Lecture Midterm I Flashcards
Leeuwenhoek
First to observe microbes ( except viruses) in 1670’s through 300x simple microscopes.
Hooke
Invented microscope and discovered cells in cork.
Redi
Disproved spontaneous generation (proposed by Aristotle), with meat in sealed flask experiment. 1600’s
Needham
Boiled nutrients, sealed with cork, and “spontaneously” grew microbes. 1740’s
Spallanzani
Boiling solution for longer and heat sealing glass prevented growth. 1768
Pasteur
Swan-necked flasks. Pasteurization for wine. Rabies vaccine. 1800’s
Koch
Agar plates, isolation of bacteria. Causative agent of anthrax. Koch’s postulates. 1870’s
Gram
Staining method based on differential retention of dye. 1880’s
Semmelweis
Handwashing prevents childbed fever. 1840’s.
Lister
Aseptic surgery. 1880’s.
Nightingale
Clean bandages and environment.
Jenner
First vaccine (smallpox/cowpox). 1772.
Compare number of cells in you vs. number of microbes on you.
You cells: 10 trillion.
Microbes on you: 100 trillion.
Name 11 components of prokaryotic cells.
cell wall, plasma membrane, flagella, pilli, fimbriae, glycocalyx, cytoplasm, ribosomes, inclusions, nucleoid
Glycocalyces
Protect cells from drying. Slime layer is a water soluble, loose biofilm. Capsules allow bacteria to disguise itself and prevent bacteria from being recognized because chemicals in many bacterial capsules are similar to chemicals normally found in body.
Flagella structure
- Made of protein (flagellin)
- 3 parts: filament, hook, basal body
- hollow core
- lengthens at the tip
Flagella arrangements
- peritrichous (all around)
- lophotrichous (few at one end)
- amphitrichous (one at each end)
- monotrichouse (one at one end)
Fimbriae
- made of protein
- biofilm formation
- movement by pulling
- electrical signals for communication
Pili
- type of fimbria
- transfer of DNA through hollow tube
Cell wall
- Made of peptidoglycan, which is made of repeating disaccharides NAG and NAM. Cross-linked by amino acid side chains
Gram positive
- Stains purple due to thick peptidoglycan layer.
- Teichoic acid and lipoteichoic acid (anchors peptidoglycan to plasma membrane).
Gram negative
- Stains pink
- Outer bilayer membrane composed of inner phospholipid layer and outer lipopolysaccharide (LPS) layer
- LPS contains lipid A (endotoxin)
- Porins allow passage of mid sized molecules such as glucose
- Periplasmic space allows for compartmentalization and enzymatic activities.
Plasma membrane
- Phospholipid bilayer
- ETC
- Selectively permeable, establish concentration gradient and electrical gradient.
Group translocation
Chemical modification on the way through. Membrane impermeable to altered form. Phosphorylation of glucose as it passes through maintains glucose gradient.
Size of prokaryotic vs eukaryotic ribosome
Prokaryotic ribosomes are 70S, eukaryotic ribosomes are 80S. Many antibacterial drugs act on bacterial 70S ribosomes without deleterious effects on 80S ribosomes of eukaryotes
Describe genetic material of bacteria
Nucleoid, no membrane around DNA. Circular chromosome, usually only 1.
Two genera of bacteria capable of forming endospores
Bacillus and Clostridium, both gram positive
Characteristics of endospores
- v. low metabolism
- resistant to drying, heat, radiation, chemicals
- remain dormant until conditions are favorable
Structure of endospores
- Core: DNA, RNA, proteins, dipicolinic acid, Ca+2
- Cortex: 2 membranes, with peptidoglycan in between
- Spore coat: layers of keratin-like protein
Name the 6 basic cell shapes
- coccus
- coccobacillus
- bacillus
- vibrio
- spirillum (stiff)
- spirochete (flexible)
Define pleomorphic
vary in size and shape
What is the most common process of prokaryote reproduction, and what are the other processes?
Binary fission is the most common. Prokaryotic cells may also divide by snapping division and reproductive structure formation (budding).
Name the arrangements of prokaryotic cells
- diplo
- strepto
- tetrad
- sarcinae
- staphylo
Characteristics of viruses
- non-living
- infectious
- acellular (no ribosomes, cytosol, or cytoplasmic membrane)
- all have genetic material
What is the extracellular form of a virus called?
virion
Describe the structure of a virus
The nucleic acid is enclosed in a capsid (protein coat) composed of capsomeres. A viral nucleic acid surrounded by a capsid is called a nucleocapsid. Some virion have a phospholipid envelope, which comes from the host cell.
Shapes of virions
- helical
- polyhedral
- complex
Name the 2 main types of viral replication strategy
- Lytic: results in the death of host cell
- Lysogeny: infected host cells grow and reproduce for many generations before they lyse. Passed on to daughter host cells. Feature of bacteriophages. Called temperate phages or lysogenic phages.
Name the 5 stages of the lytic replication cycle
- Attachment
- Entry
- Synthesis
- Assembly
- Replication
Name the 5 stages of the lysogenic replication cycle
- Attachment
- Entry
- Prophage (inserts into DNA of host cell, not active)
- Replication (of host cell, including prophage)
- Induction: prophage is excised from host cell and continues with Synthesis, Assembly, and Release.