Cell membrane: A semi-permeable barrier that surrounds the cell and controls what enters and leaves the cell
Nucleus: Contains DNA and controls the cell
Mitochondria: Site of aerobic respiration, where most of the energy for cellular respiration is produced
Cytoplasm: Where chemical reactions take place
Ribosomes: Site of protein synthesis in the cell.
Cell Wall: Only in plant cells. Made of cellulose and keeps the structure of the cell so it doesn't burst- strong
Chloroplast: Site of photosynthesis and contains chlorophyll
Permanent Vacuole: Storage area of dissolved ions/minerals and water
Plasmid: Only in prokaryotic cells. Loop of DNA
Prokaryotic cells = Don't have a nucleus
Eukaryotic cells = Have a nucleus
Bacteria reproduce by binary fission, which is the division of a bacterial cell into two identical daughter cells. They divide every 10 minutes.
Making cultures with aseptic technique:
Lift the lid of the Petridishtowards a flame to sterilise it
Put a drop of culture on the agar or spread it evenly
Putdrops/discs of antibiotics on culture if needed
Place a fewstrips of tapearound the lid to secure it but leave a gap for aerobicrespiration and incubate it at 25degrees
Measuresize of cultures/areas with nobacteria on it with pir^2
All human cells (diploids) have 23 pairs of chromosomes
Haploid cells (gametes) have only 23 chromosomes
Mitosis:
The nucleus dissolves and genetic material is duplicated
The two sets of chromosomes move to opposite sides
Mitochondria, ribosomes and other organelles are duplicated
The cell divides, producing two genetically identical diploid cells (new nuclei are formed)
Stem cells can be specialised to perform specific functions
Stem cells are found in animal embryos and plant meristems
Some stem cells are made in your bone marrow but they can only be specialised into blood cells
Embryo clones can be made of a person to harvest stem cells from. They can be used to treat conditions without them being rejected by the patient's body
Cloning can also be used to preserve species or produce crops with desired traits.
Diffusion is the movement of particles from an area of high concentration to an area of low concentration (down the concentration gradient)
The diffusion rate can be increased by:
Increasing concentration
Increasing temperature
Increasing surface area
Osmosis is the diffusion of water across a semi-permeablemembrane from an area of highconcentration to an area of lowconcentration.
Active transport is the movement of particles through a membrane via carrier proteins from an area of low concentration to an area of high concentration. This requires energy so is slower than passive transport
Osmosis Practical:
Weigh and place identicalcylinders of a potato in varyingsugarconcentration
After a set time, removeexcess water from the cylinders' surface and reweigh
Calculatechange in mass = (finalmass-initialmass / initialmass) x 100
Plot % change in mass againstconcentration and using the line of bestfit, the concentration at 0%change in mass is the same as inside the potato