Lipids: Classification and Properties
Saponifiable Lipids
Saponifiable lipids contain fatty acids, which are monocarboxylic acids that may or may not be unsaturated. When subjected to alkaline hydrolysis, they undergo saponification, forming soaps (salts of fatty acids). Examples include glycerides, waxes, phospholipids, and sphingolipids.
Unsaponifiable Lipids
Unsaponifiable lipids do not contain fatty acids and therefore do not undergo saponification reactions. This group includes terpenes, steroids, and prostaglandins.
Fatty Acids
These
Read MoreIntroduction to Genetics and Lipid Metabolism
Lipid Anabolism
Lipid anabolism involves three main processes: the synthesis of fatty acids, glycerol, and triacylglycerols.
Fatty Acid Synthesis
Fatty acid synthesis occurs in the cytosol from acetyl-CoA. This process is connected to carbohydrate catabolism, β-oxidation, and amino acid catabolism. Acetyl-CoA serves as the initiator. The first step involves transferring acetyl-CoA to a 3-carbon activator, malonyl-CoA. The addition of a malonyl-CoA molecule results in a 4-carbon chain and releases
Read MoreCell Biology: Membranes, Photosynthesis, Reproduction, and More
Transport Across the Plasma Membrane
The plasma membrane selectively allows certain substances to pass through, depending on their size. Transport occurs through several mechanisms:
- Diffusion: Movement of substances from an area of high concentration to an area of low concentration across a permeable membrane.
- Osmosis: Movement of water across a semi-permeable membrane from a region of high water concentration to a region of low water concentration.
- Active Transport: Molecules are transported from
Plant Nutrition and Energy Processes
Part 1: Nutrition, Relationship, and Reproduction
Nutrition
Nutrition is the process of taking in matter and energy that the body needs to survive.
Relationship
Relationship refers to the abstraction of the information environment surrounding an organism and its use for survival.
Reproduction
Reproduction creates new life forms with similar characteristics to their parents.
Part 2: The Role of Nutrition
The role of nutrition in a living being is the integration and transformation of matter and energy to
Read MoreNervous & Endocrine Systems: Coordination and Control
Coordination Systems
Nervous System
Composed of nerve tissue, it prepares rapid, short-lasting responses. It acts through nerve impulses propagating along nerves.
Endocrine System
Composed of endocrine glands, it prepares slow, but durable responses. It acts through chemical messengers called hormones that travel through the blood to target cells or organs.
Elements of Coordination
Receptor
A structure that perceives stimuli and transmits them to nerve centers. Sensory organs are receptors that pick up
Read MoreVision and Hearing: A Biological Overview
Vision
Pupil Dilation
At night, the pupil dilates. During the day, the pupil contracts.
Insects can see ultraviolet light. Snakes can see infrared light.
Vision Impairment
Night blindness: Difficulty seeing at night due to a Vitamin A (retinal) deficiency.
Eye Structure and Function
Cornea: Allows light to enter the eye.
Anterior chamber (aqueous humor): Nourishes the cells of the cornea.
Pupil: The opening through which light enters and exits.
Iris: Contains two muscles that adjust the pupil’s size.
Lens:
Read More