• The green objects represent ________?

• Dashed line?

• Passive or Active transport?

• Molecules in aqueous solution = solute

• Cell (or plasma) membrane

• Passive transport; Diffusion of solutes toward equilibrium

Osmosis

• Diffusion of water

– Towards equilibrium

– High concentration of water to low concentration of water

Osmoregulation = controlling water balance internally in relation to the outside environment

• Isotonic: (iso = same) cell is in a solution of equal solute concentration• Hypotonic: (hypo = below) cell is in a solution of lower solutes• Hypertonic: (hyper = above) cell is in a solution of higher solutes

• Purple objects represent ___?

• Left side passive or active?

• Right side passive or active transport?

• Transport proteins in plasma membrane

• Passive transport; high concentration to low

• Active transport; against concentration gradient– Expend energy

ATP

Energy?

• Capacity to do work

• Kinetic E– energy in motion– E.g. muscle contractions, heat, light, active

transport

• Potential E– stored energy– E.g. object at rest atop hill, food, ATP

• Energy conversion; transform from one form to another

Laws of E transformation

• 1st Law of thermodynamics– Energy conservation– E can be transferred or transformed– E cannot be created or destroyed

e.g. sunlight to starch via photosynthesis

Laws of E transformation

• 2nd Law of thermodynamics– E escape or transfer during

conversions• e.g. heat released during

muscle contractions is transferred to the environment

• Cells convert potential E to cellular E

– Organized starch or glucose molecules to ATP

– E escape leads to disorder• Entropy

= amount of disorder or chaos in a system

• How to deal with Entropy & prevent total chaos?• Energy input

– More E is required to replace the E that escapes– Plants absorb solar E (kinetic E)– Animals eat food (potential E)– chemical reactions in cells convert energy– http://www.youtube.com/watch?v=5KIhDVLbMeY

Two types of chemical reactions in regards to Energy flow

Endergonic reactions &Exergonic reactions

• Endergonic reaction

– Net input of energy

– Increasing potential E

– Building carborhydrates• making bonds• e.g. plants

photosynthesizing

• Exergonic reaction

– Chemical rxn that releases energy

– Covalent bonds of reactants have more potential E than products

– Breaking down carbohydrates

• Potential E to ATP• Breaking bonds

ATP powers cellular work

• Breaks bond via hydrolysis• Phosphorylation• Exergonic or Endergonic?• e.g. transfer of phosphate to motor protein

causes contraction (muscle cells, flagella movement)

Enzymes• Proteins that change the rate of

chemical reactionsMany act as catalysts – speed up

reactions…. How?

• Lower the activation energy= energy required to initiate a chemical

reaction

– Carbohydrates are potential E to fuel the cells– Cells convert ATP; to power a reaction– Enzymes make it easier for that reaction to

occur

Cyclist resting atop the hill is potential E… he doesn’t start speeding down the hill until the final little push to get him over the last barrier

• Enzymes are catalysts (the push)