Topic 2 Bio

• Specialised cells are designed to carry out a particular role in the body of plants
• Sperm cells role is to deliver genetic material to an egg to fertilize it
• Sperm cells have adaption like a flagellum to reach the egg, lots of mitochondria for swimming energy and has digestive enzymes which are used to break a hole into the egg
• Differentiation is the process by which cells become specialised
• All multicellular eukaryotic organisms require a continuous supply of new cells, which can be used for growth, development and repair
• Nervous system is the way our body communicates with eachother so we can co-ordinate our behaviour and respond to our surroundings
• Neurons are adapted to carry electrical impulses from one point to another, they are long thin and have a branch of connections to either end which enables them to pass messages onto other nerve cells
• For one nerve cell to communicate with another we need a synapse
• The central nervous system is the brain and spinal cord where all our thinking happens, it takes in lots of sensory info and decides what needs to be done
• Sensory neurons carry info from receptors all over the body to the central nervous system
• motor neurons send impulses back out to the body, genrally muscles or galnds could be told to release hormones
• reflex arc is the nerve pathway which underlies our unconscious reflexes like moving your hand from something hot
• stem cells are cells that divide by mitosis and produce more cells and can differentiate into different types of cells
• embryonic stem cells can differentiate into any type of specialised cell
• adult stem cells are found in bone marrow and can only differentiate into different blood cells
• drawbacks from using embryonic stem cells is theres a limited supply and ethical issues
• The four stages of mitosis is prophase, metaphase, anaphase, telophase and Cytokinesis 
• Prophase is where the the chromosomes condense and the nuclear envelops starts to break down leaving the chromosomes free in the cytoplasm
• metaphase is where the chromosomes line up at the middle of the cell
• anaphase is where the spindle fibres contract and shorten to pull the chromatids to opposite poles of the cell
• telophase is when the chromatids reach the opposite poles of the cell where they uncoil and become long and thin chromosomes again. A nuclear envelope forms around each set of chromosomes to form two nuclei
• cytokinesis is where after the steps of mitosis is the cytoplasm diving into a process and produces two daughter cells that are genetically identical
• Two features of stem cells is they are able to differentiate into specialised cells and divide by mitosis to form more cells