What does the cell theory tell us?
- A cell is the basic unit of life.
- All living things are made up of cells.
- New cells arise from pre-existing cells.
Compound light microscope
– Lower magnification
– Uses light beams to view images – Can view live specimens
Transmission electron microscope
– 2-D image
– Uses electrons to view internal structure – High magnification, no live specimens
Scanning electron microscope
– 3-D image
– Uses electrons to view surface structures – High magnification, no live specimens
Prokaryotic cells
– Lack a nucleus
– Represented by bacteria and archaea
Eukaryotic cells
– Have a nucleus that houses DNA – Many membrane-bound organelles
plasma membrane
surrounds and delineates the cell
cytoplasm
the semi-fluid substance inside the cell that contains organelles
What are some characteristics of the plasma membrane? 5
- It is a phospholipid bilayer.
- It is embedded with proteins that move in space. • It contains cholesterol for support.
- It contains carbohydrates on proteins and lipids.
- It is selectively permeable.
How do things move across the plasma membrane? 5
- Diffusion
- Osmosis
- Facilitated transport
- Active transport
- Endocytosis and exocytosis
Diffusion
random movement of molecules from a higher concentration to a lower concentration.
Osmosis
is the diffusion of water molecules.
Isotonic
solutions have equal amounts of solute inside and outside the cell and thus do not affect the cell.
Hypotonic
solutions have less solute than the inside of the cell and lead to bursting.
Hypertonic
solutions have more solute than the inside
of the cell and lead to shriveling.
H2
Facilitated transport
is the transport of molecules across the plasma membrane from higher concentration to lower concentration via a protein carrier.
Active transport
is the movement of molecules from a lower to higher concentration using ATP as energy; it requires a protein carrier.
What is the structure and function of the nucleus? 3
Bound by a porous nuclear envelope
•
• Houses chromatin: DNA with associated proteins
• Nucleolus contains ribosomal RNA (rRNA)
What is the structure and function of ribosomes? 3
- Organelles made of rRNA and protein
- Found bound to the endoplasmic reticulum and free floating in the cytoplasm
- Sites of protein synthesis
What is the endomembrane system? 2
- It is a series of membranes in which molecules are transported in the cell.
- It consists of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles.
Rough endoplasmic reticulum
studded with ribosomes used to make proteins
Smooth endoplasmic reticulum
lacks ribosomes but aids in making carbohydrates and lipids
Golgi apparatus
flattened stacks that process, package, and deliver proteins and lipids from the ER
Lysosomes
membranous vesicles made by the Golgi that contain digestive enzymes
