Cells - Science Research Topics PDF

- : Science Research Topics :- Biology Cells : Cell theory states that : Cells make up all living things. Cells are the basic building blocks of all living things Cells are extremely small so seeing them with the naked eye is nearly impossible with the exception of an egg. Unfertilised bird eggs c...

- : Science Research Topics :- Biology Cells : Cell theory states that : Cells make up all living things. Cells are the basic building blocks of all living things Cells are extremely small so seeing them with the naked eye is nearly impossible with the exception of an egg. Unfertilised bird eggs can easily be seen with the naked eye. In fact the eggs of an ostrich is the biggest cell of them all. Cell size is measured in micrometres (μm). A micrometre is 1000x smaller than a millimetre. People, trees and fish are all multicellular. Multicellular (Eukaryotes) organisms are organisms that require more than one cell to function. Animals in the Protists and Archaea kingdoms are referred to as unicellular. Unicellular (Prokaryotes) means that there is only one cell in the organism that enables it to function. Organelle : All cells contain three common components regardless : Cell membrane - A protective layer made up of proteins that makes sure of what comes in and out of the cell. Genetical information (DNA) - Deoxyribonucleic acid (DNA) is coded information that makes up who you are and tells your organelles how to function. Cytosol - A jelly-like substance that holds all of your Organelles in place. However, only Eukaryotic cells contain Organelles (specialised structures with jobs inside cells). Nucleus - Control center of the cell where the DNA is stored. It also contains the Nucleolus which makes ribosomes. Ribosomes - Ribosomes are the smallest organelle and they make proteins according to the instructions given by the DNA. Endoplasmic Reticulum (ER) - The transport system of the cell. There are 2 parts of the ER, smooth ER which makes fats and hormones and the rough ER which is covered in ribosomes. Golgi apparatus - is the delivery system of the cell and it collects, modifies and packages molecules to be transported around or outside of the cell using vesicles. Mitochondria - is the powerhouse of the cell. It converts sugar into energy the cell can use called ATP. Lysosomes - they contain digestive enzymes that break down waste. Vacuole - A large storage place that stores water and proteins. Plants have a large central vacuole compared to an animal vacuole which has many small vacuoles. Chloroplasts - They are only found in Plant cells and they contain a green pigment called chlorophyll which allows photosynthesis. Cell Wall - Only found in plants and fungi. It is a strong outer covering that helps the cell hold its shape. Animal cells are round in shape and move around often. However plant cells are rectangular in shape and hold their shape thanks to the cell wall. Photosynthesis : Photosynthesis is the process in which plants gain energy from the sun. Chlorophyll captures sunlight and uses its energy to combine carbon dioxide and water to make glucose (a type of sugar) and oxygen. Carbon dioxide + Water → Glucose + Oxygen Body Systems Respiratory system : Air enters through the nose or mouth, travels down the trachea, and then moves into the bronchi, which branch into smaller bronchioles within the lungs. At the end of these bronchioles are tiny air sacs called alveoli, where oxygen is transferred into the blood and carbon dioxide is removed. The diaphragm, a muscle beneath the lungs, plays a crucial role by contracting and relaxing to facilitate breathing. This system ensures that oxygen reaches your bloodstream while expelling carbon dioxide from your body. Nervous system : The nervous system is your body’s command center, consisting of the brain, spinal cord, and nerves. It works by sending electrical signals between the brain and other parts of the body, allowing you to move, think, and feel. The central nervous system (CNS) includes the brain and spinal cord, while the peripheral nervous system (PNS) consists of nerves that branch out from the CNS to the rest of the body. This system controls both voluntary actions, like walking, and involuntary actions, such as breathing and heartbeat. Digestive system : The digestive system is a complex network of organs that work together to break down food into nutrients your body can use. It starts in the mouth, where food is chewed and mixed with saliva. The food then travels down the esophagus to the stomach, where it is mixed with digestive juices and broken down further. From the stomach, the partially digested food moves into the small intestine, where most nutrient absorption occurs. The liver, pancreas, and gallbladder also play crucial roles by producing enzymes and bile to aid digestion. Finally, any undigested food passes into the large intestine, where water is absorbed, and the remaining waste is excreted through the rectum and anus. Circulatory system : The circulatory system, also known as the cardiovascular system, is essential for transporting oxygen, nutrients, and hormones to cells throughout the body and removing waste products like carbon dioxide. It consists of the heart, which pumps blood, and a network of blood vessels, including arteries, veins, and capillaries. Arteries carry oxygenated blood out of the heart to the body and veins bring deoxygenated blood towards the heart to become oxygenated blood. The right side of the heart sends blood towards the lungs to become oxygenated blood through the pulmonary artery. After the blood becomes oxygenated blood the pulmonary vein brings it back into the heart for it to be pumped into the left side to pump out into the body through the aorta. Also there are 4 parts of the heart including the right atrium and ventricle along with the left atrium and ventricle. Valves are like small doors in the heart that stop blood from flowing back into the heart. Genetics : Punnett squares : Punnett squares are a way to measure the probability of a child to carry the same trait as the parents. Alleles are different traits (H and h) Dominant allele : B : Brown eyes Recessive allele : b : Blue eyes Homozygous dominant = same dominant trait : BB Heterozygous = different trait : Bb Homozygous recessive = same recessive trait : bb Eg: A homozygous wolf with blue eyes mates with a heterozygous wolf with brown eyes. What's the chance that they produce a wolf with blue eyes ? Punnett Square Blue (b) Blue (b) Brown (B) Bb Bb Blue (b) bb bb Chance for blue eyes = 2/4 50% Transcription: Transcription is the process where a cell makes a copy of a gene from DNA into RNA. An enzyme called RNA attaches to the DNA at the beginning of a gene. RNA moves along the DNA, creating a strand of RNA by matching RNA bases to the DNA bases. When RNA reaches the end of the gene, it stops and releases the RNA strand. Translation : Translation is the process where the genetic code in messenger RNA is used to build proteins. This happens in the ribosomes, which are like tiny factories in the cell. The ribosome attaches to the RNA and starts reading it at the start codon. The ribosome moves along the RNA, adding amino acids one by one to form a protein chain. When the ribosome reaches a stop codon, it stops adding amino acids, and the new protein is released. Evolution : Adaptations : Adaptations are traits that help organisms survive and reproduce in their environments. These traits can be structural, behavioral, or physiological. For example, the long neck of a giraffe (a structural adaptation) allows it to reach leaves high in trees, while birds migrating to warmer climates during winter (a behavioral adaptation) helps them avoid harsh conditions. Physiological adaptations, like the production of venom in snakes, enable them to capture prey or defend themselves. Adaptations arise through natural selection, where individuals with advantageous traits are more likely to survive and reproduce, passing these traits to the next generation. Over many generations, these traits become more common, helping species thrive in their specific environments. Examples include camouflage in chameleons and mimicry in king snakes. Variation : Variation is essential for evolution because it provides the differences in traits that natural selection can act upon. These variations come from mutations (changes in DNA), random mating and fertilization (which mix up genes in new ways), and recombination (where chromosomes exchange genetic material during cell division). This genetic diversity helps populations adapt to changing environments, making them more resilient to challenges like diseases or climate changes. Natural selection : Natural selection is a process where organisms better adapted to their environment tend to survive and produce more offspring. This concept, introduced by Charles Darwin, is a key mechanism of evolution. Within a population, individuals have different traits (e.g., some are faster, some are better camouflaged). Resources like food and shelter are limited, so individuals must compete to survive. Individuals with traits that give them an advantage in their environment are more likely to survive and reproduce. These advantageous traits are passed on to the next generation. Over time, these traits become more common in the population, leading to gradual changes and adaptations. Ecosystems : Food Webs and Chains : A food chain outlines who eats whom. A food web is all of the food chains in an ecosystem. Each organism in an ecosystem occupies a specific trophic level or position in the food chain or web. Producers, who make their own food using photosynthesis or chemosynthesis, make up the bottom of the trophic pyramid. Primary consumers, mostly herbivores, exist at the next level, and secondary and tertiary consumers, omnivores and carnivores, follow. At the top of the system are the apex predators: animals who have no predators other than humans Diseases : Diabetes : Diabetes is a condition where your body has trouble handling the sugar in your blood. Normally, a hormone called insulin helps move sugar from your blood into your cells to give you energy. In diabetes, your body either doesn't make enough insulin or can't use it properly, so the sugar stays in your blood instead of getting into your cells. If diabetes isn’t managed well, it can lead to serious problems like heart disease, kidney damage, nerve damage, eye problems, and more. People with diabetes might need to take medicines like insulin or other drugs to help manage their blood sugar, eat healthy foods, and exercise to stay healthy. It’s like making sure all the sugar gets to the right places in your body so you can feel good and have lots of energy. Myopia : Myopia, also called nearsightedness, is when it's hard to see things that are far away, but close-up things are clear. For people with myopia, their eye focuses an image a little too early, making far-away things look blurry. If you have myopia, you might need glasses or contact lenses to help you see far away things clearly, or you might do special exercises or treatments to help. Hyperopia : Hyperopia, also called farsightedness, is when it's hard to see things that are close up, but far-away things are clear. For people with hyperopia, their focus on an image is a little too late, making close-up things look blurry. If you have hyperopia, you might need glasses or contact lenses to help you see close things clearly, or you might have special exercises or treatments to help. Cancer : Cancer is when some cells in your body grow out of control. Normally, cells grow, divide, and then die off when they're supposed to. But with cancer, these cells keep growing and don’t die off when they should. This can make lumps called tumors or spread through the blood and affect other parts of the body. There are different types of cancer, and they can happen in different parts of the body. Sometimes cancer can make you feel very sick, but doctors can treat it with medicines, surgeries, or other treatments to help get rid of the bad cells. Chemistry : Atoms : Atoms are tiny particles that we can not see with the naked eye. They make up everything in the universe. When the same type of atoms merge they create a pure substance. An element is a substance that is made up of only one type of atom. Such as iron. Iron is made of only iron atoms therefore it is a pure substance. However steel is made from iron and carbon atoms therefore it is a mixture. A compound is when two or more atoms combine using bonds which mean they are chemically bonded and can not be separated. When two different atoms don't merge chemically through bonds they create a mixture. Atoms in a mixture can be separated. Elements : Elements are the purest form of matter. The periodic table was designed by Dmitri Mandeleev in 1869 to order elements in order of their atomic weight. There are 118 elements currently discovered by humans however there is always the chance that we can find more elements. Periodic Table Groups : The periodic table is like a chart that organises all the elements in the universe. Elements in the same column are called groups and have similar properties. For example, Group 1 elements like sodium and potassium are very reactive with water, while Group 18 elements like helium and neon are gases that don't react with much at all. Electron Shell Configuration : Atoms have electrons that move around the nucleus in areas called shells or energy levels. The arrangement of electrons in these shells is called the electron shell configuration. Each shell can hold a certain number of electrons, and they fill up from the inside out. For example, the first shell can hold 2 electrons, the second can hold 8, and so on. States of Matter : Matter can exist in three main states: Solids: Have a definite shape and volume. The particles are packed tightly together, like in ice. Liquids: Have a definite volume but take the shape of their container. The particles are close but can move around, like in water. Gases: Have no definite shape or volume. The particles are far apart and move freely, like in the air. Acids and Bases : Acids and bases are substances that can change the colour of indicators, taste, and react with each other. Acids usually taste sour and can be found in things like lemons and vinegar. Bases taste bitter and feel slippery, like soap and baking soda. When acids and bases mix, they can neutralise each other and form water and a salt. Precipitation : A precipitation reaction happens when two solutions mix and form a solid called a precipitate. For example, if you mix a solution of silver nitrate with sodium chloride, you'll get a white solid of silver chloride. Combustion : Combustion is a chemical reaction that happens when something burns. It usually needs oxygen and gives off heat and light. For example, when you burn wood or gasoline, they combine with oxygen to produce carbon dioxide and water. Corrosion : Corrosion is when metals slowly get damaged by reacting with things in their environment, like water and oxygen. Rusting is a common type of corrosion, where iron reacts with oxygen and water to form iron oxide (rust).