B1.1 Carbohydrates and Lipids Flashcards

Review vocabulary for IB Biology B1.1 covering the properties of carbon, carbohydrate structures (monosaccharides to polysaccharides), and various types of lipids (triglycerides, phospholipids, and steroids).

Carbon Atom

An atom that contains $4$ electrons in its outer shell, allowing it to form $4$ covalent bonds with other elements and act as the backbone of every organic molecule.

Covalent Bonds

The strongest type of bond between atoms used to form stable molecules.

Macromolecule

Molecules composed of a very large number of atoms, typically formed from groups of monomers.

Condensation Reaction

A chemical process that links monomers to create polymers, such as joining amino acids into a polypeptide.

Hydrolysis Reaction

A reaction used to deconstruct polymers into monomers (e.g., polysaccharides into monosaccharides) by adding water; occurs during digestion.

Monosaccharides

The monomers of carbohydrates; common examples include glucose, pentoses ($5$ carbon rings), and hexoses ($6$ carbon rings).

Glucose

A widely used hexose monosaccharide that is soluble, stable, and yields energy when oxidized for respiration.

Polysaccharides

Polymers made up of more than $2$ monosaccharides joined via glycosidic bonds.

Glycosidic Bond

A type of covalent bond that links monosaccharides together, typically forming $1-4$ or $1-6$ bonds.

Starch

An energy storage compound in plants consisting of two forms: Amylose and Amylopectin.

Amylose

An unbranched, helical chain of $\text{α-glucose}$ linked by $1-4$ glycosidic bonds.

Amylopectin

A branched polysaccharide of $\text{α-glucose}$ containing both $1-4$ and $1-6$ glycosidic bonds.

Glycogen

A highly branched polysaccharide used as an energy store in animals, made up of tens of thousands of $\text{α-glucose}$ subunits.

Cellulose

A structural polysaccharide in plants made of thousands of $\text{β-glucose}$ molecules linked via $\text{β } 1-4$ glycosidic bonds in unbranched, linear chains.

Microfibrils

Bundles of cellulose molecules that have high tensile strength and form the basis of plant cell walls.

Inversion (in Cellulose)

The process where every alternate $\text{β-glucose}$ molecule is upside down to allow the formation of $\text{β } 1-4$ glycosidic bonds.

Glycoproteins

Proteins with an oligosaccharide chain attached, used for cell-cell recognition and as receptors.

ABO Glycoproteins

Glycoproteins found on red blood cells that determine blood type ($A$, $B$, or $O$) and affect transfusion compatibility.

Lipids

A group of non-polar organic molecules (including triglycerides, phospholipids, and steroids) that are insoluble in water but soluble in non-polar solvents.

Triglycerides

Lipids formed by the condensation of one glycerol and three fatty acids, held together by ester bonds.

Ester Bond

The covalent bond formed between a fatty acid and a glycerol molecule in a lipid.

Saturated Fatty Acid

A fatty acid with no double bonds between carbon atoms, meaning no more hydrogen atoms can be added.

Monounsaturated Fatty Acid

A fatty acid containing exactly one double bond.

Polyunsaturated Fatty Acid

A fatty acid containing two or more double bonds.

Cis-isomers

Fatty acids where hydrogen atoms are on the same side of the double bond, causing a bend in the chain and making them loosely packed (liquid at room temperature).

Trans-isomers

Fatty acids where hydrogen atoms are on opposite sides of the double bond, resulting in a straight chain that is closely packed (solid at room temperature).

Adipose Tissue

Tissue in animals where triglycerides are stored for long-term energy storage and thermal insulation.

Phospholipid

A molecule with a hydrophilic polar phosphate head and two hydrophobic non-polar lipid tails, used to form bilayers in cell membranes.

Amphipathic (Emergent Property)

The tendency of phospholipids to self-organize into micelles, liposomes, or bilayers to keep heads 'wet' and tails 'dry'.

Steroids

Hydrophobic lipids characterized by $4$ fused rings of carbon ($3$ cyclohexane rings and $1$ cyclopentane ring) with approximately $17$ carbon atoms in total.