cell biology

• The nucleus is the control center of the cell, containing the genetic material and regulating cellular activities.
• plant and animal cells are eukaryotic
• bacterial cells are prokaryotic
• animal cells:

  • nucleus
  • cytoplasm
  • mitochondria
  • ribosomes
  • cell membrane
• plant cells:

  • nucleus
  • cytoplasm
  • mitochondria
  • cell membrane
  • ribosomes
  • vacuole
  • cell wall
  • chloroplasts
• the cytoplasm is where most chemical reactions take place
• the cell membrane controls what enters and leaves
• the mitochondria releases energy through respiration
• ribosomes are where proteins are made in the cell
• the cell wall is made of cellulose and strengthens and supports the cell
• the permanent vacuole is filled with cell sap
• the chloroplasts are where photosynthesis takes place
• osmosis is where water moves from an area of high concentration to an area of lower concentration, across a semi-permeable membrane
• active transport is the movement of molecules from an area of low concentration to an are of high concentration, against the concentration gradient so requires energy
• a stem cell is a cell that can differentiate into any type of cell
• magnification = image size / real size
• cell differentiation is where a cell changes to become specialised for a particular job
• as cells change they develop different subcellular structures and turn into different types of cells which allows them to carry out specific functions
• sperm cells are specialised for reproduction with :

  • a long tail and streamlined head
  • a lot of mitochondria
  • carries enzymes in the head to digest through egg
• nerve cells are specialised for rapid signalling with:

  • being long to cover more distance
  • branched connections to connect to other nerve cells
• muscle cells are specialised for contraction with :

  • being long so space to contract
  • lots of mitochondria to generate energy
• root hair cells are specialised for absorbing water and minerals with:

  • a big surface area to absorb water and mineral ions
• phloem and xylem cells are specialised for transporting substances with:

  • being long and joined end to end to form tubes
  • hollow so stuff can flow through them
• the stage of the cell cycle where the cell divides is called mitosis
• CELL CYCLE:

  1. growth & dna replication
  2. mitosis
• binary fission is where prokaryotic cells divide
• diffusion is the spreading out of particles from an area of high concentration to an area of low concentration
• chromosomes are coiled up lengths of dna molecules  
• bacterial cells dont have a nucleus but instead have a single circular strand of dna that floats freely in the cytoplasm