B2.3 Cell Specialization

• The fusion of gametes is called fertilization, which leads to the development of a zygote.
• The zygote is a totipotent stem cell.
• Totipotent stem cells can develop into all other cell types or develop into an embryo.
• Embryonic stem cells are pluripotent, meaning that they can differentiate into all other cell types but not into an embryo.
• All cells from a multicellular organism have the same genome.
• Stem cells differentiate into specialized cells by expressing some genes and not expressing others.
• Most adult stem cells are multipotent, meaning that can form a range of closely related cells.
• Morphogens are a group of gene regulating chemicals (Transcription factors) which determine the specialized cell that develops according to their concentration.
• Morphogens are produced and released from embryo cells, and diffuse through tissues.
• Stem cells are undifferentiated cells which have an unlimited capacity to divide, and can differentiate into specialized cells.
• Stem cell niches are locations in the body where stem cells can be maintained or promoted to proliferate and differentiate.
• Specialized cells involved in the exchange of materials have adaptations to increase surface area.
• The microvilli (in red blood cells) increase the rate of absorption of nutrients and water as filtrate passes through the nephrons of the kidney.
• Gas exchange happens at the alveoli in the lungs.
• alveolar tissue is composed of two cells: ●Type I Pneumocytes are long and extremely flat cells adapted for gas exchange. ●Type II Pneumocytes are cuboid-shaped cells which secrete a surfactant that reduces surface tension in the alveoli and provides a liquid for rapid diffusion of gases.
• type II pneumocytes contain many secretory vesicles (lamellar bodies), which release the surfactant by exocytosis.
• Muscles contract and are involved in movement
• There are three types of muscle cells: Cardiac Muscle cells, Striated Muscle cells (also known as skeletal muscle) and Smooth Muscle cells
• Striated muscle is attached to the skeleton and is involved in the movement of bones
• Cardiac muscle is located in the heart, and is responsible for the continued rhythmic beating of the heart.
• both straited and cardiac muscles contain contractile myofibrils.
• Gametes are reproductive cells
• Gametes are reproductive cells
• Male gametes are sperm.
• Female gametes are eggs (ova)
• Gametes have haploid nuclei.
• When gametes fuse during fertilization, a diploid zygote is formed.