| Question | Answer |
| typical cell | -called composite cell
-varies in size, all microscopic
-varies in structure and function
-smallest living unit in body |
| structure of the cell | plasma membrane, cytoplasm, nucleus |
| plasma membrane | separates the cell from its surrounding environment and controls what enters and leaves the cell |
| cytoplasm | thick gel-like substance inside the cell composed of numerous organelles suspended in watery cytosol, each organelle performs certain functions |
| nucleus | large membranous structure near center of cell |
| fluid mosaic model | -theory explaining how cell membranes are constructed
-membranes are arranged in a sheet
-groupings of membrane molecules form rafts |
| primary structure of a cell membrane is: | -double layer of phospholipid molecules
-heads are hydrophillic (water loving)
-tails are hydrophobic
-cholesterol is scattered among bilayer |
| membrane proteins | controls what moves through membrane, some serve as a passage for Na+ ions or glucose and called transport proteins, |
| glycoprotein | carbohydrate attached to protein on a membrane, act as an identification marker |
| cytoplasm | gel-like substance of cels that include many organelles suspended in watery fluid called cytosol |
| membranous organelles | specialized sacs or canals made of cell membranes |
| nonmembranous organelles | made of microscopic filaments or other nonmembranous material |
| endoplasmic reticulum | made of canals with membranous walls and flat curving sacs arranged in parallel rows throughout cytoplasm, extend from plasma membrane to nucleus
-proteins move through canals (protein transport) |
| rough endoplasmic reticulum | -contains ribosomes
-function in protein synthesis and intracellular transportation |
| smooth endoplasmic reticulum | -no ribosomes
-synthesizes certain lipids and carbohydrates and creates membranes for use throughout cell
-removes and stores Ca++ from cell's interior |
| ribosomes | -function: synthesizes proteins
-nonmembranous structure made of large subunit and small subunit, each subunit contains rRNA
-ribosomes in the ER make proteins for export to be emedded in the plasma membrane
-free ribosomes make protein for the cell us |
| golgi apparatus | -processes protein molecules from the endoplasmic reticulum
-processed proteins leave in a vesicle to be secreted to outside of cell |
| lysosomes | -made of membranous sacs that have pinched off from golgi apparatus
-cell's digestive system --> enzymes digest defective cell parts, plasma membrane proteins, and particles that are trapped in cell |
| proteasomes | -hollow protein cylinders found in cytoplasm
-break down abnormal proteins and normal proteins no longer needed by cell |
| peroxisomes | -small membranous sacs containing enzymes tat detoxify harmful substances that enter cell
-often seen in kidney and liver cells |
| mitochondria | -microscopic sacs
-the power plant of cells, enzymes catalyze series of oxidation reactions that provide 95% of cell's energy
-had DNA --> produce own enzyme and copy itself |
| nucleus structure | spherical body in center of cell, enclosed by an envelope with many pores, nucleoplasm inside |
| nucleus function | -contains DNA -->chromatin threads in nondividing cells, chromosomes in early stages of cell division
-DNA determines both structure and function of cell and heredity |
| cytockeleton | cells framework made up of rigid rodlike pieces that provide support and allow movement and mechanisms that can move the cell or its parts |
| types of cell fibers | microfilaments, intermediate filaments, microtubules |
| microfilaments | -smallest cell fiber
-cellular muscles
-thin twisted strands of protein molecules that lie parallel to axis of cell
-cause shortening of the cell |
| intermediate filaments | -twisted protein strands slightly thicker than microfilaments
-supporting framework in many types of cells |
| microtubules | -hollow tubes
-thickest cell fibers
-move things within cell |
| centrosome | -coordinates building and breaking of microtubules in cell
-important role in cell division |
| cell extensions | cytoskeleton forms projections that extend the plasma membrane outward to form tiny fingerlike processes |
| list 3 types of cell extensions | microvilli, cilia, flagella |
| microvilli | -found in epithelial cells that line intestines
-increase surface area manyfolds |
| cilia | -found in respiratory system
-shorter and more numerous than flagella
-made of microtubules |
| flagella | -only found in human sperm
-longer than cilia |
| 3 types of direct cell connections | -desmosome (spot and belt)
-gap junction
-tight junction |
| desmosome | -fibers on outer surface of each desmosome interlock with each other, anchored internally by intermediate filaments of cytoskeleton
-spot = spot welds at various points
-belt = encircle the entire cell like a collar |
| gap junctions | -membrane channels of adjacent plasma membranes adhere to each other
-form gaps or tunnels that join the cytoplasm of two cells
-fuse two plasma membranes into a single structure
-cytoplasm is joined |
| tight junction | -occurs in cells that are joined by collars or tightly fused material
-molecules cannot permeate the craks of tight junctions
-occur in the lining of the intestines |
