Microbiology-Chapter 4: Characteristics of Prokaryotic and Eukaryotic Cells

2 Structures in eukaryotic organisms

Mitochondria and chloroplasts

Eukaryotic Structures

Nucleus (with DNA inside), rough endoplasmic reticulum with ribosomes inside, a smooth endoplasmic reticulum, mitochondrion (the powerhouse of the cell that produces ATP/energy), chloroplasts in plants cells used for photosynthesis, a plasma membrane, centrioles, a Golgi Complex, and microfilaments.

Eukaryotic cell plasma membrane

Protects and contains eukaryotic cells who do not have cell walls. This allows entry and exit from the cell (by water or more).

Bacillus shape

Rod-shaped

Coccus shape

Spherical

Organelles

The internal membrane-enclosed structure found in eukaryotic cells.

Bacteria

When spelled with a capital B, it is the name of one of the three domains; all members are bacterial. Bacteria consist of all prokaryotic organisms, except for Archaea.

Three ways eukaryotic cells can move

1. Eukaryotic flagellum: Eukaryotic flagellum are made of microtubules which make them bigger. They move in a whiplike motion (rather than circular like bacteria). 2. Eukaryotic cilia: Helps bacteria to propel themselves around. 3. Eukaryotic pseudopodia: (false feet) Amoeba create extensions of cytoplasm that is used to create movement by using projections.

Nucleoid

(Also known as nuclear region) Central location of DNA, RNA, and some proteins in bacteria. It does not contain a true nucleus.

Structure of Bacteria

(What could possibly be in, but not all have) Chromosome, pilus (fimbria), ribosomes, inclusions, flagellum, plasmid, cytoplasm, cell membrane, cell wall, capsule or slime layer.

Vacuole

A membrane bound structure that stores materials such as food or gas in the cytoplasm of eukaryotic cells.

Domain

A new taxonomic category above the kingdom level, consisting of Archaea, Bacteria, and Eukarya.

Chemotaxis

A nonrandom movement of an organism toward or away from a chemical.

Vibrio shape

Intermediate between rod-shaped and bacillus (Ex. Cholera...not a common bacterial shape)

Acid-fast bacteria

Lipid layer, peptidoglycan, and a cell membrane. Sometimes shows as gram positive on a stain, but it is not.

Spirochete

Long and spiral-shaped (ex. Syphilis)

Cell wall functions of prokaryotic organisms

Made of rigid structures that maintain the cell's shape. It also prevents the cell from bursting in case of cell swelling (when the cell membrane pushes against the cell wall).

Biofilms

Many different types of bacteria living together, that act differently when together rather than if they were existing separately.

Ribosomes

Site for protein synthesis consisting of RNA and protein, located in the cytoplasm.

Capsules and slime mold

A capsule is usually around the cell wall. It is used to protect some organisms. It can also help them to evade the immune system of their host. Immune cells can sometimes not beat bacteria with capsules because it makes them stronger. Slime mold helps with attachment purposes. This will cause bacteria to cement itself to certain places like teeth.

Eukaryotic Cells

A cell that has a distinct cell nucleus and other membrane bound structures. The nucleus consists of the cell's DNA.

Inclusion bodies

A granule or vesicle found in the cytoplasm of a bacterial cell.

Lysozyme

A small, membrane-bound organelle in animal cells than contains digestive enzymes.

Endotoxin (lipopolysaccharide)

A toxin incorporated in Gram-negative bacterial cell walls and released when the bacterium dies.

Gram negative bacterial cell wall

Also has peptidoglycan, but not as much as the gram-positive cell wall. Gram negative cell walls also have an outer membrane which is a part of the cell wall. It forms a lipid bilayer with lipopolysaccharide (made of a lipid and a sugar--called Lipid A) on the outer membrane. It is harder to get dye to stick because the cell wall/membrane is not as thick. Killing this bacteria will break down the outer membrane into lipid A and a polysaccharide. Not enough lipid A can cause a drop in blood pressure that is deadly. Bacteriocides should not be used because it can cause lipid A to decrease which can kill a patient. Gram negative contains more periplasmic space. (Porin in the cell wall) (Protein and lipopolysaccharides in the outer membrane).

Conjugation pilus

Also known as a sex pilus. It is a long spike that reaches out and attaches itself to other organisms. It spreads its DNA through the pilus to the other organism. At this point, it's not reproducing but sharing the DNA. This can share genes that make antibiotic resistance possible.

Attachment pilus

Also known as fimbria. Are small structures used to help an organism attach.

Plasmid

Chromosome outside of chromosome area that contains DNA. These will sometimes pass through a conjugation pilus to create antibiotic resistance.

Teichoic acid

Contained in the gram-positive bacterial cell wall, and consists of glycerol, phosphates, and the sugar alcohol ribitol. Occurs in polymers up to 30 units long. These polymers extend beyond the rest of the cell wall, even beyond the capsule in encapsulated bacteria. Although it's exact function is unclear, teichoic acid furnishes attachment sites for bacteriophages (viruses that infect bacteria) and probably serves as a passageway for movement of ions into and out of the cell.

Tetrad arrangement

Divides into four plains

Sarcinae arrangement

Divides into three plains

Diplo arrangement

Divides into two plains

Gram-positive bacteria cell wall

Has a lipid bilayer cell membrane. Contains cell wall associated proteins, teichoic acid, peptidoglycan, porin, and lipoteichoic acid. The cell wall mainly consists of peptidoglycan. Peptidoglycan helps stains to stick. There is almost no periplasmic space in the gram-positive bacterial cell wall.

Features of all cells

Have a plasma membrane, cytoplasm (the fluid filled matrix of the cell), and DNA.

Endospores

Not all bacteria have endospores. The Shaeffer-Fulton Spore Stain is used to check for endospores. Endospores are contained in a bacteria in a vegetative state (growing, dividing, etc.). Endospores contain a core, cortex, and spore coat. Endospores bring bacteria into a state where it isn't dead, but also isn't dividing due to high temperatures, lack of nutrients, etc. Bacteria makes endospores in unfavorable conditions. It is difficult to kill bacteria with endospores because they can become dormant, then start dividing again.

Archaea

One of the three domains of living things; all members are bacterial organisms lacking peptidoglycan in their cell walls and differing from eubacteria in many ways.

Binary fission

Process in which a bacterial cell duplicates its components and divides into two cells. This is a bacterium's way of reproduction to produce more bacterial cells.

Prokaryotic Cells

Prokaryote (means before the nucleus) Has a nucleiod region, but no nucleus. Do not have membrane bound organelles. Contain plasmids, flagellum, inclusions, and ribosomes (which is the only membrane bound organelle). All bacteria in the kingdom Monera (Prokaryotae) are prokaryotes.

Rod-shaped arrangement

Rod-shaped bacteria divide into one plain of chains or rows.

Size and shape of bacteria

Smallest of all organisms, large surface to volume area.

Flagella

Some bacteria have flagella, but not all. It is used for locomotion. Some have one flagella. Some have flagella on either end. Some have flagella all over.

Axial filament

Some bacteria use axial filaments as a means for locomotion. It is a spindle that goes through the bacteria in a corkscrew fashion to help the organism move.

Coccobacillus shape

Spherical and rod shaped intermediate

Pilus

Spikes on a cell that allow for attachment purposes.

Spirillum

Spiral-shaped

Spirochete arrangement

Spirochetes are usually arranged individually

Endosymbiosis

Symbiosis means living together. Some symbiosis are mutualistic, commensalistic, and parasitic. In endosymbiosis, organisms benefitted each other so much, that certain parts became part of the cell. An example would be mitochondria and chloroplasts. It is believed that chloroplasts used to be bacteria because they have their own DNA like bacteria. They can divide on their own without the cell dividing. They are the same size and structure as bacteria. They have their own ribosomes, which are different from regular cells, to carry out protein synthesis. This mimics bacterial functions. Mitochondria create ATP for the cell (energy).

Glycocalyx

Term used to refer to all substances containing polysaccharide external to the cell wall. (capsule and/or slime layer)

Conjugation

The transfer of genetic information from one bacterial cell to another by means of conjugation pili. The exchange of information between two ciliates (protists), or two green algae.

Staphylo arrangement

Variable plains that form a cluster of bacteria. (Staphylococcus aureus/ MRSA)

Strepto arrangement

means change; Divides in one plain; Usually occurs in a chain. (Streptococcus: Spherical and divides in one plain, sometimes becomes diplococcus which means pairs. Usually occurs in a chain (strepto) which forms streptococci.