Microbiology Flashcards
What are Archaea?
A kingdom of single celled microorganisms. They live in extreme environments and are prokaryotes as they have no cell nucleus.
What are the differences between prokaryotes and eukaryotes?
P have a petidoglycan cell wall, E have simple cell membrane.
P have no organelles or true nucleus.
Some P have flagella.
P have small ribosomes E have larger.
P cells tend to be smaller.
P have circular DNA, E have chromosomes.
P replicate by binary fission, E by mitosis or meiosis.
P are unicellular, E are usually multicellular
What is a bacterial cell wall made of? How many types are there, how can you identify them?
Peptidoglycan. There are two types that can be identified by a gram stain.
Describe the features of a gram negative bacteria.
They have a thin peptidoglycan cell wall as they have a outer membrane. They have lipopolysaccharides on the outside. These are important for evading phagocytosis.
Describe the features of a gram positive bacteria.
No outer membrane so has thick peptoglycan wall. Has teicholic acids on the surface. More susceptible to antibiotics.
What is a capsule? What does it do?
They are a sticky substance made of polysaccharide/ peptide or both. The capsule helps the evade the immune system.
What’s the difference between a capsule and slime layer?
Capsules are firmly attached and highly organised.
Slime layers are unorganised and loosely attached.
What are fibriae/ pili? What are they for?
Hair like appendages used by bacteria to attach to cells and to transfer DNA (conjugation).
What is an endospore?
A dormant form of a bacteria, resistant to harsh environments.
What type of bacteria have a outer membrane?
Gram negative
What is a chemoheterotroph?
An organism that obtains energy and nutrients from the oxidation of organic compounds that it cannot make itself.
What does phagocytic mean?
Obtaining large nutrient particles by endocytosis (engulfing food).
What happens during budding in fungi?
Parent cell forms bud on outer surface. Parent nucleus divides and one nucleus migrates into bud. Cell wall material laid down between bud and parent cell. Bud breaks away leaving scar.
What is a lichen?
What do its component parts do?
What does a lichen do?
An association between a fungi and photosynthetic cell (Cyanobacteria and green algae).
Fungi is for structure, cyanobacterium provides food.
First life forms to colonise bare rock/ soil. Act as a barometer for air quality.
What is a mycorrhizal relationship?
Mutualistic relationship between fungus and plant root.
Fungus absorbs nutrients and plant provides it with sugars for energy.
What does:
- Infectious mean?
- Non infectious mean?
An infectious disease is one that is transmitable e.g. Measles, mumps, HIV.
A non-infectious disease is one that is non-transmitable e.g. Stroke heart disease diabetes.
What does:
- Contagious mean?
- Non-contagious mean?
Transmitted by contacted with infected individual, their secretions or surfaces they have touched e.g. Flu, colds, strep throat.
Spread usually requires a mode of transmission such as a vector or transfer of bodily fluids (e.g. blood transfusions, sexual contact) e.g. Lyme disease.
What makes up the cell wall of a: Fungus Plant Animal Bacteria
Chitin
Cellulose
No cell wall
Peptidoglycan
What is a viral plaque? How is it made?
It is used to study bacteriophages. A sample is mixed with phages. Viral infection kills cells and the clearing is called a plaque.
What is the incidence of a disease?
What is the prevalence of a disease?
No. of people in a population who develop a disease at a particular time.
No. of people in a population with a disease at a particular time, takes both old and new cases into account.