topic 1 - cell biology

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cell biology

cells-

  • cells can be prokaryotic or eukaryotic
  • prokaryotic cells are small and simple cell that is single-celled 
  • eukaryotic cells are complex - inclduind all animal and plant cells  

animal cells:

  • nucleus - contains genetic material. controls cell activity (big circle in the center)
  • mitochondria - where reactions for aerobic respiration takes place (larger bits in the cell)
  • cytoplasm - gel like substance where mkst of the chemical reactions happen. containing enzymes (gel like substance in cell)
  • cell membrane - controls what goes in and out of cell (outer line of cell)
  • ribosomes - where proteins are made (smaller bits in cell)

plant cells:

  • everything animal cells have plus:
  • cell wall - supports and strengthens cell (outer part of cell)
  • permenant vacuole - contains cell sap (inner part of cell)
  • chloroplasts - where photosynthesis occurs (green small circles in cell)

bacterial cells:

  • bacteria are prokaryotic 
  • no nucleus - free floating DNA in cytoplasm 
  • plasmid - small rings of DNA
  • no chloroplasts or mitochondria 

microscopy-

  • light microscopes - use light and lenses to magnify 
  • electron microscopes use electrons instead of light to form an image 
  • equation - magnification = image size 
  •                                              real size          
  • preparing slide:
  • drop of water in the centre of a clean slide
  • cut and onion and separate its layers.
  • use tweexers to pick up a layer and place it on the slide
  • add a drop of iodine solution
  • add a cover slip on top
  • parts of a microscope: 
  • eyepiece
  • coarse adjustment knoob
  • fine adjustment knob 
  • light 
  • stage 
  • objective lenses

practicle:

  •  clip prepared slide onto stage
  • select lowest powered lens 
  • use coarse ajustment knob to move stage towards lens 
  • ajust the focus with the fine adjustment knob 
  • swap to highest powered lens 

cell differentation and specialisation-

  • differentation is where a cell changes to become specialised to do a certain job
  • unspecialised cells are called stem cells 
  • eg sperm cells
  • sperm cells are specialised for rapid signalling 
  • muscle cells are specialised for contraction 
  • rot hair cells are specialised for absorbing water and minerals 
  • phloem and xylem are specialised for transporting substances 

stem cells-

  • usually found in human embryos (bone marrow)
  • they can also be replicated for medical research or treatment - used for many diseases like replacing peoples faulty blood cells
  • however this carries risks such as the person may become contaminated and it would be passed on to the patient making them sicker 
  • stem cells can produce identical plants - helping with plant type extinction 

chromosomes and mitisis-

  • chromosome contain genetic information 
  • chromosomes are coiled up lengths of DNA
  • they control characteristics 
  • bodies have 2 copies of chromosomes - 1 mother and 1 father 
  • there are 23 pairs of human chromosomes 
  •  mitosis is multicellular cells diving to replace cells that have been damaged - part of the cell cycle 
  • the end of the cycle results in 2 new identical cells

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