Consider the amino acid alanine. An amino acid has both a weak acid and a weak base. What is the weak base What is the weak acid By lowering or raising the pH you can change both the protonation state and the charge on this molecule. Sketch the three possible forms of alanine as you go from low pH to high pH and indicate overall charge on the molecule. Below is one form of alanine

Amino acids such as alanine, are also buffers. In one minute, write down a definition of a buffer.

 A buffer is a substance that resists ph change, and a buffer consists of a weak acid or a weak base. Buffers are substances that minimize changes in concentrations of H+ and OH- in a solution.

Enantiomer One of two compounds that are mirror images of each other

One of several compounds that have the same molecular formula but differ in the covalent arrangements of their atoms

YES!

One of several compounds that have the same molecular formula and covalent arrangements but differ in the spatial arrangements of their atoms owing to the inflexibility of double bonds

Structural Isomers

Geometric Isomers

YES!

Functional Group A specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and usually involved in chemical reactions Seven main functional groups

Draw the Hydroxyl Group Alcohols End in –ol Ex. ethanol

Draw the Carbonyl group Ketones and Aldehydes Double bond to oxygen

Draw the Carboxyl Group Carboxylic acids or organic salts Ex. Acetic acid

Draw the Amino group Amines Ex. Glycine

Draw the Sulfhydryl Group Thiols Ex. Cysteine

Draw the Phosphate group Organic phosphates Ex. Glycerol phosphate

Draw the Methyl Group Methylated compounds

An organic molecule possessing both carboxyl and amino groups, Amino acids serve as the monomers of polypeptides Polypeptide A polymer (chain) of many amino acids linked together by a peptide bond Peptide Bond The covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction

A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule

Draw four amino acids with the following R groups -H -CH3 -CH2COOH -CH2NH2 Identify polar (including acidic and basic) and nonpolar groups Identify the amino acids that can form enantiomers Form a tetrapeptide showing the loss of water and the formation of three peptide bonds. Identify the amino and carboxyl termini. Put a box around the 3 peptide bonds

Hydrogen bonds are formed when a hydrogen atom covalently bonded to one electronegative is also attracted to another electronegative atom. What is the maximum number of hydrogen bonds that can form between water molecules? 4 Hydrogen bonds

Snowflakes The water molecules in an ice crystal form a hexagonal lattice, there are 2 hydrogen's for each oxygen so the chemical formula is H2O Hydrogen and Oxygen connect with covalent bonds. The bonds between H2O in the snowflake connect with hydrogen bonds. The hexagonal pattern at the molecular level carries right on through to the snowflake structure. Hence the six points.

Emergent properties of water Cohesive behavior Ability to moderate temperature Expansion upon Freezing Versatility as a solvent

Cohesion Hydrogen bonds hold water molecules together Transport water against gravity in plants The Celery Experiment =related =related As water evaporates from a leaf hydrogen bonds pull on the water molecules further down in the vein.

Ability to moderate temperature Waters high specific heat Minimize temperature fluctuations Evaporation Due to hydrogen bonds which must be broken for water to evaporate, high boiling point. Remember water is the only molecule which can form 4 hydrogen bonds other molecules can not form this many.

Expansion upon freezing Water when cooled contracts down to 4 degrees C then expands. Hydrogen bonds in ice are more ordered, snowflake. The molecules in ice are more ordered and less dense which is why ice floats in liquid water

Versatility as a solvent Solvent – the dissolving agent of a solution Water is an effective solvent because It readily forms hydrogen bonds Dissolve ionic compounds, nonionic polar molecules, and larger polar molecules like proteins with ionic and polar regions

Carbohydrates, simplest form of sugar Names for sugars end in -ose Building blocks of disacchaarides such as sucrose and polysaccharides (cellulose, starch) KEY POINTS Each carbon supports a hydroxyl group Chemical formula C x (H 2 O) y Can contain either a ketone or aldehyde depends on where the carbonyl group is

KEY POINTS Each carbon supports a hydroxyl group Chemical formula C x (H 2 O) y Can contain either a ketone or aldehyde depends on where the carbonyl group is

Consists of two monosaccharides joined by a glycosidic linkage. A covalent bond formed between two monosaccharides by a dehydration reaction. Maltose is a disaccharide formed by the linking of two molecules of glucose What type of bond is formed in a dehydration reaction between two amino acids? Peptide bond – to form polypeptide

Draw two monosaccharides with 4 carbons One of these should be an aldose and the other a ketose Identify the asymmetric carbons in each. How many different stereoisomers can be formed for the aldose and the ketose? Identify the key functional groups that identify these as carbohydrates.

What is an asymmetric carbon? Is a carbon atom that is attached to four different atoms or four different groups of atoms Knowing the number of asymmetric carbon atoms you can calculate The maximum possible number of stereoisomers for any given molecule Max # Stereoisomers = 2 n n = the # of asymmetric carbon atoms