revision notes science 2024 term 3.docx

Cell theory (original and modern). 1. All organisms are composed of one or more cells and the products of these cells. 2. All cells arise from pre-existing cells 3. Cells are specialised to perform specific functions 4. In the hierarchy of biological organisation, cells are the simplest...

Cell theory (original and modern). 1. All organisms are composed of one or more cells and the products of these cells. 2. All cells arise from pre-existing cells 3. Cells are specialised to perform specific functions 4. In the hierarchy of biological organisation, cells are the simplest collection of matter that can live. The [modern] version of the cell theory also includes: - Energy flow occurs within cells - Hereditary information (DNA) is passed on from cell to cell - All cells have the same basic chemical composition Different types of cells (animal, plant and bacteria). - Fungal Cells - Protist Cells - Archaeal Cells - Sperm Cells - Egg Cells (Ova) Cell organelles and other structures. - Cell Membrane - security - Nucleus - Control centre - Vacuole - Storage - Rare in animal cells - 80% of plant cell - Cytoplasm - Jelly thing - Cell wall - Plant cells 1. Cells -- the basic unit of life 2. Tissue -- Group of cells working together 3. Organ -- Group of tissues working together 4. Organ System -- Group of organs working together 5. Organism -- Any living thing made of one or more cells The INTERDEPENDENCE of organ systems. Organ systems work together to maintain the overall health and function of the organism. - Organ systems in the body are interconnected and rely on each other to perform their functions effectively. - For example, the circulatory system delivers nutrients produced by the digestive system to cells throughout the body. This interdependence ensures the body functions as a coordinated unit. The Three 'Dimension of health'. - Physical - Mental - Social What is disease? - A disease is an [abnormal condition] affecting the structure or function of an organism, not caused by external injury. - Diseases are characterized by specific [signs and symptoms.] - They can be caused by [external factors] (e.g., pathogens) or [internal dysfunctions]. - In humans, the term encompasses conditions that lead to [pain, dysfunction, distress, social issues, or death.] - Diseases can impact individuals [physically] and [mentally], affecting their [lifestyle and quality of life.] - [There are four main types of disease: ] - Infectious diseases,  - diseases are caused by PATHOGENS. - Chickenpox - Covid-19 - HIV/AIDS - Deficiency diseases, - Diseases that occur due to lack of nutrients [over a long period] - Survy - rickets - Hereditary diseases (could be genetic or non-genetic), - genetic in origin. - Cystic fibrosis - Haemophilia - and physiological diseases. - a condition in which the organs in the body malfunction causes illness. - Diabetes - Asthma - cancer Types of pathogens and how they are spread/contracted. - Parasites - prokaryote - Viruses - Bacteria - Fungi - Droplet contact - Sneezing, coughing - Direct physical contact - Indirect contact - Contaminated surface How viruses cause infection/disease in their host. - Viruses make us sick by killing cells or disrupting cell function.  - Viruses also use our bodies to reproduce... - They do this by invading our body cells, hijacking the machinery within the cell that makes proteins, and instead tricking our cells into make more viral particles. - The infected cell becomes filled with newly formed viral particles, and releases these viral particles so they can infect more cells and repeat the process. First, second and Third line of defence. - First - physical "BARRIERS & TRAPS" which resist entry or try to trap pathogens. - Second - refers to your immune system's "INNATE RESPONSE" to pathogens. This part of your immune system quickly destroys anything is recognises are 'not belonging' - Third - also relates to your immune system, but this time it's the immunity which you build up over time, where your immune system 'learns and remembers' infections which you have had before. This is called your "ADAPTIVE RESPONSE". Innate vs. adaptive immune response (Characteristics). Characteristic Innate Immune Response Adaptive Immune Response ---------------- ----------------------------------------- --------------------------------------------- Response Time Immediate Delayed Specificity Non-specific Highly specific Key Components Physical barriers, phagocytes, NK cells B cells, T cells, antibodies Memory No memory Has memory Mechanism Barriers, inflammation, phagocytosis Antibody production, cell-mediated immunity Names and roles of the WBCs of the Adaptive Immune response. - B cells - are responsible for the recognition of specific antigens - the protein marker in the surface of pathogens which help the Immune system recognise cells as 'self' or 'non-self - produce antibodies - T cells - Helper T cells - Activate other cells, like Killer T cells. - Killer T cells - Different to NK cells, Killer T cells are specialised in attacking cells of the body infected by viruses and sometimes also by bacteria. It can also attack cancer cells. - Memory T cells - Some T cells become Memory T cells, which easily recognise the specific pathogen and remain in the bloodstream for an extended amount of time. How antibodies work. - Antibodies are proteins which have a specific shape (at their binging site) and can attach to a specific antigen and neutralise it. - are medicines that fight bacterial infections in people and animals. They work by killing the bacteria or by making it hard for the bacteria to grow and multiply. How vaccines work. Are used to prepare the Adaptive Immune response (specifically memory cells) by exposing you to the ANTIGEN (usually NOT the whole pathogen), so that if you are exposed to the pathogen in the community, your body quickly recognises and destroys the pathogen before it has the chance to make you seriously ill. Problems with the immune system (allergies) - Common allergies result when your immune system overreacts to a (usually) harmless substance\... - During an allergic response, the adaptive immune system creates antibodies and releases histamine.