Cells

Cells

1. Types

   • Prokaryotic
     • no membrane-bound organelles
     • Simpler cell structure
     • Eg. Bacteria
   • Eukaryotic
     • contain membrane-bound organelles
     • Complex cell structure
     • Eg. Animal & Plant

2. Parts

   • Nucleus
     • Nucleus, Cytoplasm, Membrane                PROTOPLASM
     • controls vital cell activities
       • Eg.
         • Cell division
         • Cell growth
         • Cell repair
     • Porous nuclear membrane
     • Chromatin
       • DNA
       • Condense (cell division) = Chromosome
     • Nucleolus
       • plays a part in making proteins
     • Nucleoplasm
   • Cytoplasm
     • 70% water content
     • contain organelles
       • Mitochondria
         • 2 membrane
         • Break down food during respiration
           • Release ENERGY
       • Endoplasmic reticulum
         • Rough
           • produce & transport proteins (ribosomes) to Golgi apparatus
           • have ribosomes attached
         • Smooth
           • Synthesise & transport
             • lipids & steroid hormones
           • Detoxification
             • Converts harmful substances to harmless
           • No ribosomes attached
       • Ribosomes
         • Attached to ribosomes
           • Exported via vesicles outside cell
         • Free
           • For intercellular usage
       • Golgi apparatus
         • Modifies substances (synthesised by the ER)
         • Package substances into vesicles for secretion (outside cell)
       • Vesciles
         • Transport substances btw organelles
       • Vacuole
         • Storage of substances in cell
         • Animal
           • Small
           • Many
           • Store water & food
           • Usually temporary
         • Plant
           • One
           • Large
           • Central
           • Store cell sap
             • Sugars
             • Mineral salts
             • Amino acids
           • Tonoplast
             • Membrane surrounding vacuole
       • ONLY IN PLANTS
         • Chloroplast
           • Chlorophyll
             • Photosynthesis
         • Cell Wall
           • Fully permeable
           • Hard & Rigid
           • Protect cell frm phyical damage
           • Provides support
           • Cellulose
       • Centioles
   • Membrane
     • controls substances moving in and out of cell
     • Partially permeable

3. Specialised

   • Differentiation
     • Process
     • Develop special structures
       • Specific functions
   • Red blood cell
     • Contains haemoglobin
       • Binds reversibly w oxygen
     • Transport oxygen
     • Lacks nucleus
       • Free up more space
         • carry ↑ haemoglobin
     • Biconcave shape
       • ↑ S.A to V ratio
         • more oxygen can diffuse into cell
           • ↑ rate of oxygen entering RBC
     • Elastic
       • Bell-shape
         • Squeeze through vessels smaller than itself
   • Xylem vessls
     • No cross-walls / partition walls
       • No obstrction
         • Water & mineral salts can move through vessels easily
     • No protoplasm
     • Lignin deposits (vessel walls)
       • Strengthen vessels
         • prevent it frm collapsing
     • Bundled tgt
   • Root Hair Cell
     • Narrow, elongated projection
       • ↑ S.A to V ratio
         • ↑ rate of diffusion /osmosis

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