Microbiology Ch1 Flashcards
Define a microbe ?
Microorganisms: are life forms too small to be seen by the human eye, also includes viruses.
- Bacteria, archaea, and single cell eukaryotes
- Oldest forms of life
- Live in microbial communities
Functions: Make you sick, help digest food,
protect against infections, and maintain reproductive health
Describe structures and activities of microbial cells, and explain how the lack of a membrane boundary around the DNA of prokaryotes relates to the processes of transcription and translation?
Structure (all cells have the following)
1) PLASMA MEMBRANE: barrier that separates the inside of the cell from the outside environment
2) CYTOPLASM: aqueous mixture of macromolecules small organics, ions, and ribosomes in cell
3) GENOME: DNA: hereditary material
4) RIBOSOMES: Protein Synthesis structure
Activities
1) GROWTH is competitive
2) METABOLIZING nutrients to survive and reproduce
3) DNA replication
4) CENTRAL DOGMA (evolution): translation and translation
Lack of Membrane Boundary
- Transcription and translation can occur simultaneously, they don’t need to transport around organelles
Explain how cell size affects surface area-to-volume ratio, and relate this to the generally small size of microbes ?
MORPHOLOGY: cell size and shape ( 1 micrometer)
Therefore, as a cell increases in size, its surface area-to-volume ratio decreases, when a cell is small it has a higher surface area to volume ratio.
Advantages to microbes
- SURFACE AREA: More surface area relative to cell volume than larger cells (higher surface/ volume ratio)
- NUTRIENT/WASTE EXCHANGE is increased
Explain how cell size might relate to structural or functional differences among bacteria?
- Accessing Nutrients
- Moving from one location to another
- Escaping predators
Know and be able to recognize different morphologies and arrangements?
MORPHOLOGIES (Individual Shape)
- Coccus: Spherical or Ovoid
- Rod /bacillus: cylindrical
- Spirillum: flexible spiral
ARRANGEMENTS (Group Shape)
- Strepto : Chain of Cocci and Bacillus
- Straphylo : Clusters
- Single cell, diploid, tetrad
- Diplococcus: pair of two cocci
List the three domains and describe some key aspects of each?
BACTERIA: ( prokaryotes, many are known to cause diseases (pathogenic)) (circular DNA)(single cell)
ARCHAEA: (prokaryotes, extreme environments, not pathogenic, five well-described phyla) (Circular DNA)(single cell)
EUKARYA: (Plants, animals, fungi, Protozoa, algae, first unicellular, at least six kingdoms, vary dramatically in size, shape, and physiology)(Linear DNA)(Eukaryotic)
Describe viruses and explain why they aren’t included in the three-domain systems?
VIRUSES (not part of the three-domain system, because They require the machinery of the host cell to reproduce. They do not possess any similarity with the other cells. They do not have any organelles and fail to perform metabolic activities)
-Only replicate with host
-Do not carry out metabolism, no growth requirements
-Have small genomes of DNA or RNA
-Classified based on structure, genome composition and host specificity
Outline the impact that microorganisms have on society and the environment?
- AGRICULTURE : nitrogen-fixing bacteria, cellulose-degrading microbes, gut microbiome, fermentation in foods
- GLOBAL BIOMASS: creates the most global biomass in nitrogen and phosphorus
- INDUSTRY: biotechnology, biofuel production, wastewater treatment, bioremediation
How they are harmful - DISEASES (pathogens) , food spoilage, Biofilm production
- alternative fuel production, gene therapy, biomeediation, agriculture
Know the following terms: aerobic, anaerobic, oxic, anoxic, oxygenic, and anoxygenic
AEROBIC: With (involving) oxygen
ANAEROBIC: without oxygen
OXIC: environment w/ Oxygen
ANOXIC : environment w/out oxygen
OXYGENIC: produces O2
ANOXYGENIC: does not produce O2
Describe spontaneous generation and the experiment that led to the defeat of this idea?
-SPONTANEOUS GENERATION: life arises spontaneously from nonliving material
-LOUIS PASTEUR: Used a swan-necked Pasteur flask to disprove the theory of spontaneous generation, germ particles in the air is what caused the spoilage not the air itself
Define a pure culture?
PURE CULTURE: Cells from only a single type of microorganisms
-a culture in which only one strain of bacteria is present.
Highlight the scientific contributions of the following individuals: Carolus Linnaeus, Louis Pasteur, Robert Koch, Frederick Griffths
-LOUIS PASTEUR (1822-1895) - discovered alcoholic fermentation, disproved spontaneous generation
-ROBERT KOCH (1843-1910) - Koch’s Postulates (specific microbes cause specific diseases), germ theory of infectious diseases, developed solid media for obtaining pure cultures
-CAROLUS LINNAEUS: established the system of scientific nomenclature
-FEDERICK GRIFFITHS: conducted transformation experiments, transformation is a from of horizontal gene transfer (HGT), DNA acts as a carrier for genetic information
Scientific nomenclature: be able to determine morphology, arrangement, etc from a microbe’s name ?
rRNA gene sequences is ideal for Phylogenetic studies because, present in all cells, functionally constant, highly conserved sequences, of adequate length, and structure changes very little
Three-domain classification:
-They are identified by the sequences of nucleotides in the cell’s ribosomal RNAs (rRNA), as well as the cell’s membrane lipid structure and its sensitivity to antibiotics.
-Discovered that rRNA from methanogens is distinct from bacteria and Eukarya, named the new group Archaea
-Root is LUCA
-Bacteria to Archaea to Eukarya
