Cyanobacteria…

Domain: Bacteria

Kingdom: N/A

Phylum: Cyanobacteria

 Ocillatoria

Possesses trichomes

 Nostoc

Also has trichomes, & a glycocalyx slimelayer

Genus: Gloeocapsa

Single cells with glycocalyx caspules

Genus: Anabaena

Genus: Spirulina

 

 

 

 

 

 

 

Special Structures –

Heterocysts – Contain enzymes for conducting nitrogen fixation. Nitrogen fixation is the process of bacteria capturing N in gas form w/ enzymes in their body.

Akinetes– It serves as a survival structure. It is a resting cell of cyanobacteria and unicellular and filamentous green algae.^[2] Under magnification, akinetes appear thick walled with granular-looking cytoplasms.

Trichomes – Stacks of cells

Fungi

Eurkaryotic Cells

Most are multicellular but some are unicellular

Nutrition – Release digestive enzymes into environment & then absorb nutrients from broken down organic material.

3 Major groups:

1. Molds (filamentous)
2. Fleshy fungi
3. yeasts (unicellular)

Domain – Eukarya

Kingdom – Fungi

Phylum – Oomycota

Albugo bliti

Sexual oospores

&

sporangiospores

Saprolegnia

1st image – oogonium w/ sexual oospores

2nd image – asexual sporangiospores

Phylum: Zygomycota

Rhizopus stolonifer

Lecture….

Bacteria: External Structures

Flagella: Long; used for motility

Fimbriae: Used to attache to other cells & inanimate objects

Pili (penis-ish) – Exchanges DNA

Flagella:

Flagellum (latin for whip)

3 Parts

1. Filament – Composed of a protein called flagellin
2. Hook – Base of filament near cell wall
3. Basal Body – Anchors filament & hook to cell wall

Rotates: 360° turns clockwise (tumbles) & counterclockwise (runs)

Arrangements:

• Petritrichous – flagella cover entire surface
• Polar – Flagella @ one or both ends. Possible more than one.
  
• Axial Filaments (AKA Endofilaments)- flagella at both ends that spiral around cell between cytoplasmic membrane & outer membrane

Taxis (Movement): Bacterial motility in response to environmental stimuli

Positive: Movement toward stimulus 

Negative: Movement away from stimulus

Stimuli:

• Light – Phototaxis
• Chemicals – chemotaxis

Bacterial Cells: Fimbriae & Pili the “penis”

Functions:

• Fimbriae – Attache to other cells & inanimate objects
  
• Pili –  Exchanges genetic information. Composed of pilin (protein)

F + … male cell

F – …female cell

Bacterial Cell Walls:

Walls made of peptidoglycan…

Structures:

• Complex polysaccharides
  
• Alternating monosaccharide molecules in chains bonded together by polypeptides
• N – Acetylglucosamine (NAG) & N – Acetylmuramic Acid (NAM) these alternate

Tertapeptide holds vertical layers & amino acids connects horizontal layers. (look this up, this a poor explanation)

Gram Positive Cell Walls vs. Gram Negative Cell Walls

Gram-Positive cell walls:

1. Cytoplasmic membrane
2. multiple layers of peptidoglycan
3. teichoic acid (contained in the peptidoglycan)
4. acid gives cell wall negative charge

Gram-Negative Cell Walls:

1. Cytoplasmic membrane
2. Few layers of peptidoglycan
3. Outer membrane (phospholipids) – Contains lipo polysaccharieds & a substance called Lipid A which triggers immune system because it is toxic to mammalian cells

Bacteria Cells: Cystoplasmic Membranes

Structure:

• Bilayer of phospholipids
• Proteins: Integral (around); peripheral (inside)

Functions:

• Semi-permeable membrane (some molecule can pass through, not all)
• Protective
• Fluid/semi-fluid

No lab notes today.

Lecture

Found a site w/ good pictures http://www.chemistar.com/Biology/organicmolecules.html

Lipids

General Functions:

• Provide energy (9 cal/gram compared to carbs & proteints at 4cal/gram)
• Provide structure (ex. cell membranes)
  
• Some are hormones. (ex. estrogen, testosterone)

Contain C, H, O

Sources – Fats, oils, waxes, phospholipids (part of cell membranes), steroids.

Fats  are a subgroup of Triglycerides – a typical triglyceride molecule is found in oils (plants) & fats (animals).

ex.      1 glycerol + 3 fatty acids = 1 triglyceride (ester bond- connects glycerol to fatty acids)

Subgroups of Lipids…

Fats:

Saturated: maximum # of Hydrogen attached to each carbon. (no double bonds between Carbon atoms)

Monounsaturated: has only one double bond in the chain. Therefore, fewer Hydrogens & a kink in the chain. (Oleic Acid)

Polyunsaturated:2 + double bonds in the chain. Also, has less Hydrogen & more kinks in the chain. (Linoleic Acid)

Phospholipids:

1 glycerol + 2 fatty acids + 1 phosphate group + 1 organic functional group = phospholipid

Phosphate groups – Interacts with water; because the phosphate head is polar.

Fatty acid ‘legs’ – Non-polar, do not interact with water and align themselves together to be protected from the water while exposing the phosphate groups to the water.

Steroids:

• Contain 4 fused rings
• Include cholesterol  (found in cell membranes of animals)
  

Proteins

General Functions:

1. Structural
   
2. Involved in cell communications (ex. hormones)
3. Catalysts for chemical RXNs (enzymes)
   

Contains C, H, N, O (S)

Protein Monomers: Amino Acids – Single amino acids contains a central carbon, carboxyl group(COOH), amino group (NH2) & side group (R-group).

• R-group: Glutamine; Serine

Polypeptides (Polymers): 2+ amino acids linked together.

• Peptide Bonds- Protein covalent bonds
• DNA provides the instructions to make (LARGE CHAINS) proteins; they are made inside the cell linking one amino acid to another.
  
• Each protein has a unique combination of amino acids
• 20 different types of amino acids formed in living things.
  

Levels of Protein Structure:

1. Primary – The specific order of amino acids in a polypeptide chain.
   
2. Secondary – Hydrogen bonds form between the carboxyl groups & amino groups. This stage forms β -pleated sheets & α-helices throughout the polypeptides.
   
3. Tertiary – Additional bonding occurs involving R-groups to make simpe proteins (one peptide chain) functional.
   
4. Quaternary – Additional bonding occurs between more than one polypeptide chain to make functional protein (complex)

Ex. of importance of primary structure:

• Prion that causes Scrapie (sheep) : Alanine is substituted for valine and #136 resulting in a mis-fold of proteins. 
• Sickle Cell Disease (humans): Valine gets substituted for glutamate @ # 6  in hemoglobin. Valine does not interact well w/ water causing it to crystalize and form a deformed cell.
  

Protein Denaturation – The loss of tertiary or quaternary structure, resulting in a loss of function. Causes are high heat, alcohol, some metals and/or acids.

Extra Credit: Smith Lemli Opitz Syndrome – an autosomal recessive metabolic and developmental congenital disorder that causes the inability to correctly produce or synthesize cholesterol due to a low occurrence of the 7-DHC reductase enzyme.

Only a few of the symptoms:

• Small head size (microcephaly)
• Mental retardation
• Learning disabilities and behavioral problems
• Malformations of the heart, lungs, kidneys, gastrointestinal tract, and genitalia
• Hypocholesterolemia
• Paleness
• Low muscle tone (hypotonia)

 Lab

Gram Stain

Q: Is my bacteria gram positive or gram negative?

A: Use a gram stain… Thanks to Hans Gram in 1884 we have a differential stain technique that distinguishes cells based on content of cell walls

Purple colored cells = gram positive

• Gram Positive Cells – have thick peptidoglycan (multiple layers) that contains teichoic acid

Pink colored cells = gram negative

• Gram Negative Cells – Thin peptidoglycan (few layers) with outer membrane that contains lipopolysaccharides (toxic to mammalian cells)

KOH Test

Can be used to identify Gram-Positive vs. Gram-Negative cells. Potassium Hydroxide causes Gram – Negative cells to lyse (busrt), releasing a viscous liquid. (It will be ‘snotty-like’) Gram-positive cells do not lyse when mixed with KOH, so the liquid remains thin/non-viscous.

Acid Fast Stain

Q: Does the unknown bacteria have mycolic acid (was like substance) in its cell walls?

A: Use an acid fast stain.

Note: Mycolic acid is only found in gram positive cells, but not all gram positive cells have mycolic acid.