Cell Biology

• All living things are made of cells, which can either be prokaryotic or eukaryotic
• Animal and plant cells are eukaryotic and have a cell membrane, cytoplasm, and a nucleus containing DNA
• Bacterial cells are prokaryotic, much smaller, and have a cell wall, cell membrane, cytoplasm, and a single circular strand of DNA and plasmids
• Organelles are structures in a cell that have different functions
• Orders of magnitude are used to understand the size difference between objects
• If an object is 10 times bigger, it is 10^1 times bigger; if it is 1000 times bigger, it is 10^3 times bigger
• Prefixes like centi, milli, micro, and nano are used before units of measurement to show multiples of the unit
• Prefixes like centi = 0.01, milli = 0.001, micro = 0.000001, nano = 0.000000001
• In animal and plant cells, the nucleus contains DNA for protein synthesis, cytoplasm is where chemical reactions occur, and the cell membrane controls what enters and leaves the cell
• Mitochondria are where aerobic respiration occurs, providing energy for the cell
• Ribosomes are where protein synthesis occurs, found on the rough endoplasmic reticulum
• Chloroplasts in plant cells are where photosynthesis takes place, containing chlorophyll pigment
• Permanent vacuoles contain cell sap and improve cell rigidity
• Cell walls in plant cells are made from cellulose, providing strength to the cell
• Cells specialise through differentiation, gaining new sub-cellular structures to be suited to their role
• Stem cells can differentiate once early on or have the ability to differentiate throughout their life
• Examples of specialised cells in animals include sperm cells, nerve cells, and muscle cells
• Examples of specialised cells in plants include root hair cells, xylem cells, and phloem cells
• Stem cells must undergo differentiation to form specialised cells, involving genes being switched on or off to produce different proteins
• In animals, most cells differentiate early on and lose this ability, while in plants many cells retain the ability to differentiate throughout life
• Microscopes are used to view extremely small structures like cells
• Light microscopes have a maximum magnification of x2000 and a resolving power of 200nm
• Electron microscopes have a magnification of up to x2,000,000 and a resolving power of 10nm (SEM) and 0.2nm (TEM)
• Common calculations include magnification of a light microscope and size of an object using the size of the image and magnification
• Standard form is useful for working with very large or small numbers in microscopy calculations
• Standard form involves multiplying a number by a power of 10 to make it bigger or smaller
• Examples: 1.5 x 10^-5 = 0.000015, 3.4 x 10^3 = 3400
• Microorganisms are cultured in the lab using nutrient broth solution or agar gel plates
• Nutrient broth solution involves suspending bacteria in sterile nutrient broth, while agar gel plates allow bacteria to form colonies on the surface
• Steps in culturing microorganisms include sterilising Petri dishes and culture media, sealing the dish with tape, and incubating at 25 degrees
• Bacteria can multiply by binary fission, and their growth can be calculated using the formula: bacteria at beginning x 2^(number of divisions) = bacteria at end
• Microorganisms can be used to test the effects of antibiotics on their growth, showing the effectiveness of the antibiotic by the size of the inhibition zone
• Chromosomes contain coils of DNA
• Genes are short sections of DNA that code for proteins and control characteristics
• There are 23 pairs of chromosomes in each cell of the body, resulting in 46 chromosomes in total
• Sex cells (gametes) have 23 chromosomes in total
• Mitosis is a step in the cell cycle where the cell divides
• Interphase: cell grows, organelles increase, DNA is replicated, energy stores increase
• Mitosis: chromosomes line up at the equator, cell fibres pull each chromosome to either side of the cell
• Cytokinesis: two identical daughter cells form