Chapter 4 Flashcards
Cell theory
The scientific theory that the cell is the basic unit of life, of which all living things are composed, and that all cells are derived from pre-existing cells.
Plasma membrane
The selectively permeable surface membrane that encloses the cell contents and threw it all materials entering or leaving the cell must pass.
Organelle
What are the specialized structures within the cell, such as a mitochondria, goldy complex, ribosomes or contractile vacuole; many organelles are membrane enclosed.
Ratio of surface area to volume
Critical since everything that enters or leaves the cell must pass the membrane, some variations and cell shape increase the ratio of surface area to volume. Example: microvilli
Microvilli
Minute projections of the plasma membrane that increase the surface area of a cell; found mainly in cells concerned with absorption or secretion, such as those learning the intestine or the kidney tubules.
Light microscope
Princess of a tube with glass lenses at each end in which visible light passes through stained or living cells. Lenses refract light in magnify the image.
Magnification
Ratio of the size of the image seen with the microscope to actual size of the object. Light microscope magnify an object no more than 2000 X.
Resolution
Minimum distance between two points I wish they can both be seen separately.
Electron microscope
Used to study the ultrastructure of cells. The electron beam consist of energize electrons, focused by electromagnets.
Ultrastructure
Define detail of a cell, generally only observable by use of an electron microscope.
Transmission electron microscope (TEM)
2-D image, like x-ray.
Scanning electron microscope (SEM)
3-D image, only surface.
Prokaryotic cells
Bacteria and Archaea. Smaller, simpler. most do not have organelles. found in bacteria and Archaea.
Eukaryotic cells
Protist, fungi, plants, animals. Larger, more complex. Have organelles. 
Nucleoid
Region of a prokaryotic cell that contains DNA; not enclosed by a membrane.
Cell wall
The structure outside the plasma membrane of certain cells; may contain cellulose (plant cells), chitin (most fungal cells), peptidoglycan and/or lipopolysaccharide (most bacterial cells), or other material.
Flagella
A long, whip like structure extending from certain cells and used in locomotion.
Membrane-enclosed organelle
Present in eukaryotic cells. Include nucleus and cytoplasm. Allow for different cell activities to go on simultaneously. Allows cells to store energy. Chemical reactions in cells are carried out by enzymes that are bound to membranes.
Nucleus
Contains DNA. Control center of the cell.
Cytoplasm
The plasma membrane and cell contents with the exception of the nucleus.
Nuclear envelope
Double membrane that separates nuclear contents from the cytoplasm.
Nuclear pore
 Regulate passage of materials between nucleoplasm and cytoplasm.
Chromatin
The complex of DNA and proteins that makes up eukaryotic chromosomes.
Chromosome
Structure in the cell nucleus That consist of chromatin and contain the genes.
Nucleolus
Specialized structure in the cell nucleus formed from regions of several chromosomes; site of assembly of the ribosomal subunits RNA (rRNA).
RNA (mRNA)
RNA that specifies the amino acid sequence of a protein; transcribed from DNA.
The Endomembrane system
The group of membrane structures in eukaryotic cells that interact through direct connection by vesicles; includes the endoplasmic reticulum, outer membrane of the nuclear envelope, Golgi complex, lysosomes, and a plasma membrane; also called internal membrane system.
Ribosome
Organelle that is part of the protein synthesis machinery of both prokaryotic and eukaryotic cells; consist of a larger and smaller subunits each composed of ribosomal RNA (rRNA) and ribosomal proteins.