cell structure and function. the cell theory v all living things are composed of cells. v cells are...
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Cell Structure and Function
The Cell Theory All living things are composed of cells.
Cells are the basic units of structure and function in living things.
All cells come from pre-existing cells.
Cell StructureMost cells have three basic structures.–cell membrane (outer boundary)
–cytoplasm (filling)–nucleus (control center)
All cells have a cell membrane and cytoplasm.
However some do not have a nucleus. These are called Prokaryotes. (bacteria)
Cells with a nucleus are called eukaryotes. (plant, animal, fungus and protists)
Nucleus
Separates and protects the cell from its surroundings.
Regulates what enters and leaves the cell.
Made of two lipid layers: (Phospholipid bilayer)
Cell Membrane
Hydro-phyllic
(Phos-phates)
Hydro-phobic
(Fatty acids)
Phospholipid Bilayer
The Cell Membrane
CytoplasmThe area between the cell membrane and nucleus.
Contains structures called organelles and each one performs a specific job.
Cytoplasm
Nucleus (Control center)
Contains DNA which are the instructions for making molecules the cell needs.
Nucleus (Control center)Directs the activities of the cell.
Surrounded by a membrane called the nuclear membrane or nuclear envelope.
Nucleus
Nucleolus
A small region of the nucleus made up of RNA and proteins.
The nucleolus makes ribosomes.
NucleolusN
ucl
eus
RibosomesFound in prokaryotic and eukaryotic cells
Protein factories.Some ribosomes are attached to the endoplasmic reticulum.
RibosomesOthers are free in the cytoplasm.
Smallest organelle.
Ribosomes
Rough ER
Endoplasmic ReticulumTwo forms
Rough ER
Smooth ER
Endoplasmic Reticulum
Smooth ER: no ribosomes are attached. Special enzymes and chemicals are stored here. Lipids (fats) are produced
Endoplasmic Reticulum
Smooth ER: also resp. for prod. of phospholipids for cell membrane.
Rough ER: has ribosomes
attached. After proteins are made in the ribosomes they are inserted in the rough ER where they can be modified.
Endoplasmic Reticulum
Rough ER: from the ER, proteins are sent to the Golgi Apparatus
Endoplasmic Reticulum
Golgi Apparatus (UPS)
modifies, collects, and packages molecules in the cell.
Also distributes the molecules to where they need to be in the cell.
Golgi Apparatus
LysosomesCleanup crews for the cell.
Lysosomes are formed in the Golgi apparatus.
Lysosomes
Contain chemicals and enzymes that digest and breakdown waste particles.
Lysosome in action:
Vacuoles (Warehouse)Storage tanks in the cell.
Store materials like water, salts, proteins, and carbohydrates.
Plants have only one big vacuole filled primarily with water.
Vacuoles (Warehouse)
CytoskeletonThe framework of the cell.
Made of microfilaments and microtubules
Provide support and are often involved in cell movement.
Mitochondria(Generator)Generator of the cell.Changes chemical energy stored in food (sugar) into compounds easier for the cell organelles to use (ATP).
Mitochondrion
Chloroplast (Solar Panel)Where photosynthesis takes place
Found only in plant cells and algae.
Chloroplast (Solar Panel)
Traps energy from sunlight and changes it into chemical energy (makes sugars).
Plant Cell
Chloroplast
Cell WallIn addition to the cell membrane, plant (& fungus) cells have a cell wall.
Provides extra support.Made up of cellulose and lignin
Cell Wall Found outside the cell membrane
Movement of materials through the cell membrane.Cells must take in materials, and release waste products.
Molecules must be able to move in and out of the cell.
Movement of materials through the cell membrane.
They do this by diffusion.
DiffusionThe process by which molecules move from areas of higher concentration to areas of lower concentration. (spread out)
Diffusion
Driven by the random movement of molecules.
Diffusion
Two factors determine if diffusion takes place equilibrium and permeability.
higher conc. lower conc.
membraneDiffusion
Equilibrium
Equilibrium is when the concentrations on both sides of the membrane are equal.
Equilibrium
Semi-permeablemembrane
Permeability
If a molecule can diffuse across a membrane, the membrane is permeable.
Permeability
If a molecule cannot diffuse across a membrane, the membrane is impermeable to that membrane.
Selective PermeabilityMembranes are
permeable to some molecules and impermeable to others.
These membranes are described as selectively permeable or semi- permeable.
OsmosisOsmosis is a special type of diffusion:
The diffusion of water molecules through a selectively permeable membrane.
There are three types of transports across a membrane.–passive transport (diffusion)
–facilitated diffusion–active transport
Passive Transport
Energy is not required for movement across the membrane to occur.
Diffusion and osmosis are examples
Facilitated DiffusionA carrier protein
“helps” the molecule to enter or leave the cell. (Passive)
Active TransportEnergy is required for movement across the membrane to occur.
Molecules move from low to high concentration.
Two types of active transport:
–Protein pumps: Pumps specific ions
–Endocytosis: cell engulfs (eats) material.
Active Transport
Pumps Proteins stuck in the membrane act as a doorway into the cell.
Allows only specific things through the doorway.
Energy is required to open the door
Pumps
Endocytosis
Endocytosis
Type of active transport when the membrane surrounds material and pulls it into the cell
Endocytosis Types
PhagocytosisPinocytosisReceptor Mediated Endocytosis
Phagocytosis“Cell Eating”Bringing large molecules across the membrane.
Membrane becomes a vacuole when entering the cell
Pinocytosis“Cell Drinking”Moving fluids and ions across a membrane.
Usually going against the concentration gradient
Ion concentration outside the membrane is
less than inside
Membrane surrounding ions and fluids
Vacuole
Receptor Mediated Endocytosis
Same process as pinocytosis.
Specific ions are moved across the membrane
Receptor Mediated Endocytosis
Receptor proteins trigger when endocytosis should begin
ExocytosisOpposite of endocytosis
Process when cell removes waste from cytoplasm
Vacuole or lysosome fuses with cell membrane and releases materials outside the cell