Biology🙂

• Living things are capable of reproducing and carrying out life processes such as respiration, movement, eating, metabolic processes, response to stimuli, growth, excretion, and eventually dying
• The basic unit of life is the cell
• Respiration involves the metabolism of energy sources (food) and the use of these for essential life processes
• Movement can be in the form of locomotion or responses to environmental stimuli such as tropism and taxis
• All living things respond to environmental factors such as light, temperature, water, and gravity
• All living things are capable of physical increase in size due to increases in the size and number of cells
• Living things can reproduce their kind either vegetatively (asexual) or through sexual means
• Living things can take in solid substances, digest or accumulate them for growth
• A cell is the smallest unit that can carry out all life processes
• An organism can be made up of one or more cells
• Prokaryotic cells are about 5um in size, always unicellular, have no organized or membrane-enclosed nucleus, have single chromosomes in the cytoplasm, have 70S ribosomes, no cytoskeleton, and divide by binary fission
• Eukaryotic cells are usually larger than 10um, mostly multicellular except some Protists, have membrane-bound nucleus, have 2 or more chromosomes in the nucleus, have 80S ribosomes, always have a cytoskeleton, and divide by meiosis and mitosis
• A typical cell is made up of an outer covering, the cytoplasm, and a nucleus (or nucleoid region in prokaryotes)
• The outer covering of cells can be a cell wall or a membrane
• The cell wall of plants is made of cellulose, while Fungi have a cell wall made of chitin, and Bacteria have a cell wall of peptidoglycan
• The plasma membrane is more typical of animal cells and is a three-layered structure made up of phospholipids, glycoproteins, or glycolipids
• The cytoplasm is made up of fluid (cytosol) in which organelles are suspended, and it contains various inclusions such as stored food and secretory substances
• The nucleus controls all the activities of the cell and holds most of the genetic materials
• Plants and animal cells have differences such as the presence of plastids, lysosomes, location of the nucleus, presence of glyoxysomes, plasmodesmata, reserve food, and ability to synthesize amino acids and co-enzymes
• Plastids are organelles in plants and algae used in the synthesis and storage of various products
• Prokaryotic cells have a plasma membrane, cell wall, capsule, nucleoid, ribosomes, vesicles, flagellum, and pili
• Eukaryotic cells have organelles enclosed in membranes such as the nucleus, mitochondria, endoplasmic reticulum (RER and SER), Golgi apparatus, ribosomes, centrioles, and cytoskeleton
• The nucleus contains genetic materials and is surrounded by the nuclear membrane
• The endoplasmic reticulum includes the rough ER associated with ribosomes for protein synthesis and the smooth ER responsible for enzyme production and calcium storage
• The Golgi apparatus is responsible for transport and modifications of proteins and other biomolecules within the cell
• Mitochondria provide machinery for aerobic respiration and generate ATP for energy charges in the cell
• Ribosomes are responsible for protein synthesis and are associated with the RER
• Ribosome is responsible for protein synthesis
• Ribosome is associated with the RER, giving it a granular appearance
• Plastids occur in plants and algae and include chloroplasts, chromoplasts, elaioplasts, and leucoplasts
• Plastids serve as energy converters and storage in green plants and algae
• Plastids are self-replicating and have their own genetic material
• Lysosomes contain enzymes for digesting ingested materials and damaged tissues
• Cytosol is the fluid liquid with dissolved substances in the cell
• Cytoskeleton is a network of tubes, fibers, and filaments that help maintain cell shape and hold organelles in position
• Cell theory states:

  • The cell is the fundamental unit of life
  • All organisms are made up of one or more cells
  • Cells arise from pre-existing cells through cell division
  • Cells contain genetic materials passed to daughter cells during cell division
  • All cells are essentially the same in chemical composition
  • Energy flow occurs within cells
• Cell diversity refers to differences in cell size, shape, volume, structure, and complexity
• Cell size varies from 1-10um in prokaryotes to 10-100um in eukaryotes
• Cell shape is determined by its function
• Cell volume has a limit for body cells to function and communicate with other cells