Ch.2 Cells

Ecosystem ---- Community-----population----organism----organ system---organ--- tissue----cell-----molecule----atom

• their ability to move
• their internal organizations (prokaryotic vs eukaryotic)
• their metabolic activities

All organisms are composed of cells and cell products

Prokaryotic cells and eukaryotic cells

• Prokaryotic cells only domains in bacteria and archaea
• Eukaryotic cells have Plant and Animal Kingdoms, including the fungi

They consist of a single enclosed compartment that is surrounded by a plasma membrane, lacks a defined nucleus, and has a relatively simple organization.  DNA is located in a NUCLEOID region

• They contain a defined membrane-bound nucleus that is absent in prokaryotes.  The nucleus segregates the cellular DNA from the rest of the cell
• NOTE: EUKARYOTIC ORGANISMS CAN BE EITHER UNICELLULAR OR MULTICELLULAR

• 1) the plasma membrane
• 2) the cytoplasm
• 3) the nucleus

The thin/flexible layer that separates the intracellular (inside) and extracellular (outside) compartments

a type of molecule called phospholipids from a two-layered membrane (the phospholipid bilayer).

• 1) 2fatty acids chain (tail= non-polar or hydrophobic = H2O- fearing)
• 2) A phosphate group (head= polar or hydrophilic = H2O- loving)

proteins

• "Fluid": Molecules can move freely within the membrane
• "Mosaic": A diversity of proteins exists within the membrane

• Integral membrane proteins are transmembrane; they span entire width of membrane and contain both hydrophilic and hydrophobic regions
• Periphreal Membrane Proteins do not span the entire membrane; are loosely associated with other proteins or lipid molecules

• 1) attachment to cytoskeleton and extracellular matrix
• 2) cell signaling
• 3) enzymatic activity
• 4) transport
• 5) Intercellular joining
• 6) cell-cell recognition

• -they allow some substances to cross more easily than others (i.e size or charge)
• -they block passage of some substances altogether

Diffusion and osimosis

Movement of molecules from High to Low; as well as a passive transport; no energy is needed

The transport of some substances by specific transport proteins that act as selective corridors

• The passive transport of WATER across a selectively permeable membrane
• High [H2O] to Low [H2O]

• Isotonic solution (equal concentration of ions in solution and cell)
• Hypertonic solution (higher concentration of ions in solution than in cell)
• Hypotonic  solution (lower concentration of ions in solution than in cell)

The control of water balance in animals

• Mechanism by which particles enter cells
• 1)Phagocytosis
• 2) Pinocytosis
• 3) receptor-mediated endocytosis

A cell engulfs a particle and packages it within a food vacuole (ex. most WBCs)

"cellular drinking" Absorption of extracellular fluids

the binding of external molecules to membrane proteins.  Upon membrane proteins binding to certain molecules, the membrane invaginates and forms a coated pit which then pinch off to become a coated vesicle

mechanism that moves substances out of the cell; vesicles migrates to the plasma membrane; proteins from the vesicles (v-SNAREs) bind with membrane proteins (t-SNAREs); lipid layers from both membranes fuse, and the vesicle releases its contents to the outside of the cell

• Part of the cell that lies internal to the plasma membrane and external to the nucleus
• 1) cytosol
• 2) organelles
• 3) inclusions

• jelly-like, fluid-containing substance within the cell
• -consists of water, ions, and enzymes
• -Makes up half of the volume of the cytoplasm
• -Fluid in which other cytoplasmic elements are suspended

mitchondria, ribosomes, ROugh ER and smooth er, golgi appartus, cytoskeleton, lysosomes, cytoskeleton, centrioles, peroxisomes

• THey are constructed of proteins and ribosomal RNA; they are the site of protein synthesis
• -composed of two subunits (60S and 40S) that fit together to form a functional ribosome

• 1) Free ribosomes = float in cytosol; make soluble proteins (function in cytosol)
• 2) Attached ribosomes = attached to rough ER and make membrane proteins or exported proteins

Translation

The process of ribsomes

"network within the cytoplasm", an extensive system of membrane-walled envelopes and tubes.

Ribosomes stud the external surfaces; makes all membrane proteins and membrane

• Consists of tubules in a branching network; no ribosomes are attached ; NO PROTEINS ARE MADE
• but it does store Ca2+ and makes enzymes for lipid metabolism, as well as makes steroids and lipids

• Its basically the "packing& shipping center".
• -Works in partnership with the ER; sorts products of rough ER at the cis end and sends them to proper destination from the trans end

• It is the "power plant" of the cell
• -Generates most of the cell's energy (ATP) via cellular respiration
• -Enclosed by a double membrane; the inner membrane folds in forming shelf-like cristae
• -contains own DNA (maternal DNA)

• Spherical membranous bags containing digestive enzymes, "demolition crew" that break down macromolecules
• NOTE: secretory lysosomes are found in white blood cells, immune cells, and melanocytes

They digest ingested bacteria, viruses, and toxins; degrage nonfunctional organelles; breakdown glycogen and release thyroid hormone; breakdown non-useful tissue (webbing fingers and toes during fetal development); breakdown bone to release calcium

• They are ubiquitous organelles in eukaryotes that participate in the metabolism of fatty acids and other metabolites.
• -Detoxify harmful or toxic substances; Break down long chains of fatty acids (numerous in the liver and kidneys); neutralize dangerous free radicals  and break down posions.

oxidases and catalases

highly reactive chemicals with unpaired electrons

• An infrastructure of the cell consisting of a network of RODS/FIBERS that run throughout the cytosol.
• -Provides mechanical support to the cell and maintain its shape and provides machinery for various cellular movements

Microtubules, intermediate filaments, microfilaments

• Microtubules  are cylindrical strucutres made of proteins called TUBULIN, and the THICKEST
• -radiate from CENTROSOME = cell center, which are organelles that attach to and move along microtubules, which constantly assemble and dissemble.
• Intermediate filaments - protein fibers; most stable and permanent; help cells resist pulling forces = prodvie tensile strength; play a role in linking cells together

microfilaments (actin filaments)- filaments of contractile protein actin that interact with myosin to create cell division, perfrom endo- and exocytosis, and play a role on pseudopod extension and retraction; organelles also attach to and move along actin filaments, which constantly assemble and dissemble; thinnest