Lecture 1 Eukaryotic Cells, ECF And Water Balance PDF

1 2 Prof. of Medical Biochemistry & Molecular Biology 3 By the end of the lecture the student will be able to: 1. Describe the biochemical structure of cells. 2. List the two main types of cells 3. Illustrate the sources and different types of Stem cells 4. Define apoptosis an...

1 2 Prof. of Medical Biochemistry & Molecular Biology 3 By the end of the lecture the student will be able to: 1. Describe the biochemical structure of cells. 2. List the two main types of cells 3. Illustrate the sources and different types of Stem cells 4. Define apoptosis and neoplasia. 5. Enumerate cell membrane functions. 6. Define extra and intracellular fluids 4 5  Cells consist of a collection of simple and complex organic molecules, inorganic molecules, and ions. There are also organized clusters of these called supramolecular complexes. The majority of biomolecules are composed of only 6 chemical elements - C, H, O, N, S and P. 6  Prokaryotes - Small, single cell organisms lacking a membrane-bound nucleus and other subcellular compartments. Bacteria and blue-green algae are examples.  Eukaryotes - Cell or organism with membrane-bound nucleus and other well-developed subcellular compartments (organelles). Yeast, fungi, protozoans, plants and animals are eukaryotes. 7  Prokaryotes Eukaryotes 1 - Has ill defined nuclear 1- Well defined nuclear membranes membranes 2 - No or less subcellular 2- Rich in subcellular organelles as mitochondria, organelles. Golgi apparatus 8 CELL CYCLE Cells proliferate as they pass through the cell cycle and undergo mitosis. Cells destroy themselves when they are no longer needed by apoptosis. Two groups of proteins, called cyclins and cyclin-dependent kinases (Cdks), are responsible for the progress of the cell through the various checkpoints. 9 Definition of Apoptosis: it is genetically regulated form of cell death that permits the safe disposal of cells. It is a programmed controlled process of cellular self-destruction that requires certain protein releases and specific cellular signals Neoplasia: is an abnormal accumulation of cells that occurs because of an imbalance between cellular proliferation and cellular attrition. 10  STEM CELLS Stem cells: They are biological cells found in all multicellular organisms. They are responsible for the development and the regeneration of the tissue and organ systems. Stem cells are defined as clonogenic cells capable of both self-renewal and multi-lineage differentiation. 11  Sources of stem Cells 1. Embryonic stem cells (ESCs): derived from early human embros. 2. Fetal stem cells (FSCs): from placenta, membranes, amniotic fluid or fetal tissues. 3. Adult stem cell (ASCs): accessible sources of autologous stem cells in humans: 3.1. Bone marrow: 3.2. Adipose tissue: 3.3. Blood through pheresis wherein blood is drawn from the donor[similar to blood donation] passed through machine that extracts the stem cells and returns the other 12 portions of blood.  Types of stem cells: 1. Totipotent: Have the ability to become any thing from a complete human being to any type of tissue cells. 2.Pluripotent: derived from the inner mass of blastocyste and can produce number of tissue but not have the ability to produce an entire human being. Turn to any except thing Placenta 3…Multipotent: more specialized stem cells are found in adult and children e.g hemopiotic stem cells Adults that differentiate to red blood cells, white blood cells, From bone marrow platelets. 4.Unipotent: produce only one cell type with probability of self-renewal. https://drive.google.com/file/d/1S6tXjKdwfXLxkQ7aCSGUFve0eeJe1pI7/view? usp=drive_link 13 Overview about cell chemical composition Hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus normally makeup the main mass of living cells. Ninety-nine percent of the molecules inside living cells are water molecules. Cells normally contain more protein than DNA. Non-essential lipids can be generated from acetyl-CoA. Certain amino acids and unsaturated fatty acids, various inorganic elements (minerals) are essential. Most of diseases in animals are manifestations of abnormalities 15 in biomolecules, chemical reactions, or biochemical pathways. Model structure of cell membrane 16 Membranes are thin envelopes that define the volume of cells and define cellular organelles. They serve a number of essential cellular functions: 1- Membranes constitute the boundaries of cells and intracellular organelles. They provide a surface where many important biological reactions, processes occur and interaction between cells. 2- Membranes have proteins that mediate and regulate the transport of metabolites, macromolecules and ions. 3- Hormones and many other biological signal molecules and regulatory agents exert their effects via interaction with membranes 17 which have specific receptors. 4- Photosynthesis, electron transport, oxidative phosphorylation, muscle contraction and electrical activity all depend on membranes and membrane proteins. 5- Plasma membranes exchange material with extracellular environment by exocytosis and endocytosis. 6- Intracellular membranes form many of the morphologically distinguishable organelles e.g mitochondria, Golgi complex, endoplasmic reticulum, lysosomes and nuclear membranes. 18  Water Balance WATER accounts for about 50 – 60% of an average person’s weight. Fat tissue has lower percentage of water and women tend to have more fat, so the percentage of water in the average woman is lower (50 to 55%) than it is in the average man (60%). The percentage of water is also lower in older and obese people. 19  A 70 kilogram man has about 45 liters of water in  his body: 1. Intracellular Fluid (2/3 of body water) = 30 L 2. Extracellular Fluid (1/3 of body water) = 15 L Interstitial Fluid (4/5 of extracellular fluid)= 12 L Plasma (1/5 of extracellular fluid) = 3 L 20  How the body can regulates water? 1. The body obtains water primarily by absorbing it from the digestive tract in addition to the small amount of water produced during metabolism. 2. Water intake must balance water loss to maintain water balance and -- to protect against dehydration, the development of kidney stones, and other medical problems. 3. Healthy adults should drink at least 1.5 - 2.0 liters/day. 4. Drinking too much is better than drinking too little, because excreting excess water is much easier for the body than conserving water. 5. Antidiuretic hormone (ADH): secreted from the posterior lobe of pituitary gland maintain water at equilibrium through regulation of water absorption from the distal convoluted tubules of the kidney according to body needs. 5. The body regulates the amount of water in each of intracellular and extracellular compartments by moving water between these areas to keep 21 (Osmolality ) the amount in each area relatively constant. Reference 1- Harpers illustrated Biochemistry 2- Lippincott illustrated reviews integrated systems 22 23