Cell Structure,
Function and
Transport
Unit 3
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Section 7.1 – Discovery of the
Cell
The Cell Theory
1. All organisms are composed of one or more cells
a) Unicellular – made up of only ONE cell
b) Multicellular – made up of MORE than one cell (plants and
animals)
2. Cells are the basic unit of structure & organization of
organisms
3. Cells come from the reproduction of existing cells
Early Contributors
• Robert Hooke – “small rooms”
• Anton van Leeuwenhoek – “little animalcules”
• Matthias Schleiden – plant cells
• Theodor Schwann – animal cells
Check for understanding
Name 3 organisms you think have cells?
1. ?
2. ?
3. ?
Types of Cells
1. Prokaryotic
a) Do NOT have a nucleus
b) Do NOT have membrane bound organelles
c) Example: bacteria
Types of Cells
2. Eukaryotic
a) have TRUE nuclei
b) Have TRUE membrane bound organelles
c) Can be unicellular or multicellular
d) Example: plants and animals
Check for understanding
What type of cell is this?
Check for understanding
Name 2 organisms with EUKARYOTIC cells
1. ?
2. ?
Section 7.2 – The Plasma
Membrane
The Plasma Membrane
• Cells must have a plasma membrane to
maintain BALANCE
• Balance is important for survival
• This balance is called homeostasis
• Homeostasis – the ability of the body or a cell
to seek and maintain a condition of
equilibrium or stability within its internal
environment when dealing with external
changes
• Example - In humans, homeostasis happens
when the body regulates body temperature in
an effort to maintain an internal temperature
around 98.6 degrees Fahrenheit. For example,
we sweat to cool off during the hot summer
days, and we shiver to produce heat during
the cold winter season.
The Plasma Membrane
1. The membrane allows nutrients to enter and leave no
matter the external conditions
2. Allows waste to leave the cell and nutrients to enter the
cell
3. The membrane is SELECTIVELY PERMEABLE:
a)
it allows some molecules to pass through while keeping others
out of the cell (small, uncharged particles) by passive transport
b) Water constantly moves in and out of the cell
c) Other charged particles (calcium and sodium ions) and large
molecules can only be allowed in at certain times through
different mechanisms
d) The membrane helps maintain homeostasis!
Passive vs Active transport
• http://www.youtube.com/v/kfy92hdaAH0&feature=related
Structure of the Plasma
Membrane
1. Phospholipid Bilayer
a) HEAD – polar/hydrophilic (water
loving)
b) TAIL – non-polar/ hydrophobic (water
fearing)
2. The two lipids form a sandwich!
3. They prevent water soluble material
from easily moving through the
membrane
Structure of the Plasma
Membrane
4. Other substances are also found in the membrane
a) Membrane proteins – may serve as transport proteins,
chemical receptors, enzymes, regulators for cell to cell
recognition, cell connections and attachment sites for
cytoskeletal structures (that’s why its referred to as a mosaic)
i.
ii.
Peripheral – not embedded and are loosely attached to the
surface of the membrane
Integral – span the entire width of the lipid bilayer
Other substances are also found in the
membrane
b) Cholesterol – helps keep the phospholipids spaced
apart thereby adding to the fluidity of the membrane
c) Surface carbohydrates – function in cell recognition,
cell signaling, and cell adhesion.
Check for understanding
What biomolecules are involved in the plasma
membrane?
Draw a phospholipid bilayer below
Check for understanding
A cell has a defect that results in the loss of its
ability to regulate the passage of water, food, and
wastes.
What part of the cell has the defect?
Section 7.3 – Eukaryotic Cell
Structure
***The following are organelles found in the eukaryotic cell:
• 1. Cell Wall
a)
Rigid structure located on the outside of the plasma membrane
which provides additional support and protection
b) Made of cellulose
c) Only found in PLANT cells
Check for understanding
What macromolecule is cellulose?
2. Nucleus
a) The “brain” of the cell
b) Contains genetic data that are the
instructions for making proteins and
other molecules
c) Structures:
• Nuclear envelope – double membrane
of the nucleus
• Nuclear pores – allow materials to
move in and out of the nucleus
• Chromatin (chromosomes) – contain
genetic information
• Nucleolus – where the assembly of
ribosomes begin
3. Ribosomes
(protein synthesis)
a) Where cells produce proteins according to the
directions of the DNA
b) Can move in and out of the nucleus
4. Cytoplasm
a) A clear, gel like fluid inside the cell
b) Where many chemical reactions take place
c) Cytoskeleton – a network of protein filaments that
helps the cell to maintain its shape, also involved in
movement
5. Endoplasmic Reticulum
a)
b)
c)
d)
“transportation system”
Looks like a folded accordion in the cell
Moves substances throughout the cell
Rough ER – involved in the synthesis of proteins, has
ribosomes
6. Vacuoles
a) “Storage system”
b) Stores food, water, or waste products of cell
c) Plant cells have one large vacuole, animal cells have
many small vacuoles
7. Lysosome
a) Contain digestive enzymes
b) Digest excess or worn out organelles, food,
viruses, or bacteria
8. Mitochondria
a) “The power house”
b) ATP, or energy from food is released here
8. Chloroplast
a) Only found in PLANT cells
b) Captures light energy and converts it to
chemical energy
8. Centrioles
a) Play an important role in cell division
b) Occurs in pairs
8. Golgi Apparatus
a) Modify, sort, package proteins and other
materials from the ER for storage in the
cell or secretion outside the cell
Label the animal cell below
Check for understanding
What parts of cells are used for
synthesis of new molecules?
What parts of cells are used in energy
conversion?
Check for understanding
What cell parts are used for transport
of molecules?
What 2 structures are only found in
plant cells?
Check for understanding
Animal cell organelles include?
A. ___________________
B. ___________________
C. ___________________
D. ___________________
E. ___________________
F. ___________________
G. ___________________
H. ___________________