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Concept Sheet Basic Needs and Processes of Life LS.2: The student will investigate and understand that all living things are composed of cells. 1. An organism is a living thing. You, a dog, a tree, a fish, a mushroom, an amoeba, a spider, a flower and so on all have six things in common that distinguish them as living. All living organisms: - have cellular organization (are made of cells) Remember this: - contain similar chemicals (all life on Earth is carbon based. The Living things must be able to do four most abundant elements in all living things are carbon, ALL six of these things hydrogen, oxygen and nitrogen) independently. This is why viruses, - use energy (producers, aka autotrophs, are able to transform the which exhibit many of the electromagnetic energy of the sun into chemical energy that characteristics of life, as NOT they and other living things can use) living, because they cannot - respond to their surroundings (even plants respond to their reproduce without a living host cell. surroundings. Phototropism, growing toward the light, is a plant responding to the location of the light source) - grow and develop (the process of mitosis allows organisms to grow, heal and develop) - reproduce (asexual and sexual reproduction are two ways organism reproduce. Sexual reproduction relies on meiosis) There are two main types of cells, prokaryotic, cells without a nucleus, and eukaryotic, cells with a nucleus. Prokaryotic cells are found in single celled organisms, while eukaryotic cells can be found in both single cellular and multicellular organisms. 2. All living things are made up of one or more cells. The cell is the basic unit of all life. Each cell is made up of organelles, which are small structures that perform a specific function within the cell. Many organelles are visible with a basic compound light microscope, like the ones we’ve used in class. In general, plant and animal cells have many, but not all, of the same organelles. Major Organelles in Plant and Animal Cells Organelle Function Type of Cell Controls all activities in the cell and stores DNA. A big substructure in Nucleus Animal and Plant the nucleus is the nucleolus, which is where ribosomes are made Vacuole Stores water, food and waste products Animal and Plant Performs cellular respiration, the process of releasing energy for the Mitochondria Animal and Plant cell to use – “powerhouse” Endoplasmic Provides a pathway to move materials around the cell. Two parts, Animal and Plant Reticulum (ER) smooth ER and rough ER. Rough ER has ribosomes attached to it Gel-like substance (80% water) in which the other organelles are Cytoplasm Animal and Plant suspended Allows certain materials in and out of the cell. It is selectively Cell Membrane Animal and Plant permeable, acting like a screen on a window Lysosome Contains digestive enzymes to break down materials Animal and Plant Ribosome Build proteins Animal and Plant Golgi Apparatus Packages materials to be used in other places in the cell or in other cells Animal and Plant Cell Wall Provides structure for plant cells. Surrounds the cell membrane Plant Site of photosynthesis. Contains chlorophyll, the green pigment that Chloroplast Plant give plants their green color. 3. All cells are structured, shaped, in a way to help them function best. For example, red blood cells are very small and flexible to fit through capillaries, which can be as small as one cell thick. Nerve cells can be very long. The longest nerve cell in humans is 3-4 ft long! This is short compared to nerve cells in organisms like blue whales. In general, animal cells tend to be more round in structure, as this makes them more flexible and better to move and react quickly to the environment. Plant cells, in contrast, tend to be rectangular shaped. This is due to the more ridges cell wall found in plant cells. This makes stacks of plant cells more stable and strong. 4. Robert Hooke used a type of microscope to observe a piece of cork and discovered compartments that he named cells. Anton van Leeuwenhoek is credited as the first person to make a simple microscope and with it he observed single celled organisms which he called “animalcules”. These discoveries laid the groundwork to help others research cells. Cell theory is the accumulation of the work of many scientists, but the three credited with its development are Schleiden, Schwann and Virchow. Cell theory states: - All living things are composed of cells - Cells are the basic units of structure and function of living things - All cells are produced from other cells 5. Cells are continually growing, repairing dead cells within an organism. Cells do this through a process called the cell cycle. Most of a cells time is spent in interphase; when the cell is growing and copying its DNA to prepare for replication. The second stage of the cell cycle is mitosis. Mitosis creates two new cells that are an exact copy of the original cell. It has for stages: prophase, metaphase, anaphase and telophase. This leads to the stage of the cell cycle is cytokinesis, which is when the cell pinches in the middle and Memory Trick: separates to form two To remember the steps of mitosis think “I Peed on the MAT, C? Puppies as separate cells. they grow up undergo lots of mitosis and don’t pee on your rug as much. The process has to be modified slightly to make sex cells (sperm and eggs) for sexual reproduction. The process is called meiosis (my-oh-sis). The original cell creates four daughter cells instead of two. Each cell also has half the number of chromosomes as the original cell. For example, humans have 46 chromosomes in their normal cells. Sperm and egg cells only have Memory Trick: 23 chromosomes. So when the sperm To remember the difference between mitosis and meiosis, remember that and egg combine, the resulting your toes look about the same so mitosis is replication and growth. And offspring has 46 chromosomes as meiosis is for sexual reproduction because “my, oh my, what a cute baby!” well. LS.3: The student will investigate and understand that living things show patterns of cellular organization. 6. Cell are the basic unit of life. Unicellular organisms are made up of just one cell. Bacteria are an example of unicellular organisms. Multicellular organisms are made up of many cells. Animals are examples of multicellular organisms. Cellular Organization in Multicellular Organisms: Cells Tissues Organs Organ systems Organisms A group of cells that perform the same function, like a muscle cell, are organized together to form a tissue, like a muscle. In multicellular organisms, different tissues layer together to form an organ, like a stomach. Then different organs work together to form an organ system, like the digestive system. Finally, many organ systems working together form an organisms, like a mouse. An organism is the most complex of the five levels. 7. Cells need to remove waste from cells, bring in food, as well as balance water and compound levels within and outside the cell. One process of doing this is called diffusion, which is the movement of molecules along a concentration gradient, so from an area of high concentration to an area of low concentration. When it is water molecules moving across a selectively permeable membrane, this process is called osmosis. Both diffusion and osmosis are examples of passive transport because they require no energy from the cell – they occur automatically. There is another type of transport called active transport that does require the cell to use energy because it is moving molecules against the concentration gradient. LS.4: The student will investigate and understand that the basic needs of organisms must be met in order to carry out life processes. 8. Plants and animals both have basic needs. They need water, gases, food/nutrients (energy), habitat/shelter and space. These needs need to be met in a balanced way. Having too much of one thing can be harmful, just as having too little can also be harmful. For example, if an organism has too much space they will have a hard time finding mates of the same species to reproduce; however if they have too little space, diseases can quickly spread, wiping out the population. 9. Some factors that influence the life processes include: the amount of sunlight, climate changes, and natural catastrophes (like hurricanes, earthquakes and/or floods). Humans also affect ecology by building new homes, roads and shopping centers; which destroy the natural habitats of many plants and animals and often increases pollution of the air and water. LS.6: The student will investigate and understand that the basic needs of organisms must be met in order to carry out life processes. 10. All the energy in living things originally comes from the sun. Photosynthesis is the process used by producers, like plants (also called autotrophs), to change light energy into useable chemical energy. Chlorophyll is a chemical pigment found in the chloroplasts that absorbs solar radiation. The chemical equation below shows how plants use carbon dioxide and water as a reactant. These molecules are recombined using solar energy to create the products glucose (sugar) and oxygen. The glucose is stored in the plant cells and the oxygen is released into the air. Photosynthesis is the foundation of virtually all food webs. When looking at energy pyramids, the producers are at the base, which shows that most of the energy for an ecosystem is found there. The energy stored in glucose is transferred to a primary consumer, an animal that eats the plant. Then that energy is transferred again to a secondary consumer, when another animal eats the first animal. To release the energy stored in the chemical bonds of the glucose molecule it must be broken down. This process is called cellular respiration and occurs in the mitochondria of living cells. The equation for cellular respiration is the exact opposite of photosynthesis. Both plants and animals perform cellular respiration.