Final answer:
A molecule is a saturated fat when it consists of carbon chains having only single bonds between carbons, making it fully 'saturated' with hydrogen atoms. These fats have straight chains, can pack tightly together, and are solids at room temperature.
Step-by-step explanation:
A molecule is classified as a saturated fat when it is a type of simple lipid molecule with a carbon chain bonded to the maximum number of hydrogen atoms possible. This means that each carbon atom in the chain is linked to adjacent carbons by single bonds only, without any carbon-to-carbon double bonds (C=C). Saturated fatty acids comprise these simple lipid molecules and contribute to the molecule's straight chain structure, which allows them to pack closely together. Consequently, saturated fats tend to have high melting points and are typically solids at room temperature.