bio topic 2

The Cell as an Efficient Open System

• Cell Life Process

  • Intake of nutrients

  • Movement

  • Growth

  • Response to stimuli

  • Exchange of gases

  • Waste removal

  • Reproduction

• Organelles

  • Specialized structures that that are found in the cytoplasm

  • Carry out specific functions

• Cell Membrane 

  • Protective barrier that separates the cell from its surroundings

  • Controls the movement of materials in and out of the cell

  • Selectively/semi-permeable

  • 2 layer structure with lipids and proteins

  • Proteins

    • Some act as transport proteins

    • Some act as receptors

    • Some help bind the cell to things

•  Nucleus

  • Contains the DNA 

  • The ‘control center’ of the cell

  • Encased in a protective nuclear envelope

• Cytoplasm

  • The gel-like substance inside the cell

  • What the organelles are suspended in

  • Allows movement of materials and organelles

    • Called cytoplasmic streaming

• Cell Wall 

  • PLANT ONLY

  • Encloses plant cells

  • Gives the cell its shape 

  • Provides structural support for the plant

• Chloroplasts

  • PLANT ONLY

  • Contains Chlorophyll

  • Where photosynthesis occurs

    • Solar energy + 6 CO2(g) + 6 H2O(l) → 6 O2(g) + C6H12O6(aq)

• Vacuoles

  • Membrane bound structures

  • Store nutrients, cell products, and fats

    • Typically fairly small

    • ANIMAL CELLS

  • Stores water and helps the cell maintain its shape

    • Very large 

    • PLANT CELLS

• Endoplasmic Reticulum 

  • A series of interconnected tubes that branch from the nuclear envelope

  • Materials can be transported through it 

  • Rough:

    • Has ribosomes attached 

    • Associated with protein creation

  • Smooth:

    • Has no ribosomes

    • Associated with fat and oil production

• Ribosomes

  • In charge of protein synthesis (protein creation)

  • Can be free or attached to the endoplasmic reticulum

• Lysosome 

  • Membrane bound sacs 

  • Contain strong digestive enzymes

  • Also called suicide cells

  • Roles:

    • defense against foreign entities

    • destruction of damaged cell organelles

    • digestion of food molecules

• Golgi Apparatus

  • Composed of flat, disc-like sacs

  • Receives substances from the ER

  • ‘Packages’ them for transport out of the cell

• Mitochondria

  • Rod like structure

  • Specializes is cellular respiration

    • 6 O2(g) + C6H12O6(aq) → 6 CO2(g) + 6 H2O(l) + ATP

  • The ‘powerhouse’ of the cell

•  Active Transport

  • Moving molecules against the concentration gradient

  • Requires energy

• Passive Transport

  • Moving molecules with the concentration gradient

  • Doesn’t require energy 

    • Diffusion & Osmosis

2.2

The Role of the Cell Membrane in Transport

• Transport Protein

  • A protein involved in facilitated diffusion 

• Facilitated Diffusion

  • The transport of large molecules 

  • Requires no energy

  • Proteins are like a facility to help them cross the membrane

• Diffusion

  • Movement through the bi-lipid layer according to the concentration gradient

  • Any particle other than water

• Osmosis

  • Diffusion, but with water

  • The movement of water

• Concentration Gradient

  • The difference between the concentration of particles in different areas of the cell

  • Moves from high → low 

•  Solute

  • The substance being dissolved

• Solvent

  • The substance doing the dissolving

• Isotonic Solution

  • Iso means the same

  • Contains the same concentration of solute both in and out of the cell

  • Water diffuses in and out of the cell of the cell at the same rate

    • Out = in

• Hypertonic Solution

  • Hyper means more

  • High concentration of solute outside the cell

  • The water diffuses out, and the cell shrivels

    • Out > in

• Hypotonic

  • Hypo means less

  • Low concentration of solute outside the cell

  • The water diffuses into the cell, and the cell expands

  • The cell could possibly explode

    • Out < in