Chapter 3 Cell Structure

Microscopes Light Microscope Electron Microscope

Microscopes Light Microscope - light passes through one or more lenses to produce an image of a specimen. Electron Microscope

Microscopes Light Microscope - light passes through one or more lenses to produce an image of a specimen. Electron Microscope – forms an image of a specimen using a beam of electrons.

Microscopes Light Microscope - light passes through one or more lenses to produce an image of a specimen. Electron Microscope – forms an image of a specimen using a beam of electrons. – Transmission Electron Microscope – Scanning Electron Microscope

Light Pros and Cons Pros Comparatively Inexpensive Can observe living specimens Can view biological processes happening in real time. Slide prep is quick and easy Cons Magnification, depth of field, and resolution are not as great as in an Electron Microscope.

Electron Pros and Cons Pros Higher resolution/magnificatio n. Greater depth of field 3D images Cons Expensive Difficult and time consuming slide prep. Specimens need to be dyed, which kills them, so no living organisms can be observed.

Compound Light Microscope

Onion Skin Cells

Single Celled Organisms Paramecium  Amoeba   Euglena

SECTION 2 Cell Features

THE CELL THEORY

The Cell Theory: 1. All organisms are made up of one or more cells.

The Cell Theory: 1. All organisms are made up of one or more cells. 2. The cell is the basic unit of all living things.

The Cell Theory: 1. All organisms are made up of one or more cells. 2. The cell is the basic unit of all living things. 3. All cells come from existing cells.

Cell Size Why are cells so small? Total surface area Total volume Surface area:volume ratio

TWO KINDS OF CELLS 1.PROKARYOTES 2. EUKARYOTES

PROKARYOTES 1.All single celled organisms 2.Do not have a nucleus 3.Can exist in a broad range of environmental conditions 4.All have a cell wall made of strands of polysaccharides 5.Sometimes have a capsule 6.DNA is in a single circular ring

EUKARYOTES 1.Can be single or multicellular 2.Has a membrane bound nucleus which houses the cells DNA 3.Contains internal membrane bound compartments called organelles 4.DNA is in multiple chromosomes

Common Features of ALL cells: Cell Membrane Cytoplasm DNA Ribosomes

CYTOSKELETON An intricate network of protein fibers anchored to the inside of the plasma membrane. The network provides an internal framework for the cell which supports the cell shape and provides places for organelles to anchor.

CYTOSKELETON three different types of fibers: Actin Fibers: Anchor to membrane proteins forming a network just beneath the cell surface.

CYTOSKELETON three different types of fibers: Actin Fibers: Anchor to membrane proteins forming a network just beneath the cell surface. Microtubules: act as a highway system for transportation of information from the nucleus throughout the cell.

CYTOSKELETON three different types of fibers: Actin Fibers: Anchor to membrane proteins forming a network just beneath the cell surface. Microtubules: act as a highway system for transportation of information from the nucleus throughout the cell. Intermediate Fibers: help confine ribosomes and enzymes to particular regions of the cell.

The Cell Membrane a phospholipid bilayer

A Selectively Permeable Barrier

Fig (b) Space-filling model (a)(c) Structural formula Phospholipid symbol Fatty acids Hydrophilic head Hydrophobic tails Choline Phosphate Glycerol Hydrophobic tails Hydrophilic head

Fig. 7-2 Hydrophilic head WATER Hydrophobic tail WATER

Fig. 7-7 Fibers of extracellular matrix (ECM) Glyco- protein Microfilaments of cytoskeleton Cholesterol Peripheral proteins Integral protein CYTOPLASMIC SIDE OF MEMBRANE Glycolipid EXTRACELLULAR SIDE OF MEMBRANE Carbohydrate

Cell Surface Proteins Sit on the outer surface of the cell. Attached to a carbohydrate which allows the cell to advertize what type it is. Used in cell-cell recognition.

Receptor Proteins Bind specific substances, such as single molecules, outside the cell.

Transport Proteins Help substances move across the cell membrane.

Enzymes Assists chemical reactions inside the cell.

Fig. 7-9 (a) Transport ATP (b) Enzymatic activity Enzymes (c) Signal transduction Signal transduction Signaling molecule Receptor (d) Cell-cell recognition Glyco- protein (e) Intercellular joining (f) Attachment to the cytoskeleton and extracellular matrix (ECM)

Section 3 Cell Organelles Organelles are structures within a cell that preform a specific function.

NUCLEUS Houses the cells DNA and controls many functions within the cell. Surrounded by a double membrane called the nuclear envelope, which contains many small channels called nuclear pores.

RIBOSOMES An organelle composed of RNA and protein that is the site of protein synthesis. May be suspended in the cytoplasm, and make substances that will remain in the cell – “free”- ribosome. Or they may be attached to the ER, and make substances that will be exported from the cell.

ENDOPLASMIC RETICULUM A system of membranes that is found in the cells cytoplasm and that assists in the production, processing, and transport of proteins, and the production of lipids. ROUGH ER – attached ribosomes SMOOTH ER – no ribosomes

Vessicle A small membrane-bound sac that transports substances in cells.

Golgi Apparatus A set of flattened, membrane bound sacs that serve as the packaging and distribution center of the cell.

Lysosomes Small spherical organelles that contain the cells digestive enzymes

Mitochondria An organelle that harvests energy from organic compounds to make ATP (adenosine triphospahte- a cells energy source) Has an inner and an outer membrane, and also contains DNA and ribosomes.

PLANTS Plants have certain organelles unique to only them.

CELL WALL Surround the cell membrane Composed of proteins and carbohydrates, including the polysaccharide cellulose. Helps support and maintain the cell shape, protects it from damage and connects it with neighboring cells.

CHLOROPLAST The organelle in plants and algae where photosynthesis takes place. They also have two membranes and their own DNA.

VACUOLE Organelle that stores water and other materials.

Prokaryotic Cell

Animal Cell

Plant Cell

Protein Packaging & Distribution 1. Ribosomes make proteins on rough ER. The proteins are packaged into vesicles.

Protein Packaging & Distribution 2. The vesicles transport newly made proteins from the ER to the Golgi Apparatus

Protein Packaging & Distribution 3. In the golgi apparatus proteins are processed and packaged into new vesicles.

Protein Packaging & Distribution 4. Many of these vesicles move to the cell membrane and release their content outside of the cell.

Protein Packaging & Distribution 5. Other vesicles, including lysosomes, remain within the cytoplasm.