IB Biology: Carbon, Carbohydrates, and Lipids

Flashcards on carbon chemistry, macromolecules, carbohydrates, and lipids based on the introductory biology transcript.

Covalent Bond

A strong chemical bond formed by the sharing of valence electrons between two adjacent atoms.

Macromolecules

Large molecules composed of a very large number of atoms, including polysaccharides, polypeptides, lipids, and nucleic acids.

Polymer

A large, complex molecule composed of repeating smaller subunits called monomers.

Monomer

A smaller subunit that links together with other subunits to form a polymer chain.

Condensation Reaction

A chemical reaction in which two molecules are linked together with the release of a water ($H_2O$) molecule by removing a hydroxyl group ($OH$) from one molecule and a hydrogen atom ($H$) from the other.

Hydrolysis

A reaction that breaks a polymer apart into individual monomers by splitting a water ($H_2O$) molecule to reform the hydrogen ($H$) and hydroxyl ($OH$) groups on the original monomers.

Carbohydrate

A biological molecule made of carbon, hydrogen, and oxygen atoms typically present in a $1:2:1$ ratio.

Monosaccharide

The basic single sugar subunit of a carbohydrate.

Pentose

A monosaccharide structure containing $5$ carbon atoms, such as ribose ($C_5H_{10}O_5$).

Hexose

A monosaccharide structure containing $6$ carbon atoms, such as glucose ($C_6H_{12}O_6$).

Alpha Glucose

An isomer of glucose in which the hydroxyl ($OH$) group on carbon number $1$ is oriented down, following a down-down-up-down pattern across carbons $1$ to $4$.

Beta Glucose

An isomer of glucose in which the hydroxyl ($OH$) group on carbon number $1$ is oriented up, following an up-down-up-down pattern across carbons $1$ to $4$.

Amylose

An unbranched, linear form of starch composed of a single straight chain of alpha glucose molecules linked by $1\text{-}4$ glycosidic bonds.

Amylopectin

A branched form of starch composed of alpha glucose molecules linked by both $1\text{-}4$ and $1\text{-}6$ glycosidic bonds.

Glycogen

A heavily branched polysaccharide made in animals using alpha glucose with $1\text{-}4$ and $1\text{-}6$ glycosidic bonds for energy storage.

Cellulose

An unbranched polysaccharide found in plant cell walls made of alternating inverted beta glucose molecules, forming microfibrils with high tensile strength.

Glycoprotein

A membrane structure composed of a short chain of monosaccharides (oligosaccharide) bound to a protein, used in cell recognition and blood group determination.

Oligosaccharide

A short chain of monosaccharides, such as those attached to membrane proteins to form glycoproteins.

Saturated Fatty Acid

A fatty acid chain in which all carbon atoms are connected by single bonds, allowing maximum hydrogen atoms to bond to the carbon chain.

Unsaturated Fatty Acid

A fatty acid chain containing one or more double bonds between carbon atoms.

Cis Fatty Acid

An unsaturated fatty acid isomer in which both hydrogen atoms at the double bond are oriented on the same side, creating a bend in the chain.

Trans Fatty Acid

An unsaturated fatty acid isomer in which hydrogen atoms at the double bond face opposite sides, maintaining a straight chain structure.

Triglyceride

A lipid molecule composed of a glycerol ($C_3H_8O_3$) backbone linked to $3$ fatty acid chains through condensation reactions.

Phospholipid

A lipid molecule composed of glycerol attached to $2$ fatty acid chains and a phosphate group, forming amphipathic lipid bilayers in cell membranes.

Amphipathic

The property of a molecule containing both hydrophilic (water-attracted) and hydrophobic (water-repelled) parts.

Adipose Tissue

A type of fat tissue composed of cells stuffed with triglycerides that provides long-term energy storage, thermal insulation, and shock absorption.

Steroid

A hydrophobic lipid molecule characterized by $17$ carbon atoms arranged in $4$ fused rings ($3$ cyclohexane rings and $1$ cyclopentane ring).