BSc Medical Sciences: Human Biology Module (Cell Structure and Functions) PDF

BSc Medical Sciences: Human Biology Module Topic: Cell Structure and Functions  Learning Outcomes i. Describe the cell theory and its significance in biology. ii. Classify cells by their internal organisation and explain the differences between prokaryotic and e...

BSc Medical Sciences: Human Biology Module Topic: Cell Structure and Functions  Learning Outcomes i. Describe the cell theory and its significance in biology. ii. Classify cells by their internal organisation and explain the differences between prokaryotic and eukaryotic cells. iii. Relate cell structure to function, including the roles of different organelles. iv. Discuss the structure of the plasma membrane and its functions. v. Explain passive and active movements across the cell membrane, including diffusion, osmosis, and active transport. vi. Define osmosis and relate it to the actions of isotonic, hypotonic, and hypertonic solutions.  Introduction to Cell Theory Cell theory is one of the fundamental principles of biology, positing that all living organisms are made up of cells. It asserts that new cells are created from existing cells, ensuring a continuous line of genetic information passed through cell division. This theory has been instrumental in developments across medical and biological sciences. ① Cell theory made of cells all living things. are basic unit of life ②. Cells are ③ New cells come from existing cells - Historical Development of Cell Theory Developed in the mid-19th century, cell theory was formulated through the contributions of discovered plant cells several scientists, notably Matthias Schleiden - discovered animal cell and Theodor Schwann. They proposed that plants and animals are made of & cells, setting the foundation for modern cell biology and = genetics.  Major Components of Cell Theory 1. All living organisms are composed of one or more cells. Living things mode up of cells are 2. The cell is the basic unit of life, responsible for all life's processes. Cells smallest unit of life are - already exist before 3. All cells arise from-pre-existing, living cells, supporting the continuity of life. New cells comes from old cells -  Cell Classification Cells are primarily classified into two categories: prokaryotic, which lack a defined nucleus, and eukaryotic, which have a defined nucleus and complex organelles. This classification helps biologists understand and predict cellular behavior and interactions. cells Prokaryotic cells Eukaryotic Have nucleus and organelles No nucleus > - => and complex > - smaller and simpler > - Larger more Example : Plants , animals Bacteric. > - > - Example :  Prokaryotic vs. Eukaryotic Cells Prokaryotic cells are generally smaller and simpler, lacking a nucleus and most organelles. Eukaryotic cells are larger, with complex structures including a nucleus and various organelles, facilitating diverse functions within the cell. > # Feature. Prokaryotic Eukaryotic Size, Small, Large Nucleus, Absent, Present Organelles, Few, Many Eukaryotes vs Prokaryotes Cell Organelles and Their Functions Eukaryotic cells contain numerous organelles such as the nucleus, mitochondria, ribosomes, endoplasmic reticulum, and Golgi apparatus. Each plays a critical role in the cell's physiology, from genetic management to energy production and protein synthesis. Cellular evolution  Nucleus and Genetic Material ① Control ( The nucleus serves as the command center of ② genetic materials (DNA). - the cell,()housing ③ It controls cellular activities by regulating gene expression, crucial = for cell growth, division, and specialization. 2-  Mitochondria and Energy Production V - - Mitochondria are theCcell's > - powerhouses, converting nutrients into energy (ATP) through cellular respiration. This energy is essential for - - powering various cellular processes and - functions. -  Endoplasmic Reticulum and Protein - Synthesis - - The endoplasmic reticulum (ER) is subdivided - into rough ER, which is involved in protein synthesis and folding, > and Ssmooth ER, which - - plays a role in lipid synthesis and detoxification processes within the cell. ER is like roads Rough ER- > makes and folds proteins built where thing are Smooth ER- > Makes lipids and detoxifies chemicals and transported.  Golgi Apparatus and Protein Sorting - Following synthesis in the ER, proteins are transferred to the Golgi apparatus. Here, they - are modified, sorted, and packaged into - vesicles for distribution to their intended destinations within or outside the cell. Golgi is post office modifies , sorts , and ships proteins.  Lysosomes and Waste Processing Lysosomes are filled with enzymes that break down cellular - waste,x damaged organelles,S and foreign particles. This process is vital for - - maintaining cellular health and preventing - buildup of waste products. - - Lysosomes - are break like down recycling centers - waste > clean - up wastes-  Cytoskeleton and Cell Shape - - The cytoskeleton is a network of fibers that not only maintains the shape of the cell but also facilitates movement, both internally - (transport of organelles) and externally (cell - motility and muscle contraction). - - - > - internally organell ⑪ Maintains cell shape and helps with movement - - external cell  Summary notes Proteins Integral > - transport 1 Cell theory Plasma membrane Peripheral Signaling. > - - All living things are made of cells. - structure - Cells are smallest unit of life. > - phospholipid bilayer with hydrophilic head > - New cells come from pre-existing alls and hydrophobic tails Type of cells. - Proteins , cholesterol , and Carbohydrate Prokaryotic cells ! simple , no nucleus are embedded. Eukaryotic cells : complex , with a nucleus - Functions Organelles and their function - Act as a barrier, controls what enter and exit. - Facilitates transport (Passive & Active Nucleus : stores DNA , controls call - Helps cell communicate and recognize each other Mitochondria : Produces energy (ATR) - provides structural support. Ribosomes : Makes proteins Endoplasmic Reticulum : Transport mechanism Rough ER : Protein synthesis Smooth ER : Lipid production and detoxification Passive Transport : No energy needed I diffusion & osmosis Golgi Apparatus: Modifies and packages protein Active Transport : Requires energy /pumps / Vesicles Lysosomes Breaks down :. waste Cytoskeleton Gives shape with : : and help movement Osmosis and water balance Endombotic they Hypotonic Water enters the all (swells is : Isotonic : water moves equally /Balanced - close relation bu two where both hypertonic : Water leaves the cell (Shrinks organisms benefits. - Mitochondria Schloroplast have - Larger cells engulfed smaller cells > Double membranes their own DNA -> A symbiotic relationship forms - > - Smaller cells become organelles like mitochondria Schloroplast - Reproduce independently - prokaryotic-like ribosones-  Worksheet Classifying Cells and Labelling Organelles Worksheet Part 1: Classification of Cells 1. Classify the following cells as either Prokaryotic or Eukaryotic: i. A bacterial cell – Prokaryotic ii. A human liver cell – Eukaryotic iii. An amoeba – Eukaryotic iv. A plant cell – Eukaryotic 2. State three differences between prokaryotic and eukaryotic cells. 3. List two examples of prokaryotic organisms and two examples of eukaryotic organisms. Bacteria , Prokaryotic organisms : Archaea Humans plants Enkayotic organisms : ,  Plasma Membrane Structure -Interlayer The plasma membrane consists of a phospholipid bilayer with embedded proteins - that manage the entry and exit of substances, allowing the cell to maintain homeostasis and communicate with its environment. ⑦ Phospholipid Bilayer Hydrophilic heads: Face water Hydrophobic tails : Avoid water ② Proteins Integral : Transport Peripheral : Signaling ③ cholesterd Stabilizes the membrane ④ Carbohydrate cell communication and recognition.  Functions of the Plasma Membrane Beyond its role as a barrier, the plasma membrane's embedded proteins aid in transport, signal transduction, and cellular adhesion, pivotal for cellular communication and coordination. Barrier Control entery/exit of substance Transport : :- moves - materials via and active transport. passive Communication Sends and : receives signals - Recognition : identifies other calls - Support : Provides structure and shape.  Transport Mechanisms Across Cell Membranes Cells employ various transport mechanisms to move substances across the plasma membrane. These include passive transport (diffusion, facilitated diffusion, osmosis) and active transport (pumps and vesicular transport).  Passive vs. Active Transport without energy Requires energy Passive transport relies on the concentration gradient and does not require energy, whereas active transport requires energy to move substances against their concentration gradient, critical for maintaining cellular concentrations of ions and molecules. 1. Passive transport Diffusion : High- > Low concentration Osmosis : water movement facilitated diffusion Proteins ! help molecules across. Osmosis and Water Balance in Cells Osmosis is a special case of diffusion, where water moves across a semipermeable membrane from an area of lower solute - concentration to higher concentration. This process is crucial for maintaining cell volume and pressure.  The Importance of Cell Theory in Modern Biology Understanding cell theory is essential for all areas of biology and medicine. It informs research into infectious diseases, genetic disorders, and therapies, linking microscopic cellular processes with large-scale biological functions.  Worksheet Worksheet: Labelling the Plasma Membrane Components Instructions: Study the diagram of the plasma membrane provided below. Label each of the following components in the diagram: form doublelayerof i. Phospholipid bilayer: the molecules one ii. Hydrophobic tails : The inner part of bilayer (water fearing) iii. Hydrophilic heads The · outer part of bilayer (water loving) iv. Integral proteins Span across membrane , act as a channel or transporter. assist v. Peripheral proteins Found on the surface of membrane , in signaling. vi. Cholesterol molecules Found within the bilayer , stabilize the membrane vii. Glycoproteins Proteins with carbohydrate chains, help in cell recognition. viii. Glycolipids Lipids with carbohydrate chains, help in communication. ix. Protein channels Allow specific substances to pass through the membrane - Diagram:  Case studies Case Study Handout: Application of Cell Theory and Membrane Transport Case Study 1: Dehydration and Electrolyte Imbalance Scenario: A 25-year-old athlete collapses after running a marathon in hot, humid conditions. The paramedics suspect that the collapse was due to dehydration and electrolyte imbalance. Upon examination, they noticed that the athlete had been drinking only water during the race and had not consumed any electrolyte-replenishing fluids. Tasks: 1. Group Discussion: i. Discuss how cell theory explains the importance of maintaining proper electrolyte and water balance in cells. cell needs balance to function ii. Using the concept of osmosis, explain how drinking only water, without replacing lost electrolytes, could lead to cell dysfunction in this case. water enter and cause swelling 2. Membrane Transport Mechanisms: i. How does osmosis play a role in the dehydration and electrolyte imbalance seen in this athlete? water moves into thecell ii. Discuss the role of passive and active transport mechanisms in maintaining cellular homeostasis, particularly in muscle cells during intense physical activity. Passive > diffusion - , Active > lon pumps -. 3. Group Activity: i. Propose a solution to prevent dehydration and electrolyte imbalance during long-distance races. Drink electrolyte fluid ii. Explain how this solution would help maintain proper osmotic balance and cell function. Prevents 4. Presentation: swelling shrinking or i. Present your findings and solution to the class, focusing on how cell structure and membrane transport principles apply to this real-life scenario. Osmosis and ion props regulate balance - Group discussion i cell states that cells to function theory are basic unit of life. for cells properly their internal lwater environment and electrolytes) must be balanced. is without Drinking only water electrolytes creates hypotonic. environment water enters the cells , causing them to swell and potentially burst , leading to dysfunction. 2 i Osmosis cause the water to move into the cells when the surrounding is hypotonic disturbing balance and salt water. in Passive transport : allows ions like Nat and kt to diffuse naturally Active transport : uses energy (ATP) to pumpions (sodvim-potassium) pump maintaining balance during muscle contraction. 3. i Drink electrolyte-rich fluid to replace both Salt and water loss through sweat in Electrolyte fluids maintain isotonic environment preventing , water from rushing into or out of thecell keeping then stable. ⑪