Biology: Topic 1 - Cell Biology

• What are cells?


  Cells are the basic units of structure and function in living things
• What are eukaryotic cells?

  cells with a nucleus
• Are animal and plant cells multi or unicelluar?

  multicelluar
• Are bacteria cells unicellular or multicellular?

  unicellular
• Name all the features of an animal cell


  mitochondria, cell membrane, nucleus, cytoplasm, ribosomes

  
• Name all the features of a plant cell.


  Nucleus, Cytoplasm, Cell membrane, Mitochondria, Ribosomes, Cell wall, Permanent Vacuole and chloroplasts

  
• What is the function of the nucleus?


  Contains the cell's genetic material and controls the cell
• What is the function of the cytoplasm?

  Where most chemical reactions take place
• What is the function of the cell membrane?

  to control what enters and leaves the cell
• What is the function of the mitochondria?

  aerobic respiration takes place. Respiration transfers energy that the cell needs to work.
• what is the function of ribosomes

  site of protein synthesis
• what is the function of the rigid cell wall

  A rigid layer that supports the cell and provides shape.
• what is the function of the permanent vacuole

  contains cell-sap, a weak solution of sugar and salts.
• What is the function of the chloroplasts


  To make food through photosynthesis, and contains chlorophyll
• What are prokaryotes?


  cells with no true nucleus. e.g bacteria
• What do bacteria cells contain?

  cell membrane

  cell wall

  cytoplasm

  single CIRCULAR strand of DNA

  plasmids.
• What is the functions of plasmids?

  carry genes for replicating DNA.
• What is the function of the flagella

  movement
• What is magnification?


  How much bigger the image is than the specimen
• Define resolution

  the ability to distinguish between two points on an image (the amount of detail)
• State the equation that links, magnification, image size, real size

  image size = magnification x real size
• um to mm conversion

  divide by 1000
• 5mm to um


  5000um
• electron microscope


  - very expensive

  - hard to use only by scientist

  - uses electrons instead of light

  - better resolution - can see more sub-cellular structures eg. ribosomes
• light microscope


  - easy to use

  - cheap

  -relies on light

  - resolution is limited
• Microscopy Practical - Preparing the Slide

  1) Add a drop of water to the middle of a clean slide

  2) Cut up an onion & separate it out into layers. Use tweezers to peel off epidermal tissue from the bottom of layer

  3) Using tweezers, place epidermal tissue into the water on the slide

  4) Add a drop of iodine solution - a stain used to highlight objects in a cell

  5) Gently place a cover slip on top of specimen Try not to get any air bubbles under there.
• Microscopy Practical - Using a Light Microscope

  1) Clip the slide you've prepared onto the stage

  2) Select the lowest-powered objective lens

  3) Use coarse adjustment knob to move the stage just below the objective lens

  4) Look down the eyepiece. Use the coarse adjustment knob to move the stage downwards until the image is roughly in focus

  5) Adjust the focus with the fine adjustment knob, until you get a clear image of what's on the slide
• Microscopy Practical - Drawing Observations

  1) Draw what you see under the microscope using a pencil with a sharp point

  2) Make sure your drawing takes up at least half of the space available & that it is drawn with clear, unbroken lines

  3) Your drawing should not include any colouring or shading

  4) If you are drawing cells, the subcellular structures should be drawn in proportion

  5) Include a title & write down the magnification that it was observed under

  6) Label the important features of your drawing using straight, uncrossed lines
• What is differentiation?


  The process by which a cell changes to become specialised for its job
• The cells that differentiate in mature animals are mainly used for

  repairing and replacing cells. e.g skin or blood cells
• 1. Sperm cells are specialised for _____________

  2. Describe the function of sperm cells

  1. Reproduction

  2. To get male DNA to female DNA
• Describe the adaptation of sperm cells

  - long tail and streamlined head to help swim to egg

  - lots of mitochondria to provide energy needed

  - carries enzymes in its head to digest through the egg cell membrane
• 1. Nerve cells are specialised for _______________

  2. Describe the function of nerve cells.

  1. Rapid impulses

  2. Carries electrical impulses from one part of the body to another
• Describe the adaptations of nerve cells

  lots of dendrites

  long axons

  lots of mitochondria to provide energy
• 1. Muscle cells are specialised for _________

  2. Describe the function of muscle cells.

  1. contraction

  2. Is to contract quickly
• Describe the adaptation of muscle cells.

  long (so they have space to contract)

  lots of mitochondria to generate energy needed for contraction.
• 1. Root hair cells are specialised for

  2. Describe the function of root hair cells

  1. Absorbing water and minerals

  2. allows plant to absorb more water
• Describe the adaptations of a root hair cell

  long hairs provide a large surface area so more water and minerals are absorbed
• 1. Phloem and xylem cells are specialised for

  2. Describe the function of phloem and xylem cells

  1. Transporting substances

  2. transporting substances such as food and water
• Describe the adaptions of phloem cells.

  have few sub-cellular structures so stuff can flow through them