Micro Exam 1

• Nucleus contains:
• Protons (+1) charge; number of protons determines which atom
• Neutrons (no charge) add weight to nucleus
• Electrons (-1) orbit the nucleus; only part involved in chemical reactions

• 1st orbital filled when it contains 2 electrons
• 2nd orbital filled when it contains 8 electrons
• Atoms are stable when their orbitals are filled
• When their orbitals are not filled, atoms are reactive

• Atoms can fill their orbitals by sharing electrons with another atom
• A shared electron pair is called a covalent bond
• When 2 or more atoms are bonded together, a molecule is created

Water sticks to itself

Water sticks to other polar substances

Water is a good solvent for polar substances

• Water will not dissolve nonpolar substances
• There are no charges to attract water

• Cells are roughly 70% water
• Dry weight of cell is mainly Carbon
• Carbon is NOT a major constituent of the earth
• It is life’s building block because of its unique structure

• C can make up to 4 highly stable covalent bonds
• C can make single, double, or triple bonds
• C can make long stable chains with itself
• C also binds to life’s other elements (H, O, N, S, Phosphate)

• These bonds are polar
• These bonds are not as stable as C-C or C-H bonds
• These bonds are thus reactive
• Life is not inert!

• There are 4 classes of C cmpds that compose living things
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

• Building block is glucose (sugar)
• Formed by dehydration reactions
• Two together create disaccharides

• Long chains of sugars are called polysaccharides
• Function as energy storage or structure
• Examples include:
• Starchstorage
• Chitinstructure

• Building block is often glycerol
• To which Fatty Acid chains are attached
• Formed by dehydration synthesis

• Lipids are important as:
• Energy storage:
• Insulation:
• Thermal:
• Electrical:
• Building blocks of membranes
• Building block of steroids
• Fat-soluble vitamins (A, D, E, K)

• Many lipids usually found as Fatty Acids (16-18 Cs)
• Lipids are either saturated or unsaturated
• Saturated refers to having as many Hs bonded to the Cs as possible
• Unsaturated have double bonds between Cs

• Phospholipids
• 2 fatty acid chains and a phosphate head
• Amphipathic
• Building block of membranes

• Phospholipids form bilayers
• Degree of unsaturation determines membrane fluidity

• Cholesterol is a lipid
• Highly hydrophobic
• Building block of steroid hormones

• Anything that happens in the cell is due to protein
• Proteins function:
• Structure
• Transport
• Protection/Defense
• Control/regulation
• Catalysis
• Movement
• Storage

• Primary Structure: “spelling” ; actual amino acids present, the polypeptide chain
• Secondary structure: local folding pattern; α helix, β sheet, turns
• Tertiary structure: overall 3D fold; usually a mixture of secondary structure
• Quaternary structure: 2 or more protein subunits come together to make one protein
• Primary Structure determines Tertiary Structure

Actual amino acids present

• Two classes:
• DNA
• RNA

• Study of microorganisms
• Organisms too small to be seen by the naked eye
• Diameter of 1 mm or less

• Pathogens
• Primary producers
• Decomposers
• Nutrient cycling
• symbionts

• Chemical synthesis
• Fermentation
• Proteins (e.g. insulin)

• Robert Hooke (1665)
• Simple microscope; much like a magnifying glass
• Observed cork
• “little boxes” (cells)
• Later, saw cells with a double lens microscope
• Beginning of Cell Theory

• Discovered:
• Early embryos of plants
• Small invertebrate animals
• Spermatozoa
• Red blood cells
• Capillary circulation
• Microorganisms

• Belief that life arises from non-life
• Taken as doctrine until 1665

• Observation: meat left out uncovered produces maggots
• Hypothesis: Flies lay eggs on the meat that hatch into maggots

• Hypothesis: microorganisms are the same as any other organism and only come from reproduction of previously existing microorganisms
• Prediction; if broth is boiled to sterilize it and then not exposed to air, microorganisms cannot enter and the broth will remain sterile

Observation: air drawn through cotton leaves a dust deposit that contains microorganisms

Hypothesis: microbes enter broth as dust particles in the air

Prediction: IF air is allowed to enter sterile broth, but dust is not, THEN nothing will grow in the broth

pioneered use of carbolic acid spray in the OR

pioneered handwashing in obstetrics

Reduction of food spoilage organisms by heating

a process to determine the etiology (cause) of an infectious disease

• 1. The suspected pathogen must be found in all cases of the disease, but not in healthy individuals
• 2. The suspected pathogen must be isolated from a diseased host and grown in pure culture
• 3. The pure culture must produce the same symptoms when inoculated into a healthy host
• 4. The same pathogen must be isolated from the secondary host
• 5. Identical microorganisms are identified.

• 1. Some pathogens cannot be grown in pure culture
• Unknown culture
• requirements
• 2. Many pathogens are species-specific: there may be no animal models for a human disease
• 3. Some pathogens can persist
• in “carriers” who have no symptoms
• 4. Some microorganisms can cause more than one disease
• 5. Some diseases (sets of symptoms) have more than one cause

• 1. Identify the causative agent (Koch’s Postulates)
• 2. Cure or prevent the disease

• Lady Mary Montagu
• “inoculation parties”
• “customers” would have a scratch made on a limb
• Pus from the victim of a mild attack of smallpox would be smeared on open vein of customer
• Worked most of the time

Jenner 1798. Cowpox pustule material protects humans from small pox

Basic idea: pre-exposure to weakened pathogen later protects from the active pathogen.

• Pasteur & Koch knew:
• Pathogens exist that are too small to see with a light microscope and pass through filters that trap bacteria (contagious fluid)
• These pathogens cannot be grown in lab on nutrient medium
• Example: the agent that causes rabies

~1950 Viruses are obligate intracellular pathogens – must be grown in live organisms, or in tissue culture

~1960 antibodies discovered – specific antibodies can be used to identify specific viruses

• 1970s onwards. Molecular techniques –
• DNA, RNA or protein analysis- used to detect presence of viruses

• Postulate 1:
• Viral particles, viral proteins, viral nucleic acids or antibodies specific to the virus are present in infected individuals and not present in uninfected individuals
• Postulate 2:
• Viruses can be grown in tissue culture, or observed in infected tissues under the EM
• Postulate 3:
• Cell-free filtrates of infected material produce disease in animal models (if available) or in tissue culture

• Postulate 4:
• Viral particles from second host look the same, and have the same molecular characteristics as the original isolate.

• If a certain virus is consistently associated with a certain disease AND
• Methods used to prevent transmission of that virus reduce incidence of the disease OR
• A vaccine prepared using the virus prevents the disease
• Then the virus is considered to be the causative agent

• Simpler than prokaryotic glycocalyx
• Plants/algae: cellulose
• Fungi: chitin
• Yeasts: glucan, mannan

• Function:
• Strengthen plasma membrane
• Cell-cell attachment
• Cell-cell communication
• Contact inhibition

• Carbohydrates associated
• Sterols strengthen membrane
• Transport
• No group translocation

• Cell “drinking”
• Inward folding of plasma membrane brings in extracellular fluids
• May be a way for cell to recover from exocytosis

• Function:
• Shape
• Transport

• Linear
• Histones
• Chromatin
• Chromosomes

Meiosis and Mitosis

• Some bacteria have this
• Capsule
• Slime layer
• Allows bacteria to evade immune responses
• Virulent
• E.g. B.anthracis, Streptococcus pneumoniae

• Glycocalyx composed only of sugar
• Allows attachment of bacteria to surfaces
• Called biofilm

• Fungal in origin
• Inhibits enzyme that cross-links amino acids between rows of NAG/NAM
• Causes cells to burst

• 2 classes
• Lipoteichoic: spans peptidoglycan layer
• Wall teichoic: linked to peptidoglycan layer
• Function: stability, cation transport (?)

The teichoic acid help keep the peptidoglycan attached to membrane. It also may help to get cations in.

Flagella is usually found in one of four arrangements. Amphitrichous is on both ends. These can move in both directions. Lophotrichous has two on one end and the Peritrichous can be anywhere. This can move very fast because of the flagella

• Thin peptidoglycan layer
• Outer membrane
• Periplasmic space
• This contains transport proteins and degradative enzymes

Periplasam contains transport proteins.

• Lipopolysaccharide
• LPS
• O polysaccharide (differs)
• Lipid A (endotoxin)

Lipid A will cause a lot of problems so you must have antibodies to clean it up. Lipd A can have the same bacteria as the entire cell.

• Highly (– ) charged
• Functions:
• Evades phagocytosis by complement
• Barrier to antibiotics, digestive enzymes, heavy metals, bile salts, certain dyes

Every cell is negatively charged on the outside. Complement will bind to blood stream in body Complement helps macrophage find it’s target

• Obligate intracellular
• Lack cell walls
• Sterol in plasma membrane

Has to live inside of cell to survive. Wants to live in macrophage which is the bodys police force. Sterols add stability at high temperature and it prevents things from forming solids in cold temperatures. Causes TB.

• No peptidoglycan
• Psuedomurein
• No D amino acids
• No NAM
• N-acetylosaminuronic acid

• Phospholipid bilayer
• Proteins
• No carbohydrates
• No sterols

• Functions:
• Pump ions
• ATP Synthesis
• Protein secretion
• Lipid synthesis
• Breakdown of nutrients
• Transport of materials
• Pigments
• Photosynthesis
• Infolding of plasma membrane: chromatophores

Diffusion is based on size and concentration gradient. Water gets in but it is much slower. Non polar gets it. There is no energy required for facilitate diffusion. It is facilitated by the concentration gradient. Active transport is when you need something to get across that the membrane doesn’t like. Requires energy to do that. Group adds a phosphate to slap a charge on it so it cant just slip by. This is a way for the cell to accumulate things on the inside. Sometimes it does require ATP but sometimes it doesn’t.

• ~80% H2O
• Proteins
• Carbohydrates
• Lipids
• Inorganic ions
• Low MW cmpds

• Many antibiotics work by inhibiting protein synthesis
• Work only on 70S ribosomes
• Ineffective on euk ribosomes
• 30S: streptomycin, gentamicin
• 50S: erythromycin, chlroamphenicol

• Concentrate reserve deposits
• May relieve osmotic pressure
• Include:
• Gas vacuoles
• Carboxysomes
• Metachromatic
• Polysaccharides
• Lipid inclusions
• Sulfur granules
• magenetosome

• Some of the most virulent. Requires a lot of energy.
• Endosperm is a resting body. 1. Copy your DNA. 2. Separating out a small section that contains DNA. 3. Complete separate membrane within the larger membrane. 4. Peptidoglycan starts to form and it starts to dry out. 5. Enzymes break down DNA. Endospores are very resistant to high heat, UV light. Allows bacteria to sit and wait to germinate.

• Changes to endospore coat
• Physical or chemical
• Enzymes within spore break down outer layers
• H2O gets in
• Metabolism begins

Vegetative cell is one that is actively growing. Resting state is an endospore. To get to a vegetative cell it must germinate.

Heating cycles

Heat the spore up and then lower the temperature and wait (big component). It then germinates and it is a regular bacteria that you can boil and kill. It does not kill the spore but it kills the vegetative cell.

• There are 3 tenets to Cell Theory
• 1. The cell is the smallest unit of life
• 2. All living things are composed of one or more cells
• 3. All cells come from cells

• Plasma membrane - lipid bilayer
• DNA - double stranded
• Ribosomes - site of protein synthesis
• Cytoplasm - interior of cell

• All cells are composed of the same basic elements
• C, H, O, N, S, P

• All cells are composed of the 4 carbon compounds:
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids