Chapter 4: Characteristics Of Prokaryotic And Eukaryotic Cells Flashcards
Bacteria size
0.5-2um
Bacteria characteristics
- high surface to volume ratio
- receive nutrients faster&easier
- diffuse waste products easier
Bacteria shapes
- coccus: sphere
- coccobacillus: oval
- bacillus: rod shape
- vibrio: comma
- spirillum: wavy
- spirochete: corkscrew
Binary fission
Cell replicates DNA, duplicates contents, pinched in half, creates two identical daughter cells
- sometimes after BF, cells remain close to each other and form arrangements
Diplo
Two side by side
- Division in one plane
Strepto
Many side by side
- division in one plane
Tetrad
Division in 2 planes
Sarcinae
Division in 3 planes
Staphylo
Division in random planes
Bacillus
Only divide in one plane
- diplo or strepto
Pleomorphism
Within a colony of bacteria, there may be many different sizes/shapes of the bacteria
- range of size and morphology in a culture due to waste, nutrient, space, etc.
Cell wall
Found just outside cell membrane in most bacteria, gives cells their shape
Components of a cell wall
- peptidoglycan
- teichoic acid
- outer membrane
Peptidoglycan
Most important part, adds rigidity
- function: shape/structure, prevents hyper osmotic cells from overfilling and bursting
- penicillin prevents peptidoglycan cross-linking
- sugar backbone: alternating n-acetyl muramic acid and n acetyl glucosamine
- cross linked to a tetrapeptide
Teichoic acid
Consists of glycerol, phosphates, and sugar alcohol ribitol
- polymers
- unclear function, possible attachment site for bacteriophages or passageway for ion movement into and out of cell
Outer membrane
- Found in g- bacteria
- Contain lipopolysaccharides
Gran positive cell walls
- contain teichoic acid throughout
- very susceptible to penicillin
Gram negative cell walls
- Have outer membrane with LPS
- penicillin isn’t as effective
- periplasmic space
Lipopolysaccharides
lps layer has Lipid A endotoxin is released when cell wall breaks down
- can cause inflammation, shock, drop in blood pressure
Periplasmic space
Gap between cell membrane and cell wall
- easily observed in gram negative
Acid fast cell walls
Have waxy lipid layer with mycolic acid, a thick wall, and a thin layer of peptidoglycan
Cell wall deficient bacteria
Have cell membrane that contains stabilizing sterols
- ex: mycoplasma (normally don’t have a cell wall)
- L form bacteria: normally have a cell wall but revert to a form that doesn’t (L-form)
- Lyme disease, Crohn’s disease (v hard to treat)
Plasma membrane
Lets things in and out of the cell (selectively permeable)
- assists in DNA replication
- helps with protein secretion
- role in cellular respiration
- helps make cell wall
Peripheral proteins
Found outside cell membrane and function as receptors and enzymes
Integral proteins
Go through membrane to provide transport
Fluid mosaic model
Components aren’t chemically bound to each other, but are drawn to each other through hydrophobic/hydrophilic needs & can move around
Cytoplasm
Water and solutes, ions, lipids, proteins
- anything the cell needs to build things
Ribosomes
Where proteins are made
Nuclear region (nucleoid)
Bacteria have one circular chromosome located here
Plasmid
Small circular piece of DNA outside the chromosome (extrachromosomal) that contains nonessential but possible very helpful information (antibiotic resistance etc)
Endospores
Core of DNA is surrounded by cortex (double membrane with peptidoglycan in between) and spore coat (outside) for protection
- have calcium and dipocolinic acid to give spore resistance (its thought)
- bacillus anthrax, clostridium tetanus, botulism
Flagella
Function is to provide motility
- made of flagellular protein
- bacteria have filament, hook, and rings
Monotrichous
One flagella at one end
Amphitrichous
One flagella at each end
Lophotrichous
Tuft of flagella at one or more ends
Peritrichous
Covered in flagella all around
Atrichous
No flagella
Gram negative bacteria with flagella traits
- four rings, first two span wall, next two span membrane
- has basal body
Gram positive bacteria with flagella traits
- two rings, one in membrane, other between membrane and wall
- no nasal body
Flagella movement
- counterclockwise spin: bacteria move in a straight line
- clockwise spin: cause tumble motion
Chemotaxis
Movement in response to a chemical
- positive: toward attraction (nutrients)
- negative: away from repellent (waste, toxins)
Phototaxis
Movement in response to light
Pili
Short, hollow projections for attachment
Fimbrae
Attachment to other cells or faces
- related to pathogenicity (gonnorhea can attach to uterine wall and cause infection)
Conjugation pili (f pili)
Allow bacterial cells to exchange DNA (usually plasmids) between cells
Glycocalyx
Carbohydrate later outside cell
- capsule: thick and protective, hides bacteria from immune system
- slime layer: thin, sticky layer that allows the cell to adhere to other cell surfaces and prevents drying out
- can help bacteria attach to teeth and catch food
