MicroBio CH2 - Chemistry of MB

What is the nucleus of an atom composed of?

Protons & Neutrons, Electrons orbit the nucleus

What substance makes up most of the mass in living organisms?

Water (constitutes 50-99% of the mass of living organisms)

Number of protons = ?

Atomic #

Organic compounds are always composed of at least __?

Carbon and Hydrogen

What are isotopes and ions?

Ions: an atom with a diff. # of electrons (cations and anions); Isotopes: an atom with a different # of neutrons

Chemical bonds-sharing or exchange of electrons (?)

Ionic bond: one atom gives electrons to another atom, Covalent bond: atoms share electrons (polar covalent bonds: a type of covalent bond where atoms share electrons unequally, ex: water molecules, the electrons are strongly attracted to the oxygen than the hydrogens/called polarity)

(1) Four molecules formed by covalent bonds

H-H and O=O

(2) Four molecules formed by covalent bonds - cont.

CH₄ and CH₂O

Nonpolar vs Polar examples

*all in one photo

What are Hydrogen bonds?

Attraction between polar molecules; weaker than covalent bonds but essential for life (only with N, O, F)

The 4 types of bonds and their strength?

Nonpolar covalent bond: pair of electrons is nearly equally shared between two atoms (strong), Polar covalent bond: electrons spend more time around the more electronegative of two atoms (strong), Ionic bond: electrons are stripped from a cation by an anion(weaker than covalent in aqueous environments), H-bond: partial positive charges on hydrogen atoms are attracted to full and partial negative charges on other molecules or other regions of the same molecule (weaker than ionic)

What are chemical reactions?

Making or breaking of chemical bonds (biochemical reactions: chemical rxns involving living things); Involve reactants and products (reactants: things that enter the reaction, starting material; products: things that exit the reaction, or are the result of the reaction)

What are synthesis reactions?

Formation of larger, more complex molecules, require energy (endothermic), dehydration synthesis = common in biochemistry (water molecule formed), all the synthesis reactions in an organism are called anabolism

What are decomposition reactions?

Break bonds within larger molecules to form smaller atoms molecules, this releases energy (exothermic), common type is hydrolysis (components of water are added to products), all the decomposition reactions in an organism are called catabolism

Sum of all chemical reactions in an organism is called __

Metabolism

Inorganic chemicals critical for life (water H₂O)

Universal solvent: dissolves substances, allows chemical reactions to occur, Cohesion (water sticks to water), Adhesion (water sticks to anything else), High surface tension: water forming bonds along surface

What is high heat capacity? (water)

Absorbs heat and can withstand a lot of heat before changing states, slowly changes temps

Density of ice is less than the density of water? What happens?

The ice floats, can provide insulating effect; ex: lake can be frozen on top, but liquid underneath so fish can live

Inorganic chemicals critical for life: acids and bases. What are those?

Acid: dissociates into one or more H+ and one or more anions. Base: binds with H+ when dissolved in water; some dissociate into cations and OH-

• Concentration of H+ in solution expressed using the pH scale

pH scale?

pH = -log[H+]

0—7—14 (acidic, neutral, alkaline)

As H+ concentration goes down, pH goes up; As H+ concentration goes up, pH goes down

Why are acids and bases necessary?

Metabolism requires relatively constant balance of acids and bases-buffers prevent drastic changes in internal pH; microorganisms differ in their ability to tolerate pH ranges, some microorganisms can change the pH of the environment

Inorganic chemicals critical for life: also Salts, which are?

Compounds that dissociate in water into cations and anions other than H+ and OH-; create electrical differences between inside and outside of cell, transfer electrons from one location to another, form important components of many enzymes

Since inorganic chemicals are useful, macromolecules are also needed b/c they’re superstructures of life. What are macromolecules and the 4 types?

They’re very large (consists of monomers: subunits of macromolecules, polymers: chains of monomers-vary in length); 4 main types: carbs, proteins, lipids, and nucleic acids

What are carbs?

Only C, H, and O; store energy, primary fuel for organisms, for cell structure, often ends in -ose (ex: glucose/fructose), found naturally in fruits, most carbs ultimately converted into glucose including: table sugar (sucrose), and starchy carbs (rice, corn, bread, potatoes, etc.)

What are monosaccharides?

Simple sugars, most direct source of energy; like glucose, fructose, and galactose

What are polysaccharides?

Are complex carbs that are made up of large number of monosaccharides; starch, glycogen, cellulose; they matter b/c they’re used for energy storage and structural support (cell walls)

What are disaccharides and examples?

Two monosaccharides;

Maltose (malt sugar): composed of two glucose-important breakdown product of starch

Lactose (milk sugar): Composed of glucose and galactose

Sucrose (table sugar): composed of glucose and fructose

Purposes of glucose?

Glucose is a primary fuel source; fuels cellular activity when enzymes break the bonds between the atoms of glucose, releasing energy; including muscle contractions that enable you to move, and nerve activities that enable you to think; circulates in blood at a conc. of about 0.1%

Another macromolecule type; Proteins. What are they?

Made of C, O, H, and N; made of a combination of 20 diff. amino acids strung together, unique combinations = unique proteins, the order of the amino acids matters b/c diff. order = diff. protein

What are the 5 kinds of proteins (functions)?

Structural: hair, fingernails, feathers, horns, cartilage, tendons; Protective: help fight invading microorganisms, coagulate blood; Regulatory: control cell activity, constitute some hormones; Contractile: allow muscles to contract, heart to pump, sperm to swim; Transport: carry molecules such as oxygen around your body

What are the 3 types (there’s 4 but ok) of structures in proteins?

Primary: the sequence of amino acids in a polypeptide chain, similar to the sequence of letters that spell out a specific word (contains peptide bonds), Secondary: the corkscrew like twists or pleated folds formed by H-bonds between amino acids in the polypeptide chain, Tertiary: complex 3D shape formed by multiple twists and bends in the polypeptide chain based on interactions between the side chains

If the shape of a protein becomes deformed (__), it cannot function the same or loses function entirely.

Denatured; denaturation can occur from heat, high or low pH, chemicals (ex: alcohol or salt), it’s irreversible (ex: un boiled egg to boiled egg, normal protein to denatured protein)

Since enzymes are proteins, what is their role?

Enzymes speed up or catalyze reactions; often end in -ase (ex: lactase, which breaks down lactose)

Another macromolecule type, lipids. What are they?

Made from C, H, and O; lipids have more stored energy than carbs and proteins (carbs & proteins = 4 Calories/gram, lipids: 9 Calories/gram); they don’t have any unique subunits so are defined by physical characteristics, lipids do not dissolve in water and are greasy/oily to the touch

What are triglycerides?

Fatty acids + glycerol (fats, oils; major component of cell membranes; storage)

What are phospholipids?

Fatty acids + glycerol + phosphate (membrane components)

What are waxes?

Fatty acids + alcohols (mycolic acid); cell wall of mycobacteria

What are steroids?

Type of lipid that have a ringed structure; cholesterol/ergosterol, in membranes of eukaryotes and some bacteria

What are cell membrane lipids and its function(s)?

(*Phospholipid bilayer) Consists of hydrophilic and hydrophobic parts, when exposed to liquid: charged heads are attracted to the water phase, non polar tails are repelled from the water

What are the 3 types of lipids?

Fats: long term energy storage and insulation; Sterols: regulate growth and development; Phospholipids: form the membranes that enclose cells

Why does a salad dressing made with vinegar and oil, separate into 2 layers?

Hydrophobic: oil is a lipid, it consists of hydrocarbons which are non-polar; Hydrophilic: molecules that form hydrogen bonds with water

What are the 2 types of nucleic acids (final macromolecule)?

DNA: contains instructions to make proteins (chromosomes; genetic material of viruses, mediate inheritance); RNA: helps reads the DNA code and use the code to make proteins (ribosomes; mRNA, tRNA, small RNAs, genetical material of viruses → facilitate expression of genetic traits)

*double helix of DNA: adenine pairs with thymine, guanine pairs with cytosine

What is a nucleotide?

Composed of a phosphate, a pentose sugar, and a nitrogen base (either A,T,C,G or U) is the monomer of both DNA and RNA

Diff. between DNA and RNA?

DNA: alternating deoxyribose (D) and phosphate (P) w/ nitrogen bases (A,T,C,G) attached to the deoxyribose (two strands)

RNA: alternating ribose (R) and phosphate (P) attached to nitrogen bases (A,U,C,G), usually single strand

3 Types of RNA?

Messenger RNA (mRNA): copy of DNA that can be used to make a protein

Transfer RNA (tRNA): delivers the correct amino acids for proteins assembly

Ribosomal RNA (rRNA): major component of ribosomes

Adenine pairs w/ uracil

Guanine pairs with cytosine