IB Biology: Carbohydrates, Lipids, and Macromolecules Overview

What are carbohydrates?

A large group of organic compounds occurring in foods and living tissues, including sugars, starch, and cellulose.

What is the typical ratio of hydrogen to oxygen in carbohydrates?

2:1, similar to water.

What are the building blocks of carbohydrates?

Monosaccharides.

What are polysaccharides?

Polymers made up of many monosaccharides linked together.

What is the function of starch in plants?

Starch serves as a store of energy.

What are the two types of starch?

Amylose and amylopectin.

What is glycogen?

A polysaccharide used for short-term energy storage in animals.

What type of bond forms between glucose molecules in starch?

Glycosidic bonds between carbon-1 and carbon-4.

What is cellulose?

An unbranched polysaccharide composed of beta glucose molecules found in the cell wall of plants.

What are lipids?

A group of macromolecules that include fats, oils, and steroids, primarily composed of fatty acids and glycerol.

What are triglycerides?

Lipids formed from one glycerol molecule and three fatty acids.

What is the difference between saturated and unsaturated fatty acids?

Saturated fatty acids have no double bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.

What is the role of phospholipids in cells?

Phospholipids form the bilayer of cell membranes, providing structure and protection.

What are monomers?

Small molecules that join together to form polymers.

What is a condensation reaction?

A chemical reaction that combines two molecules, releasing a water molecule.

What is a hydrolysis reaction?

A reaction that involves the addition of water to break down a large molecule into smaller units.

What are pentose sugars?

Monosaccharides that contain 5 carbon atoms, such as ribose.

What are hexose sugars?

Monosaccharides that contain 6 carbon atoms, such as glucose.

What is the primary fuel for respiration in cells?

Glucose.

What is the significance of carbon in biological macromolecules?

Carbon's four valence electrons allow it to form diverse covalent bonds, creating complex macromolecules.

What are glycoproteins?

Proteins that have carbohydrate groups attached to them, playing key roles in cell recognition and signaling.

What does amphipathic mean?

Molecules that have both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts.

What is the role of water in hydrolysis reactions?

Water separates into -H and -OH, allowing a monomer to break off from a polymer.

What is the structure of amylopectin?

Amylopectin consists of long chains of alpha glucose with branching chains, allowing for compact storage.

What is the primary function of polysaccharides?

To store energy and provide structural support in cells.

What is the difference between alpha and beta glucose?

Alpha glucose has the hydroxyl group on carbon 1 below the ring, while beta glucose has it above the ring.

What is the significance of carbon's ability to form four covalent bonds?

It allows for the formation of complex and diverse organic molecules essential for life.

What are cellulose molecules composed of?

Long chains of beta glucose molecules bonded between carbon-1 and carbon-4.

What structural feature do cellulose molecules exhibit?

Every second beta glucose molecule is flipped, resulting in straight chains.

What are cellulose microfibrils?

Groups of cellulose molecules held together by hydrogen bonds, providing high tensile strength.

What is the role of glycoproteins in cells?

They are integral proteins with carbohydrate chains attached, involved in cell adhesion, communication, and immune response.

How do glycoproteins function as receptors?

They bind hormones, triggering changes in metabolism within the cell.

What is the significance of glycoproteins in the immune system?

They act as markers allowing the immune system to distinguish between self and non-self cells.

What are the ABO blood groups based on?

The presence of specific glycoprotein antigens on red blood cells.

What are the four categories of lipids?

Triglycerides, steroids, phospholipids, and waxes.

What composes a triglyceride?

One glycerol molecule and three fatty acid molecules.

How are triglycerides formed?

Through three condensation reactions between glycerol and fatty acids, releasing three water molecules.

What distinguishes fats from oils?

Fats are solid at room temperature and usually saturated, while oils are liquid and usually unsaturated.

What is the structure of a phospholipid?

One glycerol molecule attached to two fatty acids and one phosphate group.

What is an amphipathic molecule?

A molecule with both hydrophobic and hydrophilic regions, like phospholipids.

What happens to phospholipids in water?

They form a bilayer with hydrophilic heads facing water and hydrophobic tails facing inward.

What is the characteristic structure of steroids?

Four carbon rings and a hydrocarbon chain.

How do steroid hormones like oestradiol and testosterone function?

They can diffuse through the phospholipid bilayer due to their nonpolar and hydrophobic nature.

What is the primary function of triglycerides in living organisms?

Energy storage, providing more than twice the energy content of carbohydrates.

How do triglycerides contribute to insulation in animals?

They are stored in adipose tissue, providing thermal insulation.

What are monounsaturated and polyunsaturated fatty acids?

Monounsaturated fatty acids have one double bond, while polyunsaturated fatty acids have multiple double bonds.

What role do lipids play in energy storage?

They serve as compact forms of energy storage, with high energy content due to carbon-carbon bonds.

What is the function of glycoproteins in cell communication?

They allow neurotransmitters to bind, facilitating communication between cells.

What is the function of the carbohydrate chain on glycoproteins?

It has a specific shape that can act as an antigen.

What is the role of adipose tissue in cold climates?

It provides insulation to help maintain body temperature.

What is the significance of the immune response related to glycoproteins?

They stimulate an immune response when recognized as non-self.