cell structure and transport (required practical) Flashcards
what are the 2 types of cell?
eukaryotic.
prokaryotic.
what are the properties of a eukaryotic cell?
complex. (animal and plant cells)
bigger than prokaryotic.
what are the properties of a prokaryotic cell?
simple. (e.g. bacteria)
smaller than eukaryotic.
what is a eukaryote and prokaryote?
eukaryote - an organism made of eukaryotic cells.
prokaryote - a prokaryotic cell. (single cell organism)
what structures do animal cells have? (and the function of)
nucleus - genetic material and controls cell activities.
cytoplasm - gel where most chemical reactions happen and contains enzymes.
cell membrane - holds the cell together and controls what enters and exits.
mitochondria - where aerobic reaction happens.
ribosomes - where proteins are made.
what structures do plant cells have that animal cells don’t? (and the function of)
cell wall - made of cellulose and strengthens the cell.
vacuole - contains cell sap. (sugar and salts)
chloroplasts - where photosynthesis occurs. (contains chlorophyll which absorbs light)
what are the properties of a bacteria cell?
prokaryotes.
no chloroplast or mitochondria.
no true nucleus. (a single strand of DNA)
can contain some small rings of DNA called plasmids.
cell wall.
cell membrane.
cytoplasm.
how do light microscopes work?
they use a light and lenses to form a magnified image. (they can show individual cells and large subcellular structures)
how do electron microscopes work?
they use beams of electrons to form an image.
what are the differences between light and electron microscopes?
electron has a higher magnification. (and a higher resolution)
electron microscopes can see much smaller things in more detail. (internal structures of mitochondria and chloroplasts)
what is the formula for magnification?
magnification = image size ÷ real size
how do you use a light microscope? (practical)
if you want to look at a specimen under a light microscope you have to put it on a slide. (a strip of clear material where the specimen is mounted)
1. add a drop of water to the middle of a clean slide.
2. cut an onion and separate it into layers, use tweezers to peel off some epidermal tissue and put it on the slide.
3. add a drop of iodine solution to the onion.
4. place a cover slip on top carefully to create no air bubbles.
how to use the microscope.
1. clip the slide to the stage.
2. use the lowest power objective lens.
3. use the coarse adjustment knob and fine adjustment knob until you get a clear image of the slide.
4. to see the slide in a higher magnification use a higher power objective lens.
what is diffusion?
the spreading out of particles from a high concentration to a low concentration. (concentration gradient)
how do cell membranes work?
only small molecules can diffuse through cell membranes. (like oxygen glucose and amino acids)
what is osmosis?
the movement of water molecules across a partially permeable membrane from a high concentration to a low concentration. (concentration gradient)
what is a partially permeable membrane?
a membrane with very small holes in it that only lets tiny molecules through it.
how do you show osmosis at work? (practical)
- cut up a potato into multiple identical cylinders.
- get some beakers with different known concentration sugar solutions.
- measure the mass of the potato cylinders the put 1 cylinder in each beaker for ~24hrs.
- take them out and dry them with a tissue.
- remeasure their masses.
- if the potato increased in mass water has been drawn in by osmosis.
what is active transport?
moving molecules against a concentration gradient. (from low to high concentration)
