Intro to Micro
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What are 3 roles of the clinical microbiologist?
- Recover organisms from patient specimens
- Isolate and identify organisms
- Interpret antimicrobial susceptibilities
Give examples of structural arrangements for prokaryotic cells.
- single or individual
- pairs - diplo
- chains - strep
- clusters - staphylo
- tetrads - group of 4 cells
- Sarcinae - group of 8 cells
single molecule of DNA
peptidoglycan in cell wall
DNA discrete packages (chromosomes)
no peptidoglycan in cell wall
What are the four main functions of the bacteria cell wall?
- Maintains cell shape
- Protects cell from adverse conditions
- Protects cell from osmotic lysis
- Provides anchorage for flagella
Give three reasons why the bacterial cell wall is clinicaly important.
- It's ability to cause disease
- Site of action of some antibiotics
- Chemical composition helps in bacterial identification
What are three things that make up the bacterial cell wall?
What key items make up the Gram Positive cell wall?
- Many layers of peptidoglycan (thick and rigid) 20 layers
- Teichoic acid
What is are the functions of teichoic acid?
- Bind and regulate the movement of positive ions
- prevents cell lysis during growth
What are the two items that a gram negative cell wall is composed of?
- Outer membrane
- Thin layer of peptidoglycan in periplasm
What is the gram negative cell wall outermembrane composed of?
- Porin proteins
What are two types of lipopolysaccharides that make up the gram negative cell wall?
What are 4 features of a glycocalyx?
- Viscous gelatinous consistence (sticky)
- Made of polsaccharide or polypeptide
- Made inside and excreted outside the CW
Name the two types of glycocalyx.
What are 4 functions of the glycocalyx?
- Protects organism from phagocytosis
- allows adherence to surfaces
- may be used as nutrient by some bacteria
- protects against dehydration
What is flagella?
Long filamentous appendages providing motility on their own.
Name the four types of flagellar arrangements.
- Monotrichous - single, polar flagellum
- Amphitrichous - tuft at each end
- Lophotrichous - 2 or more flagella at one pole
- Peritrichous - around entire cell
What is the purpose of axial filaments, and how do they work?
- Bundles of fibrin arising at the ends of the cell beneath the outer sheat
- Wrap around the whole cell
- rotation of outer sheath propels the cell in spiral motion
What are cells that have axial filaments called?
What is fimbria composed of and what is it's overall function?
- Fimbriae is composed of hairlike appendages made of pilin(protein).
- Fimbriae's overall function is attachment (adherence to surfaces)
What is the function of pilus?
Used to join bacterial cells to transfer DNA
What are two features of O polysaccharide?
- Is antigenic (A substance that when introduced into the body stimulates the production of an antibody)
- Basis for serotyping
What are two features of Lipid A?
Releases endotoxins that cause fever and shock.
What are traits of an acid fast cell wall?
- Gram positive cell wall
- Waxy layer which is more resistant to antibiotics and is composed of glycolipids and fatty acids
Identify the cell structure:
Made up of phospholipid bilayer with proteins
What are the two main functions of the plasma membrane?
- Selective barrier
- Metabolic functions (enzymes)
- *nutrient breakdown
- *synthesis of ATP
- *photosynthesis (in plant cell)
What are 3 agents that affect the plasma membrane?
What is the cytoplasm and what is it composed of?
- Substance inside the plasma membrane
- Houses the organelles
- Composed of 80% water with proteins, CHO, lipids etc.
What is number 2 pointing at:
No need for survival
Provide advantages such as resistance to antibiotics and toxins
Name this organelle:
Site of protein synthesis
Composed of 2 subunits: 50s & 30s = 70s
Each subunit consists of rRNA and proteins
Target for certain antibiotics
When the evironmental conditions become adverse some bacteria create these.
What is the function of cilia?
Moving substances along the surface of the cell and locomotion.
What are the 3 functions of the cytoplasmic membrance? (eukaryotic)
- Provides structure
- Passive and active transport processes for the movement of substances
- Endocytosis to include phagocytosis and pincocytosis
What is the nucleus composed of?
- Nuclear envelope
- Nuclear pores
- Majority of DNA
What are the different types of bacterial stains?
- Gram stain
- Acid fast
- India Ink
- Calcofluor White
- Lactophenal Cotton blue
What are the four components that make up the gram stain?
- Crystal violet
- alcohol decolorizer
What are the 3 major needs for microbial growth?
What are the two main catergories in microbial growth?
- physical - temperature, pH
- chemical - H2O, C & N
What are the 3 primary groups based on temperature range?
- Psychophiles - cold loving - 10 – 20◦
- Mesophiles - moderate temperature loving - 20 – 40◦
- Thermophiles - heat loving - 50 – 60◦
Most bacteria grow best in what pH range?
6.5 - 7.5
What pH range do yeasts and molds prefer?
5 - 6
The force with which a solvent moves from an area of lower solute concentration to a solution of higher solute concentration
Shrinkage of the cell in hypertonic solutions.
Require high salt concentration for growth
Do not require high salt concentration but can tolerate up to 2%
What is needed for all organic compounds in cell
What are other chemical requirements needed for microbial growth aside from carbon?
Nitrogen, sulfure, phosphorus, oxygen and trace elements of iron, copper etc.
How is oxygen handled by cells?
- combining O2 with H atoms that were removed from organic compounds to form H2O
- Process yeilds energy
- Aerobic respiration
Oxygen required for growth
Can grow with or without oxygen
Unable to use molecular oxygen
Tolerate to oxygen but do not use it for growth
Decreased oxygen concentration
What are 4 examples of essential compounds the organism is not able to synthesize on it's own?
- Amino Acids
What are 3 bacterial culture requirements?
- sterile media
- proper temperature
- proper culture media to support growth of desired microorganisms
What are 4 types of media?
- Nutritive - basic components to support most bacterial growth
- Enriched - extra nutrients added that encourages growth
- Selective - inhibits growth of unwanted organisms through, salts, dyes, other chemicals
- Differential - contain compounds that allow differentiation based on metabolic differences
What are four types of bacterial division?
- Binary fission - most
- Aerial Spore
Time for a cell to divide and it's population to double
Little or no cell division
growth rate = death rate
Death is greater than growth
Death phase or Log decline
What are 4 methods for measuring microbial growth?
- Plate counts
- density measurment (turbidity)
- direct microscopic count
What is a bacterial colony?
- Population of cells arising from a single bacterium
- Visible with the naked eye on culture medium
Sum of all chemical reactions that occur in an organism.
Either require or release enegery
What are the two classes of chemical reactions?
Identify the chemical reaction class:
breakdown complex organic compounds
usually hydrolytic reactions
Identify the chemical reaction class:
Reactions that require (E) to create new bonds
Synthesis of complex organic compounds
involve dehydration rxns
generate materials for cell growth
The following steps are included in what process:
Bacteriophage attaches to bacterial cell wall
Injects DNA into cell
Synthesizes new phage DNA and protein coats
Donor cell lysed and phage released
Phage infects new bacterial cell
Donor bacterial DNA recombines with reipient
Organisms that colonize a host with causing disease
Organism that does not normally cause disease but can become pathogenic under certain conditions
A disease causing organism
Manner in which a disease develops
Ability of organism to cause disease
Degree of pathogenicity
disease constantly present in a certain population
Disease aquired by many people in a given area in a short time
Incidence of a specific disease
# of deaths associated with a specific disease
Organismm that lives at the expense of the host
Organism that benefits from the host
Organism that has a neutral affect on the host
host infected with a pathogenic organism with manifesting disease
infection aquired during hospitilization.
Aquired as an infant
competes with pathogens for nutrient space
sythesize nutrients in intestinal tract
contributes to overall health of the host
also called lithotrophs
Feed on others
Require an organic C source
also called organotrophs
Nutrients from dead organic matter.
Gene has gone through translation and produced a functional protein
Expression (expressed gene)
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