Prokaryotic and eukaryotic

• Cell membrane structure


  Fluid mosaic phospholipid bilayer model
• Diffusion is the net movement of molecules from a region of high particle concentration to a region of lower particle concentration
• Facilitated diffusion is a form of diffusion which requires substances to be assisted across a cell membrane by transport proteins
• Osmosis is the movement (diffusion) of water across a selectively permeable membrane from a region of high water concentration (low solute) to a region of low water (high solute) concentration
• Active transport is the process of using energy to move a substance across a membrane from a region of low concentration to a region of higher concentration
• Passive transport does not require energy
• Active transport requires energy
• Active transport


  Substances move from an area of low to high concentration
• Passive transport


  Substances move from an area of high to low concentration
• Phagocytosis involves solids moving into a cell
• Exocytosis involves solids OR liquids moving out of a cell
• Endocytosis involves solids OR liquids moving into a cell
• Calculation of the surface area to volume ratio of a spherical cell with a 1.5cm radius: SA = 4πr^2 = 28.27cm^2, V = πr^3 = 14.14cm^3, SA ÷ V = 2:1
• The shape with the smallest SA:V is a sphere
• The SA:V gets smaller as a cell grows larger
• Higher temperature leads to a faster diffusion rate
• Greater concentration gradient leads to a faster diffusion rate
• A thinner membrane leads to a faster diffusion rate
• Prokaryotic cells lack internal membrane-bound organelles, do not have a nucleus, are significantly smaller than eukaryotes, usually have a single circular chromosome, and exist as single cells
• Eukaryotic cells have specialised organelles for various biochemical processes such as photosynthesis, cellular respiration, and synthesis of complex molecules
• Living things are made of cells with requirements for survival including energy, matter, nutrients, and waste removal
• Glucose is the primary energy source in most cells, used to drive chemical reactions
• Cellular respiration reacts glucose and water to create energy in the form of ATP
• The Sun provides energy for plants and algae to obtain glucose via photosynthesis
• Cellular respiration


  Reacts glucose and water to create energy in a form that can be readily used (ATP)
• Photosynthesis


  The Sun provides energy for plants and algae to obtain glucose via photosynthesis (autotrophs). Other organisms rely on autotrophs to provide them with glucose (chemical energy) when consumed
• Cells need matter


  The synthesis of large molecules (macromolecules) is required by cells to build cellular structures and maintain biochemical processes which keep them alive (communication, energy transfer, relay of genetic information etc)
• Macromolecules


  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
• Plants synthesise macromolecules


  From simple precursors e.g. carbon dioxide and oxygen gas
• Heterotrophs


  Ingest complex molecules which get broken into simpler substances via digestion. These substances are then built into a variety of macromolecules within the organism
• Cells need simple nutrients

  Carbohydrates are the most common compounds present in organisms. They are an important energy source and are used to synthesise other macromolecules
• Carbohydrates


  • Monosaccharides are simple sugars e.g. glucose. When two monosaccharides link together, a disaccharide is formed e.g. sucrose. Many saccharides linking together forms a polysaccharide e.g. starch and cellulose
• Cells need simple molecules and macromolecules


  Cells require additional substances to function properly (e.g. amino acids, lipids, nucleic acids, ions and water)
• Cells require


  • Amino acids, lipids, nucleic acids, ions and water
• Cells need to remove wastes

  Wastes are created by cellular respiration and cell metabolism, these unwanted and sometimes toxic by-products must be removed from cells (e.g. nitrogenous wastes, excess water or ions and metabolic heat)
• Wastes


  • Nitrogenous wastes (ammonia, urea and uric acid), excess water or ions, metabolic heat
• MRS GREN stands for
• Primary energy source in cells is Glucose
• Macromolecules are required by cells to build cellular structures and to maintain biochemical processes which keep them alive (communication, energy transfer, relay of genetic information etc)
• Main four categories of macromolecules are Carbohydrates, lipids, proteins and nucleic acids