Microbiology Flashcards
What are the four main groups of microorganism?
- bacteria
- viruses
- protozoa
- fungi
Which of the microorganisms are eukaryotes?
- fungi
- protozoa
Which of the microorganisms are prokaryotes?
- bacteria
What are the features of bacteria?
- prokaryotes / no true nucleus
- contain cytoplasm
- have flagellum (some)
- DNA is in circular strand
- peptidoglycan cell wall
- lack of membrane-bound organelles
What are the features of viruses?
- non-living & acellular
- protective shell called a capsid, contains genetic material
- rely on the host to reproduce
- very small, much smaller than bacteria
- viral envelope surrounds capsid
- shapes - helical, complex & polyhedron
What are the features of fungi?
- eukaryotic
- disperse by producing spores
- saprophytic
- reproduce sexually and asexually
- cell walls of chitin
- form hyphae (multicellular)
- many = mycelium
What are the features of protozoa?
- eukaryotic
- unicellular
- can reproduce asexually and sexually (think it’s mostly asexual)
- heterotrophic
- some have flagella
- can be multinucleate
What are the main differences between bacteria and viruses?
- bacteria are larger
- bacteria are prokaryotic cells, viruses are acellular
- bacteria have a cell wall made of peptidoglycan or liposaccharide, viruses have a capsid
- bacteria have ribosomes, viruses do not
- bacteria reproduce asexually, viruses require a host cell
What are the similarities between bacteria and viruses?
- do not have a nucleus
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Label the bacterial cell
What is the structure of the bacterial cell wall?
- contains peptidoglycan - made from polysaccharides cross-linked with unusual peptides
- can be gram positive or gram negative
What is the function of the bacterial cell wall?
- great mechanical strength
- responsible for strength, rigidity, shape
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What is the structure of the bacterial plasma membrane?
- phospholipid
- phosphate heads
- fatty acid chains
What is the function of the bacterial plasma membrane?
- selectively permeable
- barrier
- protective
- controls metabolism of the cell
What is the structure of the bacterial flagella?
- long & thin
- made of protein
- attached to the cell through the cell wall & the membrane
- could have one or many
What is the function of the bacterial flagella?
- movement
What is the structure of the bacterial capsule?
- capsule is located outside the cell wall
- usually consists of polysaccharides
What is the function of the bacterial capsule?
- provide strength
- protects against the body’s defences
- increases resistance to disinfectants and antibiotics
What is the structure of the bacterial pili?
- thin rigid fiber
- made of protein
- protrudes from the bacterial cell surface
- smaller than flagella
- densely packed
What is the function of the bacterial pili?
- responsible for adhesion
- allows bacteria to stick together to form clumps
- stick to mucous membranes
- allows to attach to human cells to spread disease
What is the function of the bacterial cytoplasm?
- where metabolism, and replication are carried out
What is the structure of the bacterial cytoplasm?
- viscous fluid
- contains nuclear mass and ribosomes
What is the structure of a bacterial inclusion?
- numerous inclusion bodies, or granules, in the bacterial cytoplasm
- never enclosed by a membrane
What is the function of a bacterial inclusion?
- storage vessels.
- Glycogen is stored as a reserve of carbohydrate and energy.
What is the structure of the bacterial mesosome?
- Mesosomes or chondrioids are folded invaginations in the plasma membrane of bacteria
What is the structure of the bacterial ribosomes?
- two subunits
- smaller than eukaryotic ribosomes
What is the function of the bacterial ribosomes?
- protein synthesis
What is the structure of the bacterial nucleoid?
- irregularly shaped region that contains all or most of the genetic material
- not surrounded by a nuclear membrane
- the genome of prokaryotic organisms generally is a circular double-stranded piece of DNA
What is the function of the bacterial nucleoid?
- contains genetic material
- essential for controlling the activity of the cell and reproduction
- where transcription and replication of DNA take place
What is the difference between gram positive and gram negative bacteria?
- gram negative cell wall contains lipoproteins - give the wall greater strength compared to gram positive.
What occurs during binary fission?
- bacterial cell elongates
- bacteria replicates its DNA
- cell membrane/envelope then pinches inwards around the DNA
- cell membrane meets in the middle
- divide is formed, two distinct cells can be seen
- cells separate to form two separate cells
Is binary fission sexual or asexual?
asexual
How do viruses reproduce?
- attachment - virus binds to a specific receptor on the host cell surface
- penetration - the viral nucleic acid enters the cell
- synthesis of new components - viral nucleic acid takes control of the cell metabolism stopping the cells normal nucleic acid and protein synthesis. Viral nucleic acid is replicated using nucleotides from the host cell. Protein coats are manufactured using amino acids of the host cell.
- assembly - whole virus particles are made when the nucleic acids are surrounded by the protein coats
- release - many viral particles are released when the cell bursts open (lysis) or by slow leakage
Label a growth curve
What occurs during the lag phase of a growth curve?
- slow growth due to time and lack of energy
What occurs during the log phase of a growth curve?
- exponential growth
- lots of nutrient medium
- more cells = more replication = more cells…
What occurs during the stationary phase of a growth curve?
- number of living = number of dying
- nutrients being depleted, toxic products beginning to accumulate
What occurs during the death phase of a growth curve?
- more dying than viable
What factors affect the growth of bacteria?
- nutritional factors
- temperature
- pH
- oxygen concentration
- osmotic requirements
What elements are required for nutrition for bacterial growth?
- nitrogen - for amino acids (proteins)
- carbon - main constituent of cellular material
- potassium - required for chemical reactions within the cell
- magnesium - for chemical reactions
- calcium - for chemical reactions & for endospore production
What are organisms who obtain their energy from light called?
Phototrophs