The Journey of DNA 11/30 & 12/4
Objective: I understand what makes up DNA and can create a sequence strand of DNA.
Vocabulary: DNA, chromosome, histone, nucleotide,
cytosine, guanine, adenine, thymine, double helix, DNA
sugar, phosphodiester bond
What is DNA? Let's find out. To begin with the end in
mind, we are going to draw out the parts of the DNA
molecule.
Discussion Questions:
1. What is the relationship between the backbone and
the bases?
2. What do you think the purpose of the bases is?
3. What do you think would happen if the bases change
their sequence?
OBJECTIVE of this section is to understand the structure
and purpose of DNA.
DNA: The Blueprint of Life
In every living organism, all processes are controlled by DNA. DNA is contained in chromosomes.
Chromosomes: direct and control all the processes necessary for life, including passing themselves onto offspring
Chromosomes are made up of DNA wrapped around proteins called histones.
When DNA is in its loose form (unwound) in the nucleus, the genes are active &
available for transcription
When DNA is fully condensed into coils (its chromosomal form) the genes are
inactive
The Molecular Structure of DNA consists of 2 strands that wrap around each other.
Look like a long, twisted ladder called a double helix. Made up of repeating subunits
called nucleotides
Nucleotide is made up of 3 parts:
5-Carbon Sugar, a Phosphate, and a nitrogenous base
Nucleotide can have 1 of 4 nitrogenous bases attached to it.
Adenine: a purine(double-ringed nitrogenous base)
Guanine: a purine
Cytosine: a pyrimidine(single-ringed nitrogenous base)
Thymine: a pyrimidine
The nucleotides can link up to form a single strand of DNA. The nucleotides are linked
together by phosphodiester bonds.
Analogy of the Spool and Thread
Be ready to defend your thoughts on the analogy, or elaborate on others.
Discussion Questions:
1. If the "string" is pulled out are the genes then inactive or active?
2. How do you think the cell structure would change if there were no histone proteins
for DNA to wrap around?
3. Imagine you have to fit all of your clothes in your closet into 1 (normal size) suitcase.
How would you go about doing this?
Working with your partner, draw a picture of a nucleotide.
Check for understanding
1. What are the 3 parts of the DNA molecule?
a. Adenine, Thymine, Cytosine
d. Thymine and Cytosine
5. DNA is contained in
b. Ribose, Adenine, Phosphate
a. Histones
c. Phosphate, Ribose, Base
b. Chromosomes
d. Base, Phosphate, Cytosine
2. What are the 2 pairs of bases in DNA?
a. Adenine - Cytosine, Guanine Thymine
b. Adenine - Thymine, Cytosine Guanine
c. Adenine - Guanine, Cytosine Thymine
d. Thymine - Cytosine, Guanine Adenine
3. Which bases are purines?
a. Adenine and Guanine
b. Adenine and Cytosine
c. Adenine and Thymine
d. Thymine and Cytosine
4. Which bases are pyrimidines?
c. Nucleotides
d. Spool
6. Chromosomes are made up of
a. Histones and DNA
b. DNA and nucleotides
c. DNA and bases
d. Histones and bases
7. What sugar is found in DNA?
a. Adenosine
b. Adenine
c. Ribose
d. Sucrose
8. What bonds are between bases in DNA holding
the 2 strands together?
a. Phosphodiester Bonds
a. Adenine and Guanine
b. Hydrogen Bonds
b. Adenine and Cytosine
c. Ionic Bonds
c. Adenine and Thymine
d. Covalent Bonds