B2.1 Cell Structure

• Cells are the basic structural and functional units of all life.
• All living things are composed of cells.
• All new cells arise from pre-existing cells.
• All* cells contain:

  • Nucleus
  • Cytoplasm
  • Cell Membrane
  • Mitochondria
• Plant cells also contain: chloroplasts, vacuole and cellulose cell wall.
• nucleus:

  • Contains genetic material (DNA)
  • DNA is a code to make proteins
  • Proteins controls cell activities
• Cytoplasm:

  • Composed mainly of water
  • Contains organelles 
  • Metabolic reactions occur here
• Mitochondria:

  • Aerobic Respiration
  • Produce ATP (energy  from Glucose
• Cell Membrane:

  • Selectively permeable
  • Controls what enters and leaves the cell to maintain a constant internal environment
• celluloses/ cell wall :

  • Contains cellulose
  • Provides structural support/ strength
  • prevents cells from bursting
• vacuole :

  • Contains cell sap
  • Sap = water with dissolved sugars, amino acids & minerals
• chloroplast :

  • Contain chlorophyll 
  • Chlorophyll traps light energy for photosynthesis
• Structure: cilia are hair like structure which can beat to move particles out of respiratory system

  Function: movement of mucus and trapped particles out of trachea of respiratory system

  
• Structure: hair like extension increases surface area for maximum absorption of water.

  Function: absorption of water and mineral ions from soil

  
• Structure: help absorb maximum light for photosynthesis

  • packed with chloroplasts containing chlorophyll 
  • brick-like shape means many cells can be stacked together

  Function: chlorophyll absorbs light energy for photosynthesis

  
• red blood cells 


  Structure: maximises cell’s ability to carry oxygen

  • biconcave = large surface area and short diffusion distance
  • haemoglobin = carries oxygen
  • no nucleus = more space for haemoglobin
  • no mitochondria = no respiration so not using up oxygen
  • thin/ flat = short diffusion distance for oxygen. Function:  carry oxygen to cells
• Function: reproduction - contain female genetics

  Structure:

  • Nucleus (haploid) - contains half genetic information.
  • Large cell with lots of cytoplasm containing stored energy for cell division after fertilisation.

  
• Function: reproduction - contains male genetics and carries this to female gamete for fertilisation.

  Structure

  • Tail to swim to egg
  • Mitochondria to provide energy to tail
  • Nucleus (haploid) - contains half genetic information 

  
•  random movement

  • particles have kinetic energy
  • particles are constant random motion
• concentration gradient

  • particles move from higher to lower concentrations
  • down their concentration gradient
• equilibrium

  • as particles diffuse and spread out evenly, equilibrium is reached.
• • Cell membranes are selectively permeable - some substances can pass in and out of the cell but other cannot.
  • Molecules move from higher to lower concentrations.. 
• • oxygen enters cells by diffusion
  • oxygen is used up in cells by respiration
  • this creates low oxygen concentration inside the cell
  • oxygen diffuses down concentration gradient into cell
• • carbon dioxide is created in cells by respiration
  • this creates a high concentration of carbon dioxide in the cells
  • carbon dioxide diffuses out of cells
  • from high concentration inside cell to lower concentration outside cell.