Unit 1 Notes
(Chapter Seven)
“Cellular Structure & Function”
7-1 Life Is Cellular
Objective: Differentiate between a prokaryotic cell and a eukaryotic cell.
A. The Cell Theory
1. All living things are composed of cells.
2. Cells are the basic units of structure and function in living things.
3. New cells are produced from existing cells.
B. Prokaryotes and Eukaryotes
1. All cells contain 2 things:
a. Cell membrane
b. DNA
2. 2 types of cells determined by whether they have a nucleus (structure that contains the
cell’s genetic information)
3. Eukaryotes- cells that contain nuclei.
a. Large and complex.
b. The genetic material is separated from the rest of the cell in the nucleus.
c. Examples: plants, animals, fungi, and protists.
4. Prokaryotes- cells that do not contain nuclei.
a. Evolved before nuclei developed.
b. Small and simple.
c. The genetic material is not contained in a nucleus.
d. Example: bacteria
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7-3 Eukaryotic Cell Structure
Objectives: Identify the structure and function of the parts of a typical eukaryotic
cell. Compare and contrast structures of plant and animal cells.
A. Comparing the Cell to a Factory
1. Cells are like a factory; each structure in a cell is like a machine and they work together to
make a product.
2. Organelles- “little organs”- specialized structures inside the cell.
3. 2 major parts of eukaryotic cell:
a. Cytoplasm- portion of the cell outside the nucleus.
b. Nucleus- control center of the cell.
B. Organelles
1. Nucleus—
a. Nuclear envelope- 2 membranes that surround the nucleus and allow material to
move in and out of the nucleus through pores
b. Chromatin- granular material that consists of DNA bound to protein.
c. Chromosomes- threadlike structures formed from chromatin.
d. Nucleolus- dense region where ribosomes are made.
2. Ribosomes- small particles of RNA and protein found throughout the cytoplasm.
a. Proteins are assembled by ribosomes.
3. Endoplasmic Reticulum (ER) - site where lipid components of the cell membrane are
assembled, along with proteins and other materials that are exported from the cell.
a. Rough ER- ribosomes form on the ER- proteins are synthesized and exported.
b. Smooth ER- no ribosomes- contains collection of enzymes that perform
specialized tasks
4. Golgi Apparatus- modify, sort, and package proteins and other materials from the ER for
storage in the cell or secretion outside the cell.
5. Lysosomes- break down lipids, carbohydrates, and proteins to be used by the cell- also
remove “junk” that clutters the cell.
6. Vesicles- waste removal; a bubble-like membranous structure that digests metabolic
wastes within the cell
7. Vacuoles- saclike structure that store materials
a. Cells have a large vacuole that contains liquid.
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b. Also found in some single-celled organisms
8. Mitochondria- convert chemical energy stored in food into compounds the cell can use.
a. “Powerhouse” of the cell
b. have an outer and inner membrane
c. Contain their own DNA
9. Chloroplasts- capture energy from sunlight and convert it into chemical energy
(photosynthesis)
a. Contain chlorophyll (green)
b. Contain their own DNA
10. Cytoskeleton- network of protein filaments that helps the cell maintain its shape; also
involved in movement
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7-4 Cell Boundaries
Objectives: Explain the processes of diffusion, facilitated diffusion, and active
transport. Predict the effect of a hypotonic, hypertonic, or isotonic solution on a cell.
Discuss how large particles enter and exit cells.
A. Cell Membrane and Cell Wall
1. Cell membranes help organisms maintain homeostasis (the ability of a cell to seek and
maintain a condition of equilibrium or stability within its internal environment when
dealing with external changes )by controlling what substances may enter or leave cells
2. Cell membrane- a thin, flexible barrier that surrounds all cells.
a. Regulates what enters and leaves the cell, and provides protection and support.
b. Lipid bilayer- 2 layers of lipids that makes the cell membrane flexible, and forms a
barrier between the cell and its surroundings.
3. Most cell membranes have protein molecules embedded into the bilayer. Carbohydrates
and other molecules are able to attach to the proteins.
4. Cell wall- a strong supporting layer around the cell membrane
a. found in plant cells
b. Provides support and protection
c. Mostly composed of cellulose
B. Diffusion (Passive transport)
1. Concentration- the amount of a solute in a solution.
2. Diffusion- process in which molecules move from an area of high concentration to an
area of low concentration.
a. Diffusion depends on random particle movement, so substances can diffuse
across a membrane without the cell using energy.
3. Equilibrium- when the concentration of the solute is the same throughout the solution.
4. If a substance is able to diffuse across a membrane, it is permeable.
5. If a substance cannot pass through a membrane, it is impermeable.
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6. A membrane that allows some things, and not others, to pass through is selectively
permeable.
C. Osmosis (Passive transport)
1. Osmosis- the diffusion of water through a selectively permeable membrane.
2. Isotonic- “same strength”- the concentration of water is equal on both sides of the
membrane.
3. Hypertonic- “above strength”- concentrated
4. Hypotonic- “below strength”- diluted
5. Osmotic pressure- pressure that exists on the hypertonic side of a membrane
6. Cells will usually be hypertonic in fresh water because they contain salt, sugar, protein,
and other molecules.
a. Water will move into the cell.
b. The cell will swell and burst.
c. To prevent bursting, cells are contained in isotonic solutions, or have a cell wall.
D. Facilitated Diffusion (Passive transport)
1. Facilitated Diffusion- the protein in the cell membrane helps molecules cross the
membrane by creating a channel.
a. Does not require energy.
E. Active Transport
1. Active Transport- the movement of a substance against the concentration gradient.
a. Requires energy.
b. Small molecules use protein pumps located in the cell membrane.
c. Large molecules use processes called endocytosis and exocytosis.
2. Endocytosis- process of taking material into the cell using the pockets of the cell
membrane. The pocket breaks loose and forms a vacuole in the cytoplasm.
a. Phagocytosis- “cell eating”- the cytoplasm engulfs this package.
b. Pinocytosis- cell takes in liquid from the surrounding environment
3. Exocytosis- vacuole membrane around the material fuses with the cell membrane,
forcing the contents out.
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