Cell Chemistry (and introduction material) Flashcards
What about microbes do people study
Biochemistry morphology physiology genetics ecology (interaction of microbes) evolution
Aspects of Microbiology
- Understanding basic life processes
- microbes are excellent models for understanding cellular processes in unicellular and multicellular organisms (understanding transcription, translation, and metabolism) - Applying knowledge learned from microbes to benefit humans
- microbes play an important role in medicine, agriculture, and industry
Importance of Microorganisms
- oldest form of life
- microbes found almost everywhere (most in ocean/soil)
- largest mass of living material on Earth (make up 1/3-1/2 of world’s biomass)
- help carry out major processes for biogeochemical cycles (nitrogen and carbon cycle)
- other life forms require microbes to survive -they cause many human/animal diseases
- cause most plant disease
- cause 99.99% of all decomposition
- many useful products are made by/with/contain microorganisms
Domain Bacteria
- usually single-celled
- majority have peptidoglycan cell walls
- lack a membrane-bound nucleus
- found almost everywhere and some in extreme environments
- cyanobacteria and some others produce significant amounts of oxygen
Domain Archaea
- distinguished from Domain Bacteria by unique rRNA sequences
- lack peptidoglycan cell walls
- have unique cell membrane lipids -many live in extreme environments
Domain Eukarya
cells have organelles and are specialized. Organisms in this domain are multicellular
Protists- generally larger than Bacteria and Archaea (algae, protozoa, slime molds, water molds)
Fungi- chemo heterotroph absorbers (gain energy through oxidation of electron donors in their environment)
Acellular Infectious Agents
not consisting of cells
- Viruses -smallest of all microbes -requires host cell to replicate -cause ranges of diseases, some cancers
- Viroids and Virusoids -infectious agents composed of RNA
- Prions -infectious proteins
Antony van Leeuwenhoek (1632-1723)
first person to observe and accurately describe microorganisms (used simple microscope)
Conflict over spontaneous generation
spontaneous generation
- living organisms (microbes) could develop from nonliving or decomposing matter
- This theory was discredited by Redi in the 17th century because he showed that maggots on decaying meat came from fly eggs
Louis Pasteur
helped disprove spontaneous generation Conducted experiment that: had two flasks with sterile liquid with bent necks preventing air from coming into flasks. flask with broken neck and exposed to air grew microbes and flask that wasn’t exposed to air did not grow microbes Other contributions: demonstrated that alcohol fermentation was a result of microbe activity. developed the process of pasteurization. developed vaccines for chicken pox, anthrax, and rabies
Robert Koch (1843-1910)
established relationship between bacteria and certain illnesses
Koch’s Postulates:
- the microorganism must be present in every case of the disease but absent from healthy individuals
- the suspected microorganism must be isolated and grown in a pure culture
- the same disease must result when the isolated microorganism is inoculated into a healthy host
- the same microorganism must be isolated again from the diseased host
Limitations of Postulates:
- some organisms cannot be grown in pure culture (some cellular and all viruses)
- using humans in completing postulates is unethical
Ionic Bonds
- bonds formed by the attraction of oppositely charged ions (cation and anion)
- gain or loss of electrons forms ions
- electrical polarity of water molecules can disrupt forces holding ions together
- electrons aren’t shared just an attraction
Covalent Bonds
strong bond where electrons are shared between atoms to fill valence shell of atoms
- single bonds allow rotation
- double bonds do not allow rotation but allow bending -triple bonds aren’t found in biological systems
*whether polar or nonpolar the net charge of bond is zero (no ions)
Hydrogen Bonds
weak bonds that form due to electrostatic interactions between hydrogen atoms and more electronegative atoms. (proteins and amino acids)
- multiple hydrogen bonds impart considerable stability to molecules
- play major roles in biological properties of proteins
- plays major role in the solubility and other properties of water
Van Der Waals forces
short lived attraction when molecules are very close important in: -enzymes binding substrates and membrane fluidity
Phosphoanhydride
ATP
Significance: energy metabolism
Hydroxyl Group
alcohol (OH-)
-more polar/water soluble
Example: glucose
Significance: lipids/carbohydrates
Carboxyl group
can act as an acid
Example: acetate
Significance: organic, amino, or fatty acids. lipids or proteins
Methyl group
Acetyl group
Hydrocarbons
nonpolar and hydrophobic
- made up of ONLY hydrogen and carbon
- ane suffix
Amino acid
NH2 is the amino group
OH- is the carboxylic acid group (makes it more polar and water soluble)
R is functional group
Carbohydrates
Play important roles in cell walls and as energy storage molecules
Monomers= monosaccharides and disaccharides (sugars)
*organic compounds that contain carbon, hydrogen, and oxygen at a ratio of 1:2:1
-polar molecules (hydrophilic)
Most biologically significant ones are:
- Pentoses (5 carbon sugars) - backbones of nucleic acids
- Hexoses (6 carbon sugars) - monomeric constituents of cell wall polymers and energy reserves
Sugar derivatives
when other chemical substances replace one or more of the hydroxyl groups on the sugar (acetyl group replaces hydroxyl group on glucose)
Polysacchrides
glycosidic bonds: covalent bonds linking adjacent sugars together
possible bonds are alpha and beta bonds (crosses plane of ring structure)
-different bonds mean different functional properties
Alpha 1, 6-Glycosidic bond
Alpha-1, 4-Glycosidic Bond
Beta-1, 4-Glycosidic bond
Triglycerides
composed of 3 fatty acid tails bonded to 3 carbon alcohol (glycerol)
function: energy storage
- contains ester bonds between glycerol and fatty acids
- fatty acids consist of carboxyl group and hydrocarbon chain
Complex lipids
simple lipids that contain additional elements such as P, N, S, or hydrophilic organic compounds like sugars
example: phospholipids- contains 2 fatty acids, glycerol, phosphate group, and something attached to phosphate (ethanolamine)
Nucleic Acids, DNA, RNA
Nucleid Acid: polymer of nucleotides
DNA: polymer of deoxribonucleotides (genetic material in all cells and some viruses)
RNA: polymer of ribonucleotides (plays role in protein synthesis in all cells, and is genetic material for most viruses)
Sterols and Hopanoids
- lipids that provide membranes with rigid structure
sterols: found in all eukaryotes but few prokaryotes
hopanoids: found in many prokaryotes, but no eurkaryotes
Nucleotides
nitrogen base attached to 5-carbon sugar by N-glycosidic bond and bonded to a phosphate
- major components of nucleic acids
- key forms of chemical energy (ATP)
- carriers of sugars in biosynthesis or polysacchrides
- regulatory molecules for certain enzymes or metabolic events
N-glycocitic bond
bond between adenine and a sugar
Glycosidic bonds
covalent bonds linking adjacent sugars together
*alpha or beta orientations
Phosphoester bond
phosphate attached to a sugar (nucleotides)
*phosphodiester bond is a covalent bond that connects two adjacent nucleotides on the same strand
2 classes of nucleic acid nitrogen bases
Purine bases: (adenine and guanine) contain two fused heterocyclic rings
- Adenine (A) *in DNA and RNA
- Guanine (G) *in DNA and RNA
Pyrimidine bases: (thymine, cytosine, and uracil) contain a single six-membered heterocyclic ring
- Cytosine (C) *in DNA and RNA
- Thymine (T) *in DNA only
- Uracil (U) *in RNA only
ATP
Proteins
made up of amino acids
- side chains of amino acids impart chemical properties
- amino acids with similar chemical properties are grouped into families
- a protein is a functional unit consisting of one or more polypeptides
Amino Acids
Two important functional groups:
- carboxylic group (-COOH)
- amino group (-NH2)
adjacent amino acid monomers are held together by covalent peptide bonds
Enantiomers
sterioisomers or mirror image isomers
- same chemical properties but different physical properties
racemases: enzymes capable of interconverting specific enantiomers
Polypeptides
series of amino acid sequences joined together by peptide bonds (each polypeptide has an amino end and a carboxyl end)
*a polypeptide could be a whole protein or just a subunit of a larger protein
-a protein is a functional unit
Secondary structure and Tertiary structure
Secondary: folds or twists in parts of polypeptide that form a more stable structure (bond between amino group H and carboxyl group O)
Tertiary: held together by
- hydrogen bonds
- electrostatic interactions
- hydrophobic interactions with water
- covalent bonds between -SH groups from two different amino acids (disulfide bonds)
Denaturation
unfolding of polypeptide chains
due to:
- extremes of pH
- high temperatures
- certain chemicals
