01/12/2015- NO GUM PLEASE!
Materials
Agenda
Notebook
Pen/Pencil
Packet
Cell Book-74
Objective: Today
we will learn
about DNA,
RNA, and
protein
Synthesis
Agenda
Agenda
Daily question
DNA PPT
Brain pop
Daily Question:
What does DNA
stand for?
DNA STRUCTURE
EACH CELL IN YOUR BODY
CONTAINS DNA…BUT WHAT IS
IT? WHAT DOES IT LOOK LIKE?
What is DNA?

DNA- Deoxyribonucleic acid

stores and passes on genetic information
within cells from one generation to the next
James Watson, Francis Crick, Maurice Wilkins, and Rosalind
Franklin are three of the scientists credited with the
discovery of the structure of the DNA molecule.
What does DNA look like?

What do you think?
What is DNA made up of?

The sides are made
up of deoxyribose
sugar and
phosphates.

The rungs (steps)
are formed by pairs
of nitrogen bases
What is DNA made up of?
The sugars are
chemicals on the
outside of the
double helix that
hold the bases
together
 Phosphates are the
chemicals that join
the sugars together

What is DNA made up of?

There are 4 nitrogen bases in DNA:
Adenine (A)
 Guanine (G)
 Cytosine (C)
 Thymine (T)

Adenine always pairs with Thymine
 Cytosine always pairs with Guanine

What is a Nucleotide

A unit of DNA that consists of:
1 nitrogen base
 1 deoxyribose sugar
 1 phosphate

Different Forms of DNA

Chromatin- thread like
chains of uncoiled DNA

Chromosome- rodshaped coils of
chromatin

Gene- the basic unit of
heredity that consists of
a segment of DNA on a
chromosome
DNA
The Master Molecule of Life
THE DNA MOLECULE
•DNA-Deoxyribonucleic acid- stores and passes on
genetic information from one generation to the
next
•Many scientists believe that the discovery of the
structure of DNA was the most important
biological breakthrough of the 20th century
•James Watson, Francis Crick, and Maurice Wilkins
are three of the scientists credited with the
discovery of the structure of the DNA molecule.
•They discovered that chromosomes are made
up of long strands of DNA molecules. It is the
DNA molecules in chromosomes that make up
genes.
•A gene is the basic unit of heredity that
consists of a segment of DNA on a chromosome
The Structure of DNA
The DNA molecule looks like a twisted ladder, or spiral
staircase
The sides of the ladder are made up of molecules of
the sugar deoxyribose and phosphate groups. The rungs
of the ladder are formed by pairs of substances called
nitrogen bases
The sugars are chemicals on the outside of the double
helix that hold the bases together
Phosphates are the chemicals that join the sugars
together
There are 4 nitrogen bases in DNA:
Adenine (A) Thymine (T)
Guanine (G) Cytosine (C)
THE Structure of DNA (cont)
The order of these substances on the
DNA molecule determines what type of
gene it is.
Adenine always pairs with Thymine
Cytosine always pairs with Guanine
The order of the nitrogen bases on a
DNA molecule determines the particular
genes on a chromosome
The genetic code is actually the order
of nitrogen bases on the DNA molecule
(ACGGTTCAAG) for example
A Diagram of the DNA molecule
DNA Replication
When does DNA Replication occur?
Before Mitosis begins- Interphase
Cell Division: Stage1- Interphase
Why is DNA Replication an important
cell process?
• Ensures that each daughter cell will
have all of the genetic information it
needs to carry out its activities.
Forming
daughter cell
DNA (genetic
information)
Forming
daughter cell
DNA (genetic
information)
Structure of DNA
Sides (DNA Ladder)
• Alternating molecules of
• Deoxyribose sugar
• Phosphate
Phosphate
Deoxyribose
sugar
Rungs (DNA Ladder)
• Made up of pairs of
nitrogen bases
• adenine
• thymine
• cytosine
• guanine
Nitrogen
base
Ladder Rungs
•Letters A, T, G, C
•Used to represent the four
bases that make up
ladder’s rungs
•Nitrogen bases on one
side of ladder “match
up” in specific way with
bases on the other side.
•Adenine always pairs with
Thymine (A-T)
•Guanine always pairs
with Cytosine (G-C)
Nitrogen
Base
Nitrogen
base
Pairing pattern of the nitrogen bases
• key to understanding how DNA
replication occurs.
Replication Process
Step 1:
•Two sides of
the DNA
molecule
unwind and
separate
between paired
nitrogen bases
on each rung.
•Like a zipper
unzipping
Replication Process
Step 2:
•Nitrogen bases floating
in nucleus pair up with
bases on each half of the
DNA molecule.
•A always pairs with T
•G always pairs with C
Replication Process
Step 3:
•Once new bases are
attached, two new
DNA molecules
formed.
•Order of bases in
each new DNA
molecule exactly
matches the order in
the original molecule.
http://www.cfkeep.org/uploads/dna_re
plication.mov
http://video.search.yahoo.com/search/video?p=dna+structure&ei=UTF8&fr=sbc-web&x=wrt