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UNDERSTANDING DNA
MOLECULE OF HEREDITY
Biology
11th Grade
By Patricia Mbugua
OBJECTIVES
Students will identify the DNA
molecule and understand its function
as a molecule of heredity
Students will be able to identify and
name the function of the DNA bases,
sugar, and phosphate
Structure of DNA
The letters DNA stand for
DeoxyriboNucleic Acid
The basic unit used to make a
strand of DNA is called a nucleotide
A single nucleotide consists of a
sugar molecule, a phosphate group,
and a base
Video on the Function of the DNA
Click on this website to view a video
on the DNA as a molecule of heredity
http://genetics.gsk.com/flash_dna_actual.htm
STRUCTURE OF THE
NUCLEOTIDE
The nucleotide is held together by a
backbone made of sugars and
phosphate group
The backbone carries four types of
molecules called bases
It is the sequence of these four
bases that encodes information
The main job of the DNA is to
encode the sequence of amino acids
residues
BASES
The DNA’s strands twist forming a
double helix shape
The DNA double helix is stabilized by
hydrogen bonds between the bases
attached to two strands
The four bases found in DNA are
Adenine-A, Cytosine – C, Guanine-G,
Thymine-T
BASE PAIRING
Each type of the base on one
strand forms a bond with just one
type of base on the other strand
This is called complementary base
pairing
Adenine bonds only with Thymine
A-T
Cytosine bonds only with guanine
C-G
How the code works
A stretch of DNA could be
AATGACCATThis would code for a
different gene than a stretch
that reads GGGCCATAG
This four bases have endless
combinations just like the
letters of the alphabet can
combine to make different
words
What did we learn?
QUIZ
Click on the DNA molecule
A
B
RIGHT
WELLDONE
NEXT
Click the base that pairs with
Adenine
Guanine
Thymine
You missed it
OOPS WRONG ANSWER
BACK
Excellent
Good Job
Remember to continue
working
On the DNA molecule!
Credit
References:
http://genetics.gsk.com/flash_dna_actual.htm
http://www.biologycorner.com/worksheets/DNAcoloring.html
http://school.discovery.com/quizzes6/muskopf/dna.html
WRONG
TRY AGAIN
BACK