2.1.1 Cells

• Prokaryotic Flagella


  Thinner and does not have a 9+2 arrangement. The energy to rotate the flagellum comes from chemiosmosis, not ATP. It is attached to the cell membrane by a basal body and a molecular motor causes the hook to rotate giving it a whip like movement, propelling the cell.
• Prokaryotic Cell Wall

  Made from peptidoglycan, also known as merino. Complex polymer made from amino acids and sugar.
• Prokaryotic Ribosomes

  Smaller than eukaryotic ribosomes, 70S, necessary for protein synthesis, although larger (80S) ribosomes are involved in forming more complex proteins
• Prokaryotic DNA


  Generally have one molecule of DNA, a chromosome, which is supercoiled to make it more compact. The DNA is not contained within a nucleus.
• Prokaryotes


  Unicellular, simple structure, DNA is not contained in a nucleus, they have few organelles that are not membrane bound.
• Stroma


  Stroma are an internal network of membranes which form sacs called thylakoids. Several thylakoids stacked together are called a granum. Granum are joined together by a membrane to make lamellae. Grana contains the chlorophyll pigments. Internal membranes provides large SA, needed for enzymes, proteins and molecules necessary for photosynthesis.
• Chloroplasts

  Responsible for photosynthesis in plant cells, found in the cells in the green parts of plants, e.g. stems and leaves, but not the root. Have a double membrane structure, and fluid enclosed in it called stroma. Starch produced by photosynthesis is present as starch grains. Chloroplasts make their own DNA and ribosomes and therefore, also their own proteins.
• Tonoplast


  Membrane of a vacuole in a plant cell, is selectively permeable.
• Vacuoles


  Membrane lined sacs in the cytoplasm containing cell sap. Important in maintaining turgor, so that the contents of the cell push against the cell wall and maintain rigid framework for the cell. Mostly permanent in plants, can appear in animals but is usually not permanent.
• Cellulose Cell Wall

  Plants have a cell wall made of cellulose. Freely permeable to allow substances in and out of the cell and also strong enough to give the cell its shape. The contents of the cell presses against the wall to keep it rigid, supporting the cell and the plant as a whole. Also acts as a defence mechanism, protecting the cells contents from pathogens.
• Secretory vesicles


  Carries proteins that are to be released from the cell; the vesicle moves towards and fuses with the cell surface membranes, releasing its contents by exocytosis.
• Protein production

  1. Proteins synthesises at ribosomes bound to the ER

  2. Pass into cisternae & are packaged into transport vesicles

  3. Vesicles moves towards Golgi via cytoskeleton

  4. Vesicles fuse with the cis face of the Golgi; proteins enter

  5. Proteins are structurally modified before leaving the Golgi in vesicles from its trans face.
• Golgi apparatus


  Compact structure of cisternae, doesn't have ribosomes. Is responsible for modifying proteins and packaging them into vesicles.
• Ribosomes

  Constructed from RNA molecules made in the nucleolus, site of protein synthesis. Not membrane bound.
• Rough Endoplasmic Reticulum


  Has ribosomes bound to its surface and is responsible for the synthesis and transport of proteins.
• Smooth Endoplasmic Reticulum


  Network of cisternae (flattened sacs) that is responsible for lipid and carbohydrate synthesis and storage.
• Cilia

  Can be mobile or stationary. Stationary cilia are used for sensory organs (e.g. nose); mobile cilia beat in a rhythmic manner to create a current and causes fluids and objects adjacent to the cell to move.
• Flagella


  Whiplike tails found in one-celled organisms to aid in movement. Longer than cilia. Sometimes used as a sensory organelle detecting chemical changes in the cell's environment.
• Centrioles


  Composed of microtubules, two associated centrioles form a centrosome (assists in cell division)
• Cytoskeleton

  Has three main components: Microfilaments; formed from actin and is responsible for cell movement. Microtubules; tubes formed from globular tubules proteins that helps with the movement of the cell. Intermediate fibres; gives mechanical strength to the cell and maintains their structure.
• Lysosomes

  Specialised forms of vesicles that contain hydrolytic enzymes; they break down waste material in the cells. Play a role in the immune system (break down pathogens), and a role in programmed cell death.
• Vesicles


  A single membrane with fluid inside that transports materials inside the cell.
• Mitochondria


  Site of the finale stages of cellular respiration, where energy is stored as ATP. Have a double membrane. Inner membrane is highly folded and called cristae, the fluid interior is called the matrix. They contain a small amount of DNA called mitochondrial DNA (mt)DNA. Can produce their own enzymes and reproduce themselves.
• Nucleolus


  Area within the nucleus that is responsible for producing ribosomes, composed of proteins and RNA. RNA is used to produced rRNA which is combined with proteins to make the ribosomes needed for protein synthesis.
• DNA

  Directs the synthesis of all proteins required by the cell (the protein synthesis occurs outside of the nucleus at ribosomes). Associates with proteins called histones and forms a complex called chromatin. Chromatin coils and condenses to make chromosomes; only visible when cells prepare to divide.
• Nucleus


  Contains coded genetic information in the form of DNA. Usually the biggest single organelle in the cell.
• Metabolism

  All of the chemical reactions that occur within an organism; Anabolism (synthesis/building up of molecules) and Catabolism (breaking down of molecules)
• Eukaryote


  A cell that contains a nucleus and membrane bound organelles.
• Prokaryotes


  Single-celled organisms that do not have a membrane-bound nucleus; simple structure of just a single undivided internal area called the cytoplasm