G Biology

• Cell membrane or plasma membrane is made of phospholipids and serves as a boundary between what is inside the cell and its external environment.
• Cytoplasm is the liquid portion of the cell where organelles are suspended.
• Cell wall is an extra layer of membrane that protects the cell and provides structural support, made of cellulose (plant cell) and chitin (fungal cells).
• Cytoskeleton is made of complex proteins (protein filaments) including Microtubules, Intermediate Filaments, and Microfilaments.
• Centriole is present only in animal cell and is produced in Centrosomes, aiding in cell division.
• Ribosomes produce polypeptide, are free floating or attached to ER, contain genetic material and are the command center of the cell, covered with a nuclear membrane.
• Endoplasmic reticulum forms sacs called “cisternae” and is divided into Smooth ER for storage and synthesizes lipids, and Rough ER for synthesis and packaging of proteins.
• Golgi apparatus forms sacs like ER for packaging and transporting of molecules in the cell, collecting molecules to form macromolecules.
• Phloem is also responsible for transporting photosynthetic products like carbohydrates, and is composed mainly of living cells: sieve elements, companion cells, and parenchyma cells.
• Vascular bundles → vascular cambium → secondary xylem and phloem.
• Dermal tissue serves as the outer protective covering of the plant, and includes the epidermis, phellogen, phellem, and phelloderm.
• The epidermis originates from protoderm (apical meristem) and is the outermost layer of the plant, containing specialized cells such as hairs or trichomes, bulliform cells, and stomata.
• Vascular bundles are xylem and phloem arranged in structures.
• Secondary phloem → cork cambium or phellogen → cork cells → phellem or cork.
• Phloem is responsible for the upward transport of water and minerals from roots to shoots and leaves, and is composed of tracheary elements, fibers, and parenchyma cells.
• Periderm is formed when the epidermis differentiates further, and along with other tissues, forms periderms.
• Lysosomes break down food that enters the cell and destroy the cell when it undergoes programmed cell death.
• Peroxisome digests toxic materials.
• Mitochondria is where cellular respiration happens, contains “cristae” (inner membrane).
• Smooth muscles are not striated in appearance, involuntary, and are located in the digestive and respiratory tract, internal organs, and heart.
• Cardiac muscle is striated in appearance, involuntary, and controls the movement of internal organs.
• Types of cells present in the nervous system are neurons and glial cells.
• There are two types of adipose tissue: white adipose tissue, which is unilocular, and brown adipose tissue, which is multilocular.
• Vacuole stores nutrients, wastes, and water.
• Skeletal muscles are striated in appearance, voluntary, and are attached to bones via tendons.
• Muscle tissues are the only tissues with cells that can contract.
• Adipocytes are located in the linings of all organs, the dermis of the skin, mucous membranes in reproductive and urinary tracts, tendons, ligaments, the dermis of the skin and glands, lymph nodes and organs, bone marrow, spleen, trachea, nose, ribs, vertebral discs, joints, heart valves, ears, epiglottis, larynx, skeletal system, lymphatic system, and throughout the body.
• Adipocytes store energy in the form of fats and are also used for protection and insulation.
• There are three types of muscle tissues: smooth muscle, cardiac muscle, and skeletal muscle.
• Nervous tissue is the foremost tissue present in the nervous system and controls all bodily functions and processes.
• Plastids are specialized membrane-bound organelles in plants and algae, examples include Chloroplasts.
• Plant tissues are classified into Meristematic Tissues, Permanent Tissues, and Organ Systems.
• Meristematic tissues are areas for growth and differentiation, examples include Apical Meristem, Lateral Meristem, and Intercalary Meristem.
• Permanent tissues are derived from meristematic tissues but have lost the ability to divide, examples include Ground Tissues, Vascular Tissues, and Dermal Tissues.
• Ground tissue is considered as simple permanent tissues.
• Parenchyma is composed of thin-walled cells and is made up of cellulose and hemicellulose, vital for plants to repair wounds and damages, functions for storage, secretion, photosynthesis, and transport.
• Collenchyma is composed of mature elongated flexible thick-walled cells and is made up of mostly cellulose and pectin, supports young leaves and stems.
• Sclerenechyma is composed of mostly dead, fibrous, crystal-like cells and is made up of the polymer lignin, supports mature plant organs and is important in transportation and conduction.
• Pith and cortex originate from ground meristem (apical), are composed of parenchymatous cell (pith) and collenchymatous cell (cortex).
• Vascular tissue is considered to be complex permanent tissues, originates from provascular meristem (apical), examples include Xylem.