Cells
Smallest living unit
Most are microscopic
Discovery of Cells
Robert Hooke (mid-1600s)
Observed sliver of cork
Saw “row of empty boxes”
Coined the term cell
Cell theory
(1839)Theodor Schwann & Matthias Schleiden
“ all living things are made of cells”
(50 yrs. later) Rudolf Virchow
“all cells come from cells”
Principles of Cell Theory
All living things are made of cells
Smallest living unit of structure and function of all organisms is the cell
All cells arise from preexisting cells
(this principle discarded the idea of
spontaneous generation)
Cell Size
Characteristics of All Cells
A surrounding membrane
Protoplasm – cell contents in thick fluid
Organelles – structures for cell function
Control center with DNA
Cell Types
Prokaryotic
Eukaryotic
Prokaryotic Cells
First cell type on earth
Cell type of Bacteria and Archaea
Prokaryotic Cells
No membrane bound nucleus
Nucleoid = region of DNA concentration
Organelles not bound by membranes
Eukaryotic Cells
Nucleus bound by membrane
Include fungi, protists, plant, and animal cells
Possess many organelles
Representative Animal Cell
Representative Plant Cell
Organelles
Cellular machinery
Two general kinds
Derived from membranes
Bacteria-like organelles
Plasma Membrane
Contains cell contents
Double layer of phospholipids & proteins
Phospholipids
Polar
Hydrophylic head
Hydrophobic tail
Interacts with water
Membrane Proteins
1. Channels or transporters
Move molecules in one direction
2. Receptors
Recognize certain chemicals
Membrane Proteins
3. Glycoproteins
Identify cell type
4. Enzymes
Catalyze production of substances
Cell Walls
Found in plants, fungi, & many protists
Surrounds plasma membrane
Cell Wall Differences
Plants – mostly cellulose
Fungi – contain chitin
Cytoplasm
Viscous fluid containing organelles
components of cytoplasm
Interconnected filaments & fibers
Fluid = cytosol
Organelles (not nucleus)
storage substances
Cytoskeleton
Filaments & fibers
Made of 3 fiber types
Microfilaments
Microtubules
Intermediate filaments
3 functions:
mechanical support
anchor organelles
help move substances
Centrioles
Pairs of microtubular structures
Play a role in cell division
Nucleus
Control center of cell
Double membrane
Contains
Chromosomes
Nucleolus
Nuclear Envelope
Separates nucleus from rest of cell
Double membrane
Has pores
DNA
Hereditary material
Chromosomes
DNA
Protiens
Form for cell division
Chromatin
Nucleolus
Most cells have 2 or more
Directs synthesis of RNA
Forms ribosomes
Endoplasmic Reticulum
Helps move substances within cells
Network of interconnected membranes
Two types
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Rough Endoplasmic Reticulum
Ribosomes attached to surface
Manufacture protiens
Not all ribosomes attached to rough ER
May modify proteins from ribosomes
Smooth Endoplasmic Reticulum
No attached ribosomes
Has enzymes that help build molecules
Carbohydrates
Lipids
Golgi Apparatus
Involved in synthesis of plant cell wall
Packaging & shipping station of cell
Golgi Apparatus Function
1. Molecules come in vesicles
2. Vesicles fuse with Golgi membrane
3. Molecules may be modified by Golgi
Golgi Apparatus Function (Continued)
4. Molecules pinched-off in separate vesicle
5. Vesicle leaves Golgi apparatus
6. Vesicles may combine with plasma membrane to secrete contents
Lysosomes
Contain digestive enzymes
Functions
Aid in cell renewal
Break down old cell parts
Digests invaders
Vacuoles
Membrane bound storage sacs
More common in plants than animals
Contents
Water
Food
wastes
Mitochondria
Have their own DNA
Bound by double membrane
Mitochondria
Break down fuel molecules (cellular respiration)
Glucose
Fatty acids
Release energy
ATP
Chloroplasts
Derived form photosynthetic bacteria
Solar energy capturing organelle
Photosynthesis
Takes place in the chloroplast
Makes cellular food – glucose
Molecule Movement & Cells
Passive Transport
Active Transport
Endocytosis
(phagocytosis & pinocytosis)
Exocytosis
Passive Transport
No energy required
Move due to gradient
differences in concentration, pressure, charge
Move to equalize gradient
High moves toward low
Types of Passive Transport
1. Diffusion
2. Osmosis
3. Facilitated diffusion
Diffusion
Molecules move to equalize concentration
Osmosis
Special form of diffusion
Fluid flows from lower solute concentration
Often involves movement of water
Into cell
Out of cell
Solution Differences & Cells
solvent + solute = solution
Hypotonic
Solutes in cell more than outside
Outside solvent will flow into cell
Isotonic
Solutes equal inside & out of cell
Hypertonic
Solutes greater outside cell
Fluid will flow out of cell
Facilitated Diffusion
Differentially permeable membrane
Channels (are specific) help molecule or io