Chapter 3 Cell Structure

Resolution: measure of clarity of an image Section 3-1 Cell Size: Magnification: quality of making an image appear larger than actual size Resolution: measure of clarity of an image e- microscopes have ↑ mag/resolution

Section 3-1 Light microscopes: Form an image when light passes through 1 or more lenses to produce an enlarged image of specimen

Electron microscopes use beam of e- rather than light to view specimen Section 3-1 Types of Microscopes: Electron microscopes use beam of e- rather than light to view specimen Live organisms can’t be viewed w/ e- microscope

Transmission Electron Microscope: Section 3-1 Transmission Electron Microscope: e- beam directed at very thin slice of specimen stained w/metal ions e- that pass through strike fluorescent screen, forming an image; can’t view live specimen

Scanning Electron Microscope: Section 3-1 Scanning Electron Microscope: e- beam is focused on specimen coated w/ very thin layer of metal Shows 3D details of surface of specimen; can’t view live specimen Neutrophil (yellow) engulfing anthrax (orange)

e- surrounded by 48 iron atoms Section 3-1 Scanning Tunneling Microscope: Needle-like probe measures differences in voltage caused by e- that leak, or tunnel, from surface of object being viewed Shows 3D details of surface of specimen Live specimens can be viewed e- surrounded by 48 iron atoms

Small cells function more efficiently than large cells Section 3-2 Cell Size Small cells function more efficiently than large cells If cell’s surface area–to-volume ratio is too low, subs can’t enter/leave cell well enough to meet cell’s needs

1. All LT are made of 1 or more cells Section 3-2 Cell Theory has 3 parts: 1. All LT are made of 1 or more cells 2. Cells are basic units of structure/function in organisms All cells arise from existing cells All cells have: Cell membrane Cytoplasm Cytoskeleton DNA Ribosome

Prokaryotic cells (bacteria): Section 3-2 Prokaryotic cells (bacteria): Single-celled organisms; no nucleus or internal compartments Have cell wall, may have cilia/flagella Have circular molecule of DNA E. coli bacteria cell

Eukaryotic cells (all other LT): Nucleus contains cell’s DNA Section 3-2 Eukaryotic cells (all other LT): Nucleus contains cell’s DNA Other internal compartments, organelles Typical animal cell

Phospholipid made of phosphate group and 2 fatty acids Section 3-2 Cell membrane: Selectively permeable membrane, determines which substances enter/leave cell Selective permeability caused by the way phospholipids interact w/ water Phospholipid made of phosphate group and 2 fatty acids

Section 3-2 Proteins are embedded in the phospholipid bilayer to help move substances across cell membrane “Outside of the cell” “Inside of the cell”

Internal compartment stores cell’s DNA Section 3-3 Nucleus: Internal compartment stores cell’s DNA Nucleus controls cell’s functions Nuclear envelope is double membrane surrounding the nucleus Nuclear pores are small openings scattered over surface of nuclear envelope

Structure where proteins are made Endoplasmic Reticulum (ER): Section 3-3 Ribosome: Structure where proteins are made Endoplasmic Reticulum (ER): Extensive network of internal membranes that move proteins and other subs through cell; acts as a highway

Carry newly made proteins through cytoplasm from ER to Golgi apparatus Section 3-3 Vesicles: Carry newly made proteins through cytoplasm from ER to Golgi apparatus Golgi apparatus: Set of flattened, membrane-bound sacs that serve as packaging/distribution center of cell

Mitochondria: (aka “powerhouse”) Section 3-3 Lysosome: Sacs of enzymes that engulf/breakdown large substances into smaller ones Mitochondria: (aka “powerhouse”) Organelles that convert food energy from organic compounds to make ATP ATP: Main energy currency of cell; “spendable”

Plants have 3 structures not found in animal cells: Section 3-3 Plants have 3 structures not found in animal cells: 1. Cell Wall: support/maintain shape of cell; protects cells, connect cell to adjacent cells 2. Chloroplasts: uses light energy to make organic compds from CO2/water 3. Large Central Vacuole: stores water, nutrients, wastes

Summary of Organelles: Section 3-3 Summary of Organelles: