SAC 1A

Cards (58)

  • hypotonic
    When a cell gains volume because the solute concentration inside the cell is higher than outside the cell, water will cross into the membrane to dilute it.
  • hypertonic
    when a cell loses volume because the solute concentration outside of the cell is higher than inside of the cell. This means that the solute can't pass through the membrane
  • tonicity
    The ability of an extracellular solution to make water move into or out of a cell by osmosis
  • osmosis
    the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell's partially permeable membrane.
  • compare and contrast osmosis in animal and plant cells - hypertonic solution

    An animal cell in a hypertonic solution will shrivel up and eventually die. A plant cell placed in a hypertonic solution will shrink and undergo plasmolysis; however, the plant is able to recover from this solution once it's returned to an isotonic or hypotonic solution.
  • compare and contrast osmosis in animal and plant cells - hypotonic solution

    In a hypotonic solution (water moves inside the cell), animal cells will get lysed because they do not tolerate high water concentrations. In contrast, plant cells will not burst in the hypotonic solution due to their thick cell wall.
  • name and explain bulk movement of substances into and out of a cell
    exocytosis
    bulk transport in which materials are transported from inside to the outside of the cell in membrane-bound vesicles that fuse with the plasma membrane
  • explain how molecules cross the plasma membrane via facilitated diffusion and active transport
    In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers. A concentration gradient exists for these molecules, so they have the potential to diffuse into (or out of) the cell by moving down it.
  • facilitated diffusion vs active transport
    Facilitated diffusion occurs along a concentration gradient from high concentration to low concentration and does not require energy, while active transport from low concentration to high concentration occurs against the concentration gradient and requires energy.
  • active transport
    occurs when molecules move from low concentration to high concentration facilitated by carrier proteins or pores in the membrane
  • facilitated diffusion
    molecules move from the region of higher concentration to the region of lower concentration assisted by a carrier
  • describe the chemical properties of substances that can and cannot readily diffuse across the plasma membrane
    - small, uncharged/lipid-soluble molecules are able to pass through (oxygen, carbon dioxide, water)

    - larger, charged molecules require the help of proteins (glucose, ions such as H+)
  • explain why some substances can and cannot readily diffuse across the plasma membrane
    when a molecule has to enter the cell it first has to interact with the polar part of the lipid membrane and then with the inner non-polar part of the membrane to pass through, hence if it is a polar molecule, it will face repulsions and will not be able to pass through without the assistance of transmembrane proteins, but, in the case of non-polar molecules, there is no repulsion from the fatty acid part of the phospholipids and hence it can pass through the membrane. When the non-polar molecules are too big some other mechanisms may be utilized (like receptor-mediated endocytosis).
  • how do fatty acids affect membrane fluidity?
    Saturated fatty acid makes the model membrane more rigid, while the presence of unsaturated fatty acid increases its fluidity.
    the membrane becomes compressed in decreasing temperatures, pressing in on each other, making the membrane fairly rigid.
  • how does ethanol affect membrane fluidity?
    Ethanol increases membrane fluidity as it is a nonpolar solvent, meaning it can dissolve nonpolar substances such as lipids. If a cell is placed in ethanol, its membrane will become permeable, allowing substances to leak into and out of the cell.
  • how does temperature affect membrane fluidity?
    higher energy increases the energy and therefore the movement of molecules, increasing the rate of diffusion
  • factors that increase or decrease membrane fluidity
    temperature, ethanol and fatty acids
  • DESCRIBE + STRUCTURE: protein channels
    DESCRIBE: transport of water-soluble ions
    STRUCTURE: a channel
  • DESCRIBE + STRUCTURE: cholesterol
    DESCRIBE: helping the bilayer to stay fluid in different environmental conditions
    STRUCTURE: embedded in phospholipid bilayer
  • DESCRIBE + STRUCTURE: peripheral protein
    DESCRIBE: help with transport or communication
    STRUCTURE: bound to membrane by protein-protein interactions
  • DESCRIBE + STRUCTURE: integral proteins
    DESCRIBE: transporting larger molecules across the cell membrane
    STRUCTURE: have polar and non-polar regions
  • DESCRIBE + STRUCTURE: phospholipid bilayer
    DESCRIBE: prevents large molecules/charged molecules (ions) from diffusing directly across the membrane without the use of a channel protein
    STRUCTURE: phosphate containing head (hydrophilic + polar), fatty acid tail (hydrophobic + non-polar)
  • DESCRIBE + STRUCTURE: glycoprotein
    DESCRIBE: cell to cell recognition - recognise another cell as familiar or foreign
    STRUCTURE: the whole glycoprotein structure
  • DESCRIBE + STRUCTURE: carbohydrate
    DESCRIBE: allows the immune system to differentiate between body cells and foreign cells/tissues
    STRUCTURE: attached to lipids and proteins - top of glycoprotein
  • DESCRIBE + STRUCTURE: glycolipid
    DESCRIBE: to maintain the stability of the cell membrane and to facilitate cellular recognition.
    STRUCTURE: a lipid and a carbohydrate
  • LIST: components in the fluid mosaic model
    glycolipid
    carbohydrate
    glycoprotein
    phospholipid bilayer
    integral proteins
    peripheral protein
    cholesterol
    protein channel
    transmembrane protein
  • cytoskeleton
    supports and shapes cell, helps position and transport organelles, provide strength, assists in cell division and aids cell movement
  • cytoplasm
    responsible for cell shape, material transport and products for cellular respiration and storage
  • cell wall
    provide support, strength, and protection for plants
  • chloroplast
    produce energy through photosynthesis
  • ribosomes
    where protein synthesis happens - reads coded info + makes amino acids to make protein chains
  • lysosome
    specialised vesicles that contain powerful digestive enzymes to break down material - recycling and security
  • vesicle
    small fluid-filled double membrane in cytoplasm - transport substances in/out of cells
  • golgi apparatus
    protein modification and export - shipping department
  • smooth endoplasmic reticulum
    lipid production; detoxification - accessory production (makes decorations for the toy)
  • mitochrondria
    energy production - powerplant
  • rough endoplasmic reticulum
    protein production - export out of the cell - primary production line (makes the toys)
  • nucleus
    controls and regulates the activities of the cell - room where the blueprints are kept
  • explain why compartmentalisation is important in cells
    in eukaryotes, specific cellular functions are compartmentalised into the cell nucleus and organelles surrounded by intracellular membranes. Compartmentalisation improves the efficiency of many cellular functions and prevents potentially dangerous molecules from roaming freely within the cell.
  • 3 examples of eukaryotic organisms

    animals, plants, fungi