Macromolecules Lecture Review

Flashcards for reviewing key concepts about macromolecules, including carbohydrates, lipids, and their properties, as well as their synthesis, breakdown, and biological functions.

How is food energy measured, and what is its equivalent in calories?

Food energy is measured in Calories (capital C), which equals 1000 calories or 1 kilocalorie (kcal).

What are macromolecules?

Macromolecules are large, complex molecules composed of smaller molecules, possessing emergent properties like forming large structures, catalyzing reactions, and signaling/recording information.

What are the four major classes of biological macromolecules?

The four major classes are Carbohydrates, Lipids, Proteins, and Nucleic Acids.

What are most macromolecules built from, and what links them together?

Most macromolecules are polymers, built from repeating monomers linked by covalent bonds.

Which class of biological macromolecules is an exception to being a polymer of single monomers?

Lipids are an exception to being polymers of single monomers.

What type of reaction forms polymers from monomers?

Monomers form polymers by condensation reactions called dehydration reactions, which remove a water molecule.

What type of reaction disassembles polymers into monomers?

Polymers can disassemble by hydrolysis, a reaction that adds a water molecule to break a bond.

How is the immense variety of polymers achieved from a small set of common monomers?

Great diversity comes from the arrangement of monomers into polymers, allowing an immense variety to be built from a small set (40-50 common types).

What are enzymes and what is their role in macromolecule reactions?

Enzymes are biological molecules, mostly proteins, that catalyze (speed up) hydrolysis and dehydration reactions, with specific enzymes for each macromolecule class.

What is the general formula for carbohydrates, and what is their primary function?

Carbohydrates are represented by the general formula (CH2O)n, with a Carbon:Hydrogen:Oxygen ratio of 1:2:1. They primarily provide immediate and short-term energy to the body in the form of glucose.

What are the three main subtypes of carbohydrates?

The three main subtypes are Monosaccharides, Disaccharides, and Polysaccharides.

What are monosaccharides and provide three examples that are structural isomers of a hexose?

Monosaccharides are the simplest water-soluble sugars. Examples include Glucose, Galactose, and Fructose (all C6H12O6).

How are disaccharides formed?

Disaccharides consist of two monosaccharides joined by a glycosidic linkage.

Name three common disaccharides and their common names.

Lactose (milk sugar), Maltose (used for brewing), and Sucrose (common table sugar).

What are polysaccharides?

Polysaccharides are long chains of monosaccharides joined by glycosidic linkages, which can be branched or unbranched and may consist of multiple types of monosaccharides.

What are the major storage polysaccharides in plants and animals, respectively?

Starch is the major storage polysaccharide in plants, while Glycogen is the major storage form of glucose in animals.

What is cellulose and where is it found?

Cellulose is a polymer of glucose that forms a major component of the tough walls enclosing plant cells.

Why can most organisms digest starch but not cellulose?

Most organisms have enzymes to break the α 1-4 glycosidic linkages found in starch but lack enzymes for the β 1-4 glycosidic linkages found in cellulose.

What is chitin, and what makes it unique among structural polysaccharides?

Chitin is an important structural polysaccharide found in the exoskeleton of arthropods and fungal cell walls. It is unique because it contains nitrogen.

What are lipids and what is their defining characteristic?

Lipids are a diverse group of non-polar hydrocarbons without repeating monomers, primarily characterized by being hydrophobic (water-fearing).

What are the primary functions of lipids?

Lipids serve as long-term energy stores, provide insulation, act as building blocks for some hormones, and are important components of cellular membranes.

What smaller molecules make up a fat (triglyceride)?

A fat (triglyceride) is made from two kinds of smaller molecules: glycerol and fatty acids.

What is an ester linkage?

An ester linkage is a covalent bond formed between an acid and an alcohol (RCOOR'), often found in fats.

Describe saturated fatty acids.

Saturated fatty acids have the maximum number of hydrogen atoms possible, no double bonds between carbons, and are typically solid at room temperature due to tight packing.

Describe unsaturated fatty acids.

Unsaturated fatty acids have one or more double bonds between carbons, which cause 'kinks' due to cis double bonds, leading to loose packing and typically being liquid at room temperature.

What are trans fats and why are they associated with health risks?

Trans fats are unsaturated fats with hydrogens on opposite sides of the double bond (trans configuration). They are often created through hydrogenation of vegetable oils and are associated with increased LDL cholesterol (bad cholesterol) and heart disease risk.

What are essential fatty acids and provide an example.

Essential fatty acids are required by the body but cannot be synthesized internally, so they must be obtained through diet. An example is omega-3 fatty acid.

What is the unique structure of phospholipids that allows them to form cell membranes?

Phospholipids have a hydrophilic 'head' (containing a phosphate group) and two hydrophobic 'tails' (fatty acids), making them amphipathic molecules that form a bilayer in cell membranes.

What are steroids characterized by, and what key molecule is an example?

Steroids are lipids characterized by a carbon skeleton consisting of four fused rings. Cholesterol is a key example, found in cell membranes and serving as a precursor for hormones.

What are anabolic steroids and why are they dangerous?

Anabolic steroids are synthetic variants of the male hormone testosterone that are abused by some athletes, leading to serious health consequences and ethical issues in sports.

What are waxes composed of and what is their primary function?

Waxes are long fatty acid chains esterified to long chain alcohols. They are hydrophobic and primarily function to prevent water from sticking to surfaces, such as on feathers of aquatic birds or plant leaves.