Magnetobacterium
microorganisms with an unusual feature: cellular structures called magnetosomes. Prefer areas with little or no oxygen.
Biologists agree that all living things share at least four processes of life
growth, reproduction, responsiveness, and metabolism
Growth
living things can grow; that is, they can increase in size
reproduction
Reproduction means that they increase in number, producing more organisms organized like themselves. Reproduction may be accomplished asexually (alone) or sexually with gametes (sex cells).
Responsiveness
All living things respond to their environment. They have the ability to change themselves in reaction to changing conditions around or within them. Many organisms also have the ability to move toward or away from environmental stimuli�a response called t
Metabolism
Metabolism can be defined as the ability of organisms to take in nutrients from outside themselves and use the nutrients in a series of controlled chemical reactions to provide the energy and structures needed to grow, reproduce, and be responsive. Metabo
Theodor Schwann and Matthias Schneiden
developed the theory that all living things are composed of cells. Cells are living entities, surrounded by a membrane, that are capable of growing, reproducing, responding, and metabolizing.
Prokaryotes
They can make proteins simultaneously to reading their genetic code because a typical prokaryote does not have a membrane surrounding its genetic material (DNA)
Eukaryotes
Have a membrane called a nuclear envelope surrounding their DNA, forming a nucleus, which sets eukaryotes in domain Eukarya.
Organelles
Specialized structures that act like tiny organs to carry on the various functions of the cell.
Glycocalyx
May be composed of polysaccharides, polypeptides, or both
Capsule
When the glycocalyx units of organic chemicals firmly attached to the cell's surface
Flagella
Are long structures that extend beyond the surface of a cell and it's glycocalyx and propel the cell through its environment. (Thin filament, a hook, basal body)
peritrichous
flagella that cover the surface of the cell
spirochetes
spiral-shaped bacteria that have flagella at both ends that spiral tightly around the cell instead of protruding the surrounding medium
endoflagella
form an axial filament that wraps around the cell between its cytoplasmic membrane and an outer membrane.
taxis
movement in response to a stimulus
fimbriae
many bacteria have rodlike proteinaceous extensions. these sticky, bristle like projections adhere to one another and to substances in the environment.
Neisseria gonorrhoeae
causes gonorrhea
biofilms
slimy masses of microbes adhering to a substrate by means of fimbriae and gly cocalyces
pilus
special kind of fimbria . Cells use pili to transfer DNA from one cell to the other via a process termed conjugation.
peptidoglycan
What bacterial cell walls are composed of. (a complex of polysaccharide) is composed of two types of regularly alternating sugar molecules called NAG and NAM, which are structurally similar to glucose. Chains of NAG and NAM are attached to other chains by
Gram-positive
bacterial cell walls have a relatively thick layer of peptidoglycan that also contains unique chemicals called teichoic acids.Some teichoic acids are covalently linked to lipids, forming lipoteichoic acids that anchor the peptidoglycan to the cytoplasmic
Gram-negative
cell walls have only a thin layer of peptidoglycan, but outside this layer is another, outer bilayer membrane composed of two different layers or leaflets. The inner leaflet of the outer membrane is composed of phospholipidsand proteins, but the outer lea
Lipid A
the lipid portion of LPS
Endotoxin
The erroneous idea that lipid A is inside Gram-negative cells. A dead cell releases lipid A when the outer membrane disintegrates, and lipid A may trigger fever, vasodilation, inflammation, shock, and blood clotting in humans.
periplasmic space
Between the cytoplasmic membrane and the outer membrane of Gram-negative bacteria. This includes peptidoglycan and periplasm. Periplasm contains water, nutrients, and substances secreted by the cell, such as digestive enzymes and proteins involved in spec
cytoplasmic membrane
Beneath the glycocalyx and the cell wall. cell membrane or plasma membrane. Composed of phospholipids and associated proteins.
Phospholipid bilayer
A phospholipid molecule is bipolar; that is, the two ends of the molecule are different. The phosphate-containing heads of each phospholipid molecule are hydrophilic; that is, they are attracted to water at the two surfaces of the membrane. The hydrocarbo
fluid mosaic model
mosaic indicates that the membrane proteins are arranged in a way that resembles the tiles in a mosaic, and fluid indicates that the proteins and lipids are free to flow laterally within a membrane.
selectively permeable
It allows some substance to cross it while preventing the crossing of others. Ex a phospholipid bilayer, Large molecules cannot cross through it; ions and molecules with an electrical charge are repelled by it; and hydrophilic substances cannot easily cro
concentration gradient
The difference in concentration of a chemical on the two sides of a membrane
Passive processes
the electrochemical gradient provides the source of energy; the cell does not expend its energy reserve. Passive processes include diffusion, facilitated diffusion, and osmosis.
Diffusion
is the net movement of a chemical down its concentration gradient that is, from an area of higher concentration to an area of lower concentration. It requires no energy out put by the cell, a common feature of all passive processes. For example, oxygen, c
Facilitated Diffusion
Some of these proteins act as channels or carriers to allow certain molecules to diffuse down their concentration gradients into or out of the cell.The cell expends no energy in facilitated diffusion; electrochemical gradients provide all of the energy ne
Osmosis
Water molecules cross from the side of the membrane that contains a higher concentration of water (lower concentration of solute) to the side that contains a lower concentration of water (higher concentration of solute). In osmosis, water moves across the
Isotonic
When solutions on either side of selectively permeable membrane have the same concentration of dilutes, neither side of selectively permeable membrane will experience a net loss or gain of water
Hypertonic
When the concentrations of solutions are unequal, the solution with the higher concentration of solutes is said to be hypertonic. A cell placed in a hypertonic solution will therefore lose water and shrivel (crenation)
Hypotonic
The solution with a lower concentration of solutes is hypotonic in comparison. water will diffuse into a cell placed in a hypotonic solution because the cell has a higher solutes to water concentration.
Active transport
utilizes transmembrane permease proteins; however, the functioning of this transports proteins requires the cell to expend ATP to transport molecules across the membrane.
Uniport
If only one substance is transported at a time
Antiports
Transports two chemicals but in opposite directions
Symports
two substances move together in the same direction across the membrane by means of a single carrier protein.
Coupled transport
For example, H+ moving into a cell down its electrochemical gradient by facilitated diffusion provides energy to carry glucose into the cell, against the glucose gradient. The two processes are linked by a symport. However, cellular energy may still be ut
Group translocation
the substance being actively transported across the membrane is chemically changed during transport. As glucose is transported across the bacterial cell membrane, it is phosphorylated; that is, a phosphate group is added to the glucose. The glucose is cha
Cytoplasm
Cytoplasm is semitransparent, fluid, elastic, and aqueous. It is composed of cytosol, inclusions, ribosomes,and, in many cells, a cytoskeleton. Some bacterial cells produce internal, resistant, dormant forms called endospores.
Cytosol
The liquid portion of the cytoplasm. It is mostly water, but it also contains dissolved and suspended substances, including ions, carbohydrates, proteins (mostly enzymes), lipids, and wastes. The cytosol of prokaryotes also contains the cell's DNA in a re
Inclusions
are often found within bacterial cytosol. Inclusions may include reserve deposits of lipids, starch, or compounds containing nitrogen, phosphate, or sulfur. The presence of specific inclusions is diagnostic for several pathogenic bacteria
polyhydroxybutyrate
polymer of glucose molecules
electrical gradient
Substances that have concentration gradients across cell membranes are electrically charged chemicals. For example, a greater concentration of negatively charged proteins exists inside the membrane, and positively charged sodium ions are more concentrated
gas vesicles
aquatic cyanobacteria contains inclusions that store gases in
protein sacs.
endospores
Which are important for several reasons, including their durability and potential pathogenicity. Endospores are not reproductive structures. Instead, endospores constitute a defensive strategy against hostile or unfavorable conditions. The process of endo
Non membranous organelles in bacteria
ribosome and cytoplasm
Ribosomes
are the sites of protein synthesis in cells. Bacterial
cells have thousands of ribosomes in their cytoplasm, which gives cytoplasm a grainy appearance
Ribosomal RNA
All ribosomes are composed of two subunits, each of
which is composed of polypeptides and molecules of RNA called ribosomal RNA (rRNA)
Cytoskeleton
Which is composed of three or four types of protein fibers. Bacterial cytoskeletons play a variety of roles in the cell. For example, one type of cytoskeleton fiber wraps around the equator of a cell and constricts, dividing the cell into two. Another typ
glycocalyx
That is anchored to its cytoplasmic membrane via covalent bonds to membrane proteins and lipids. The functions of eukaryotic glycocalyces, which are not as structurally organized as prokaryotic capsules, include helping to anchor animal cells to each othe
Cellulose
The walls of plant cells are composed of, a polysaccharide that is familiar to you as paper and dietary fiber.
membrane rafts
Eukaryotic cells use membrane rafts to localize cellular processes, including signaling the inside of the cell, protein sorting, and some kinds of cell movement. Some viruses, including those of AIDS, Ebola, measles, and flu, use membrane rafts to enter h
endocytosis
Which involves physical manipulation of the cytoplasmic membrane around the cytoskeleton, Endocytosis
occurs when the membrane distends to form pseudopods
(false feet) that surround a substance, bringing it
into the cell
Phagocytosis
Eats if a solid is
brought into the cell
pinocytosis
Drinks if only liquid is brought into the cell.
food vesicle
Nutrients brought into a cell by endocytosis
amoeboid action
The cell extends a pseudopod, and then the cytoplasm
streams into it
Exocytosis
Another solely eukaryotic process, is the reverse of endocytosis in that it enables substances to be exported from the cell.
Differences between Eukaryotes and Prokaryotes flagella
Eukaryotic flagella are within the cytoplasmic membrane; they are internal structures that push the cytoplasmic membrane out around them. Their basal bodies are in the cytoplasm. Second, the shaft of a eukaryotic flagellum is composed of molecules of a gl
Cilia
Which extend the surface of the cell and are shorter and more numerous than flagella. No prokaryotic cells have cilia. Like flagella, cilia are composed primarily of tubular microtubules, which are arranged in a "9 + 2" arrangement of pairs in their shaft
Eukaryotic Ribosomes
Within the cytosol of eukaryotic cells are protein-synthesizing
ribosomes that are larger than prokaryotic ribosomes; instead of 70S ribosomes, eukaryotic ribosomes are 80S and are composed of 60S and 40S subunits. In addition to the 80S ribosomes found w
Eukaryotic Cytoskeleton
Composed of an internal scaffolding of fibers and tubules. The eukaryotic cytoskeleton acts to anchor organelles and functions in cytoplasmic streaming and in movement of organelles within the cytosol. Cytoskeletons in some cells enable the cell to contra
centrioles
which lie at right angles to each other near the nucleus
centrosome
in a region of the cytoplasm, plants, algae, and most fungi (and prokaryotes) lack centrioles
but usually have a region of cytoplasm corresponding
to a centrosome. Centrioles are composed of nine triplets of tubular microtubules arranged in a way that res
Nucleus
is usually spherical to ovoid and is often the largest organelle in a cell. Some cells have a single nucleus; others are multinucleate, while still others lose their nuclei. This is often referred to as "the control center of the cell" because it contains
nucleoplasm
the semiliquid matrix of the nucleus
nucleoli
which are specialized regions where RNA is synthesized.
chromatin
which is a threadlike mass of DNA associated with special proteins called histones that play a role in packaging nuclear DNA. During mitosis (nuclear division), chromatin becomes visible as chromosomes
nuclear envelope
Surrounding the nucleus is a double membrane, which is composed of two phospholipid bilayers, for a total of four phospholipid layers.
nuclear pores
Within the The nuclear envelope that function to control the import and export of substances through the envelope.
endoplasmic reticulum (ER)
Continuous with the outer membrane of the nuclear envelope is a netlike arrangement of flattened hollow tubules. The ER traverses the cytoplasm of eukaryotic cells. Endoplasmic reticulum functions as a transport system and is found in two forms: smooth en
Smooth endoplasmic reticulum
plays a role in lipid syn- thesis as well as transport
Rough endoplasmic reticulum
Is rough because ribosomes adhere to its outer surface. Proteins produced by ribosomes on the RER are inserted into the lumen (central canal) of the RER and transported throughout the cell.
Golgi body
is like the "shipping department" of a cell: it receives, processes, and packages large molecules for export from the cell. Not all eukaryotic cells contain this.
secretory vesicles
The Golgi body packages secretions in sacs, which then fuse with the cytoplasmic membrane before dumping their contents outside the cell via exocytosis.
Vesicle and Vacuole
Are general terms for such sacs. Large vacuoles are found in plant and algal cells that store starch, lipids, and other substances in the center of the cell. Often a central vacuole is so large that the rest of the cytoplasm is pressed against the cell wa
Lysosomes
Which are found in animal cells, contain catabolic enzymes that damage the cell if they are released from their packaging into the cytosol. The enzymes are used during the self-destruction of old, damaged, and diseased cells and
to digest nutrients that h
Peroxisomes
Are vesicles derived from ER. They contain oxidase and catalase, which are enzymes that degrade poisonous metabolic wastes (such as free radicals and hydrogen peroxide) resulting from some oxygen-dependent reactions. Peroxisomes are found in all types of
Mitochondria
Are spherical to elongated structures found in most eukaryotic cells. Like nuclei, they have two membranes, each composed of a phospholipid bilayer. The inner membrane forms numerous folds called cristae that increase the inner membrane's surface area. Th
Chloroplasts
Are light-harvesting structures found in photosynthetic eukaryotes. Chloroplasts have two phospholipid bilayer membranes and DNA. The
pigments of chloroplasts gather light energy to produce ATP
and form sugar from carbon dioxide. Numerous membranous
sacs
endosymbiotic theory
The presence of circular DNA, 70S ribosomes, and two bilipid membranes in these semiautonomous organelles, This theory suggests that eukaryotes formed from the union of small aerobic17 prokaryotes with larger anaerobic prokaryotes. The smaller prokaryotes