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Cell Biology (Stem cells (Must be able to describe where stem cells are…

- - - - Over time these cells continue to undergo mitosis and form specialised cells
        
        Cells in the early embryo have not differentiated meaning that any cell is capable of differentiating into any type of body cell
  - - - Leukaemia is a cancer of the bone marrow
        
        To treat this, the patients existing bone marrow is destroyed using radiation
        
        The patient then receives a transplant of bone marrow from a donor
        
        The stem cells in the bone marrow now divide and form new bone marrow. They also differentiate and form blood cells
      - Problems
        
        The donor has to be compatible with the patient. Otherwise the white blood cells produced by the donated bone marrow could attack the patients body
        
        There is a risk that viruses can be passed from the donor to the patient
    - - An embryo is produced with the same genes as the patient
      - Stem cells from the embryo can be translated into the patient without being rejected by the patient's immune system
      - Once inside the patient, the stem cells can then differentiate to replace cells which have stopped working correctly
      - This could be used to treat medical conditions such as diabetes and paralysis
      - But some people have ethical or religious objections to the procedure
    - - Rare plants can be cloned to stop it from going extinct
      - Cloned crops can be produced by crop plants for farmers
- - - - One bacterial cell splits into two bacterial cells (Binary Fission)
  - - - Where n is the amount of divisions that happened, so in 40 minutes 2 rounds of divisions happened and so on
- - - - Clean bench with disinfectant solution. This kills microorganisms that contaminate our culture
        
        Sterilise the inoculating loop by passing it through a Bunsen burner flame
        
        Open the sterile agar plate near flame to kill bacteria in the air
        
        Use the loop to spread the bacteria evenly on the plate
        
        Place Sterile filter paper discs containing antibiotic into the plate
        
        Incubate the plate in 25°C for a few days
    - - To calculate the effectiveness of the antibiotic you must calculate the area of the zone of inhibition using π r²
  - - - In agar plates bacterial colonies are visible
    - - The inoculating loop has to be sterilised by passing it through a Bunsen burner flame
    - - This stops the lid from falling off and unwanted microorganisms entering
- - - - One set of each chromosome is pulled to each end of the cell
      - The nucleus also divides
    - - The cytoplasm and the cell membrane divide to form identical cells
    - - The DNA replicates to form two copies of each chromosome
      - The cell also grows and copies its internal structures such as mitochondria and ribosomes
- - - - The oxygen molecules move into the cell by diffusion from a high concentrated area to a low concentrated area
      - The oxygen used to create energy produces Carbon Dioxide
        
        There is a higher concentration of CO2 in the cell than outside so the CO2 diffuses out of the cells
  - - - This is because the particles have more kinetic energy and are moving faster
- - - - Cells on the surface can get enough oxygen by diffusion but cells at the centre of a cell will not get enough as they are too far away from the surface
      - To solve this issue animals have gotten special structures with high surfaces areas such as lungs in mammals and animals also have a transport system to carry gases around the body
  - - - Deoxygenated blood passes into the filament. Oxygen diffuses from the water into the blood. The oxygenated blood returns to the body
    - - Filaments give the gills are massive surface area
      - The filaments also have a thin membrane to provide a short diffusion pathway
      - The filaments have an efficient blood supply to take the oxygenated blood away. This makes sure that the concentration gradient is always high
- - - - If the cell is then placed in water then osmosis will take place and water will from outside of the cell to the inside of the cell
        
        In the case of an animal cell, the cell will expand and could even burst
        
        However in the case of a plant cell, the cell wall prevents the plant cell of bursting and the cell becomes swollen. Scientist call this turgid
      - If the cell is placed in a very concentrated solution
        
        In the case of an animal cell, water would leave the cell due to osmosis and the cell would shrink
        
        And in the case of a plant cell, osmosis removes water from the plant cell causing it to shrink. Scientists says this plant has become flaccid
- - - - Using a cork borer to produce three cylinders of potato with the same diameter
        
        Using a scalpel trim the cylinders to the same length (around 3 cm)
        
        Measure the length of each cylinder using a ruler and the mass of each cylinder using a balance
        
        Now place each cylinder into a test tube
        
        Add 10cm³ of 0.25 molar sugar solution to the second test tube
        
        Add 10cm³ of distilled water to the third test tube
        
        Add 10cm³ of 0.5 molar sugar solution to the first test tube
        
        Leave the potato cylinders overnight, allowing osmosis to take place
        
        Next remove the potato cylinder and gently roll them on a paper towel to remove any surface moisture
        
        1 more item...
- - - - This is as the concentration of sugars in the lumen is lower than the concentration of sugars in the cell
        
        The sugars are then transported from the cells into the bloodstream
      - The energy for active transport is provided by the large number of mitochondria in the cells
    - - The concentration of the ions in the soil is lower than the concentration of ions in the cell
        
        Active transports then moves the ions into the root hair cell which is then transported using the xylem into the leaves
      - To provide the energy for active transport the root hair cell has a larger number of mitochondria
- - - - Such as Animal Cells and Plant Cell
    - - Such as bacterial cells
      - Much smaller than Eukaryote cells
- - - - Stage is where the microscope slide is placed
      - The stage has clips that are used to hold the slide in place
      - Below the stage is a lamp or a mirror beneath the stage.Which then passes light through the microscope slide
      - 3 Objective lenses with magnifications of 4x,10x or 40x
      - Eyepiece is where you would look through
        
        The Eyepiece contains the eyepiece lens which has a magnification of 10x
    - - Then select the lowest power objective lens and use coarse focussing dial to position the objective lens so it's just above the slide
        
        Then look down the at the eyepiece and start turning the coarse focusing dial so it increases the distance between the lens and the slide
        
        This is done until the cells come to focus, then use the fine focusing dial to bring the cells into clear focus
        
        At this point a higher power objective lens can be used and then the fine focussing dial to bring the cells back into focus
- - - - When cells become specialised scientists call that differentiation
    - - The hairs on a root increase the surface area of the root, so it can absorb water and minerals more effectively
      - Do not contain chloroplasts as they are underground and will not absorb sunlight
    - - Found in the plant stem. They form long tubes that carry water and dissolved minerals from the roots to the leaves
      - Xylem have thick walls containing Lignin. This provides support to the plant
      - Xylem cells are dead
      - The end walls between the cells have broken down forming a long tube, so water can flow easily
    - - Phloem tubes carry dissolved sugars up and down the plant
      - Consists of only 2 types of cells
        
        Phloem vessel cells
        
        Have no nucleus and only limited cytoplasm
        
        The end walls of the vessels cells have pores called sieve plates
        
        These features allow dissolved sugars to move through the cell interior
        
        Phloem Companion Cell
        
        Connected by pores
        
        Mitochondria in the companion cells provides energy for the vessel cell
- - - - The job of a sperm cell is to join an ovum. This process is called Fertilisation
        
        During Fertilisation the genetic information of the ovum (egg cell) and the sperm combine
      - Sperm cells contain their genetic information in their nucleus however they only contain half the genetic information of a normal adult cell
      - Sperm cells have a long tail and are streamlined which allows them to swim to the ovum more effectively
      - Some Sperm cells are filled with mitochondria which provides the energy needed for swimming
      - Sperm cells contain enzymes which allow them to digest their way through the outer layer of the egg cell
    - - The job of a nerve cell is to send electrical impulses/signals around the body
      - The axon carries the electrical impulses from one part of the body to the other
      - Myelin insulates the axon and speeds up the transmission of nerve impulses
      - Dendrites increase the surface area so that other nerve cells can connect more easily
      - The end of the axon has synapses which allows the impulse to travel from one nerve cell to another
    - - Muscles can contract
      - Muscles cell contracts, these protein fibres shorten, decreasing the length of the cell
      - Muscle cells are also packed full of mitochondria to provide energy for muscle contraction
      - Muscle cells work together to form muscle tissue