Micro chapter 4

It is primarily the structure of cell walls and membranes and the absence of organelles (specialized cellular structures that have specific functions)

What distinguishes prokaryotes from eukaryotes?

Endoplasmic reticulum

- within the cytoplasm of eukaryotic cells is the _____ ______, an extensive network of flattened membranous sacs or tubules called cisternae

Spirochetes

Another group of spirals that are helical and flexible & move by means of axial filaments, which resemble flagella but are contained within a flexible external sheath are called

Golgi complex

An organelle that consists of 3 to 20 cisternae that are often curved, giving it a cup like shape - package them in secretory or storage vesicles (lysosomes)

Staphylococci

Cocci that divide and multiple planes and form grape like clusters or broad sheets are called

Streptococci

Cocci that divide and remain attached and chain like patterns are called

Sarcinae

Cocci that divide and three planes and remain attached in cubelike groups of eight are called

Tetrads

Cocci that divided into planes and remain in groups of 4 are known as

Polar

Flagella that may be at one or both poles or ends of the cell

Peritrichous

Flagella that may be distributed over the entire cell

Endosymbiotic theory Endosymbiosis

Theory explaining origin of eukaryotes from prokaryotes pioneered by Lynn Margukis - larger bacterial cells lost their cell walls & engulfed smaller bacterial cells. This relationship, in which one organism lives within another, is called ______ - some bacteria were actually mitochondria or chloroplast like

Passive process

Substances cross the membrane from an area of high concentration to an area of low concentration (move with the concentration gradient) without any expenditure of energy (ATP) by the cell

Chloroplasts

Unique organelle in algae & green plants - membrane-enclosed structure that contains both pigment chlorophyll & the enzymes required for the light-gathering phases of photosynthesis - the chlorophyll is contained in flattened membrane sacs called thylakoids; stacks of thylakoids are called grana

Axial filaments or endoflagella

spirochetes move by means of _____ _______, or ______, bundles of fibrils that arise at ends of the cell beneath an outer sheath and spiral around the cell

Eukaryotic

______ organisms include algae, Protozoa, fungi, plants & animals.

Diplococci

Cocci that remain in pairs after dividing are called

Glycocalyx

(Meaning sugar coat) is the general term used for substances that surround cells. - A viscous (sticky), gelatinous polymer that is external to the cell wall & composed of polysaccharide, polypeptide or both. - It's made inside the cell and secreted to the cell surface. - if the substance is organized and is firmly attached to the cell wall, it can be described as a capsule - if the substance is an organized and only loosely attached to the cell wall, it's described as a slime layer - also can protect a cell against dehydration, & it's viscosity may inhibit the movement of nutrients out of the cell

Extracellular polymeric substance (EPS)

- A glycocalyx that helps cells in a biofilm attached to their target environment and to each other is called - protects the cells within it, facilitates communication among them, & enables the cells to survive by attaching to various surfaces in their natural environment

Hypertonic solution (Hyper means above or more)

- A medium having a higher concentration of solute than inside the cell has - most bacterial cells placed in the solution will shrink and collapse or plasmolyze because water leaves the cells by osmosis

Isotonic solution (Iso means equal)

- A medium in which the overall concentration of solutes equals that found inside a cell. - water leaves and enters the cell at the same rate (no net change) - cell's contents are in equilibrium with the solution outside the cell wall

Mycoplasma

- Are the smallest known bacteria that can grow & reproduce outside living host cells. - B/c of their size & b/c they have no cell walls, they pass through most bacterial filters & were first mistaken for viruses - their plasma membranes are unique among bacteria in having lipids called sterols, which are thought to help protect them from lysis (rupture)

Rough ER

- Continuous with nuclear membrane & usually unfolds into a series of flattened sacs - outer surface is studded with ribosomes, site of protein synthesis - a factory for synthesizing secretory proteins & membrane molecules

Ribosomes Ribosomal RNA Prokaryotic Eukaryotic Eukaryotic

- In all eukaryotic and prokaryotic cells, function as the sites of protein synthesis - composed of two subunits each of which consists of a protein and a type of RNA called _______ RNA - _______ ribosomes differ from ______ ribosomes and the number of proteins and rRNA Molecules they contain; they are also somewhat smaller and less dense than ribosomes of ______ cells - _____ cells are called 70S ribosomes - ______ cells are called 80S ribosomes

Carboxysomes

- Inclusions that contain the enzyme ribulose 1,5-diphosphate carboxylase. - Photosynthetic bacteria use carbon dioxide as their sole source of carbon & require this enzyme for carbon dioxide fixation - CO2 fixation

Archaea

- May lack walls or may have unusual walls composed of polysaccharides & proteins but not peptidoglycan. - These walls contain a substance similar to peptidoglycan called pseudomurein (no "NAM" or D amino acids) - generally cannot be gram-stained but appear gram negative because they don't contain peptidoglycan

Hypotonic solution (Hypo means under or less)

- Outside the cell is a medium whose concentration of solutes is lower then that inside the cell - most bacteria live in these solutions & the cell wall resists further osmosis & protects cells from lysis - cells with weak cell walls (such as gram - bacteria) May burst or undergo osmotic licenses as a result of excessive water intake

Osmotic pressure

- Pressure required to prevent the movement of pure water (water with no solutes) into a solution containing some solutes - pressure needed to stop the flow of water across a selectively permeable membrane

Prokaryotic cytoplasm

- Refers to the substance of the cell inside the plasma membrane - about 80% water and contains primarily proteins (enzymes), carbohydrates, lipids, inorganic ions, and many low molecular weight compounds - inorganic ions are present in much higher concentrations in this area than and most media - is thick, aqueous, semi transparent and elastic - major structures are a nucleoid (containing DNA), particles called ribosomes, and reserve deposits called inclusions - lacks a cytoskeleton and cytoplasmic streaming

Peptidoglycan

- The bacterial cell wall is composed of a macromolecular network called ______, which is present either alone or in combination with other substances - consists of a repeating disaccharide attached by polypeptide to form a lattice that surrounds and protects the entire cell

Plasma (cytoplasmic) membrane

- Thin structure lying inside the cell wall and enclosing the cytoplasm of the cell - (prokaryotic) consist primarily of phospholipids which are the most abundant chemicals in the membrane and proteins - (eukaryotic) also contain carbohydrates and sterols such as cholesterol

Pili

- Usually longer than fimbriae & number only one or 2 per cell. - involved in motility & DNA transfer

Inclusions

- Within the cytoplasm of prokaryotic cells are several kinds of reserve deposits known as ______ - cells may accumulate certain nutrients when they're plentiful & use them when the environment is deficient - some are common to a wide variety of bacteria, whereas others are limited to a small number of species & therefore serve as a basis for identification

Fimbriae

- allow attachment - Can occur at the poles of the bacterial cell or can be distributed evenly over the entire surface of the cell. - can number anywhere from a few to several hundred per cell - have a tendency to adhere to each other and to surfaces. As a result, they are involved in forming biofilm and other aggregations on the surfaces of liquids, glass & rocks. - can also help bacteria adhere to epithelial surfaces in the body - when absent, colonization cannot happen & no disease ensues

Plasmids (prokaryotic)

- bacteria often contain small usually circular double-stranded DNA molecules called ________ - not connected to the main bacterial chromosome and they replicate independently of chromosomal DNA

L forms

- can lose their cell walls & swell into irregularly shaped cells - named for the Lister Institute, where they were discovered - they may form spontaneously or develop in response to penicillin (which inhibits cell wall formation) or lysozyme (which removes the cell wall) - can live & divide repeatedly or return to the walled state

Cell wall

- complex semi rigid structure responsible for the shape of the cell - surrounds the underlying, fragile plasma (cytoplasmic) membrane and protects it and the interior of the cell from adverse changes in the outside environment - almost all prokaryotes have them - major function is to prevent bacterial cells from rupturing when the water pressure inside the cell is greater than that outside the cell - also helps maintain the shape of a bacterium and serves as a point of anchorage for flagella - important because it contributes to the ability of some species to cause disease and is the site of action of some antibiotics - composition is used to differentiate major types of bacteria

Phospholipid molecule

- contains a polar head composed of a phosphate group and glycerol that is hydrophilic (water loving) and soluble in water and nonpolar tails, composed of fatty acids that are hydrophobic (water fearing) and insoluble in water

Smooth ER

- extends from the rough ER to form a network of membrane tubules - doesn't have ribosomes on the outer surface of its membrane - does contain unique enzymes that make it functionally more diverse than rough ER - does synthesize phospholipids, fats & steroids

Conjugation (sex) pili

- hairlike appendages used to transfer DNA to another cell (longer than fimbriae) - Some pili are used to bring bacteria together allowing the transfer of DNA from one cell to another, a process called conjugation

Gas vacuoles

- hollow cavities found in many aquatic prokaryotes, including Cyanobacteria, anoxygenic photosynthetic bacteria & halobacteria are called ___ ____ - each consists of rows of several individual gas vesicles, which are hollow cylinders covered by protein - maintain buoyancy so that the cells can remain at the depth in the water appropriate for them to receive sufficient amounts of oxygen, light & nutrients - buoyancy in aquatic prokaryotes

Plasma (cytoplasmic) membrane

- in eukaryotes, they contain carbohyrates, which serve as attachment sites for bacteria & as receptor sites that assume a role in such functions as cell-cell recognition. - also contain sterols in eukaryotes, which are complex lipids not found in prokaryotic plasma membranes

Magnetosomes

- inclusions of iron oxide surrounded by invaginations of the plasma membrane. - formed by several gram-negative bacteria & act like magnets - bacteria may use them to move downward until they reach a suitable attachment site - in vitro, they can decompose hydrogen peroxide, which forms in cells in the presence of oxygen - iron oxide destroys H2O2

Facilitated diffusion

- integral membrane proteins function as channels of carriers that facilitate (help) the movement of ions or large molecules across the plasma membrane -use of transporters

Polysaccharide granules

- typically consist of glycogen & starch, & their presence can be demonstrated when iodine is applied to the cells. - energy reserves

Metachromatic Granules collectively known as volutin

- large inclusions that take their name from the fact that they sometimes stain red with certain blue dyes such as methylene blue. - represents a reserve of inorganic phosphate that can be used in the synthesis of ATP - generally formed by cells that grow in phosphate-rich environments - found in algae, fungi, & Protozoa, as well as in bacteria - phosphate (ATP reserves)

Nucleus Nuclear envelope

- most characteristic eukaryotic organelle - usually spherical or oval, is frequently the largest structure in the cell, & contains almost all of the cell's hereditary info (DNA) - contains most of the cell's DNA, which is combined w/ several proteins including some basic proteins called histones & nonhistones -contains chromosomes - surrounded by a double membrane called _____ ______. - tiny channels in the membrane called ______ ____ allow the nucleus to communicate with the cytoplasm; they control the movement of substances between the nucleus & cytoplasm

Nucleoid (nuclear area) prokaryotic

- of a bacterial so usually contains a single long, continuous, and frequently circularly arranged the thread of double-stranded DNA called the bacterial chromosome - this is the cells genetic information which carries all the information required for the cell's structures and functions - can be spherical, elongated, or dumb-bell shaped

Lysozyme

- particularly active on the major cell wall components of most gram-positive bacteria, making them vulnerable to lysis. - catalyzes hydrolysis of bonds between the sugars in the repeating disaccharide "backbone" of peptidoglycan

Cell wall

- some contain cellulose: found in plants - chitin: found in most fungi, crustaceans and insects - Glycocalyx: A layer of material containing substantial amounts of sticky carbohydrates. Strengthens the cell surface, helps attach cells together and may contribute to cell-cell recognition - do not contain peptidoglycan (The framework of a prokaryotic cell wall)

Mitochondria

- spherical or rod-shaped organelles that appear throughout the cytoplasm of most eukaryotic cells - the number per cell varies among different types of cells - consists of a double membrane similar in structure to plasma membrane - outer membrane is smooth but inner mitochondrial is arranged in series of folds called cristae - center is a semifluid substance called the matrix - called the "powerhouses of the cell" b/c of their central role in ATP production - contain 70S ribosomes & some DNA of their own - can reproduce more or less on their own by growing & dividing in 2

Protoplast

- the cellular contents that remain surrounded by plasma membrane may remain intact if lysis doesn't occur; this wall-less cell is termed a _____. - is spherical & is still capable of carrying on metabolism

Spheroplast

- the cellular contents, plasma membrane & remaining outer wall layer are called a _____, also a spherical structure - for lysozyme to exert its effect on gram negative cells, the cells are first treated with EDTA which weakens ionic bonds in the outer membrane & thereby damages it, giving the lysozyme access to the peptidoglycan layer

Simple diffusion

-Net (overall) movement of molecules or ions from an area of high concentration to an area of low concentration. - movement continues until the molecules or ions are evenly distributed = equilibrium - cells rely on this process to transport certain molecules (oxygen & carbon dioxide) across their cell membranes

What two meanings does "bacillus" have in microbiology?

1. Bacillus refers to a bacterial shape 2. When capitalized and italicized it refers to a specific genus

Three basic parts of a flagellum

1. Filament: is constant and in diameter and contains the globular (roughly spherical) proteins flagellin arranged and several chains that intertwine and form a helix around a hollow core. And most bacteria, filaments are not covered by a membrane or sheath, as in eukaryotic cells. 2. The filament is attached to a slightly wider hook, consisting of a different protein 3. The basal body, which anchors the flagellum to the cell wall and plasma membrane

3 types of Endocytosis

1. Phagocytosis 2. Pinocytosis 3. Receptor-mediated Endocytosis

Distinguishing characteristics of eukaryotes (5)

1. Their DNA is found in the cell's nucleus, which is separated from the cytoplasm by a nuclear membrane, and the DNA is found in multiple chromosomes 2. Their DNA is consistently associated with chromosomal proteins called histones and with non-histones 3. They have a number of membrane enclosed organelles, including mitochondria, endoplasmic reticulum, Golgi complex, lysosomes, & sometimes chloroplasts. 4. Their cell walls, when present, are chemically simple. 5. Cell division usually involves mitosis, in which chromosomes replicate and an identical set is distributed into each of two nuclei.

Distinguishing characteristics of prokaryotes (5)

1. their DNA is not enclosed within a membrane and is usually a singular circularly arranged chromosome 2. Their DNA is not associated with histones; other proteins are associated with the DNA 3. They lack membrane enclosed organelles 4. Their cell walls almost always contain the complex polysaccharide peptidoglycan 5. They usually divided by binary fission. During this process The DNA is copied and the cell splits into two cells. Binary fission involves fewer structures and processes than eukaryotic cell division.

Spirochetes

A group of bacteria that have unique structure and motility

Vacuoles

A space or a cavity in the cytoplasm of a cell that's enclosed by a membrane called a tonoplast - in plants, they may occupy 5-90% of the cell volume, depending on the type of cell - derived from the Golgi complex - some serve as temporary storage organelles for substances such as proteins, sugars, organic acids & inorganic ions - others form during endocytosis to help bring food into the cell - may take up water, enabling plant cells to increase in size & also providing rigidity to leaves & stems

Gram negative

Alcohol dissolves the outer membrane of _____-____ cells & even leaves small holes in the thin peptidoglycan layer through which crystal violet-iodine diffuse - lets purple dye "out"

Germination

An endospore returns to its vegetative state by a process called _____. - is triggered by physics or chemical damage to the endospore's coat. The enzymes then break down the extra layers surrounding the endospore, waters, & metabolism resumes

Diplobacilli

Appear in pairs after division

gram positive

Application of alcohol degrades peptidoglycan of ____-____ cells to make it more impermeable to the crystal-violet iodine -purple dye stays in cell

Microtubules

Are long, hollow tubes made up of a protein called tubulin

Lipid inclusions

Are revealed by staining cells with fat-soluble dyes, such as Sudan dyes - energy reserves

Cocci

Are usually round but can be oval, elongated, or flattened on one side. When divided to reproduce, The cells can remain attached to one another.

How do bacilli divide?

Bacilli divide only across their short axis.

What do prokaryotes include?

Bacteria and Archaea

Ribosomes

Attached to the outer surface of the rough endoplasmic reticulum, which are also found free in the cytoplasm - sites of protein synthesis in the cell

Spiral bacteria

Bacteria that have one or more twists; they are never straight

Atrichous

Bacteria that lack flagella are referred to as (without projections)

Vibrios

Bacteria that look like curved rods are called

Active process

Cell must use energy (ATP) to move substances from areas of low concentration to areas of high concentration (against the concentration gradient)

Sulfur granules

Derive energy by oxidizing sulfur & sulfur-containing compounds. - energy reserves

Phagocytosis

During _____, cellular projections called pseudopods engulf particles & bring them into the cell. Used by white blood cells to destroy bacteria & foreign substances

Endocytosis

Eukaryotic cells can use a mechanism called ______ which occurs when a segment of the plasma membrane surrounds a particle or large molecule, encloses it & brings it into the cell

Lysosomes

Formed from Golgi complexes & look like membrane-enclosed spheres - have only a single membrane & lack internal structure - contain as many as 40 different kinds of powerful digestive enzymes capable of breaking down various molecules. Enzymes can digest bacteria that enter the cell - found in human white blood cells

Transport vesicle (of Golgi complex) Transfer vesicles

Fuses with a cistern of the Golgi complex, releasing proteins into the cistern. Proteins are modified & move from one cistern to another via ______ _____ that bud from the edges of the cisternae

Flagella

If the projections are few and our long in relation to the size of the cell, they are called _____ - in prokaryotes and eukaryotes

What are the possible structures external to the prokaryotic cell wall?

Glycocalyx, flagella, axial filaments, fimbriae & pili

Monotrichous

If polar, flagella may be a single flagellum at one pole

Lophotrichous

If polar, flagella may be a tuft coming from one pole

Amphitrichous

If polar, flagella may be at both poles of the cell

Cilia

If the projections are numerous and short, they are called ______ - only in eukaryotes

Flagella

Long filamentous appendages that propel bacteria that some prokaryotic cells have

Pinocytosis

In ______, the plasma membrane folds inward, bringing extracellular fluid into the cell, along with whatever substances are dissolved in the fluid

Centrosome

Located near the nucleus, consists of 2 components; the pericentriolar area & the centrioles - pericentriolar material is a region of cytosol composed of dense network of small protein fibers - protein fibers & centrioles

Single bacilli

Most bacilli appear as single rods called

Monomorphic

Most bacteria maintain a single shape which is called

Osmosis

Net movement of solvent molecules across a selectively permeable membrane from an area with a high concentration of solvent molecules to an area of low concentration of solvent molecules

Streptobacilli

Occur in chains

Peroxisomes

Organelles similar in structure to lysosomes but are smaller - form by the division of preexisting peroxisomes - contain one or more enzymes that can oxidize various organic substances - also contain enzyme catalase which decomposes H2O2

Spirilla

Other bacteria that have a helical shape, like a corkscrew, and fairly rigid bodies & move by means of a propeller like external appendages called flagella

Peptide cross-bridge

Parallel tetrapeptide side chains may be directly bonded to each other or linked by a _______ ____-____, consisting of a short chain of amino acids

Simple diffusion Facilitated diffusion Osmosis

Passive processes include _____ ______, _____ ______, & ________

Sporulation or sporogenesis

Process of endospore formation within a vegetative cell takes several hours & is known as _____ or ______ - in the first observable stage, a newly replicated bacterial chromosome & a small portion of cytoplasm are isolated by an in growth of the plasma membrane called a spore septum.

Bacterial shape bacillus

Rod-shaped (meaning little staffs)

Pleomorphic

Some bacteria can have many shapes not just one

Secretory vesicles (of Golgi complex)

Some of the processed proteins leave the cisternae in ____ _____, which detach from the cistern & deliver the proteins to the plasma membrane, where they're discharged by endocytosis

Storage vesicles (of Golgi complex)

Some processed proteins leave the cisternae in vesicles that are called _____ ______. - major is a lysozyme

Bacterial shape coccus

Spherical (meaning berries)

Bacterial shape spiral

Spiral

Coccobacilli

Still other bacilli are oval and looks so much like cocci that they are called

Organelles

Structures with specific shapes & specialized functions & are characteristic of eukaryotic cells. Include the nucleus, endoplasmic reticulum, Golgi complex, lysosomes, vacuoles, mitochondria, chloroplasts, peroxisomes, & centrosomes

Receptor-mediated Endocytosis

Substances bind to receptors in the membrane. When binding occurs, the membrane folds inward. - one of the ways viruses can enter animal cells

Cytoplasm

The ______ of eukaryotic cells encompasses the substance inside the plasma membrane & outside the nucleus . - the substance in which various components are found

Eukaryotic cell Prokaryotic cell

The _______ ____ is typically larger & structurally more complex than the _______ _____

Motility

The ability of an organism to move by itself

Active transport

The cell uses energy in the form of ATP to move substances across the plasma membrane

Gram-negative

The cell walls of ___-_____ bacteria consist of one of a very few layers of peptidoglycan and an outer membrane. - does not contain teichoic acids - contain only a small amount of peptidoglycan, they are more susceptible to mechanical breakage

Endospores

When essential nutrients are depleted, certain gram positive bacteria (Clostridium & Bacillus) form specialized "resting cells" called _____ - highly durable dehydrated cells with thick walls & additional layers - formed internal to the bacterial cell membrane - when released into the environment, they can survive extreme heat, lack of water, & exposure to many toxic chemicals & radiation

Axial filaments

Which are anchored at one end of the spirochete, have a similar structure to that of flagella. The rotation of the filaments produces a movement of the outer sheath that propels the spirochetes in a spiral motion

Protoplasts & Spheroplasts Osmotic lysis

_____ & ______ burst in pure water or very dilute salt or sugar solutions b/c the water molecules from the surrounding fluid rapidly move into & enlarge the cell, which has a much lower internal concentration of water. This rupturing, called _____ ____.

Gram-positive

_____-_____ bacteria, the cell wall consists of many layers of peptidoglycan, forming a thick, rigid structure. - contain teichoic acids, which consist primarily of an alcohol & phosphate

Penicillin Lysis

______ interferes with the final linkage of the peptidoglycan rows by peptide cross bridges. As a result the cell wall is greatly weakened & the cell undergoes _____, destruction caused by rupture of the plasma membrane and the loss of cytoplasm