Microbes Flashcards
Microbes
Living organisms and nonliving entities, microscopic size, ubiquitous (found everywhere)
Roles of Microbes
Affect human health e.g more microbes live in out body than there are cells
Essential for life on this planet e.g produce oxygen via photosynthesis
Decomposition of dead organisms and their waste products (Saprophytes)
Antibiotic production (natural)
Food production e.g yoghurt
Genetic engineering e.g compounds like insulin
Categories of microbes
Acellular
Cellular
Types of cellular microbes
Prokaryotes
Types of acellular microbes
Viruses
Prions
Types of prokayotes
Bacteria
Archea
Types of Eukaryotes
Fungi
Yeast
Protozoa
Pathogens and percentage of organisms that are pathogens
Disease causing micro-organisms
3% of microbes
Non pathogens
Microbes that do not cause disease
Opportunistic pathogens
Microbes that usually harmless but can cause disease if they colonise the wrong part of the body or when we are vulnerable to infection e.g Candida Albicans (thrush)
Infectious disease
Disease caused by pathogenic microorganisms (e.g bacteria, viruses, parasites or fungi)
Spread directly or indirectly from one person to another
Acellular microbes
Microbes that need to invade other cells to replicate or perform physiological functions
(energy generation or protein synthesis)
Not considered to be alive
Virus
Made of a genome of either DNA or RNA and a protein coat called a capsid made of proteins called capsomeres
Properties of Viruses
Can not replicate on their own (need host cell)
Have either DNA or RNA not both
Do not divide by binary fission, mitosis or meiosis
Can not produce their own energy
Can not produce their own proteins
Classifying Viruses
Type of genetic material Shape of capsid Number of Capsomeres Presence or absence of an envelope Type of host it infects Types of disease it produces Its target cell Its antigenic properties
Bacteriophages
Viruses that infect bacteria
Animal Viruses
Viruses taht infect animals
Viroids
Infectious particles that consist of short pieces of RNA that interfere with the function of plant cells
Prions
Infectious particles that consists of small proteins that can cause neurological conditions in humans and animals
Prokaryotes features
Free floating DNA in cytoplasm
Have a complex cell wall consisting of peptidoglycan
No internal membranes
Ribosomes smaller and less dense then eukaryotic cells
Single celled
Components of Prokaryotes
Plasma membrane Chromosome Plasmid Cytoplasm Cell wall
Plasma membrane
Encloses all the contents of the cell
Composed of phospholipids and proteins
Chromosomes
Single, long, circular DNA molecule
Highly coiled around itself
In cell nucleus
Plasmid
Small circular pieces of DNA that are not part of the main chromosome
Can have none, one or many plasmids
Exchange of plasmids from one bacterium to another can result in development of multi-drug resistant strains of bacteria
Cytoplasm
A semi liquid substance that contains water ,salts, enzymes, nutrients, proteins, carbohydrates and lipids
Cell wall
Rigid structure on the outside of the plasma membrane
Provides rigidity, strength and protection for the cell
Major component is a complex molecule (peptidoglycan) which is only found in bacteria
Gram positive bacteria
Think layer of peptidoglycan on the outside of the surface of the cell wall
Gram negative bacteria
Have a thinner layer of peptidoglycan but it is sandwiched between layers of other complex molecules
Glycocalyx
Layer of slimy, gelatinous material excreted on the outside of the cell wall
Types of glycocalyx in bacteria
Capsules
Slime layer
Capsule
A highly organised layer, firmly attached to the outside of the cell wall
Helps prevent bacteria from being phagocytised by the cells of you immune system (live longer)
Slime layer
A not highly organised layer and it is not firmly attached t the cell wall
Helps bacteria move along surfaces
External structures of bacteria
Glycocalyx
Flagella
Fimbriae (pili)
Flagella
Threadlike appendages that function to move bacteria around
Possess flagella = motile
Fimbriae (pili)
Hair like structures that are observed on the outside surface of bacteria
Roles of different types of Fimbriae (pili)
Allow attachment of bacteria to surfaces
Allows transfer of genetic material
Endospores
Thick walled structures that contain a copy of the chromosomes and some of the cytoplasm
Allows bacteria to survive in adverse conditions
When endospores land in a suitable environment it germinates to produces new bacteria
Binary Fission
Prokaryotic cells way of reproducing whereby a parent cell splits into 2 halves producing 2 new cells
Features of Eukaryotes
DNA contained in Nucleus
Eukaryotes of animals do not possess a cell wall
Eukaryotes of plants have simple cell wall consisting of cellulose
Have organelles
Ribosomes are larger and denser than prokaryotes
Single celled of multicellular
Types of Eukaryotes
Fungi - Yeasts, moulds and mushrooms
Algae
Kingdom protista (protozoa, lichens, slime mounds)
Fungi and two subgroups of fungi
Includes yeasts, mould and mushrooms
Found almost everywhere
Saprophytic fungi - Lives on organic matter in water and soil
Parasitic fungi - lives on/in animals and plants
Algae
Photosynthetic
Range in size from small, unicellular microscopic organisms through to large multicellular organisms
Kingdom protista eukaryotes
Protozoa
Lichens
Slime moulds
Protozoa
Most are unicellular
Found in soil and water
More like animal cells than plant cells
Life cycle of protozoa
Trophozoite stage - the motile, feeding, dividing stage
Cyst stage - non motile, dormant, survival stage
Groups of protozoa
Amoebas
Ciliates
Flagellates
Non-motile protozoa (Sporozoites)
Amoebas
Move by extending portion of their cell membrane and cytoplasm in structure (Pseudopodia)
Ciliates
Move using a large number of hair like cilia on the outside surface of the cell
Flagellates
Move using a whip like flagella
Non motile protozoa (Sporozoites)
Do not contain pseudopodia, cilia or flagella
