Keyword:Biol120CellTheoOrg

Topics

History and Cell Types

Membranes and Organelles
Cell Support
Cell Control
Cell Synthesis
Cell Metabolism
Cell Movement
Cell Transport
Passive Diffusion
Facilitated Diffusion
Osmosis
Active Transport
Bulk Transport

History and Cell Types

Cell theory

• Robert Hooke-first to see "cells"
  
  
  
  
  
• German microscopist Lorenza Oken (1805)-"All living organisms originate from and consist of cells . . "
  first statement of cell theory
  
  
  
• Schleiden and Schwann-all living things composed of cells
  
  
  
• Virchow-all cells come from cells-biogenetic law (remember spontaneous generation ?)
  
  
  
  
  

These statements very important in guiding cell research

Cell Types

cell:






Levels of organization:

• cell
  
  
  
  
  
• tissue
  
  
  
  
  
  
• organs
  
  
  
  
  
• systems
  
  
  
  
  
  
  

Size






Why are many cells so small ?

• surface to volume hypothesis
  
  
  
  
  
  
  
  
• increase rate of chemical reactions in enclosed space
  
  
  
  
  
  
  
  

Eukaryotic vs. Procaryotic cells

• prokaryotes
  
  
  
  
  
  
  
  
  
• eucaryotes
  
  
  
  
  
  
  
  
  
  

Some taxonomists believe a 3 kingdom system is more representative of organismal relationships because of the great differences between some procaryotic groups

Kingdoms= Archaebacteria, Eubacteria, Eukaryotes other systems being proposed ?

Membranes and Organelles

Membranes and organelles

Cell support

Cell membrane: very important structure; regulates passage of materials, provides support
What does membrane look like ? Singer's fluid mosaic model

• transport proteins
  
  
  
  
  
  
  
  
  
  
  
  
• receptor proteins
  
  
  
  
  
  
  
  
  
  
  
  
• recognition proteins
  
  
  
  
  
  
  
  
  
  
  
  

Cell walls

• Plants
  
  
  
  
  
  

Microtrabecular lattice







Cell control

Nucleus ("kernel")-











Cell synthesis (cytomembrane system)-process metabolites

• endoplasmic reticulum (er)
  
  
  
  
  
  
  
  
  
  
  
  
• Golgi bodies
  
  
  
  
  
  
  
  
  
  
  
  
  
• Lysosomes
  
  
  
  
  
  
• Peroxisomes
  
  
  
  
  
• Vacuoles-"empty cavity"
  
  
  
  
  
  
  

Cell metabolism

• mitochondria
  
  
  
  
  
  
  
  
  
  
• chloroplasts
  
  
  
  
  
  
  
  
  
  
  

Cell Movement

Microtubules and microfilaments-work with the microtrabecular lattice to move cells

• Microtubules
  
  
  
  
  
  
  
  
  
  
  
  
• microfilaments
  
  
  
  
  
  

Examples:

• cilia and flagella
  
  
  
  
  
• centrioles and spindle fibers
  
  
  
  
  
  
  

Cell Transport

Cell Transport

Types of transport

• Passive diffusion:
  
  
  
  
  
  
  
  
  
  
  
  

Diffusion is physically influenced by

• heat
  
  
  
  
  steepness of gradient
  
  
  
  
  
  
  size of the particles
  
  
  
  
  
  
  
  
  electrical charge
  
  
  
  
  
  pressure gradient
  
  
  
  
  
  
  
  
  
  

Fluid mosaic model of membrane









Facilitated diffusion: Movement of a substance with a concentration gradient mediated by a transport structure, often associated with a membrane






















Osmosis- osmosis is the movement of water across a selectively permeable membrane to areas of low to high solute concentration (high to low water concentration)













Tonicity: osmotic environment of a cell may be described as isotonic: water potential equal on both sides of the membrane

• hypotonic:
  
  
  
  
  
  
  
  
  
• hypertonic:
  
  
  
  
  
  
  
  
  
  

Turgor












Active transport
The cell uses carrier proteins and energy to move substances against a concentration gradient













Why invest energy ?



















































Bulk transport in cells
Protein channels deal with low volume translocations Animal cells

• Endocytosis (pinocytosis and phagocytosis)
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
• Exocytosis
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

Comments or questions about this section of Western Online should be directed to jackjd@wkuvx1.wku.edu
Last Modified: Sept. 4, 1995
All contents copyright (C) 1995.
Western Kentucky University.