Eagle Zone-write the question
1. The cytoplasm is divided in which phase
of the cell cycle?
2. Provide the phases of mitosis?
3. What is the purpose of the cell cycle?
How does our body replace
old cells?
More Than Skin Deep
Cell Cycle
TAKS
• TAKS Objective 2 – The student will
demonstrate an understanding of
living systems and the environment.
TEKS
• The student knows the structures and functions
of nucleic acids in the mechanisms of genetics.
The student is expected to
(A)describe components of
deoxyribonucleic acid (DNA); and illustrate
how information fro specifying traits of an
organism is carried in the DNA;
(B)explain replication, transcription, and
translation using models of DNA and ribonucleic
acid
Engage
• Snakes shed their entire epidermis 4-8
•
times per year.
Humans shed their entire epidermis every
15 to 30 days.
– What factors cause your epidermis (skin) to
shed that often?
• How do Bloodhounds detect a person’s
scent when tracking?
Explore 1: Cell Cycle Research
• Never Ending Cycle online activity
• Student will complete a cell cycle diagram
with detailed description of cellular activity
in each of the cell cycle phases.
Cell Cycle
Explain: Cell Cycle
• All cells constantly replace themselves by
a process called mitosis, which is a small
section of the cell cycle.
• New skin cells push the older generation
of cells toward the surface of the skin,
where they are finally shed as a flake-like,
lifeless, residue
What are the two main phases of the cell cycle?
Cell Cycle
includes
G1 phase
Interphase
M phase
(Mitosis)
is divided into
is divided into
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase
Eagle Zone
Review for quiz using the
online game or your notes
from last class
Quiz- write in complete sentences
1. What are the two main phases of the cell cycle?
2. Explain what happens during the Synthesis phase of the cell cycle.
3. How many new cells are produced at the conclusion of the cell
cycle?
4. What is the main difference between Mitosis and cytokinesis (what
is dividing)?
5. Why is the cell cycle important? (what is its purpose?)
The Cell Cycle?
Cell cycle – the changes a cell goes
through during its life span.
contains 2 main steps.



1.Interphase (LONGEST phase of the
cell cycle and has three parts)




G1 (growth-Everyday Cellular Activity)
S (DNA Synthesis)
G2 (growth-Other Organelles Replicated)
2. M-Phase or Mitotic Phase (Shortest
phase)


Mitosis (Division of nucleus)
Cytokinesis (Cytoplasm Division)
Explore 2: S Phase
Berry Full of DNA Lab
Exploration 2
Strawberry DNA Lab
Review: Interphase (G1)
•
•
•
•
•
•
What is the main purpose of a cell that is in G1?
G1 Phase: During this stage the cell is carrying on
its everyday activities.
If the cell’s surface to volume ratio gets too big
then the cell must get ready to divide.
Do some cells entering a resting state?
What is this phase called?
G0 Phase: Resting State - Some cells leave the
cell cycle and stay here much longer than others
ex) brain, nerve, etc…
Exploration 3
DNA Jewelry
Instructions For A Human
Being
Section 12-1
Explain: DNA
Nucleotides
Adenine
Guanine
Phosphate
group
Cytosine
Thymine
Deoxyribose
Section 12-1
Structure of DNA
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
DNA


Deoxyribose Sugar
Base Pairs
A-T

Phosphate
G-C
Getting The Letters Out
What is a DNA Nucleotide?
The basic building block of nucleic acids
containing a sugar, base, and a
phosphate.
P
B
S
S = Deoxyribose Sugar
B = Adenine, Guanine, Cytosine, Thymine
P = Phosphate
Sugar
Phosphate
Bases
(Nitrogenous Bases)

These chemicals are often called nitrogenous bases
because of the high content of nitrogen (N) atoms
Nucleotide


The Sugar and the Phosphate make up the
backbone of the structure
The bases make up the rungs of the ladder
Different Types of Nucleotides in
DNA
Deoxy---Adenine
Deoxy----Thymine
|
|
P
P
Deoxy---Cytosine Deoxy----Guanine
|
|
P
P
Many Nucleotides Together
Parts of DNA




Has a
Sugar/Phosphate
Backbone
Bases make up the
steps of the ladder
A-T
G-C
DNA Structure
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Replication Practice

On your paper, complete the missing
DNA strand by adding the
complementary bases.

ATCGTTGCCATC
TAGCAACGGTAG

DNA Replication
DNA Replication
A Closer Look
»
»
»
»
DNA before replication: 1 double helix
»
DNA after replication: 2 identical double
helixes
»
Section 12-2
DNA Replication
New strand
Original
strand
DNA
polymerase
Growth
DNA
polymerase
Growth
Replication
fork
Replication
fork
New strand
Original
strand
Nitrogenous
bases
Getting Ready
Step 1
Unwinding and Unzipping
Unwind and Unzip
Helicase Enzyme
Step 2
Separates
Polymerase Enzyme
Step 3
Picking up Complementary Bases
Separation and Adding Bases
5’----3’
Step 4
Rewind
Two New DNA Molecules
• Each DNA Molecule with a Parent and Daughter Strand
DNA Replication Video
• http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::
535::535::/sites/dl/free/0072437316/120076
/micro04.swf::DNA%20Replication%20For
k
Interphase (G2)
•
G2 phase: The rest of the cell’s
organelles are reproduced.
Elaborate: Photo 51

Scientific contributions to the discovery
of the DNA structure.