Chapter 4 Organization of the cell Flashcards
Homeostasis
The balanced internal environment of the body; the automatic tendency of an organism to maintain
such a steady state.
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 through which all materialsentering or leaving the cell must pass.
organelles
One of the specialized structures within the cell, such as the mitochondria, Golgi complex, ribosomes, or contractile vacuole; many organelles are membrane-enclosed.
microvilli
Minute projections of the plasma membrane that increase the surface area of the cell; found mainly in cells concerned with absorption or secretion, such as those lining the intestine or the kidney tubules.
light microscope (LM),
- The optical microscope, often referred to as light microscope, is a type of microscope which uses visible light and a system of lenses to magnify images of small samples.
- Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century.
Magnification
Magnification is the process of enlarging something only in appearance, not in physical size.
resolving power
The ability of a microscope to show fine detail, defi
ned as the minimum distance between two points at which they are seen as separate images; also called resolution.
electron microscope (EM),
- A microscope capable of producing high resolution, highly magnified images through the use of an electronbeam (rather than light).
transmission electron microscope (TEM)
Transmission electron microscopes (TEMs) produce images of thin sections;
scanning electron microscope (SEM)
scanning electron microscopes
(SEMs) produce images of surfaces.
Cell fractionation
The technique used to separate the components of
cells by subjecting them to centrifugal force.
ultrastructure
The fine detail of a cell, generally only observable by
use of an electron microscope.
cell homogenate
uniform in composition or character (i.e. color, shape, size, weight, height, distribution, texture, language, disease, temperature, etc.)
centrifuge
A device used to separate cells or their components by
subjecting them to centrifugal force.
differential centrifugation
is a common procedure used to separate certain organelles from whole cells for further analysis of specific parts of cells.
density gradient centrifugation
Involves the centrifugation of material through a centrifugation medium of higher or graded density. When exposed to a elevated centrifugal force, cellular components migrate through the medium and separate based on their density.
prokaryotic cells
A cell that lacks a nucleus and other membrane-enclosed organelles; includes the bacteria and archaea
(kingdoms Bacteria and Archaea)
eukaryotic cells
An organism whose cells have nuclei
and other membrane-enclosed organelles. Includes protists, fungi,
plants, and animals.
nucleoid
Region of a prokaryotic cell that contains DNA; not
enclosed by a membrane.
cell walls
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, whiplike structure extending from certain cells and used in locomotion.
- 9x2 arrangement of microtubules is characteristic of virtually all eukaryotic cilia and fl agella.
ribosomes
Organelles that are part of the protein synthesis machinery of both prokaryotic and eukaryotic cells; consist of a larger and smaller subunit, each composed of ribosomal RNA (rRNA) and ribosomal proteins.
cytoplasm
The plasma membrane and cell contents with the exception of the nucleus.
nucleoplasm
The contents of the cell nucleus.
cytosol
The fluid component of the cytoplasm in which the organelles are suspended.
endomembrane system
The group of membranous structures in eukaryotic cells that interact through direct connections by
vesicles; includes the endoplasmic reticulum, outer membrane of the nuclear envelope, Golgi complex, lysosomes, and the plasma membrane;
vesicles
Any small sac, especially a small, spherical,
membrane-enclosed compartment, within the cytoplasm.
nucleus
(2) A cell organelle in eukaryotes that contains the DNA and serves as the control center of the cell.
regeneration
The process of renewal, restoration, and growth that makes genomes, cells, organisms, and ecosystems resilient to natural fluctuations or events that cause disturbance or damage.
DNA
Double-stranded nucleic acid; contains genetic information coded in specifi c sequences of its constituent nucleotides.
nuclear envelope
The double membrane system that encloses the
cell nucleus of eukaryotes.
nuclear pores
Structures in the nuclear envelope that allow passage
of certain materials between the cell nucleus and the cytoplasm.
nuclear lamina
A dense (~30 to 100 nm thick) fibrillar network inside the nucleus of most cells.
replication
The process by which DNA is duplicated; ordinarily
a semiconservative process in which a double helix gives rise totwo double helices, each with an “old” strand and a newly synthesized strand.
genes
A segment of DNA that serves as a unit of hereditary information; includes a transcribable DNA sequence (plus associated sequences regulating its transcription) that yields a protein or RNA product with a specific function.
messenger RNA (mRNA)
RNA that specifi es the amino acid sequence
of a protein; transcribed from DNA
chromatin
The complex of DNA and protein that makes up eukaryotic chromosomes.
chromosomes
Structures in the cell nucleus that consist of chromatin
and contain the genes. The chromosomes become visible under the microscope as distinct structures during cell division.