Chap 3-Cells And Tissues Flashcards
Nucleus
Gene containing control center that houses DNA
Directs all cellular activity
Plasma membrane
Defines the limits of the cell
Acts as a selectively permeable membrane that regulates the entry and exit of the cell materials
Cytoplasm
Site of most cellular activities
Contains organelles and inclusions
Nuclear Envelope (Nuclear Membrane)
Defines the limits of the nucleus
Acts as a selectively permeable membrane that regulates the entry and exit of substances
Nucleolus
Site where ribosomes are assembled prior to migration into the cytoplasm
Chromatin
Contains genetic material (DNA)
Forms the chromosomes during mitosis
Lipid molecules (phospholipids)
Provide the medium in which protein molecules float
Form the basic fabric of the membrane
Relatively impermeable to most water-soluble molecules
Cholesterol Molecules
Have a stabilizing effect and help keep the membrane fluid
Protein Molecules
Responsible for most of the specialized functions of the membrane
Act as enzymes
Serve as receptors or binding sites for hormones or other chemical messengers
Act as carriers that bind to substances and move them through the cell membrane
Form pores through which water and small molecules can move
Carbohydrate Molecules
Add an identification tag to mark protein molecules
Makes the cell membrane a fuzzy, sticky sugar-rich area
Glycoprotein Molecule
Determine blood type
Act as receptors that certain bacteria, viruses or their toxins can bind to
Play a role in cell-to-cell interactions
Cytosol
Semitransparent fluid which is largely water, containing dissolved nutrients and a variety of other solutes
Organelles
Literally the “little organs”, specialized cellular compartments, within the cytosol
Inclusions
Chemical substances dispersed in the cytoplasm that may or may not be present, depending on specific cell type
Most are stored nutrients or cell products
Centrosome
Composed of 2 rod-shaped bodies that lie at right angles to each other
Internally made up of fine microtubing
Directs formation of the mitotic spindle during cell division
Cilia
Whip-like cellular extensions
Move substances along cell surface
Flagella
Projections that are substantially longer than cilia
Propel the cell itself; found in sperm as a single propulsive flagellum
Lysosomes
Membranous sacs
Contain enzymes that digest worn cellular parts or substances that enter cells