Cells ch3

• Membranous (surrounded by a cell membrane):
• -mitochondria
• -peroxisomes
• -lysosomes
• -endoplasmic reticulum
• -golgi apparatus

• Nonmembranous (not surrounded by membrane):
• -cytoskeletan
• -centrioles
• - ribosomes

• rod-like, double-membrane structure w/shelflike cristae (invaginations)
• provide most of cells ATP via aerobic cellular respiration
• contain their own DNA and RNA

• interconnected tubes and parallel membranes enclosing cisternae
• continuous with nuclear membrane
• 2 varieties: Rough ER, Smooth ER

located b/w plasma membrane and nucleus

-Cytosol: water w/solutes (protein, salts, sugars, etc)

-Cytoplasmic organelles: metabolic machinery of a cell

- Inclusions: granules of glycogen or pigments, lipid droplets, vacuoles, and crystals

• granules containing protein and rRNA (ribosomal RNA)
• ***site of protein synthesis***
• Free ribosomes synthesize soluble proteins
• membrane-bound ribosomes, on rough ER, synthesize proteins to be incorporated into membranes or exported from teh cell

• external surface studded w/ribosomes
• manufactures all secreted proteins
• synthesizes membrane integral proteins and phopholipids

tubules arranged in a looping network

• enzyme (integral protein) functions:
• 1) in the liver -- lipid and cholesterol metabolism, breakdown of glycogen, and, along with kidneys, detoxification of drugs, pesticides, and carcinogens
• 2) synthesis of steroid-based hormones
• 3) in intestinal cells - absorption, synthesis, and transport of fats
• 4) in skeletal and cardiac muscle - storage and release of calcium

stacked and flattened membranes and associated vesicles close to the nucleus

• modifies, concentrates, and packages proteins and lipids:
• - transport vessels from ER fuse w/convex cis face of Golgi apparatus
• - proteins then pass through golgi to trans face
• - secretory vesicles leave trans face of golgi stack and move to designated parts of cell

• spherical membranous bags containing digestive enzymes such as acid hydrolases
• digest ingested bacteria, viruses, and toxins
• degrade nonfunctional organelles
• break down and release glycogen
• break down bone to release Ca2+
• destroy cells in injured or non-useful tissue (autolysis)
• "garbage cans of cells"

• overall function =
• produce, store, and export biological molecules
• degrade potentially harmful substances

• membraneous sacs containing powerful oxidases and catalases
• detoxify harmful or toxic substances
• neutralize dangerous free radicals (highly reactive chemicals w/unpaired electrons)

elaborate series of rods throughout cytosol

-Microfilaments (actin subunits, spherical like pearls on a string, 7nm diameter)

-intermediate filaments (fibrous protein, resembles a twisted cord, 10nm diameter)

-Microtubules (tubulin subunits, resembles hollow tube, 25 nm diameter)

• "cell center"
• generates microtubules, organizes mitotic spindle
• contains centrioles: small tubes formed by microtubules

• cilia and flagella
• -whiplike, motile extensions on surfaces of certain cells
• - contain microtubules and motor molecules
• - cilia move substances across cell surfaces
• - longer flagella propel whole cells (tail of sperm)

• Microvilli
• -fingerlike extensions of plasma membrane
• -increase surface area for absorption
• -core of actin filaments for stiffening

• cylindrical structures make of tubulin proteins
• support the cell and give it shape
• involved in intracellular and cellular movements
• form centrioles and cilia and flagella, if present

• fine filaments composed of the protein actin
• involved in muscle contraction and other types of intracellular movement
• help form the cell's cytoskeletan

• protein fibers; composition varies
• the stable cytoskeletan elements
• resist mechanical forces acting on the cell

• paired cylindrical bodies, each composed of 9 triplets of microtubules
• organize a microtubule network during mitosis (cell division) to form the spindle and asters
• form the bases of cilia and flagella

• short cell-surface projections; each cilium composed of 9 pairs of microtubules surrounding a central pair
• coordinated movement creates a unidirectional current that propels substances across cell surfaces

• like a cilium, but longer; only example in human is the sperm tail
• propels the cell

• largest organelle
• surrounded by the nuclear envelope
• contains fluid nucleoplasm, nucleoli, and chromatin
• control center of cell
• responsible for transmitting genetic info and providing instructions for protein synthesis

• membrane made of a double layer of lipids (phospholipids, cholesterol, and so on) within which proteins are embedded
• proteins may extend entirely through lipid bilayer or protrude on only one face
• most externally facing proteins and some lipids have attached sugar groups
• serves as external cell barrier and acts in transport of substances into or out of cell
• maintains resting potential that is essential for functioning of excitable cells
• externally facing proteins act as receptors (for hormones, neurotransmitters...), transport proteins, and in cell-to-cell recognition

• double-membrane structure pierced by pores
• outer membrane continuos w/the endoplasmic reticulum
• separates the nucleoplasm from the cytoplasm and regulates passage of substances to and from nucleus

dense spherical (non-membrane bounded) bodies, composed of ribosomal RNA and proteins

• granular, threadlike material composed of DNA and histone proteins
• DNA constitutes the genes
• DNA (30%), histone proteins (60%), RNA (10%)
• arranged in fundamental units called nucleosomes
• condense into barlike bodies called chromosomes when the cell starts to divide