Introduction to Microbiology Flashcards
(21 cards)
How many prokaryotic cells are in the environment?
10^30
There are more prokaryotic cells on earth than stars in the universe
How much of the total biomass is made up of prokaryotes?
Approximately half the biomass carbon on the planet
3 to 5 x 10^17 g carbon
10^11 tonnes
What is a petagram?
1Pg=10^15g=1 Gigaton
Who first observed microorganisms?
Robert Hooke in 1665. He was also the inventor of the compound microscope
Why did microbiology develop more in the 19th century?
Interest in disease and food spoilage. There was no proof at this point that disease and food spoilage was caused by microorganisms
What are microorganisms?
Small organisms, measured in thousandths of a millimetre
Usually free-living unicells or clusters of cells
Examples: Fungi, Algae, Protozoa, Bacteria, Archaea
What are cells?
Basic unit of all living organisms
Common features: Cell envelope, Nucleic Acids, Ribosomes, Cytoplasm
What are the two cell types, and what category does each microorganism group fall under?
Prokaryotic Cells- Bacteria, Archaea
Eukaryotic Cells- Fungi, Algae, Protozoa, Plants, Metazoa
What is the cell membrane structure in a basic cell?
Lipid bilayer
Hydrophobic fatty acid ester-linked to hydrophilic head (phosphorylated glycerol)
What is the cell membrane in Archaea structure?
Hydrophobic fatty acid ether-linked to hydrophilic head (glycerol)
Fatty acids often branched and cyclic isoprenoids
Cyclic tetraether lipids can form a monolayer functionally identical to a lipid bilayer. They join at their tails
What is the fluid mosaic model?
Representation of lipid bilayer
Lipid bilayer forms a lipid bag around cell
Contains proteins that float in the lipid bilayer
Structural, transport and catalytic proteins
What are the other lipid components of the cell membrane?
Sterols ( eukaryotes and a few bacteria) and hopanoids (eukaryotes and bacteria)
What are cell walls made of in different cell types (eukaryotes)?
Cell walls usually only in eukaryotes but can be in bacteria and archaea in some cases
Cellulose (monomer=glucose)- plants, algae, some fungi
Chitin (monomer= N-acetylglucosamine)- fungi
Mannas (monomer=mannose)- fungi, plants
Xylans (monomer=xylose)- fungi, plants
What is the structure of cell walls in bacteria?
Complex
Contains peptidoglycan- polysaccharide chains cross-linked by peptides
What is the structure of cell walls in archaea?
-Pseudopeptidoglycan
•N-acetylglucosaminw
•N-acetyl-talosaminuronic acid
•Different peptide cross links
-Glycoprotein, protein, polysaccharides
•S-layer
•Hexagonal array of proteins or glycoproteins
How can we differentiate between two major bacterial groups?
Cell wall structure helps us differentiate between these two major groups of bacteria based on a differential staining procedure (The Gram Stain)
Cell envelopes can either be Gram positive or Gram negative
What are the types of nucleic acids?
Deoxyribonucleic acid
Ribonucleic acid
What are the types of RNA?
Ribosomal RNA- rRNA
Messenger RNA- mRNA
Transfer RNA- tRNA
Small Interfering RNA- siRNA
Micro RNA- miRNA
Small Nuclear RNA- snRNA
Small Nucleolar RNA- snoRNA
Piwi-interacting RNA- piRNA
What are the Pyrimidines and Purines?
Pyrimidines- Cytosine, Thymine, Uracil
Purines- Adenine, Guanine
What are Ribosomes and what are their structure?
Direct process of protein synthesis by a process known as translation
Two subunits- large and small
Come in different sizes
•Eukaryotes: 80S= 60S + 40S
•Prokaryotes: 70S= 50S + 30S
Complex of over 50 proteins and three different RNA molecules (5/5.8, 16/18S, 23/28S
What are some unique structures found in some prokaryotes?
Pili
Fimbriae
Sheaths
Polysaccharide Capsules (glycocalyx)
Gas vesicles
Heterocysts
Endospores
