Cells Structure and Function
Lesson 1
1. Understanding Cells – Early Scientists
a. Robert Hooke- studied the bark of a cork tree with a microscope and found tiny individual boxes he
called cells
b. Anton Von Leeuvenhoek- studied pond water and scrapings of his teeth
2. Cell Theory—Schleiden, Schwann and Virchow’s observations combined into 3 truths about cells:
a. The cell is the smallest unit of structure and function in a living thing
b. All living things are made of cells
c. Cells come from other cells.
3. Basic Cell Substances:
a. Water—makes up 70% of each cell, surrounds cells, dissolves substances that need to enter/leave cells,
insulates the body, helps maintain homeostasis.
b. Macromolecules—form by joining many small molecules together and enable cells to function.
i. Nucleic Acids—form long chains of molecules called nucleotides. Genetic Material consists of
DNA (deoxyribonucleic acid) and proteins are made from RNA (Ribonucleic Acid)
ii. Proteins—essential for every function of a cell. Made from chains of amino acid molecules.
RNA tells the proteins how to link together
iii. Lipids—Large macromolecule that does not dissolve in water, protective barriers in walls and
membranes of cells, store energy and helps with cell communication. Cholesterol, Vitamin A
iv. Carbohydrates—composed of sugar molecules, store energy, provide structural support and are
necessary for cell communication.
Chapter 2
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Cells Structure and Function
Lesson 2
4. Cell Types
a. Prokaryotic—Usually simple unicellular organisms. The genetic material within a prokaryotic cell is not
surrounded by membranes. Example: bacterial cells
b. Eukaryotic—larger and complex cells. Often contain organelles with specific functions that are
membrane bound. Examples: Plants, animals, fungi, protists are all eukaryotic.
5. Cell Appendages
a. Some unicellular organisms use flagella (whip-like tails) and cilia (tiny hairs that beat back and forth) to
move around.
6. Plant Cells vs. Animal Cells
a. Plant Cells have a few organelles that animal cells don’t have:
i. Cell Walls – Stiff structure outside the cell membrane of a plant cell. It protects the cell and
gives it structure and support. (Some bacterial, fungal and protist cells also have cell walls)
ii. Chloroplasts—organelles within a plant cell that capture sunlight to be used for food.
Photosynthesis occurs here.
1. Chlorophyll- pigment within chloroplasts that captures the sunlight
b. Both Animal and Plant Cells have the following organelles. The organelles function the same way within
each type of cell.
i. Cell membrane- flexible covering that protects the insides of a cell from the outside. Only lets
certain substances in that are necessary to the cell such as water and sugars.
ii. Cytoplasm—fluid within a cell that contains salts and other molecules.
1. Cytoskeleton is made from a network of proteins that act like a framework for the cell—
helping it to keep a certain shape and move. (Some unicellular organisms such as
amoebas need a cytoskeleton to allow it to move.)
iii. Nucleus—Directs all cell activity and contains genetic information
1. Nucleolis—structure within a nucleus that makes ribosomes which make proteins
2. Nuclear Envelope—Surounds the nucleus like a envelope protects a letter that is in the
mail. It has pores that allow certain materials in and out.
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Cells Structure and Function
iv. Ribosomes—float around in the cytoplasm and are also found on the Endoplasmic Reticulum.
Ribosomes make proteins
v. Endoplasmic Reticulum “ER” –Organelle that stretches from the nucleus throughout most of the
cell.
1. Rough ER—has ribosomes attached to it. Proteins are made here.
2. Smooth ER—lacks ribosomes and makes lipids and cholesterol. Also functions to
remove harmful substances from a cell.
vi. Mitochondria—organelles within cells that break down —ATP molecules (adenosine
triphosphate) to release energy for growth, cell division and material transport.
vii. Golgi Bodies / Golgi Apparatus—prepares proteins for their specific functions by wrapping them
in membrane structures called vesicles. Vesicles transport materials in a cell.
viii. Lysosomes—are vesicles in a cell that break down and recycle damaged cell parts.
ix. Vacuoles—saclike organelles that store food or water or waste material in a cell.
1. Animal cells may contain several vacuoles
2. Plant cells usually have one very large vacuole.
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Cells Structure and Function
Lesson 3
7. Moving Cellular Material
a. The cell membrane is semi-permeable—it only lets certain materials into and out of the cell.
b. Needed substances must be moved into the cell and waste needs to be let out of the cell
i. Passive Trasnport- the movement of substances through a cell membrane without using the
cells’energy.
1. Diffusion—the movement of molecules across a cell membrane from an area of high
concentration to an area of low concentration
a. Many types of molecules can diffuse in this way.
b. Diffusion will continue until there is an equal concentration of substance on
both sides of the membrane. This is called equilibrium.
c. Osmosis—Is the diffusion of water across a cell membrane from an area of
higher concentration to an area o lower concentration
2. Facilitated Diffusion—Sometimes larger molecules cannot make it though a cell
membrane and need to be brought in by transport proteins
a. Carrier proteins—help large sugar molecules across a cell membrane
b. Channel proteins—help large sodium ions and potassium ions across a cell
membrane.
ii. Active Transport –The movement of substances across a cell membrane only by using the cell’s
energy
1. Substances move from areas of low concentration outside the cell to areas of high
concentration inside the cell.
2. Carrier proteins help bring in needed materials and expel waste from cells.
iii. Endocytosis—The process during which a cell takes in a substance by surrounding it with with
the cell membrane
1. Super large substances that cannot enter a cell by diffusion or transport proteins such as
bacteria and viruses.
iv. Exocytosis—The process during which a cells vesicles release their contents outside the cell.
1. Proteins leave a cell this way.
Chapter 2
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Cells Structure and Function
Lesson 4
8. Cells and Energy
a. Cellular Respiration—A series of chemical reactions that convert the energy in food molecules into a
usable form of energy called ATP. Humans and other animals carry out cellular respiration.
**Energy from the food you eat is converted into energy that your body uses
C6H12O6 + 6O2
ATP Energy + 6CO2 + 6H2O
i. Step 1: Glycolysis-- Happens in the cytoplasm. Glucose (sugar) is broken down into smaller
molecules
1. Only a small amount of energy ATP is released
ii. Step 2: Reactions in the mitochondria
1. The broken down sugar molecules are broken down more with oxygen.
a. Large amounts of usable energy ATP are generated
i. All cell processes are powered with this energy.
ii. Waste products are given off in this process
1. Water and Carbon Dioxide
b. Fermentation - Takes place in the cytoplasm only without the presence of Oxygen in eukaryotes or
prokaryotes. Makes less ATP Energy than cellular respiration.
i. Lactic Acid Fermentation -- Cheese / yogurt are made as bacteria and fungus undergo lactic acid
fermentation
C6H12O6
ATP Energy + Lactic Acid
ii. Alcohol Fermentation—bacteria and yeast undergo a type of fermentation that produces
alcohol and carbon dioxide as waste products. Bread , beer and wine are possible because of it.
C6H12O6
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ATP Energy + CO2 + Alcohol
Cells Structure and Function
c. Photosynthesis—A series of chemical reactions that convert light energy, water, and carbon dioxide into
the food-energy molecule glucose and the waste product , oxygen. Plants carry out photosynthesis.
i. Takes place as chlorophyll absorbs sunlight within the chloroplasts of a plant. The sunlight is
used with carbon dioxide and water to produce sugars
Light energy
6CO2 + 6H2O
C6H12O6 + 6O2
ii. Important because it creates food for animals and insects and adds oxygen to the atmosphere
to be used by animals. Without plants there could be no animals.
Chapter 2
Cardone
Cells Structure and Function
Chapter 2
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