Characteristics of Living Organisms PDF

Characteristics of Living Organisms Overview: Living organisms exhibit specific characteristics that distinguish them from non-living entities. These include movement, respiration, sensitivity to stimuli, growth and development, reproduction, excretion, and nutrition, which are...

Characteristics of Living Organisms Overview: Living organisms exhibit specific characteristics that distinguish them from non-living entities. These include movement, respiration, sensitivity to stimuli, growth and development, reproduction, excretion, and nutrition, which are essential for survival and adaptation in their environments. Movement: o Action causing a change in position or place. Respiration: o Chemical reactions breaking down nutrient molecules to release energy. Sensitivity: o Ability to detect environmental changes (stimuli) and respond accordingly. Growth and Development: o Growth: Permanent increase in size/mass through cell number/size increase. o Development: Increase in complexity as an organism matures. Reproduction: o Process of producing offspring of the same kind. Excretion: o Removal of toxic materials, metabolic waste products, and excess substances from organisms. Nutrition: o Intake of organic substances and mineral ions for growth and tissue repair. Cellular Organization: o Unicellular organisms consist of one cell; multicellular organisms consist of many cells. o Levels of organization: Cells → Tissues → Organs → Organ Systems. Types of Organisms: o Eukaryotic Organisms: Animals, plants, fungi, protoctists (cells with nucleus and membrane-bound organelles).  o Prokaryotic Organisms: Bacteria (lack nucleus and membrane-bound organelles). Animal Characteristics: o Multicellular, no cell walls or chloroplasts, store glycogen, possess nervous coordination, capable of movement. Classification of Living Organisms Overview: The classification of living organisms organizes them into groups based on shared characteristics. It includes five major groups: Animals, Plants, Fungi, Protoctists, and Bacteria, with distinctions between eukaryotic and prokaryotic organisms. Eukaryotic Organisms: o Contain a nucleus and membrane-bound organelles (e.g., mitochondria, chloroplasts). o Include Animals, Plants, Fungi, and Protoctists. Prokaryotic Organisms: o Lack a nucleus and membrane-bound organelles. o Primarily consist of Bacteria. Viruses: o Neither classified as prokaryotic nor eukaryotic. o Composed of genetic material surrounded by a protein coat; cannot carry out metabolic processes independently. Animal Classification: o Multicellular organisms without cell walls or chloroplasts. o Store carbohydrates as glycogen and exhibit nervous coordination for movement. Plant Classification: o Multicellular organisms with cell walls made of cellulose. o Capable of photosynthesis due to the presence of chloroplasts; store carbohydrates as starch.  Fungi Classification: o Can be unicellular (e.g., yeast) or multicellular (e.g., Mucor). o Have cell walls made of chitin and obtain nutrients through saprotrophic nutrition. Protoctists Classification: o Mostly unicellular eukaryotes that do not fit into other kingdoms. o Examples include algae and amoebas. Bacteria Classification: o Microscopic, single-celled prokaryotes with cell walls made of murein/peptidoglycan. o Some possess flagella for movement and can have plasmids containing DNA. Biological Molecules and Enzymes Overview: Biological molecules are essential compounds that make up living organisms, including carbohydrates, proteins, and lipids. Enzymes are specialized proteins that catalyze biochemical reactions, playing a crucial role in metabolism by facilitating the conversion of substrates into products. Carbohydrates: o Composed of carbon, hydrogen, and oxygen. o Simplest units include monosaccharides (e.g., glucose). o Disaccharides (e.g., sucrose) form from two monosaccharides. o Polysaccharides (e.g., starch, glycogen, cellulose) consist of many monosaccharides. o Functions: Energy source (glucose), storage (starch, glycogen), structural component (cellulose). Proteins: o Made of amino acids (20 different types). o Amino acids link to form polypeptides/proteins with unique sequences.  o Functions: Growth, tissue repair, transport (e.g., hemoglobin for oxygen). Lipids: o Composed of carbon, hydrogen, and oxygen. o Basic structure includes 1 glycerol and 3 fatty acids. o Functions: Energy storage, insulation, cell membrane structure. Enzyme Function: o Operate on the lock-and-key hypothesis. o Each enzyme has a specific active site complementary to its substrate. o Formation of an enzyme-substrate complex leads to product formation while the enzyme remains unchanged. Factors Affecting Enzyme Activity: o Temperature: ▪ Reaction rate increases with temperature due to higher kinetic energy until optimum temperature (~40°C). ▪ Above optimum, enzymes may denature, reducing activity. o Other factors can include pH levels and substrate concentration. Food Tests: o Methods to identify biological molecules in food samples. o Common tests include Benedict's test for reducing sugars, iodine test for starch, and Biuret test for proteins. Transport Mechanisms in Cells Overview: Transport mechanisms in cells are vital for maintaining homeostasis and facilitating the movement of substances across cell membranes. These mechanisms include diffusion, osmosis, and active transport, each with distinct processes and energy requirements. Diffusion: o Definition: Net movement of molecules from higher to lower concentration down the concentration gradient due to random motion.  o Importance: Essential for gas exchange (e.g., oxygen and carbon dioxide) and nutrient absorption. o Factors Affecting Rate: ▪ Temperature: Higher temperature increases kinetic energy, enhancing diffusion. ▪ Surface Area to Volume Ratio: Larger ratios increase diffusion rates (e.g., root hair cells). ▪ Concentration Gradient: Greater gradients lead to faster diffusion. ▪ Distance: Longer distances decrease diffusion rate. Osmosis: o Definition: Movement of water molecules from high water potential to low water potential through a partially permeable membrane. o Characteristics: Passive process that does not require energy; crucial for maintaining cell turgor and fluid balance. o Context: Occurs when two solutions are separated by a semi-permeable membrane. Active Transport: o Definition: Movement of particles from lower to higher concentration against the concentration gradient using energy from respiration. o Energy Requirement: Requires ATP produced during cellular respiration; cells with high active transport have many mitochondria. o Mechanism: Involves membrane carrier proteins that change shape to transport ions/molecules. o Examples: Uptake of minerals by root hair cells, glucose absorption in intestines, and kidney nephron function. o Factors Affecting Active Transport: ▪ Temperature: Affects enzyme activity and respiration rate, influencing energy availability. ▪ Oxygen Concentration: Necessary for aerobic respiration to release energy for active transport.  Factors Affecting Diffusion and Active Transport: o Temperature: Influences molecular movement and energy production. o Oxygen Availability: Critical for energy production in active transport. o Environmental Conditions: Excess water can hinder mineral uptake in roots due to lack of oxygen for respiration. Cell Differentiation and Stem Cells Overview: Cell differentiation is the process by which unspecialized cells, such as embryonic stem cells, develop into specialized cell types with distinct functions. This process is crucial for the formation of various tissues and organs in an organism, and it involves both embryonic and adult stem cells. Zygote Formation: o Occurs when a sperm cell fertilizes an egg cell. o The zygote divides by mitosis to form an embryo, initially consisting of identical cells. Embryonic Stem Cells: o Found in early embryos; capable of differentiating into any cell type. o Can divide continuously through mitosis, providing a source for all specialized cells in the body. Adult Stem Cells: o Remain in differentiated organisms; have limited differentiation potential. o Example: Bone marrow stem cells can produce only blood cells. Differentiation Process: o As the embryo develops, cells begin to take on specific roles (e.g., skin, muscle, blood). o Influenced by genetic and environmental factors, leading to specialized structures and functions. Stem Cell Therapy: o Utilizes stem cells to treat or prevent diseases and repair damaged tissues.  o Advantages: ▪ Embryonic stem cells can differentiate into any cell type, offering broad therapeutic potential. ▪ Autologous stem cells (from the patient) reduce the risk of transplant rejection. o Disadvantages: ▪ Adult stem cells have limited differentiation capabilities. ▪ Ethical concerns regarding the use of embryonic stem cells, including the destruction of embryos. Specialized Cells: o Examples include ciliated cells (sweep mucus), root hair cells (absorb water/minerals), xylem vessels (transport water), and nerve cells (transmit impulses). Each has adaptations suited to its function. Cell Structure and Function Overview: Cell structure and function encompass the various components of cells, their organization, and how they work together to sustain life. Cells are the basic units of living organisms, with distinct structures that perform specific functions essential for survival and growth. Cell Membrane: o Elastic structure made of proteins and fats. o Partially permeable; controls entry and exit of substances. Cytoplasm: o Jelly-like substance composed of water and salts. o Site of chemical reactions; holds organelles in place. Nucleus: o Contains DNA; regulates cell activities including division. Vacuoles: o Small in animal cells (vesicles); large in plant cells (large vacuoles).  o Stores water, food, wastes, and pigments; supports plant cell shape by pressing against the cell wall. Chloroplasts: o Contains chlorophyll; site of photosynthesis. o Converts light energy into chemical energy (glucose) and stores starch. Cell Wall: o Rigid structure providing support; prevents bursting from excess water absorption. o Fully permeable, allowing all molecules to pass through. Mitochondria: o Known as the powerhouse of the cell; site of aerobic respiration. o More abundant in active cells (e.g., muscle cells) due to higher energy demands. Ribosomes: o Sites of protein synthesis; join amino acids to form proteins. Levels of Organization: o Cell: Basic unit of life; contains organelles. o Tissue: Group of similar cells performing a shared function (e.g., muscle tissue). o Organ: Collection of different tissues working together (e.g., stomach). o Organ System: Group of organs with related functions (e.g., digestive system). Cell Differentiation: o Process where embryonic stem cells develop into specialized cells (e.g., skin, muscle, blood cells). o Adult stem cells remain after differentiation, capable of producing various cell types.