B1 - cell biology

• Plant, animal and fungi cells are eukaryotic. 
• Eukaryotic cells have a nucleus, mitochondria, chloroplasts, and a cell membrane where’s as prokaryotic cells don’t.
• Eukaryotic cell diagram

  
• Bacteria cells are prokaryotic
• Prokaryotic cell Diagram:

  
• DNA is a single molecule/ loop, found free in the cytoplasm of a cell. Additional DNA is found on one or more rings called plasmids
• DNA is found in the nucleus
• DNA is found in the nucleus
• Specialised cells are cells that have a specific structure and function, adapted to perform a particular task within the body
• Examples of specialised cells are root hair cells, nerve cells, muscle

  cells, sperm cells, red blood cells and female egg cell
• The function of a muscle cell is to generate movement and the specialisation is contraction and movement

  
• the function of a nerve is communication between different parts of the body and their specialisation is dendrites which receive signals and axons which send signals

  
• Function of a sperm cell is reproduction and is specialisation is its tale and its coating on its head

  
• The function of a root hair cell is to absorb water and minerals from soil and the specialisation is there long and thin

  
• The function of the female egg cell is reproduction and the specialisation is that it contains food

  
• the function of a red blood cell is transporting oxygen from the lungs around the body and the specialisation is haemoglobin

  
• Cell differentiation is the process where a cell develops new sub-cellular structures (structures inside the cell) to let it preform a specific function when this happens the cell becomes specialised
• Eukaryotic cells is a complex cell e.g. animal or plant cell whereas a prokaryotic cell is a simple cell e.g. bacteria
• Cell membrane holds the cell together and controls what enters and leaves
• Nucleus contains genetic material (DNA) that controls the activity of the cell
• Cytoplasm is a gel-like substance where chemical reactions happen. It contains enzymes that control these reactions
• Chloroplast is the site of photosynthesis and contains chlorophyll.
• Cell wall provides strength and support to the cell
• Mitochondria is the site of aerobic respiration reactions
• Ribosomes is the site of protein synthesis in the cell.
• The fine adjustment knob on a light microscope is used to focus the lens until a clear image of whats on the slide appears
• There are two types of microscopes light microscopes and electron microscopes
• Electron microscopes have a higher resolution and magnification than light microscopes (resolution is the ability to distinguish between two points. Magnification is the process of making something look bigger)
• Electron microscope are more expensive whereas light microscopes are cheeper
• Light microphones are portable where as electron microscopes are much bigger and are fixed in one space
• Light microscopes can use live specimens where as electrons microscopes can’t
• Magnification = image size ÷ real size
• Root hair cells which are cells in plants that are specialised for absorbing water and minerals from the soil
• Xylem cells function to transport water and minerals up plants. They are specialised for their function because the cells are long and are joined end to end, forming hollow tubes this means the substance can flow through them
• exocrine acinar cells function to produce lots of digestive enzymes (proteins) which are secreted from the pancreas (the cells may contain a large number of ribosomes for the synthesis of digestive enzyme)
• In human body cells chromosomes are normally found in pairs
• Mitosis is the stage of the cell cycle when the cell divides into two identical daughter cells (clones itself)
• Meiosis is cell division where the cell divides twice to produce 4 genetically varied cells (gametes)
• A normal human body cell contains 23 pairs of chromosomes (23 maternal & 23 paternal chromosomes make 23 pairs 46 in total)
• Binary fission is a type of simple cell division used by bacteria to multiply