Chapter 3- Cellular level of Organization Flashcards
What are the basic concepts of the cell theory?
- cells are the building blocks of all plants and animals
- all cells come from the division of preexisting cells
- cells are the smallest units that perform all vital physiological functions
- each cell maintains homeostasis at cellular level
Extracellular Fluid (ECF)
- watery medium surrounding cells
* called INTERSTITIAL FLUID (ICF), meaning something standing between, in most tissues
Plasma Membrane
separates cell contents from extracellular fluid
Cytoplasm
- material between cell membrane and nuclear membrane
- contains 2 subdivisions:
1. Cytosol 2. Organelles
Nonmembranous organelles
*not completely enclosed by membranes
*in direct contact with cytosol
EX: cytoskeleton, microvilli, centrioles, cilia, ribosomes
Membranous organelles
*enclosed in a phospholipid membrane
*isolated from cytosol
EX: mitochondria, nucleus, ER, Golgi apparatus, lysosomes
Microvilli
STRUCTURE: membrane extensions containing microfilaments
FUNCTION: increase surface area for absorption
EX: digestive systems
Cytoskeleton
STRUCTURE: fine protein filaments or tubes
Centrosome: organizing center containing pair of centrioles
FUNCTION:
*strength and support
*intracellular movement of structures and materials
4 Functions of the plasma membrane
- Physical isolation: Barrier btwn ISF & cytoplasm
- Regulation of Exchange w/ the Environment: ions and nutrients enter
- Sensitivity to environment: *extracellular fluid composition, chemical signals
- Structural support: Anchors cells and tissues
Membrane Lipids: Phospholipid bilayer
Barrier to ions and water-soluble compounds
- provides some control as to what enters or leaves the cell
- **Hydrophilic heads, ***Hydrophobic tails
Hydrophilic Heads
Toward watery environment, both sides
Hydrophobic Fatty-Acid Tails
Inside membrane
6 Types of Membrane Proteins
- Anchoring proteins (stabilizers)
- attach to inside/outside structures - Recognition proteins (identifiers)
- label cells as normal or abnormal - Enzymes
- catalyze reactions - Receptor proteins
- bind and respond to ligands (ions, hormones) - Carrier proteins
- transport specific solutes through membrane - Channels
- regulate water flow (aquaporins) and solutes through membrane
Glycocalyx
“sugar coat”
Integral proteins
within the membrane
Peripheral proteins
bound to inner or outer surface of the membrane
Organelles
structures with specific proteins
Microfilaments
- assist with cell movement and are made of a protein called actin.
- Actin works with another protein called myosin to produce muscle movements, cell division, and cytoplasmic streaming.
- keep organelles in place within the cell.
Microtubules
- larger, and help with cell functions such as mitosis and various cell transport functions.
- Composed of subunits of protein tubulin
- Stiff and resist bending forces.
Centrioles
Control movement of DNA strands during cell division
Cilia
Beat rhythmically to move fluids/secretions across the cell.
Ribosomes
Build polypeptides in protein synthesis
-2 types:
Free rib. in cytoplasm: manufacture proteins for cell
Fixed rib. attached to ER: manufacture proteins for secretion
Endoplasmic Reticulum
- Smooth ER: lacks ribosomes, tubular cisternae
2. Rough ER: has attached (fixed ribosomes), modification of newly synthesized proteins, export to golgi apparatus