Chapter 7

Cell Structure and Function

Life is Cellular (7-1)

The Cell Theory Robert Hooke- English physicist saw the

outline of cells in cork. Matthias Schleiden-said all plants are

made of cells. Theodor Schwann-said all animals were

made of cells. Rudolf Virchow- said that cells came

from pre-existing cells.

What is the Cell Theory?

All living things are composed of cells.

Cells are the basic units of structure and function in living things.

New Cells are produced from existing cells.

Basic Cell Structure

Cell Size Average 5-50 micrometers in diameter Smallest 0.2 micrometers across

(bacteria) Largest 1000 micrometers (Amoeba,

Chaos chaos) Seen without a microscope

What are cells made of?

Cell membrane- thin, flexible barrier around the cell

Cell wall- Strong layer around the cell membrane (plants only)

Nucleus-contains genetic material & regulates cell functions

Cytoplasm-Material inside cell membrane (not counting the nucleus)

Prokaryotes v. Eukaryotes

Prokaryotes- smaller and simpler. Have cell membrane, cytoplasm, but no nuclei. All bacteria

Eukaryotes-contains nuclei, cell membrane, cytoplasm, and organelles.

Cell Structures (7-2)

Cell wall- support (not in animal cells) Nucleus- Contains DNA (hereditary

info) Discovered by Robert Hooke Chromatin-DNA bound to proteins. Chromosomes- contains genetic info that

is passed to future generations Nucleolus- dense structure inside

nucleus. Nuclear Envelope- Allows movement in &

out of the nucleus

Cytoskeleton

Helps cell maintain shape. Involved in many forms of

movement. Microtubules-hollow tubes of protein

that help to make up cytoskeleton Microfilament- Component of

cytoskeleton long thin fibers aide in movement & support.

Organelles in the Cytoplasm

Ribosomes- site of protein assembly Endoplasmic Reticulum (ER)- where

components of cell membrane are assembled.

Golgi Apparatus- enzymes here attach carbohydrates & lipids to proteins.

Lysosome- Breaks down Carbs, lipids, & proteins into forms usable by the cell.

Organelles cont.

Vacuoles- Storage place for water, salts, proteins, and carbs.

Chloroplast- Found mostly in plants. Use energy from the sun to make food during a process known as photosynthesis

Mitochondria- (power-house) Where energy is made and stored.

Movement through the membrane (7-3)

Core of the cell membrane is a double-layered lipid bilayer.

Concentration- amount of mass of a solute in a given volume of solution. 12g of salt, 3L of water= 12g/3L,or 4g/L

Diffusion-movement of molecules from high concentration to low concentration- does not require energy.

Osmosis- Diffusion of water through a selectively permeable membrane (only allows certain substances to pass)

Osmotic Pressure (effects of osmosis) Isotonic- equal amount of dissolved

materials as inside the cell Hypertonic- Higher concentration of

dissolved materials than inside the cell. (Wilt)

Hypotonic- Lower concentration of dissolved materials than inside the cell. (burst)

Facilitated Diffusion-movement of substance through protein channels

instead of the cell membrane. (does not require addition of energy)

Active Transport-Requires energy. Endocytosis-takes materials into the cell

through “pocket” in the cell membrane Phagocytosis- when large particles are

taken into the cell by endocytosis. (Pac-Man)

Exocytosis- removal of large amounts of materials from the cell.

Diversity of cellular life (7-4)

Unicellular- 1 celled prokaryote/eukaryote

Multicellular- cell specialization (separate roles for each type of cell)

Levels of organization CellsTissuesOrgansOrgan system

Organism 11 major organ system (muscular,

skeletal, circulatory, nervous, etc.)