Cells

• Cell surface membrane


  Thin layer of protein & fat<|>Supports & holds the part of the cell together<|>Semi-permeable<|>Contains phospholipids
• Cytoplasm


  Jelly like fluid that fills the cell<|>Made up of 70% water<|>Place where metabolic reactions occur
• Nucleus


  Contains genetic material in form of DNA<|>Chromosomes store information inherited from organism's parents<|>Controls all cellular activities<|>Needed for cell division
• Cell wall


  Made up of cellulose<|>Provides shape & support to cell (when the cell is turgid, full of water it prevents it from bursting)<|>Fully permeable
• Protoplasm


  Chloroplast<|>Large central vacuole
• Chloroplast


  Contains a green pigment called chlorophyll<|>Chlorophyll absorbs sunlight energy and uses it for photosynthesis<|>Contains starch grains (tiny pieces of starch)
• Large central vacuole


  Fluid filled sac<|>Contains sugars & other solutions called cell sap<|>Separated by cytoplasm by a tonoplast<|>Permeable
• Animal cells have much smaller vacuoles called vesicles
• Ribosomes


  Produces protein by joining amino acids to form long chain<|>Very small in size<|>Site for protein synthesis
• Mitochondria


  Place where anaerobic reactions take place (chemical reaction that uses oxygen to break down glucose to release energy for cell to use)<|>Function as power house of a cell
• Bacterial cell


  Unicellular<|>Have cell wall made up of peptidoglycan<|>Circular DNA<|>Have plasmid (small circular molecules of DNA)<|>Some have flagellum (allow it to move)<|>No chloroplast, nucleus & mitochondria<|>Ribosomes are used in protein synthesis
• Magnification= size of drawing / actual size
• Conversion factors

  • 1 m = 100 cm
  • 1 cm = 10 mm
  • 1 m = 1000 μm
  • 1 mm = 1000 nm
  • 1 m = 10^9 nm
  • 1 cm = 10^4 μm
  • 1 m = 10^6 μm
• Cell


  The basic living unit of organisation for all organisms
• Metabolism


  All the chemical reactions that occur inside a cell, taken together
• Cell theory


  • Organisms can be unicellular or multicellular
  • The cell is the basic unit of life
  • All cells arise from pre-existing cells
• Cells vary considerably in size, shape and what they contain because they often have different functions
• A cell has basic needs similar to those of living organisms (nutrients, substances, water, oxygen)
• Organelles


  Internal cell structures each of which plays a specific functional role in the cell
• Protoplasm


  The mass of living matter that makes up the cell
• Protoplasm states


  Sol state (liquid)<|>Gel state (semi-solid)
• Cell surface membrane (plasma membrane)


  A delicate, thin layer surrounding the cell made up of proteins and lipids (phospholipids)
• Nucleus


  The most easily seen organelle, spherical in shape and surrounded by a nuclear envelope, controls the normal activities of the cell
• Chromatin


  Long thread-like structures made of DNA, involved in cell division, condense to become chromosomes during cell division
• Nucleolus


  One or two spherical bodies inside the nucleus, play an important role in the building up of ribosomes
• DNA (deoxyribonucleic acid)


  The blueprint of life, discovered by Watson and Crick in 1953, has a double-helix structure
• Cytoplasm


  The part of the protoplasm surrounding the nucleus, where chemical reactions take place
• Mitochondrion


  Small spherical/rod-shaped organelles that function as the "powerhouse" of the cell, involved in respiration and the release of energy from food
• Centrioles


  Tiny structures close to the nucleus, important in cell division, absent in most plant cells
• Cell wall


  A non-living layer of cellulose polysaccharide that surrounds the cell membrane, provides support and shape to the cell, is fully permeable
• Vacuole


  A fluid-filled sac surrounded by a tonoplast (semi-permeable membrane), used for storing water, minerals, and waste products
• Chloroplast


  An organelle that contains chlorophyll and is involved in the conversion of light energy to chemical energy
• Starch grains


  Small, insoluble carbohydrate particles that store excess food in plant cells
• Structural differences between animal and plant cells

  • Plant cell has a rigid cell wall made of cellulose, stores food as starch, contains chloroplasts with chlorophyll
  • Animal cell lacks a cell wall, stores excess carbohydrates as glycogen granules, lacks chloroplasts
• Red blood cells are highly specialised cells that lack a nucleus, allowing them to carry more haemoglobin for oxygen absorption and delivery to tissues
• Red blood cells have a flattened, biconcave shape that allows them to squeeze through tiny capillaries to supply oxygen to tissues
• Red blood cells have a lifespan of 120 days/4 months, after which they break down and the haemoglobin is converted to bilirubin and excreted
• About 200,000 million red blood cells wear out and are replaced each day
• Calculating magnification of a drawing


  Size of drawing / Actual size = Magnification