RandomGuy
10-06-2006, 04:53 PM
im gonna put all my notes on IA so we can all read together lol and also so i dont have to flip between .doc files. thank you for your patronage
Cell Structure and Function
Historical Overview
Robert Hooke
1600s
First to view plant cells
Historical Overview
Matthias Schleiden and Theodor Schwann
Mid 1800s
All living things composed of cells
Historical Overview
Rudolf Virchow
Cells arise only from other cells
Theory of spontaneous generation challenged
Cell Theory
Every organism is composed of one or more cells
The cell is the smallest unit having the properties of life
The continuity of life arises directly from the growth and division of cells
Cell Size
Cell Shape
Prokaryotic Organisms
Single cells
No nucleus or organelles
Smaller, less complex
Surface to Volume
Volume increases faster than surface area
Basic Features of All Cells
Plasma membrane
Nucleus (or nucleoid)
Cytoplasm
Plasma Membrane
Cell membrane
Encloses the cell
Mediates interactions between the cell and its environment
Nucleus (nucleoid)
Nucle = pit or kernel
Control center of the cell
Houses DNA
Cytoplasm
Cyto = cell
Plasm = shaped, molded
Between cell membrane and nucleus
Major functional area
Site where most cellular activities occur
Nucleus
Control center
Computer
Design department
Construction boss
Board of directors
Nuclear envelope
Nucleoli
DNA + Nucleoplasm
Nucleolus is the site of ribosome assembly
Nuclear Envelope
Double membrane barrier
Each membrane is a phospholipid bilayer
Fluid-filled space between each membrane (perinuclear cisterna)
Fuse nuclear pores
Allows transport of large molecules
The nuclear envelope allows selective exchange of materials
Chromatin contains DNA, which codes for the synthesis of proteins
Cytoplasm
Cytosol
Organelles
Inclusions
Cytosol
Viscous (thick fluid)
Mostly water
Semitransparent
Suspension
Organelles
Inclusions
Soluble proteins
Salts
Sugars
Organelles
Metabolic machinery
Specific functions
Inclusions
Chemical substances
Varies between types of cells
Organelles
Endoplasmic reticulum
Smooth
Rough
Golgi Body
Ribosomes
Mitochondria
Lysosomes
Vacuoles
Central Vacuole
Chloroplasts
Plastids
Cytoskeleton
Unique to eukaryotic cells
This structure acts as both muscle and skeleton, for movement and stability
The long fibers of the cytoskeleton are polymers of subunits
Cytoskeletal Elements
Microtubules
Largest elements
Composed of tubulin
Arise from microtubule organizing centers (MTOCs)
Microtubules act as a scaffold to determine cell shape, and provide a set of "tracks" for cell organelles and vesicles to move on
Microtubules also form the spindle fibers for separating chromosomes during mitosis
When arranged in geometric patterns inside flagella and cilia, they are used for locomotion
Microfilaments
Composed of actin
Most abundant cell protein
Microfilaments' association with the protein myosin is responsible for muscle contraction
Microfilaments can also carry out cellular movements including gliding, contraction, and cytokinesis.
Intermediate Filaments
Only in animal cells of certain tissues
Most stable cytoskeletal elements
Provide tensile strength for the cell
Motor Proteins
Kinesin and Dynein move along microtubules
Myosin move along microfilaments
Motor Proteins
Kinesin and Dynein move along microtubules
Myosin move along microfilaments
http://www.sciencemag.org/feature/data/1049155.shl
Flagella and Cilia
Structures for cell motility
9 + 2 internal structure
Pseudopods (False Feet)
Temporary
Irregular lobes
Project from body
Locomotion
Catch prey
Amoebas
Macrophages
Cell Membrane Structure and Function
Plasma Membrane
The plasma membrane isolates the cell while allowing communication with its surroundings
Membranes are fluid mosaics in which proteins move within layers of lipids
The phospholipid bilayer is the fluid portion of the membrane
Lipid Bilayer
Main component of cell membranes
Gives membrane its fluid properties
Fatty acid tails sandwiched between hydrophilic heads
Phospholipids
Fluid Mosaic Model
Membrane is a mosaic of
Phospholipids
Glycolipids
Sterols
Proteins
Most phospholipids and some proteins can drift through membrane
Adhesion Proteins
Help cells adhere (stick) to one another or to proteins
Communication Proteins
Match up with identical proteins of an neighbor cell and form a channel
Connects the cytoplasm of the two cells
Chemical and electrical signals pass through these channels
Receptor Proteins
Docking station for hormones or other signals
The docking of hormones (or others) cause the cell to change its activities
Recognition Proteins
Cell ID
Identifies the cell as belonging to a body or tissue
Or identifies the cell as foreign
Movement across membranes occurs by both passive and active transport
Molecules in fluids move in response to gradients
Passive Transporters
Passive transport includes simple diffusion, facilitated diffusion, and osmosis
Plasma membranes are selectively permeable to diffusion of molecules
Some molecules move across membranes by simple diffusion
Channels that allow specific solutes to move through without an energy cost
Diffusion
Concentration or electric gradients
Concentration Gradient
Means the number of molecules or ions in one region is different than the number in another region
In the absence of other forces, a substance moves from a region where it is more concentrated to one where its less concentrated - down gradient
Selective Permeability
Diffusion
The net movement of like molecules or ions down a concentration gradient
Although molecules collide randomly, the net movement is away from the place with the most collisions (down gradient)
Factors Affecting
Diffusion Rate
Steepness of concentration gradient
Steeper gradient, faster diffusion
Molecular size
Smaller molecules, faster diffusion
Temperature
Higher temperature, faster diffusion
Electrical or pressure gradients
Osmosis
Across a membrane
Water molecules tend to diffuse down water concentration gradient
Total number of molecules or ions dictates concentration of water
Tonicity - relative solute concentrations
Tonicity
Fluid Pressure
Hydrostatic pressure
Fluids exert pressure to any contact surface
When at rest (static) it acts with equal magnitude in all directions.
Osmotic pressure
Hydrostatic pressure produced by osmosis
Turgor pressure
Turgidity
Positive internal pressure in a cell resulting from osmotic pressure
Active Transporters
Pumps specific solutes across the membrane
Works against a concentration gradient
Uses energy
Transport Proteins
Span the lipid bilayer
Interior is able to open to both sides
Change shape when they interact with solute
Move water-soluble substances across a membrane
Membrane Cycling
Exocytosis and endocytosis continually replace and withdraw patches of plasma membrane
Passive and Active Transport
Doesnt require energy inputs
Solutes diffuse through a channel inside the proteins interior
Net movement is down concentration gradient
Cell Junctions
Communication centers
Send and receive signals
Send and receive materials
Recognition of same cell type
Join cell of same type
Cell Structure and Function
Historical Overview
Robert Hooke
1600s
First to view plant cells
Historical Overview
Matthias Schleiden and Theodor Schwann
Mid 1800s
All living things composed of cells
Historical Overview
Rudolf Virchow
Cells arise only from other cells
Theory of spontaneous generation challenged
Cell Theory
Every organism is composed of one or more cells
The cell is the smallest unit having the properties of life
The continuity of life arises directly from the growth and division of cells
Cell Size
Cell Shape
Prokaryotic Organisms
Single cells
No nucleus or organelles
Smaller, less complex
Surface to Volume
Volume increases faster than surface area
Basic Features of All Cells
Plasma membrane
Nucleus (or nucleoid)
Cytoplasm
Plasma Membrane
Cell membrane
Encloses the cell
Mediates interactions between the cell and its environment
Nucleus (nucleoid)
Nucle = pit or kernel
Control center of the cell
Houses DNA
Cytoplasm
Cyto = cell
Plasm = shaped, molded
Between cell membrane and nucleus
Major functional area
Site where most cellular activities occur
Nucleus
Control center
Computer
Design department
Construction boss
Board of directors
Nuclear envelope
Nucleoli
DNA + Nucleoplasm
Nucleolus is the site of ribosome assembly
Nuclear Envelope
Double membrane barrier
Each membrane is a phospholipid bilayer
Fluid-filled space between each membrane (perinuclear cisterna)
Fuse nuclear pores
Allows transport of large molecules
The nuclear envelope allows selective exchange of materials
Chromatin contains DNA, which codes for the synthesis of proteins
Cytoplasm
Cytosol
Organelles
Inclusions
Cytosol
Viscous (thick fluid)
Mostly water
Semitransparent
Suspension
Organelles
Inclusions
Soluble proteins
Salts
Sugars
Organelles
Metabolic machinery
Specific functions
Inclusions
Chemical substances
Varies between types of cells
Organelles
Endoplasmic reticulum
Smooth
Rough
Golgi Body
Ribosomes
Mitochondria
Lysosomes
Vacuoles
Central Vacuole
Chloroplasts
Plastids
Cytoskeleton
Unique to eukaryotic cells
This structure acts as both muscle and skeleton, for movement and stability
The long fibers of the cytoskeleton are polymers of subunits
Cytoskeletal Elements
Microtubules
Largest elements
Composed of tubulin
Arise from microtubule organizing centers (MTOCs)
Microtubules act as a scaffold to determine cell shape, and provide a set of "tracks" for cell organelles and vesicles to move on
Microtubules also form the spindle fibers for separating chromosomes during mitosis
When arranged in geometric patterns inside flagella and cilia, they are used for locomotion
Microfilaments
Composed of actin
Most abundant cell protein
Microfilaments' association with the protein myosin is responsible for muscle contraction
Microfilaments can also carry out cellular movements including gliding, contraction, and cytokinesis.
Intermediate Filaments
Only in animal cells of certain tissues
Most stable cytoskeletal elements
Provide tensile strength for the cell
Motor Proteins
Kinesin and Dynein move along microtubules
Myosin move along microfilaments
Motor Proteins
Kinesin and Dynein move along microtubules
Myosin move along microfilaments
http://www.sciencemag.org/feature/data/1049155.shl
Flagella and Cilia
Structures for cell motility
9 + 2 internal structure
Pseudopods (False Feet)
Temporary
Irregular lobes
Project from body
Locomotion
Catch prey
Amoebas
Macrophages
Cell Membrane Structure and Function
Plasma Membrane
The plasma membrane isolates the cell while allowing communication with its surroundings
Membranes are fluid mosaics in which proteins move within layers of lipids
The phospholipid bilayer is the fluid portion of the membrane
Lipid Bilayer
Main component of cell membranes
Gives membrane its fluid properties
Fatty acid tails sandwiched between hydrophilic heads
Phospholipids
Fluid Mosaic Model
Membrane is a mosaic of
Phospholipids
Glycolipids
Sterols
Proteins
Most phospholipids and some proteins can drift through membrane
Adhesion Proteins
Help cells adhere (stick) to one another or to proteins
Communication Proteins
Match up with identical proteins of an neighbor cell and form a channel
Connects the cytoplasm of the two cells
Chemical and electrical signals pass through these channels
Receptor Proteins
Docking station for hormones or other signals
The docking of hormones (or others) cause the cell to change its activities
Recognition Proteins
Cell ID
Identifies the cell as belonging to a body or tissue
Or identifies the cell as foreign
Movement across membranes occurs by both passive and active transport
Molecules in fluids move in response to gradients
Passive Transporters
Passive transport includes simple diffusion, facilitated diffusion, and osmosis
Plasma membranes are selectively permeable to diffusion of molecules
Some molecules move across membranes by simple diffusion
Channels that allow specific solutes to move through without an energy cost
Diffusion
Concentration or electric gradients
Concentration Gradient
Means the number of molecules or ions in one region is different than the number in another region
In the absence of other forces, a substance moves from a region where it is more concentrated to one where its less concentrated - down gradient
Selective Permeability
Diffusion
The net movement of like molecules or ions down a concentration gradient
Although molecules collide randomly, the net movement is away from the place with the most collisions (down gradient)
Factors Affecting
Diffusion Rate
Steepness of concentration gradient
Steeper gradient, faster diffusion
Molecular size
Smaller molecules, faster diffusion
Temperature
Higher temperature, faster diffusion
Electrical or pressure gradients
Osmosis
Across a membrane
Water molecules tend to diffuse down water concentration gradient
Total number of molecules or ions dictates concentration of water
Tonicity - relative solute concentrations
Tonicity
Fluid Pressure
Hydrostatic pressure
Fluids exert pressure to any contact surface
When at rest (static) it acts with equal magnitude in all directions.
Osmotic pressure
Hydrostatic pressure produced by osmosis
Turgor pressure
Turgidity
Positive internal pressure in a cell resulting from osmotic pressure
Active Transporters
Pumps specific solutes across the membrane
Works against a concentration gradient
Uses energy
Transport Proteins
Span the lipid bilayer
Interior is able to open to both sides
Change shape when they interact with solute
Move water-soluble substances across a membrane
Membrane Cycling
Exocytosis and endocytosis continually replace and withdraw patches of plasma membrane
Passive and Active Transport
Doesnt require energy inputs
Solutes diffuse through a channel inside the proteins interior
Net movement is down concentration gradient
Cell Junctions
Communication centers
Send and receive signals
Send and receive materials
Recognition of same cell type
Join cell of same type