Enzymes for metabolism in Chemistry

Poll

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Enzymes for metabolism in Chemistry

by Chloe Cook

​What is metabolism?

• ​Metabolism is the sum of chemical reactions occurring in your body

• ​Building big molecules from small molecules is called anabolism

• ​Breaking down big molecules into small ones is known as catabolism

Multiple Choice

What is the smallest sub unit that proteins broken down into?

• Polypeptides

• Amino Acids

• Glucose

• Glycerol and Fatty Acids

Multiple Choice

What is the smallest sub unit that starch can be broken into?

• Glycerol

• Fatty Acids

• Amino Acids

• Glucose

Multiple Choice

What are the sub units that make up a triglyceride?

• Glycerol and Fatty Acids

• Amino Acids

• Polypeptides

• Glucose

Multiple Choice

Which class of chemical reaction best represents anabolic metabolism (Building up molecules)?

• Condensation Reactions

• Hydrolysis Reaction

• Acid Base Reaction

• Esterification

Multiple Choice

Which class of chemical reaction best describes what happens in catabolic reactions?

• Condensation Reactions

• Hydrolysis Reactions

• Oxidation of Alcohols

• Making Amides

​You are what you eat

• ​We digest macronutrients and break them down into their key sub units - this usually releases energy

• ​Then we build them back up again into the structures and fuel that make up you and your energy reserves - this usually absorbs energy

​What are Enzymes?

• ​Enzymes are usually tertiary proteins that have a very specific 3D structure

• ​This structure allows for an active site that is specialized to fit only one very specific substrate

• ​Enzymes speed up the rate of a chemical reaction without taking place int he chemical reaction

• ​Enzymes catalyse the hydrolysis and condensation reactions that keep us alive!

Model for Enzyme function

• ​There are two models of enzyme function

• ​The lock and key states that the active site is a set and unmovable 3D shape that is complementary to the substrate

• ​The induced fit model states that the active site can mould itself around the substrate and put pressure on molecules to make or break their bonds

Multiple Choice

Which enzyme do you think catalyses the breakdown of carbohydrates?

• Lipase

• Pepsin

• Amylase

• Protease

Multiple Choice

Which enzyme catalyses the breakdown of fats?

• Amylase

• Lipase

• Oilase

• Pepsin

Multiple Select

Which enzyme breaks down proteins?

• Pepsin

• Protease

• Amylase

• Lipase

​Describing how enzymes work

• ​They are a biological catalyst that increases the rate of reaction by providing an alternate reaction pathway.

• ​Their tertiary 3D shape allows for a complimentary fit of a substrate via various intermolecular bonds

• ​You want do discuss specific bonds broken/made and product produced

​Enzymes can identify different optical isomers

• ​Since enzymes have such a specific active site, they can recognize only one of a pair of enantiomers. So if a molecule is chiral (like amino acids) then only one of the mirror images will fit into the active site

Open Ended

Pepsin is a protein that hydrolysis proteins in the stomach. Explain what happens what an enzyme catalyses the hydrolysis of a protein (3 Marks)

​Enzymes work best in very specific environments

• ​Human enzymes work best at a temperature of 37 degrees

• ​Different enzymes work best in different pH's

  • ​Pepsin works best in acidic pH because it operates int he stomach

  • ​Lipase works best in basic pH's because it's int he same location as bile

  • ​Amylase loves a neutral pH

​Denaturation

• ​Denaturation is when the intermolecular bonds that keep the important 3D shape of the tertiary enzyme together are interrupted

• ​This means that the enzyme unravels, and the active site changes, so it is no longer complimentary to the substrate it is supposed to metabolize.

​Denaturation in Temperature

• ​High temperatures denature enzymes

• ​The high kinetic energy means that all intermolecular bonds in the tertiary structure are interrupted

• ​Cold temperatures do not denature enzymes - they just slow them down due to low kinetic energy

​Denaturation in Acidic and Basic Solutions

• ​In an acidic solution, the excess of H+ ions really screw with hydrogen bonds in particular, but also dipole dipole and electrostatic attractions

• ​This also disrupts the tertiary structure of an enzyme

• ​Bases do the same sort of thing, except this time it is the excess of OH- ions doing the damage

Multiple Choice

Which of the following statements about enzymes is correct?

• The induced fit model suggests that the shape of an enzyme remains constant 

• Enyzmes may have their tertiary structure altered when catalysing reactions

• Enzymes can catalyse reactions over a broad range of temperatures

• Enzymes change the equillibrium constant of a reaction

Multiple Select

An enzyme

• Can distinguish between optical isomers

• catalyses the forward and reverse reactions

• always needs a coenzyme to function

• is not able ot change shape

​Coenzymes

• ​Coenzymes are small organic molecules, like vitamins, that are required by some enzymes to catalyze a reaction

• ​Coenzymes often help by forming a complex witht he enzyme and completing the complimentary shape of the active site

• ​They can also help with electron transfer in a chemical reaction, since a lot of vitamins are strong reductants/oxidants

Multiple Choice

Coenzyme A is involved int he synthesis of lipids. Coenzyme A is

• A vitamin that is a precursor for an enzyme

• A substrate in the synthesis of fatty acids

• required by all enzymes to catalyze a reaction

• A small organic molecule that forms a complex with an enzyme

Open Ended

Describe the difference between the hydrolysis of a protein and denaturation of a protein by referring to the primary, secondary and tertiary structures of a protein (2 Marks)

Open Ended

There are two different optical isomers of of Vitamin C - L-Ascorbic acid and R-Ascorbic acid. Explain why one one optical isomer is active in the human body (2 Marks)

Open Ended

Ascorbic Acid (Vitamin C) acts as a co-enzyme for a number of different enzymes in the human body, since it is an excellent reductant. Describe the chemical and physical interactions of Vitamin C with enzymes to enable them to catalyse reactions (3 Marks)