Cells and organisation

• A eukaryotic cell is a type of cell which contains a true nucleus along with membrane-bound organelles.
• An eyepiece graticule is a scale bar inside the eyepiece of a light microscope which can be calibrated against a stage micrometer to measure structures.
• Plasmodesmata are microscopic channels between plant cell walls that facilitate symplastic transport.
• A stage micrometer is a scale that can be mounted to the stage of light microscopes and can calibrate eyepiece graticule.
• Magnification is how much bigger a sample appears under the microscope than it is in real life.
• Resolution is the ability to distinguish between two points on an image.
• The cell theory is that all organisms are composed of cells - either single cellular or multicellular.
• All cells come from pre-existing cells.
• Cells are the basic unit of life.
• The nucleolus is found within the nucleus and is the site of ribosome production.
• The cell membrane is a bilayer of phospholipids with proteins embedded in it and it controls what enters and leaves the cell.
• The cell wall is bundles of cellulose fibres arranged in a cross-cross pattern and it gives strength to plants.
• The smooth endoplasmic reticulum is interconnected channels of membrane with no ribosomes and it is where steroids and lipids are made.
• The nucleus is surrounded by a double membrane with pores in it and it contains genetic material. It also contains the DNA which codes for proteins.
• The rough endoplasmic reticulum is interconnected channels of membrane with ribosomes on the outside and it is where proteins are modified.
• The cytoplasm is the liquid part of the cell where many chemical reactions in the cell happen.
• The mitochondria is a bean-shaped organelle which has an outer membrane and an inner membrane which is folded to form cristae and the liquid is matrix. This is where aerobic respiration occurs.
• The chloroplast has a double membrane and the liquid is called stroma and the membrane stacks are called grana. This is the site of photosynthesis.
• The Golgi apparatus is a stack of curved, flattened sacks made of membrane and proteins are made on the ribosomes and move through the channels.
• The ribosome is a very small organelle that is made up of two subunits and it is where proteins are made.
• The lysosome is a small membrane-bound sack which may contain digestive enzymes and some are involved in transport of chemicals and others may contain digestive enzymes.
• The centrioles are a pair of short cylinders and each cylinder is made of nine fibres. These form the poles of the spindle during cell division in animal cells.
• The cell wall is made from peptidoglycan and surrounds the membrane for rigid structure and support.
• The capsule is a protective, slimy layer which helps the cell to retain moisture and prevent dehydration.
• The plasmid is a small circle of DNA which codes for proteins.
• The flagellum is a tail-like structure which move and rotates the cell.
• The pill are hair-like structures made from thin protein tubes which allow the cell to adhere to surfaces.
• The ribosomes in a prokaryotic cell are 70s.
• The mesosome is a folded cell-surface membrane which is the possible site of respiration.
• The circular DNA is a closed loop of DNA which contains many genes and it codes for proteins.
• 1m is 1000mm, 1mm is 1000 micro metres and 1 micrometer is 1000 nano metres.
• The equation for magnification is size of image/actual size of specimen.
• A tissue is a group of similar cells carrying out a similar function.
• An organ is a group of tissues working together to carry out a specific function.
• An organ system is a group of organs working together to carry out a gross function.
• The 4 fundamental tissues are epithelial, connective, muscle and nervous.
• Epithelial tissue is lining tissues which line insides of tubes or cavities, and fit neatly in a layer. They lie on basement membrane and have no direct blood supply.
• Examples of epithelial cells are squamous, cuboidal, columnar, and ciliated.
• Connective tissue doesn’t fit closely together and are surrounded by extracellular matrix. This matrix is fibrous, hard or fluid and these lie below basement membrane.
• Examples of connective tissue are loose, cartilage, bone or blood.