Ch. 4 Study Guide Flashcards
List the two characteristics typically used to describe prokaryotic cells
- Lack nucleus
- Lack organelles
What are the characteristics we ascribe to living cells?
Reproduction
Heredity
Growth
Responsiveness
Metabolism
Transport
How can a bacteria exhibit reproduction?
Conjugation
How can a bacteria exhibit heredity?
DNA replication
How can a bacteria exhibit growth?
Increasing in population size or enlargement of individual size via maturation
How can a bacteria exhibit responsiveness?
Reacting to stimuli such as light, chemicals, or other cells.
-Chemotaxis
How can a bacteria exhibit metabolism?
Enzymes create cell components or produce energy
How can a bacteria exhibit transport?
Carrying substances in/out of cell, secreting substances, excreting waste, relies on cell membrane
What are the two major types of prokaryotic cells?
Bacteria
Archaea
Describe the coccus shape
Spherical ball-shaped
Describe the bacillus shape
cylindrical, rod-like
Describe the spirilla shape
Rigid spiral shape
External flagella
Describe the vibrio shape
A gently curved rod
Describe the spirochete shape
A coiled, loose spiral with endoflagella, flexes as it moves
Describe pleomorphism
Normal variability of cell shapes in a single species
Describe the coccobacillus shape
Short and plump, en elongated coccus
What is an arrangement?
A bacteria’s style of grouping
Describe a diplo arrangement
pairs of 2
Describe a strepto arrangement
a chain
Describe a staphylo arrangement
irregular clusters
Describe a sarcinae arrangement
A cubical packet or 8, 16, or more
Describe a tetrad arrangement
Group of 4
Describe a palisades arrangement
Rows of a fence post
What is the size difference between a typical bacterial cell and a typical plant/animal cell?
Skin cell: 30 micrometers
Bacteria: much smallet
What is the primary factor that determines the size and shape of a bacterial cell?
Cell wall
What is the surface area to volume ratio?
The smaller the cell, the bigger the SA/V ratio
Compare the S/V ratio between a coccus and bacillus shaped bacteria
Coccus will have a higher S/V ratio
What are the major types of lipids typically found in bacterial membranes?
Phospholipids: bilayer
Lipoproteins
Define selective permeability
Allowing certain substances through
Define passive diffusion.
Does is require energy?
Provide an example.
The substance is propelled down its concentration gradient. No energy is required.
Osmosis
Define facilitated diffusion.
Does it require energy?
Provide an example.
Specialized carrier proteins move a substance from high to low concentration.
No energy is required.
Glycerol uniporter in E. coli
Define active transport.
Does it require energy?
Provide an example.
Substance transport (up or down a gradient) that requires a carrier protein and energy.
Acquires energy from ATP.
Carrier-mediated active transport.
What is peptidoglycan?
Describe the basic structure.
How do they connect?
Network of polysaccharide chains. Forms a latticework.
Cross-linked by short peptides.
Compare/contrast G-positive cell walls and G-negative cell walls.
G-positive:
-thick peptidoglycan cell wall
-cell membrane
G-Negative:
-Outer membrane of peptidoglycan, with lipopolysaccharides and lipoproteins
-Thinner cell wall of peptidoglycan
-cell membrane
What are the three basic parts of lipopolysaccharides?
- Lipid molecules
- Polysaccharides
- G-negative lipopolysaccharides work as endotoxins (lipid component)
Describe a capsule, it’s composition, and function
Loose, gel-like covering or slime.
Made of simple polysaccharides.
Protection and Virulence.
Describe a slime layer, its composition, and function
Loose glycocalyx.
Simple polysaccharides.
Hydration, nutrient retention, and adhesion
Describe fimbriae, their composition, and functions
Bristle-like fibers.
Mostly protein.
Adhesion, biofilm formation, aids in invasion.
Describe flagella, their composition, and functions
Long projections for cell motility
Describe pili, their composition, and functions
Appendages of pilin (protein) used for DNA transfer between cells: Conjugation
Do bacteria have cytoskeletons?
Yes: made of Actin
What are two differences between axial filaments and flagella
Axial Filaments: endoflagella in the periplasmic space of spirochetes, aka Periplasmic Flagella
Flagella: external, not endoflagella, not in spirochetes
Define monotrichous flagella
a cell with a single flagella on one end
Define lophotrichous
bacteria with a tuft of flagella on one or both ends
Define peritrichous
Bacteria with flagella dispersed all over the cell
Define amphitrichous
bacteria with a single flagellum or a tuft of flagella on opposite ends
What is a polar flagellar arrangement?
Flagella at one or both ends of cell
How do flagellar swimming motility and spirochete flagellar motility differ?
Flagellar swimming involves runs and tumbles (smooth linear counterclockwise movement vs. reversal via clockwise movement)
Spirochete endoflagella contract and twist/flex the cell to move
Why is bacterial chemotaxis referred to as a “biased random walk” ?
The runs and tumbles caused by flagellar reversal
How does an endospore’s basic structure/unique molecules contribute to its resistance to environmental stress?
Dipicolinic acid and calcium concentrations provide an endospore’s heat resistance by dehydrating the cell.
Heat requires a certain amount of water to destroy proteins and bacteria
Why are bacterial endospores of particular concern to the food industry?
They can inhabit soil and dust.
They resist ordinary cleaning methods such as boiling water, soaps, etc.
Require pressurized steam at 120 degrees C for 20-30 mins to safely can food.
What are the three purposes of taxonomic systems?
Identification
Nomenclature
Classification
What is the value/practical application of each of the 3 objectives of a taxonomic system?
Identification: define systematic and specific criteria to determine an organism’s identity
Nomenclature: naming system that supports communication and reflects their classification
Classification: group related organisms that reflect and describe evolutionary relationships
