Biology 1406 Exam 1 ch.3

List the classes of macromolecules that make up living organisms.

Proteins. Carbohydrates. Lipids. Nucleic Acids.

Describe the unifying structural features of carbohydrates.

They all have similar atomic composition: CH2On; they function primarily in storing and transporting chemical energy and as sources of carbon for building new macromolecules.

Describe the need for chaperone proteins in a cell.

They protect the three-dimensional structures of other proteins. They bind to their partner proteins just as they are being made and also when they become denatured preventing them from binding to the wrong substances.

Predict the effects of various environmental factors on a protein's structure.

- Increases in temperature cause more rapid molecular movements and thus can break hydrogen bonds and hydrophobic interactions. - Changes in pH can change the pattern of ionization of exposed carboxyl and amino groups in the R groups of amino acids, thus disrupting the pattern of ionic attractions and repulsions. - High concentrations of polar substances such as urea can disrupt the hydrogen bonding that is crucial to protein structure. Urea was used in the experiment on reversible protein denaturation. - Nonpolar substances may also disrupt normal protein structure in cases where hydrophobic interactions are essential to maintain the structure.

Identify the primary functions of carbohydrates in living organisms. Energy storage

1. They are a source of stored energy that can be released in a form usable by organisms. 2. They are used to transport stored energy within complex organisms. 3. They serve as carbon skeletons that can be rearranged to form new molecules. 4. They form extracellular assemblies such as cell walls that provide structure to organisms.

Contrast Condensation and Hydrolysis reactions, and why are they important.

A condensation reaction occurs when two molecules join to form a larger molecule and release a smaller molecule(s) in the process.The opposite of a condensation reaction that releases a water molecule is called a hydrolysis reaction. This happens when one molecule is split into two via the addition of a water molecule.

Identify predominant chemical bond type in biological molecules.

Covalent bonds form when an electron is shared between two elements and are the strongest and most common form of chemical bond in living organisms. Covalent bonds form between the elements that make up the biological molecules in our cells.

Identify the portions of an amino acid molecule that are the same and different for every amino acid.

Each amino acid has the same fundamental structure, which consists of a central carbon atom, also known as the alpha carbon, bonded to an amino group (NH2), a carboxyl group (COOH), and to a hydrogen atom. For each amino acid, the R group (or side chain) is different.

Given a polymeric macromolecule found in living organisms, identify the bonds that are broken by hydrolysis reactions as the macromolecule is broken down to its monomeric building blocks.

Hydrolysis reactions result in the breakdown of polymers into their component monomers. Water reacts with the covalent bonds that link the polymer together. For each covalent bond that is broken, a water molecule splits into two ions (H+ and OH-), each of which becomes part of one of the products.

Describe protein denaturation

If a protein is heated slowly and moderately, the heat energy will disrupt only the weak interactions, causing the secondary and tertiary structure to break down. The protein is then said to be denatured. Denaturation is usually caused by external stress on the protein, such as solvents, inorganic salts, exposure to acids or bases, and by heat.

Identify the basic structure of amino acids.

It consists of a central carbon atom, also known as the alpha (α) carbon, bonded to an amino group (NH2), a carboxyl group (COOH), a hydrogen atom and a side chain (R group).

Identify the characteristics of lipids.

Lipids are made up of: carbon, hydrogen, and oxygen. They are colloquially called fats, and are hydrocarbons that are insoluble in water because of their many nonpolar covalent bonds.

Identify the bond linkage formed during triglyceride synthesis.

Making a triglyceride involves three condensation (dehydration) reactions. In each reaction, the carboxyl group of a fatty acid bonds with a hydroxyl group of glycerol, resulting in a covalent bond called an ester linkage and the release of a water molecule.

Identify monomer, dimer, polymers, give examples.

Monomers: A molecule that is a building block for larger molecules (polymers). For example, an amino acid acts as the building blocks for proteins. There are four main monomers: amino acids, nucleotides, monosaccharides and fatty acids. Dimers. A chemical compound composed of two identical or similar subunits or monomers. Ex: carboxylic acid, acetic acid. Polymer: a large molecule made of repeating subunits (monomers). For example, a carbohydrate is a polymer that is made of repeating monosaccharides. Ex: DNA.

Identify the monomeric structures that make up for each macromolecule group, i.e. the Glycogen, monomers are glucose; Proteins, amino acids monomers.

Proteins: are formed from different combinations of 20 amino acids. Carbohydrates: can form giant molecules by linking together chemically similar sugar monomers (monosaccharides) to from polysaccharides. Nucleic acids: are formed from four kinds of nucleotide monomers linked together in long chains. Lipids: also form large structures from a limited set of smaller molecules, but in this case noncovalent forces maintain the interactions between the lipid monomers that are held together by covalent bonds. (glycerol, fatty acids)

Identify the structures of saturated and unsaturated triglycerides.

Saturated fatty acids, all the bonds between the carbon atoms in the hydrocarbon chain are single bonds-there are no double bonds, and pack together tightly. Unsaturated fatty acids, the hydrocarbon chain contains one or more double bonds, and are prevented from packing together tightly.

Explain how the "R" groups confer properties of an amino acid.

The R group determines the characteristics (size, polarity, and pH) for each type of amino acid.

Identify the major functional groups and describe how each affects the properties of a macromolecule that contains them.

The functional groups are: Hydroxyl; Polar, Forms hydrogen bonds with water to help dissolve molecules. Enables linkage to other molecules by condensation. Aldehyde; Polar, C=O group is very reactive. Important in building molecules and in energy-releasing reactions. Keto; Polar, C=O group is important in carbohydrates and in energy reactions. Carboxyl; Charged, acidic. Ionizes in living tissues to form COO- and H+. Enters into condensation reactions by giving up -OH. Some carboxylic acids are important in energy-releasing reactions. Amino; Charged, basic. Accepts H+ in living tissues to form -NH3+. Enters into condensation reactions by giving up H+. Phosphate; Charged, acidic. Enters into condensation reactions by giving up -OH. When bonded to another phosphate, hydrolysis releases much energy. Sulfhydryl; By giving up H, two -SH groups can react to form a disulfide bridge, thus stabilizing protein structure. Methyl; Nonpolar, important in interacting with other nonpolar molecules and in energy transfer.