Pregnancy Stages, Development & Changes: A Guide
Fertilization
The process by which two gametes fuse to create a new individual with a genome derived from both parents.
It is caused by the entry of the sperm inside the egg, which then forms a coating around it that prevents fertilization by a second sperm.
Nesting
The fertilized egg travels to the uterus and implants in the uterine membrane, which has been previously prepared by hormone action to welcome, shelter, and nourish it. At this time, the embryo consists of two distinct classes of cells:
- One
Protein Structure, Properties, and Functions
Protein Structure and Properties
Primary Structure
The primary structure of proteins is the linear sequence of amino acids. This simplest structure is crucial because it determines higher-level structures. The peptide bond’s planarity causes amino acid rotation around the alpha carbon, resulting in a zigzag pattern. The variety of possible sequences is virtually unlimited.
Secondary Structure
The secondary structure is the spatial arrangement of the amino acid sequence, a direct result of alpha carbon
Read MorePhotosynthesis and Chemosynthesis: Processes Explained
Photosynthesis
Light-Dependent Reactions
Acyclic Phase
- Photon Absorption and Water Photolysis: Photons arrive at photosystem II (PSII), exciting electrons in chlorophyll P680. These electrons are passed to an electron acceptor. To replace the lost electrons, water molecules are split (photolysis) within the thylakoid lumen, releasing oxygen and protons.
- Photophosphorylation: Electrons move through the electron transport chain, from PSII to plastoquinone (PQ), then to the cytochrome complex, and finally
The Digestive System and Biomolecules: A Comprehensive Guide
Biomolecules
Lipids
Lipids are a group of biomolecules insoluble in water and tend to float on it due to their low density. They consist of:
- Fats
- Waxes
- Phospholipids
- Steroids
Fats
Fats serve as energy reserves and protect internal organs from the cold. For example, polar bears have a thick layer of fat covering their bodies.
Waxes
Wax molecules have a protective function and are stable. Waterfowl have their feathers coated with wax, which allows them to maintain body heat and repel water.
Phospholipids
Phospholipids
Read MorePhotosynthesis, Respiration, Cell Types & Mendel’s Laws
Photosynthesis
Light-Dependent Reactions
Chlorophyll, the pigment giving plants their green color, resides within the thylakoid membranes of chloroplasts. This pigment captures light energy, exciting electrons in its molecules. This triggers a series of reactions, including the photolysis of water. Oxygen is released into the atmosphere, and hydrogen atoms are captured by organic molecules like NADP+, which becomes NADPH (used in the dark phase).
Dark Reactions (Calvin Cycle)
Occurring in the chloroplast
Read MoreThe Skeletal System: Structure, Function, and Types of Bones
The skeletal system performs several crucial functions, including:
- Mechanical Support: Provides a framework for the body and its soft tissues, maintaining body morphology.
- Postural Maintenance: Enables the body to maintain positions like standing.
- Dynamic Support: Facilitates gait, locomotion, and body movements by acting as levers and attachment points for muscles.
- Containment and Protection: Safeguards vital organs from external pressure or impact, such as the ribs protecting the lungs.
- Metabolic Storage: