Bio ch5 metabolism

Anabolism

• Simple to complex molecules

• Photosynthesis

• Energy input

Metabolism

• Complex to simple molecules

• Cellular respiration

• Energy released to drive other chemical reactions or be lost as heat

Usage of enzymes

Provide a reaction pathway with lower activation energy

Serves as a biological catalyst

Amylase catalyses the hydrolysis of starch into maltose →

What are properties of enzymes?

• Affected by temperature and pH

• Highly specific in action

• Reusable → remains unchanged; small amount needed to catalyse a reaction

• Protein molecule - operate inside or outside cell → remains active even when extracted outside the body

• Biological catalyst → would not be chemically altered or used up

Catalysing hydrogen peroxide

H2O2 ——(catalase)→ H2O + O2

Formation of enzyme substrate complex

• substrate molecule binds to active site of enzyme

• forms enzyme-substrate complex

• hydrolysis occurs sucrose into glucose and maltose

• products are released

• enzymes are available to reuse with an empty active site

How does temperature affect the rate of enzymatic reactions?

1. Below optimum temperature: inactive, temp rises → rate of reaction increases

2. At optimum temperature: rate of enzymatic reaction reaches maximum

3. Above optimum temperature: higher temp, rate of reaction decreases; breaking of bonds → active site changes shape → no longer fits the substrate molecule → denatured and is irreversible

4. ** below → inactive; above → denatured

How does pH affect the rate of enzymatic reactions?

• narrow pH range

• Outside optimum pH → active sites do not fit substrate → denatured (both higher and lower than optimum pH)

• protease has acidic optimum pH; amylase is neutral; lipase is slightly alkaline

How do inhibitors affect the rate of enzymatic reactions?

1. Decrease rate of reaction

2. Non-competitive: change shape of enzyme active site → increase enzyme

3. Competitive: block entry of substrate into active site → increase substrate concentration

4. Heavy metals like mercury and silver and lead ions/ cyanide

Enzymes in food processing

1. Fruit juice extraction: extract pectinases from fungi → clarify fruit juice (make it clear) and break down cell walls

2. Baby food and meat tenderizer: proteases which can pre-digest proteins (for babies → easier to absorb and digest) (for meat: soften before cooking)

3. Syrup: amylase to catalyse break down corn starch into sugars

Enzymes in stonewashed jeans

1. Use stones: break cellulose fibres, fabric less stiff and remove blue dye partially

2. Enzymes: break down cellulose fibres for lower production cost

Enzymes in medical field

• Glucose test strip: test glucose in urine (diabetes); oxidization of glucose and causes color change

• Dissolve blood clots: blood clots to seal cuts in blood vessel walls and stop bleeding → excessive will block blood flow to heart and brain → stroke and heart attack → enzymes to dissolve blood clots

Enzymes in personal care

Contact lens cleaner: remove protein deposits with protease in order to avoid eye infection, discomfort, destroy of cornea

Biological washing powder: using amylase, protease and lipase to break down the starch, protein and lipids in food stains

Enzymes in Biofuels

• Starch (sugar cane and maize) is broken down into sugars by suitable enzymes

• Sugars are fermented with enzymes to produced ethanol, a fuel for vehicles

Advantages of using enzymes

• speed up chemically reactions for mass production and higher yield

• specific in action → produce specific products and undesirable products are less likely to be generated

• reusable → covert a lot of substrates into useful product

• mild conditions → lower production cost

• enzyme activity can be easily regulated with adjusting pH and temperature

• non toxic and biodegradable → produce fewer pollutants