" stand for?______________________________
In the diagram above, what does the "P" stand for?______________________________
How many different types of nitrogen bases are there in DNA?
___________
Name them:___________________________________________
If each nucleotide contains ______ nitrogen base, how many different types of DNA nucleotides can be
formed? ____________________
NOTE: Another type of nucleotide, Uracil, will replace the Thymine nucleotide in RNA molecules.
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
The drawing below is a MODEL representing a short piece of a DNA molecule. The key identifies
phosphates, sugar and nitrogen bases.
The bonds that hold the molecules together in DNA are
_______________________________________________
The bonds holding the nitrogen bases are NOT covalent but
are ____________________________________________

Circle a nucleotide on the drawing above.

What does each nucleotide have in common? __________________________________________________

How do nucleotides differ from each other? ___________________________________________________

Notice that each nucleotide bonds with a nucleotide above and below it. This forms a strand of DNA.

How many strands make up a molecule of DNA? _______________________________________________

The two strands are then twisted into a spiral shape, double stranded structure called a
_______________________________________________________________________________________
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Look at the model of DNA on the previous page. Use a red, blue, yellow and green colored pencil and follow
the directions to answer the questions:
1) Look at drawing A. Circle a nucleotide on the right hand side or strand of the DNA molecule.
What three parts can you identify?
1. ____________________ 2. _________________________ 3. __________________________
List the names of the different bases: __________________________________________________
______________________________________________________________________________
2) Color the circled nucleotide. Color sugar red and the phosphate blue. What is the name of the
nitrogen base that you have circled? ___________________. Color the bases as follows: adenine
and guanine-yellow, cytosine and thymine-green.
3) Circle another nucleotide on the left hand strand of the DNA molecule. Color the sugar,
phosphorous and nitrogen base as above.
4) Imagine that the molecule of DNA in drawing A looks like a ladder. What two molecules make up
the sides of the ladder? ________________________ and ________________________________
5) What two molecules make up the rungs of the ladder? (Rungs are where you place your feet.)
_________________________________ and ____________________________________________
6) Color the remainder of the DNA molecule in drawing A according to the directions.
7) At what point are the right and left strands of DNA nucleotides joined?________________________
8) Is there any order to the pairing of the nitrogen bases down the center of the DNA molecule?
_________________________________________________________________________________
_________________________________________________________________________________
Is this a pairing of purines with pyrimidines? ____________________________________________
9) Is there any order to the nucleotides down the right hand strand of the DNA molecule? __________
10) Is there any order to the nucleotides down the left hand strand of the molecule? ________________
IN SUMMARY:
1) In a molecule of DNA, adenine is always paired with ______________________________
2) In a molecule of DNA, guanine is always paired with ______________________________
3) In a molecule of DNA, a purine is always paired with a ____________________________
4) We call this system of base pairing _________________________________________________
5) If the sequence of nucleotides in one strand of a DNA molecule is T-A-C-G-G-T-C-A-A, what
would be the complementary base pairs on the other strand? ______________________________
6) Describe the shape of the DNA molecule in drawing B.
________________________________________________________________________________
7) We call this twisted, double strand shape a ___________________________________________
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Who discovered the structure of DNA?
James Watson and Frances Crick (1953) __________________________________________________
____________________________________________________________________________________
Rosalind Franklin (1951) ______________________________________________________________
The Human Genome Project
Genome _______________________________________________________________________________
Completed in 2003, the Human Genome Project (HGP) was a 13-year project coordinated by the U.S.
Department of Energy and the National Institutes of Health. During the early years of the HGP, the Wellcome
Trust (U.K.) became a major partner; additional contributions came from Japan, France, Germany, China, and
others. Project goals were to:
 identify all the approximately 20,000-25,000 genes in human DNA,
 determine the sequences of the 3 billion chemical base pairs that make up human DNA,
 store this information in databases,
 improve tools for data analysis,
 transfer related technologies to the private sector, and
 address the ethical, legal, and social issues (ELSI) that may arise from the project.
(Source: http://www.ornl.gov/sci/techresources/Human_Genome/home.shtml)
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DNA Replication
https://www.youtube.com/watch?v=5qSrmeiWsuc
When and why must the DNA molecule be copied?
____________________________________
This is called__________________________________.
The following is a model showing REPLICATION of a very short piece of DNA:
List the steps in DNA replication:
1) DNA unwinds and unzips ________________________________________________________________
2) DNA polymerase helps to link free floating DNA nucleotides
_____________________________________________________________________________________
_____________________________________________________________
3) Covalent bonds join _____________________________________________
______________________________________________________________
4) Each new DNA strand formed contains
______________________________________________________________
______________________________________________________________
Note: If an error is made during replication, what is it called? ________________
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