cell division

• carries genetic information in a molecule called DNA

  chromosome
• a type of cell division that ensures that when a cell divides each new cell produced has the same genetic information

  mitosis
• where does DNA exist?

  nucleus and chromosomes
• Each section of a chromosome that contains the code for the production of a particular protein is called a gene
• Each chromosome is made from a single molecule of DNA, but when a cell is ready to divide, the DNA copies itself, then coils and condenses to form the chromosomes that we see in micrographs
• how many chromosomes does a human body contain?

  46
• what is the pair of chromosome that carries the sex chromosome

  23rd
• females are referred to as XX
• males are referred to XY
• cells divide when:

  an organism grows and an organism is damaged and needs to produce new cells
• It is essential that any new cells produced contain genetic information that is identical to the parent cell.
• cell cycle

  
• what is the formula of length of time in phase?

  observed number of cells at that stage divided by total number of cells observed multiplied by total length of time cycle
• cells that have not gone differentiation

  stem cells
• develops from a fertilised egg

  embryo
• Cells at the early stages in the development of the embryo 

  stem cells
• if cells are removed from the embryo it is called

  embryonic cells
• cells that has remained in the adult body

  adult stem cells
• where can you find adult stem cells in the body

  brain, eyes, blood, heart, liver, bone marrow, skin, muscle
• where does cell division in plant occur?

  meristems
• The main meristems are close to the tip of the shoot, and the tip of the root.
• In a growing shoot, new cells are being produced continuously near the tip. As the cells become older, further away from the tip, they become differentiated – they enlarge and develop vacuoles
• Animals and plants produced by sexual reproduction begin life as a single cell – a fertilised egg or zygote
• how can a cell produce a multicellular organism?

  divide and differentiate
• why do cells need to divide and differentiate?

  to fulfil specific roles
• what are the specialised cells in animal?

  circulatory system, excretory system, muscular system, nervous system, respiratory system, reproductive system, skeletal system
• circulatory system


  Transport substances, defend the body, regulate temperature
• excretory system


  Remove waste products and unwanted substances, regulate the water content of the body
• muscular system


  bring about movement
• nervous system


  Respond to internal and external stimuli and conditions, carry messages for the body work as a coordinated whole
• respiratory system


  Deliver oxygen for respiration and remove waste
• reproductive system


  Bring about fertilisation to produce new offspring
• skeletal system


  To bring about movement, support and protect internal structures, produce blood cells, store and release calcium
• what are the specialised cells in plants?

  leaf: palisade mesophyll, spongy mesophyll, guard cells, phloem: sieve tubes, companion cells, xylem: xylem vessels, growing points: meristem
• palisade mesophyll

  carry out photosynthesis
• spongy mesophyll

  Allow gases to circulate for the exchange of gases between the leaf and the environment, carry out some photosynthesis
• guard cells

  Open and close to control the exchange of gases – carbon dioxide, water vapour and oxygen
• sieve tubes


  Transport products of photosynthesis, including sugars and amino acids, from the leaf to where they are needed
• companion cells


  Provide the energy required for transporting substances in sieve tubes
• xylem vessels


  Transport water and dissolved minerals from the roots, up the plant