Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chp.6: The Cell - Coggle Diagram
Chp.6: The Cell
Microscopy
- Microscopes are used to visualize cells
- In a light microscope, visible light is passed through a specimen and then through glass lenses
- Lenses refract the light so that the image is magnified
Parameters of microscopy
- Magnification, the ratio of an objects image size to its real size
- Resolution, the measure of the clarity of the image, or the minimum distance of two distinguishable points
- Contrast, visible differences in brightness between parts of the sample
- Scanning electron microscopes (SEM's) focus a beam of electrons onto the surface of a specimen, providing images that look 3-D
- Transmission electron microscopes (TEM's) focus a beam of electrons through a specimen to study the internal structure of cells
Cell Fractionation
- Cell fractionation takes apart and separates the major organelles from one another
- Centrifuges fractionate cells into their component parts
- Biochemistry and cytology help correlate cell function with structure
-
Eukaryotic Cells
- The Nucleus contains most of the DNA in a eukaryotic cell
- Ribosomes use the information from the DNA to make proteins
The Nucleus
- The nucleus contains most of the cell's genes and is usually the most conspicuous organelle
- The nuclear envelope encloses the nucleus, separating it from the cytoplasm
- The nuclear envelope is a double membrane; each membrane consists of a lipid bilayer
- Pores, lined with a structure called a pore complex, regulate the entry and exit of molecules from the nucleus
- The nuclear side of the envelope is lined by the nuclear lamina, which is composed of proteins and maintains the shape of the nucleus
- Ther is evidence for a nuclear matrix, a framework of protein fibers throughout the interior of the nucleus
Ribosomes
- Ribosomes are complexes made of ribosomal RNA and protein
- Ribosomes build proteins in two locations: In the cytosol and on the outside of the endoplasmic reticulum or the nuclear envelope
The Endomembrane System
- The endomembrane system consists of: Nuclear envelope, Endoplasmic reticulum, Golgi apparatus, Lysosomes, Vacuoles, and Plasma membrane
- The endoplasmic reticulum accounts for more than half of the total membrane in many eukaryotic cells
- There are two distinct regions of ER: Smooth ER, which lacks ribosomes and Rough ER, whose surface is studded with ribosomes
- Smooth ER: Synthesizes lipids, Detoxifies drugs and poisons, and stores calcium ions
- Rough ER: Secrete glycoproteins, distributes transport vesicles, and is a membrane factory for the cell
- The Golgi apparatus consists of flattened membranous sacs called cisternae
- The Golgi apparatus: Modifies the products of the ER, manufactures certain macromolecules, and sorts/packages materials into transport vesicles
- A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules
- Lysosomal enzymes work best in the acidic environment inside the lysosome
- Hydrolytic enzymes and lysosomal membranes are made by rough ER and then transferred to the Golgi apparatus for further processing
- Some lysosomes probably arise by budding from the trans face of the Golgi apparatus
- Vacuoles are very large vesicles derived from the ER and Golgi apparatus
- Vacuoles perform a variety of functions in different kinds of cells
- Food vacuoles are formed by phagocytosis
- Contractile vacuoles pump water out of cells
- Central vacuoles contain a solution called sap
- These components are either continuous or connected via transfer by vesicles