Unit 1 AoS1

• Surface Area


  Area exposed the extracellular environment
• Volume


  Amount of space that a substance occupies
• Calculating SA:V


  Divide Surface Area by Volume
• Higher SA:V ratio


  More efficient cell exchange
• Organelles in the cell

  • Nucleus
  • Ribosome
  • Endoplasmic reticulum
  • Golgi apparatus
  • Mitochondria
  • Cytoskeleton
  • Centrioles
  • Cell membrane
  • Lysosomes
  • Smooth endoplasmic reticulum
  • Cell wall (Plants & prokaryotes)
  • Vacuole (smaller in animal cells, bigger in plant cells)
  • Chloroplast (Plants only)
  • Flagellum & Cilium
• Nucleus


  • Contains DNA, codes for all cellular proteins
• Ribosome


  • Reads message from DNA regarding which protein to make
  • Based on those messages, ribosome strings together a protein chain
• Endoplasmic reticulum


  • Modifies protein chain into functional shape
  • Called 'rough' as studded with ribosomes
• Golgi apparatus


  • Makes some changes to the functional protein & packages it into a vesicle so that it can be delivered outside cell
• Mitochondria


  • Uses oxygen & glucose
• Cytoskeleton


  • Microtubules which support cell's structure
• Centrioles


  • Cylindrical structures involved in cell division (only visible in cell division)
• Cell membrane


  • Phospholipid bilayer that surrounds the entire cell & assist the regulation of materials in and out of cell
• Lysosomes


  • Contains digestive enzymes that break down waste products from the cell
• Smooth endoplasmic reticulum


  • Contains enzymes involved in synthesis of molecules such as steroids & phospholipids
• Cell wall (Plants & prokaryotes)

  • Surrounds cell membrane & provides the plant with shape, support & protection
  • Made of carbohydrates (cellulose) in plants
  • Made of peptidoglycan in prokaryotes
• Vacuole (smaller in animal cells, bigger in plant cells)

  • Filled with water & dissolved nutrients
  • Help plants keep its shape
• Chloroplast (Plants only)


  • Contains pigment (chlorophyll), absorbs sun energy & uses it to split water & carbon dioxide, converting it into glucose (photosynthesis)
  • Glucose used as an energy source
• Flagellum & Cilium


  • Hair-like structures on the surface of cells contain arrangement of microtubules
  • Assist with cell movement & to move substances around the cell
• Differences in Plant & animal cells

  • Plant cells have additional cell wall
  • Plant cells contain chloroplast organelle
• Movement across membrane


  • Passive transport (Simple diffusion, Facilitated diffusion)
  • Active transport (Active transport, Endocytosis/exocytosis)
• Passive transport


  No ATP required
• Simple diffusion


  Transport of small hydrophilic substances (lipophilic)
• Facilitated diffusion


  Transport of dissolved hydrophilic substances down concentration gradient<|>Involved protein transporters
• Active transport


  Transport of dissolved hydrophilic substances against concentration gradient<|>Involved protein transporters (pumps)
• Endocytosis/exocytosis


  Bulk transport of macromolecules & liquids
• Role of plasma membrane

  • Acts as a protective boundary
  • Acts to keep out foreign molecules
  • Allows cells to communicate with each other
  • Involved in cell recognition
• Diffusion


  Net movement of molecules from high to low concentration
• Factors affecting rate of diffusion

  • Temperature - increase in kinetic energy
  • Molecular size
  • Steepness of gradient - more difference, faster movement
• Osmosis


  Passive movement of water from a region of high water conc. to low water conc. to reach equilibrium
• Tonicity


  • Isotonic - no net movement
  • Hypotonic - water moves into cell, cell could burst
  • Hypertonic - water moves out of the cell, cell could shrink
• Factors affecting movement of substances

  • Molecular size
  • Presence of net charge
  • Solubility in lipid solvents
  • Direction of concentration gradient
• Chromosomes


  Tightly coiled DNA that forms when cell divide
• Chromatin


  A mixture of DNA & proteins that form chromosomes, comprised of protein (histones) & DNA
• Sister chromatids


  The copy of DNA made during interphases, two copies of each chromosomes are called sister chromatids which split during cell division
• Centromere


  The join between sister chromatids
• Telomere


  Repetitive non-coding DNA found at the end of chromosomes which protect the chromosome from damage
• Homologous chromosomes


  A set of one maternal & one paternal chromosome that pair up with each other inside the cell<|>They contain the same traits & loci (genes in same location)
• Purpose of Cell replication


  • To replace other cells that have worn out or have become damaged (maintenance)
  • To all multicellular organisms to grow
  • To repair damaged cells after injury
  • Restores the nucleus-to-cytoplasm ratio (SA:V ratio)
• Cell cycle (IPMATC)


  • Interphase (G1, S, G2, G0)
  • Mitosis (Prophase, Metaphase, Anaphase, Telophase)
  • Cytokinesis