Download DNA - Images

WARM UP #4
2/5/13
1) Where did the virus originate?
2) A vector is an intermediate carrier for
the virus. What species was the
vector in CONTAGION?
3) What species was the 1st host for the
virus?
4) What are the symptoms?
Components and
Structure of DNA—
Chromosomes and
DNA Replication
Chapter 12
Section 1-2
What’s This All About?
• Essential Question:
– What makes you
different from
others?
• Objectives:
• Understand that
chromosomes are
structures in the
nucleus of a cell
that carry genes
• Understand the
structure of the DNA
molecule
Fact Is…
• A humans DNA length is approximately
3m long per cell!
DNA Background
Genes—Found in Chromosomes
Chromosomes—Found in Nucleus
• Genes do three critical things:
1. Carry information from one generation to
the next
2. Determine heritable characteristics
3. Easily copied and replicated
Why Do We Need DNA
• DNA is often called the blueprint of life.
• DNA contains the instructions for making
proteins within the cell.
What DNA is?
• Made up of long molecules of units
called Nucleotides
– Made up of:
• Phosphate
• 5-Carbon sugar (deoxyribose)
• Nitrogenous (nitrogen containing) base
• Twisted Ladder—Double Helix
Structure of a Nucleotide
1. Deoxyribose
2. Phosphate Group
3. Nitrogen Base
One Strand of DNA
• The backbone of the molecule is
alternating phosphate and
deoxyribose
• The teeth are nitrogenous bases.
• These three parts together make up a
nucleotide
Nitrogen Bases
Rungs of the ladder
• Purines
– Two Ring Structures
– Adenine
– Guanine
• Pyrimidines
–
–
–
–
One Ring Structure
Thymine
Cytosine
Uracil
Complimentary Strand
• Adenine always
bonds with
Thymine
• Cytosine always
bonds with
Guanine
So How are We Different?
• Nitrogen bases can be arranged in any
order creating lots of possibilities!
• Example: ATTTCGGGGCA or
CGGGAAATTT
• The complimentary strand must
correspond though
DNA Replication
• Every time a cell divides it
MUST copy itself
• Each cell has a complete
set of DNA molecules
Steps to Replication
1. An DNA polymerase (enzyme) breaks
the hydrogen bonds between the
nitrogen bases, unzipping it
2. Each strand builds its opposite strand
by base pairing
3. End up with 2 identical DNA
molecules (1 original strand—1 new
strand)
DNA 3-D Model
• With a partner, you will each paint 4
popsicle sticks
• Let the sticks dry
• Label the sticks as A-T or C-G bases
• We will place pipe cleaners on them to
make a double helix
Warm-Up #2
2/1/12
1) What is the structure of DNA called?
2) What are the individual components of
DNA called?
3) What is a gene?
4) Where is DNA stored?
Warm-Up #3
2/2/12
1) What are the three components of a
nucleotide?
2) What bond holds the nitrogen bases
together?
3) What enzyme “unzips” DNA before
replication?
4) Why must DNA be replicated?
Warm-Up #4
2/3/12
1) What does a purine look
like?
2) What does a pyrmidine
look like?
3) What is the scientific name
for DNA?
4) What is the picture
demonstrating?
DNA Model
• By the end of today:
– 4 sticks are red and white
– 4 sticks are blue and yellow
– Dry sticks have pipe cleaner attached