Cells

• the nucleus contains a nuclear envelope, nuclear pores, nucleolus, nucleoplasm and chromosomes
• the function of the nucleus is DNA replication and transcription(making mRNA) and it contains the genetic code for each cell
• The nucleolus- smaller sphere inside the nucleus which is the site of rRNA production and makes ribosomes
• Rough and Smooth endoplasmic reticulum have folded membranes called cisternae
• Rough ER have ribosomes on the cisternae
• RER function is protein synthesis
• SER function is to synthesise and store lipids and and carbohydrates
• Golgi apparatus process and package proteins and lipids for transporting to other parts of the cell
• lysosomes -organelles in the cytoplasm which contain digestive enzymes and are used to break down old organelles like phagocytosis
• Mitochondria- site of aerobic respiration, produce ATP from glucose
• Chloroplasts- found only in plant cells, site of photosynthesis
• chloroplasts- contain chlorophyl in the thylakoids
• Ribosomes- used in protein synthesis(80s in eukaryotic cell)
• REM also has ribosomes dotted along the surface as this is the location of extracellular protein synthesis
• RER- once a protein has been made the membrane can pinch off to form a vesicle and be transported around the cell
• Centrioles- only found in animal cells not plant, they are a bundle of microtubules and used when a cell divides. They move to the opposite ends of the cells and produce spindle fibres that will attach to the chromosomes and pull them apart
• mitochondria- site of respiration
• cell wall- made of cellulose and provides mechanical strength to the cell
• cell membrane- regulates passage of the substances in and out of the cells
• vacuole- filled with cell sap and helps maintain the cell shape (only in plant cells) sometimes animals have a semi permanent vacuole
• capsule(prokaryotic cells only) -protects bacteria from dying out in certain conditions or being discovered by the immune system
• mesosomes( prokaryotic cells only)-have the same function as mitochondria
• nucleotide(prokaryotic cells only)- long single strand of DNA as they don't have a nucleus
• plasmids(prokaryotic)- small circular loops of DNA
• Ribosomes(prokaryotic)- smaller than eukaryotic cells (70s)
• flagella and pili- they are used to help the bacteria reproduce and communicate
• magnification- how many times larger the image is compared to the actual object
• Resolution- minimum distance between two objects in which they can still be viewed as separate
• magnification = size of image/size or real object
• optical microscopes have low resolution and magnification, can have coloured images and the specimen can be live
• Electron microscope(scanning or transmission) a beam of electrons is condensed to make he image. The specimen must be in a vacuum, black and white images, higher magnification and resolution
• Transmission electron microscope- extremely thin specimen is stained. Some parts absorb the electrons and appear dark. The image is 2D
• Scanning electron microscope- specimen does not need to be thin. The image is 3D
• SEM- electrons are beamed onto the surface and the electrons are scattered in different ways
• TEM- an electron gun produces a beam of electrons hat pass through the specimen
• cell fractionation: used to isolate different organelles so they can be studied
• cell fractionation: it has to be COLD to reduce enzyme activity and to inactivate any enzymes that are breaking down the organelles
• cell fractionation: it has to be ISOTONIC so it prevents the organelles from bursting under osmotic pressure
• cell fractionation: has to be a buffered solution to prevent fluctuations of ph
• cell fractionation: the cell must be broken down(homogenised) using a blender in a cold, buffered and isotonic solution. The solution is filtered to remove large cell debris