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,Prokaryote Small, simple, unicellular cell, no nucleus Eg. Bacteria.
Eukaryote Complex, contains nucleus, all animal or plant cells.
Animal cells (5) nucleus -holds genetic information and controls activities of all sub
cellular structres
,cytoplasm- Gel-like substance where most of the chemical reactions take place and have
enzymes which control these reactions
cell membrane- Control what goes in and out of the cell
mitochondria- where aerobic respiration takes place. Respiration transfers energy needed for
the cell to work
ribosomes- Where the proteins are made in cell.
Plant cells Everything Animal cell has +
Cell wall- made of cellulose, Strengthens and supports cell
Permanent vacuole- holds cell sap, weak solution of sugar and salts
Chloroplasts- Where photosynthesis takes place. Hold pigments called chlorophyll which
absorb light to convert to food for cell.
Bacteria cell (5) cytoplasm- Gel like substance which is where chemical reactions take
place, Has enzymes which control reactions
cell membrane- controls what goes in or out of the cell
cell wall- made of cellulose, Strengthens and supports cell
No nucleus- Has a DNA strand which floats freely in cytoplasm
plasmid- Circular rings of DNA
Microscopy- Types of microscopes Light microscopes
Electron microscopes
Light microscopes Use light and lenses to magnify a specimen. Able to see cells and large
sub cellular structres like nuclei
Electron microscopes Use electrons to magnify a specimen. Able to see in much higher
resolution. eg. ribosomes or plasmids.
Magnification Formula Magnification = image size / real size
Microscopy Practical - Preparing the Slide 1. add drop of water to middle of clean slide
2. cut onion, seperate into layers, use tweezers to peel off epidermal tissue from bottom of on
of the layers
3. use tweezers to place epidermal tissue onto water on the slide.
4. add drop of iodine solution, used to highlight objects in a cell by adding colour to them
, 5. place cover slip on top, to do this, stand cover slip upright on slide next to water. carefully
tilt and lower so covers the specimen. try not to get air bubbles- they'll obstruct view
Microscopy practical- Using the microscope 1. clip slide on stage
3. use coarse adjustment knob to move stage up to just below objective lens
4. look down eyepiece, use coarse adjustment knob to move stage down until image is in
roughly focus
5. adjust focus with fine adjustment knob until clear image is visible.
6. if you need to see slide with higher magnification, switch to higher-powered objective lens.
Microscopy practical- Drawing observations 1. draw what you see with sharp pencil2. make
sure it is drawn with clear, unbroken lines
3. no colouring or shading
if drawing cells, sub cellular structres should be drawn in proportion
4. include title of what you are drawing, magnification it was observed under
5. label important features
Converting between units millimetre to Micrometre---- Divide by 1000
Micrometre to NanoMetre---- divide by 1000
Cell differentiation differentiation is where a cell becomes specialised to carry out a
specific function. Develop sub cellular structres and become new cells.
lost in animal cells as an early age but lots of plants don't loose the ability.
Examples of specialised cells Sperm cells- reproduction
Nerve cells- rapid signalling
Muscle cells- contraction
Root hair cells- absorbing minerals and water
Phloem and Xylem cells- transporting substances
Sperm cells Get from male DNA to female DNA
long tail, streamlined head to swim to egg
Lots of mitochondria to provide energy needed
carries enzymes to digest through egg cell membrane
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