A View of the CellA View of the CellChapter 7 Notes Chapter 7 Notes

MicroscopesMicroscopes The microscope was invented by The microscope was invented by

Leeuwenhoek.Leeuwenhoek. A compound light microscope A compound light microscope

has a series of lenses and light.has a series of lenses and light. Electron microscope uses a Electron microscope uses a

beam of electrons instead of beam of electrons instead of light. Can magnify objects up to light. Can magnify objects up to 500,000 times their size.500,000 times their size.

The Cell TheoryThe Cell Theory All organisms are made of one All organisms are made of one

or more cells.or more cells. The cell is the basic unit of The cell is the basic unit of

structure of organization of structure of organization of organisms.organisms.

All cells come from existing All cells come from existing cells.cells.

The 2 types of CellsThe 2 types of CellsProkaryotes and EukaryotesProkaryotes and Eukaryotes There are 2 types of cells.There are 2 types of cells. Prokaryotic cells – these cells do not have a Prokaryotic cells – these cells do not have a

nucleus, they do not have organelles attached nucleus, they do not have organelles attached to the cell membrane. These are small cells. to the cell membrane. These are small cells.

Bacteria cells are prokaryotic cells.Bacteria cells are prokaryotic cells.

Eukaryotic cellsEukaryotic cells Eukaryotic cells – these cells do have a nucleus, they Eukaryotic cells – these cells do have a nucleus, they

do have organelles attached to the membrane. do have organelles attached to the membrane. These cells can be much larger than prokaryotic These cells can be much larger than prokaryotic cells.cells.

An organelle is a specialized structure in a cell that An organelle is a specialized structure in a cell that carries out a specific function. A “little organ.”carries out a specific function. A “little organ.”

The Plasma MembraneThe Plasma Membrane All cells are surrounded by a plasma All cells are surrounded by a plasma

membrane.membrane. This is a flexible boundary between the cell This is a flexible boundary between the cell

and its environment, to allow a steady and its environment, to allow a steady supply of nutrients to come into the cell no supply of nutrients to come into the cell no matter the external conditions.matter the external conditions.

The plasma membrane helps to maintain The plasma membrane helps to maintain homeostasis. homeostasis.

It has selective permeability. A process in It has selective permeability. A process in which only certain molecules can pass which only certain molecules can pass through the membrane and others are kept through the membrane and others are kept out.out.

Structure of the Structure of the Plasma MembranePlasma Membrane

The plasma The plasma membrane is membrane is made up of a made up of a phospholipid phospholipid bilayer.bilayer.

This is two layers This is two layers of phospholipid of phospholipid molecules.molecules.

Plasma Membrane (cont.)Plasma Membrane (cont.) The membrane is referred to as a “fluid The membrane is referred to as a “fluid

mosaic.” This means it is not a rigid mosaic.” This means it is not a rigid membrane, it’s shape and form can membrane, it’s shape and form can change and move.change and move.

Cholesterol molecules throughout the Cholesterol molecules throughout the membrane help stabilize the membrane help stabilize the phoshopholipids and keep the fatty acid phoshopholipids and keep the fatty acid tails from sticking together.tails from sticking together.

Transport proteins are also found in the Transport proteins are also found in the membrane to move needed substances or membrane to move needed substances or waste materials through the membrane.waste materials through the membrane.

Cell Structures and Their FunctionsCell Structures and Their Functions

Some organisms have an Some organisms have an additional boundary additional boundary between the cell and the between the cell and the environment. This is the environment. This is the cell wall. Plants, fungi, cell wall. Plants, fungi, bacteria, and some bacteria, and some protists have cell walls.protists have cell walls.

Cell wall – a fairly rigid Cell wall – a fairly rigid structure located outside structure located outside the plasma membrane the plasma membrane that provides additional that provides additional support and protection.support and protection.

Plant cells are separated by transparent cell walls.

NucleusNucleus

The nucleus is the control The nucleus is the control center of the cell. It contains center of the cell. It contains directions to make proteins. directions to make proteins. The nucleus controls the The nucleus controls the activities of the organelles.activities of the organelles.

The nucleus is surrounded The nucleus is surrounded by a nuclear membrane.by a nuclear membrane.

Nucleolus – an organelle in Nucleolus – an organelle in the nucleus that makes the nucleus that makes ribosomes.ribosomes.

Micrograph of a cell nucleusshowing the darkly stained nucleolus.

CytoplasmCytoplasm

The cytoplasm is everything inside the cell The cytoplasm is everything inside the cell membrane and outside the nucleus.membrane and outside the nucleus.

It contains most of the organelles for the It contains most of the organelles for the cell. It is the clear, gelatinous fluid inside a cell. It is the clear, gelatinous fluid inside a cell.cell.

Organelles and their FunctionsOrganelles and their Functions

Endoplasmic reticulum – the site of cellular Endoplasmic reticulum – the site of cellular reactions.reactions.

Rough endoplasmic reticulum – it is ER Rough endoplasmic reticulum – it is ER with ribosomes attached to its surface.with ribosomes attached to its surface.

Ribosomes – carry out protein synthesis. Ribosomes – carry out protein synthesis. (they make proteins).(they make proteins).

Golgi apparatus – sorts and packages Golgi apparatus – sorts and packages proteins to be sent out to where they are proteins to be sent out to where they are needed.needed.

Nucleus, ER, and Golgi ApparatusNucleus, ER, and Golgi Apparatus

1. Nucleus2. Nuclear Pore3. Rough Endoplasmic Reticulum4. Smooth Endoplasmic Reticulum5. Ribosome on rough ER6. Proteins that are transported7. Transport vesicle8. Golgi Apparatus

Vacuoles and LysosomesVacuoles and Lysosomes

Vacuole – a Vacuole – a membrane bound membrane bound compartment used for compartment used for temporary storage of temporary storage of materials. (10) They materials. (10) They are used to store food, are used to store food, enzymes, wastes, and enzymes, wastes, and other materials.other materials.

Lysosome – contain Lysosome – contain digestive enzymes (12)digestive enzymes (12)

Energy transformersEnergy transformers

Chloroplasts – cell organelles that capture Chloroplasts – cell organelles that capture light energy and convert it to chemical light energy and convert it to chemical energy. Found in plant cells and some energy. Found in plant cells and some protists. This is the site of photosynthesis.protists. This is the site of photosynthesis.

Mitochondria – membrane bound Mitochondria – membrane bound organelles in plant and animal cells that organelles in plant and animal cells that transform energy for the cell. Break down transform energy for the cell. Break down chemicals and into usable forms.chemicals and into usable forms.

Organelles for Cellular SupportOrganelles for Cellular Support Cytoskeleton – forms a Cytoskeleton – forms a

framework for the cell. It framework for the cell. It is a constantly changing is a constantly changing structure.structure.

Microtubules – thin, Microtubules – thin, hollow cylinders made of hollow cylinders made of protein that make up the protein that make up the rods for the cytoskeleton.rods for the cytoskeleton.

Microfilaments – small, Microfilaments – small, solid fibers that help solid fibers that help make up the cytoskeletonmake up the cytoskeleton

Centrioles – occur in Centrioles – occur in pairs, made of pairs, made of microtubules, help in cell microtubules, help in cell division.division.

Microtubules are green,Microfilaments are red,Nuclei are blue.

Organelles for LocomotionOrganelles for Locomotion

Cilia – short, numerous Cilia – short, numerous hair-like projections that hair-like projections that aid in locomotion. Motion aid in locomotion. Motion is similar to that of oars is similar to that of oars on a boat.on a boat.

Flagella – a long, whip-Flagella – a long, whip-like projection used in like projection used in locomotion. A cell can locomotion. A cell can have one or two flagella.have one or two flagella.

Unicellular organisms use Unicellular organisms use these a major means of these a major means of locomotion.locomotion. Flagella on e. coli bacterium.