Download Ch. 7 Notes - Duplin County Schools

Chapter 7
Cell Structure and
Function
7.1 The Discovery of Cells
 Robert Hooke
– Discovered 1st cell
– Observed dead
cork cells
– Named the cell:
basic unit of living
organisms
Anton van Leeuwenhoek
Looked at & described the 1st living cell
The Cell Theory

Matthias Schleiden & Thomas Schwann
– Schleiden  Botanist
– Schwann  Zoologist
 Developed the cell theory:
1. All life forms are made from one or more
cells.
2. Cells only arise from pre-existing cells.
3. The cell is the smallest form of life.
Two basic cell types:
1. Prokaryote
o Before a nucleus (NO Nucleus)
o Single-celled
2. Eukaryote
o Has a nucleus
o Unicellular or multicellular
o Contained organelles (membrane bound
structures)
A.
Which one is a prokaryotic cell?
Is B. a plant or an animal cell?
B.
7-2 Eukaryotic Cell Structure
 Contain Organelles which means “little
organs”.
 Each cell contains Cytoplasm which holds
all of the organelles.
Nucleus: Control center of the cell
Contains DNA
Has a nuclear envelope & Nucleolus
Ribosomes: make proteins
most numerous organelle in the cell
Found on and off of ER
Endoplasmic Reticulum:
Smooth makes and
transports lipids
Rough transports
proteins
Two types of ER:
Smooth (no ribosomes)
Rough (has ribosomes)
Golgi Apparatus: Stores and
packages chemicals
Lysosome: “Stomach of the cell”
Vacuole that contains
digestive enzymes
Mitochondria: “Powerhouse of the
cell”
Chloroplast:
Capture sunlight and convert it into
chemical energy in a process called photosynthesis
7-3 Cell Boundaries
 All cells are surrounded by a cell
membrane (also called a plasma
membrane).
 Some cells are surrounded by a cell wall
(especially plant cells).
 Both serve as a boundary between the cell
and its environment.
 The Cell membrane is semi-permeable.
The Plasma Membrane
FUNCTIONS:
1) Controls what enters and leaves the cell
(maintaining homeostasis with selective
permeability)
2) Protects the cell
 Also the cell wall’s main function!!
PM continued…
 PM is made of a
bilayer of
phospholipids!!
 Two ends to a
phospholipid:
– Hydrophilic
– Hydrophobic
 Two types:
– Saturated
– Unsaturated
Fluid Mosaic Model (PG. 182)
Random movement of Molecules
 Robert Brown – Brownian Motion
 Molecules are in a constant state of motion
– Gas = fast movement
– Liquid = medium movement
– Solid = slow movement
 Molecules move from high concentrations to
low concentrations because of a
concentration gradient.
Diffusion Through Cell Boundaries
 Diffusion: the movement of particles
from and area of high concentration to
low concentration
 Osmosis is the diffusion of water
Diffusion
Three types of solutions (Pg. 186)
1) Isotonic: concentrations on both sides of the
plasma membrane are equal
 No net movement
2) Hypertonic: concentration of dissolved
substances outside the cell are higher than
inside
 Water moves out  Cell Shrinks
3) Hypotonic: concentration of dissolved
substances inside the cell are higher than
outside
 Water moves in  Cell Swells
Two types of transport


Passive Transport
Move with the
concentration
gradient
 NO energy
required
1. Simple Diffusion
2. Osmosis
3. Facilitated
Diffusion


Active Transport
Move against the
concentration
gradient
 Energy
REQUIRED
1. Endocytosis
a) Pinocytosis
(drinking)
b) Receptormediated
endocytosis
c) Phagocytosis
(Eating)
2. Exocytosis