Download Notes 2-4

7th Grade Life Science
Mr. Fisk
Chapter 2 – Living Things
Engage: Show Cells - Discuss
Objectives:
1. Identify the role of the cell wall and the cell
membrane in the cell.
2. Describe the functions of cell organelles.
3. Explain how cells are organized into manycelled organisms.
Introduction
Page 1 of 8
7th Grade Life Science
Mr. Fisk
2-4: LOOKING INSIDE CELLS
A. Introduction -- Let’s go for an imaginary
journey inside a living organism visiting
its tiny cells.
1. Cells -- very small.
(Exception -- egg yolk)
2. Structures in cell functions:
a. Protection
b. Support
c. Barrier
d. Building & repairing cell parts
e. Transporting material
f. Storing & releasing energy
g. Getting rid of wastes
h. Increasing in number
Introduction
Page 2 of 8
7th Grade Life Science
Mr. Fisk
Journey Through the Trunk of Oak Tree:
B. Cell Wall -- Support & Protection
1. Strong & stiff.
2. Made of cellulose -- non-living
material -- long chain of sugar
molecules.
3. Plant cells only.
4. H2 O, O2 & CO2 can pass through.
C. Cell Membrane -- Doorway of the cell – like a
window screen.
1. Plant Cell -- just inside cell wall.
2. Animal Cell -- outer covering of cell.
3. Jobs:
a. Protection & support.
Cholesterol strengthens cell
membrane.
b. Control movement of materials
into and out of the cell.
c. Help maintain homeostasis.
Introduction
Page 3 of 8
7th Grade Life Science
Mr. Fisk
D. Nucleus -- Control center of the cell.
1. Control center.
2. “Brain” of the cell.
3. Nuclear Membrane (envelope) -- like cell
membrane.
4. Chromosomes (Chromatin):
a. Rod-like objects.
b. Direct all the activities of the cell
(growth & reproduction).
c. Pass on traits to new cells.
d. Made of nucleic acids -- store
information that helps a cell
make the proteins it requires
(like enzymes & hormones).
2 Nucleic Acids:
DNA -- Store information remaining
in nucleus.
RNA -- Carrying its protein building
instruction leaves the nucleus through pores
in the nuclear membrane.
Introduction
Page 4 of 8
7th Grade Life Science
Mr. Fisk
5. Nucleolus -- “little nucleus”
Site of ribosome production.
E. Endoplasmic Reticulum: Transportation
system of the cell.
1. Cytoplasm -- Region between the
nucleus & cell membrane.
(thick jelly-like substance).
2. E.R. -- Clear, tubular passageways
3. Job -- Transportation of protein.
F. Golgi Bodies – “Cells Mail Room” – receive
protein & other newly formed materials from the
endoplasmic reticulum – package them &
distributes them to other parts of the cell.
Introduction
Page 5 of 8
7th Grade Life Science
Mr. Fisk
G. Ribosome -- Protein factories of the
cell.
1. Attached to surface of E.R.
2. Made of RNA.
Protein-making sites of the cell.
3. Some ribosomes also found in
cytoplasm.
H. Mitochondria -- Powerhouse of the cell.
1.
2.
3.
4.
Introduction
Supply energy.
Rod-shaped.
Respiration – Sugar → Energy.
The more active the cell, the more
mitochondua.
(i.e. human lives - 1000).
Page 6 of 8
7th Grade Life Science
I.
Mr. Fisk
Vacuoles -- Storage tanks for cells.
1.
2.
3.
4.
Round water-filled sac.
Plants -- large.
Animals -- small.
Store -- food, wastes, & H2 O.
J. Lysosomes -- Clean-up crews for cells.
1. Digestive activities.
2. Job:
a. Enzymes break down food
molecules into smaller ones.
b. Digest old cell parts.
K. Chloroplasts -- Energy-Producers for cells.
1. Green -- Chlorophyll.
2. Photosynthesis.
Introduction
Page 7 of 8
7th Grade Life Science
Mr. Fisk
L. Cell Specialization
1. In multicellular organisms cells are different
– specialized to perform specific functions.
Example: Nerve Cells – Transmit information
from one part of the body to another. Red
blood cells carry oxygen throughout your body.
2. Cells → Tissues → Organs → Systems
→ Organism
Introduction
Page 8 of 8