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.
nucleoli
Specialized structure in the cell nucleus formed from regions of several chromosomes; site of assembly of the ribosomal subunits.
nucleolar organizer
a chromosomal region around which the nucleolus forms. This region is the particular part of a chromosome that is associated with a nucleolus after the nucleus divides.
endoplasmic reticulum
An interconnected network of internal membranes in eukaryotic cells enclosing a compartment, the ER lumen. Rough ER has ribosomes attached to the cytosolic surface; smooth ER, a site of lipid
biosynthesis, lacks ribosomes.
ER lumen
The lumen of the endoplasmic reticulum (ER) is the area enclosed by the endoplasmic reticulum membrane
Smooth ER
The smooth endoplasmic reticulum has functions in several metabolic processes. It synthesizes lipids, phospholipids, and steroids.
rough ER
the rough endoplasmic reticulum (often abbreviated RER or Rough ER) (also called ergastoplasm) is studded with protein-manufacturing ribosomes giving it a “rough” appearance (hence its name)
molecular chaperones
Proteins that help other proteins fold properly.
Although not dictating the folding pattern, chaperones make the process more efficient.
proteasomes
A large multiprotein structure that recognizes and
degrades protein molecules tagged with ubiquitin into short, nonfunctional peptide fragments
transport vesicle
Small cytoplasmic vesicles that move substances
from one membrane system to another.
Golgi complex
Organelle composed of stacks of fl attened,
membranous sacs. Mainly responsible for modifying,
packaging, and sorting proteins that will be secreted or targeted to other organelles of the internal membrane system or to the plasma membrane; also called Golgi body or Golgi apparatus.
cisternae
Stacks of flattened membranous sacs that
make up the Golgi complex.
Lysosomes
Intracellular organelles present in many
animal cells; contain a variety of hydrolytic enzymes.
vacuole
A fluid-filled, membrane-enclosed sac found
within the cytoplasm; may function in storage, digestion, or water elimination
tonoplast
The membrane surrounding a vacuole.
contractile vacuoles
A membrane-enclosed organelle found in certain
freshwater protists, such as Paramecium; appears to have an osmoregulatory function
Peroxisomes
In eukaryotic cells, membrane enclosed
organelles containing enzymes that produce or degrade hydrogen peroxide.
Serial endosymbiosis
The hypothesis that certain organelles such as
mitochondria and chloroplasts originated as symbiotic prokaryotes that lived inside other, free-living prokaryotic cells
mitochondria
Intracellular
organelles that are the sites of oxidative phosphorylation in eukaryotes; include an outer membrane and an inner membrane.
aerobic respiration
In aerobic respiration the terminal electron acceptor is molecular oxygen; in anaerobic respiration the terminal acceptor is an inorganic molecule other than oxygen.
intermembrane space
the region between the inner membrane and the outer membrane of a mitochondrion or a chloroplast. The main function of the intermembrane space is oxidative phosphorylation
outer mitochondrial membrane
The outer mitochondrial membrane, which encloses the entire organelle, is 60 to 75 angstroms (Å) thick. It has a protein-to-phospholipid ratio similar to that of the eukaryotic plasma membrane (about 1:1 by weight).
inner
mitochondrial membrane
is the mitochondrial membrane which separates the mitochondrial matrix from the intermembrane space.
cristae
Shelflike or fingerlike inward projections
of the inner membrane of a mitochondrion
apoptosis
Programmed cell death; apoptosis is a normal part of an organism’s development and maintenance.
necrosis
Uncontrolled cell death that causes infl ammation and damages other cells
caspases
Any of a group of proteolytic enzymes that are active in the early stages of apoptosis
free radicals
Toxic, highly reactive compounds with unpaired electrons that bond with other compounds in the cell and interfere with normal function
photosynthesis
Th e biological process that captures light energy and
transforms it into the chemical energy of organic molecules (e.g., carbohydrates), which are manufactured from carbon dioxide and water.
Chloroplasts
Membranous organelles that are the
sites of photosynthesis in eukaryotes; occur in some plant and algal cells.
chlorophyll
A group of light-trapping green pigments
found in most photosynthetic organisms
carotenoids
A group of yellow to orange plant pigments
synthesized from isoprene subunits; include carotenes and xanthophylls
stroma
A fl uid space of the chloroplast, enclosed by the chloroplast inner membrane and surrounding the thylakoids; site of the reactions of the Calvin cycle
thylakoids
An interconnected system of fl att ened,
saclike, membranous structures inside the chloroplast.
grana
A stack of thylakoids within a chloroplast.
plastids
A family of membrane-enclosed organelles
occurring in photosynthetic eukaryotic cells; include chloroplasts, chromoplasts, and amyloplasts and other leukoplasts.
proplastids
Organelles that are plastid precursors; may mature into
various specialized plastids, including chloroplasts, chromoplasts, or leukoplasts.
Chromoplasts
Pigment-containing plastids; found mainly in fl owers
and fruits.
Leukoplasts
Colorless plastids; include amyloplasts, which are used
for starch storage in cells of roots and tubers
cytoskeleton
The dynamic internal network of protein fibers that
includes microfilaments, intermediate filaments, and microtubules.
Microtubules
Hollow, cylindrical fibers consisting of tubulin protein subunits; major components of the cytoskeleton and found in mitotic spindles, cilia, flagella, centrioles, and basal bodies.
tubulin
proteins that make up microtubules in eukaryotic cells.
Microtubule-associated proteins (MAPs)
Include structural proteins that help regulate microtubule assembly and cross-link
microtubules to other cytoskeletal polymers; and motors, such as kinesin and dynein, that use ATP to produce movement.
kinesin
Is a protein belonging to a class of motor proteins found in eukaryotic cells. Kinesins move along microtubule (MT) filaments, and are powered by the hydrolysis of adenosine triphosphate (ATP) (thus kinesins are ATPases).
Dynein
a motor protein (also called molecular motor or motor molecule) in cells which converts the chemical energy contained in ATP into the mechanical energy of movement.
microtubule-organizing centers
(MTOCs)
The region of the cell from which microtubules are anchored and possibly assembled. The MTOCs of many organisms (including animals, but not fl owering
plants or most gymnosperms) contain a pair of centrioles.
centrosome
An organelle in animal cells that is the main microtubule-organizing center; typically contains a pair of centrioles and is important in cell division.
centrioles
- One of a pair of small, cylindrical organelles lying at right angles to each other near the nucleus in the cytoplasm of animal cells and certain protist and plant cells.
- They are known as 9 × 3 structures because they consist of nine sets of three att ached microtubules arranged to form a hollow cylinder
mitotic spindle
Structure consisting mainly of microtubules that
provides the framework for chromosome movement during cell
division.
cilia
One of many short, hairlike structures that project from the surface of some eukaryotic cells and are used for locomotion or movement of materials across the cell surface.
basal body
Structure involved in the organization and anchorage
of a cilium or flagellum. Structurally similar to a centriole; each is in the form of a cylinder composed of nine triplets of microtubules (9 × 3 structure).
primary cilium
primary cilia are found on nearly every cell in the body
Microfilaments
Thin fibers consisting of actin protein subunits; form
part of the cytoskeleton.
cell cortex
is a specialized layer of cytoplasmic protein on the inner face of the plasma membrane of the cell periphery. It functions as a modulator of plasma membrane behavior and cell surface properties.
myosin
A protein that together with actin is responsible
for muscle contraction.
pseudopodia
A temporary extension of an amoeboid cell that is used for feeding and locomotion.
glycocalyx
A coating on the outside of an animal
cell, formed by the polysaccharide portions of glycoproteins and glycolipids associated with the plasma membrane.
extracellular
matrix (ECM)
A network of proteins and carbohydrates
that surrounds many animal cells.
fibronectins
Glycoproteins of the extracellular matrix that bind to
integrins (receptor proteins in the plasma membrane).
Integrins
Receptor proteins that bind to specifi c proteins in the
extracellular matrix and to membrane proteins on adjacent cells; transmit signals into the cell from the extracellular matrix.
middle lamella
The layer composed of pectin polysaccharides that
serves to cement together the primary cell walls of adjacent plant cells.
