Cell biology

• The nucleus is the control center of the cell, containing genetic material (DNA) that determines an organism's characteristics.
• Chromosomes are thread-like structures made up of DNA and proteins found inside the nucleus.
• Genes are segments of DNA that contain instructions for making specific proteins or controlling other genes.
• Cell membrane - A thin layer surrounding the cytoplasm that regulates what enters or leaves the cell.
• Cytoplasm - The jelly-like substance within cells where most chemical reactions occur.
• Prokaryotes


  • Bacteria
  • Archaea
• Prokaryotes


  Cells have DNA in a single 'loop' and are also a lot smaller than regular Eukaryotic cells
• Prokaryotes


  Have a cell wall and cell membrane, but not enclosed in a nucleus
• Eukaryotes


  Cells contain DNA in a membrane-bound organelle and have a cell wall (except for animal cells)
• Eukaryotes


  • Plants
  • Fungi
  • Animals
• Eukaryotes


  Cells have a nucleus that contains genetic material, cytoplasm, ribosomes, and mitochondria (except for plant cells)
• Plant cells


  Have a nucleus, cytoplasm, ribosomes, mitochondria, chloroplasts, a central vacuole, and a cell wall
• Animal cells


  Have a nucleus, cytoplasm, ribosomes, mitochondria, and a cell membrane
• Cell membrane - A thin layer surrounding the cytoplasm that regulates what enters or exits the cell.
• Cytoplasm - The fluid substance within the cell where most chemical reactions occur.
• Ribosome - Small structures responsible for protein synthesis.
• Protein synthesis involves transcription, where RNA copies a gene sequence from DNA, and translation, where ribosomes read the mRNA to make a protein.
• Cellular respiration converts glucose into ATP through glycolysis, the Krebs cycle, and oxidative phosphorylation.
• Mitochondria - Organelles responsible for producing energy through cellular respiration.
• Photosynthesis occurs in chloroplasts and uses light energy to convert carbon dioxide and water into sugar molecules.
• Vacuole - Storage compartment for water, nutrients, waste products, and pigments.
• Mitochondrion - Responsible for producing energy through cellular respiration.
• Nucleus - Contains the genetic information of the cell and controls its activities.
• Types of organisms


  • Prokaryotes
  • Eukaryotes
• Active transport is the movement of molecules AGAINST their concentration gradient, requires energy from cellular respiration
• Active transport


  The movement of molecules across a cell membrane from a region of low concentration to high concentration, requiring energy from cellular respiration
• Translocation is the movement and replacement of sugars made from photosynthesis through the phloem tubes to be used by the rest of the plant
• Transpiration


  1. Evaporation of water from leaves

  2. Causes a flow of water and minerals from roots to leaves through the xylem tubes
• Diffusion


  The net movement of particles from an area of high concentration to an area of low concentration
• Factors affecting rate of diffusion

  • Concentration gradient
  • Temperature
  • Surface area
• During interphase, the cell synthesises proteins and replicates its DNA
• DNA is organized into chromatin during interphase.
• Chromosomes are made up of DNA and proteins called histones.
• Lysosome - Contains digestive enzymes that break down food particles and worn-out organelles.
• Chloroplast - Site of photosynthesis, containing thylakoids and grana.
• During interphase, chromatin condenses into visible chromosomes during prophase.
• Prophase - Chromosomes condense and become visible under a microscope
• Ribosome - Sites of protein synthesis.
• In prophase, the nuclear envelope breaks down and the centrioles move towards opposite poles of the cell.
• Centrioles - Help form spindle fibres during mitosis.