B1 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
• Prefixes like centi, milli, micro, and nano are used before units of measurement to show multiples of the unit
• 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

  The nucleus contains genetic material, including DNA, which controls the cell's activities.
• 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
• Bacterial cells have a different structure and function compared to animal and plant cells
• Cytoplasm, cell membrane, and cell wall are present in bacterial cells
• Bacterial cells have a single circular strand of DNA and plasmids
• Cells specialise through differentiation, gaining new sub-cellular structures for specific roles
• Stem cells can differentiate once early on or retain the ability to differentiate throughout 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 with specific functions
• Almost all animal cells differentiate early on and lose this ability, except for stem cells
• 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 are used to view tissues, cells, and large sub-cellular structures
• Electron microscopes have a magnification of up to x2,000,000 and are used to view deep inside sub-cellular structures
• Common calculations in microscopy include magnification and size of an object
• Standard form is useful for working with very large or small numbers in microscopy calculations
• Microorganisms are cultured in labs using nutrient broth solution or agar gel plates
• Culture medium contains carbohydrates, minerals, proteins, and vitamins for microorganism growth
• Steps in culturing microorganisms include sterilising Petri dishes, using inoculating loops, and incubating at suitable temperatures
• Bacteria can multiply by binary fission as fast as every 20 minutes under suitable conditions
• Microorganisms can be used to test the effects of antibiotics on their growth
• Steps in testing antibiotics include soaking paper discs in antibiotics, placing them on agar plates, and measuring the zone of inhibition
• Chromosomes contain coils of DNA
• A gene is a short section of DNA that codes for a protein and controls a characteristic
• 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
• Cell division by mitosis is important in growth, development, and replacing damaged cells
• Stem cells are undifferentiated cells that can produce many more similar cells