Enzymes-Definition

Biological catalysts that speed up the rate of chemical reactions Without being used up in the reaction.

Enzymes are made up of Proteins.

How enzymes work;

How enzymes work is described by the “Lock and Key” Mechanism.

Enzymes are made up of proteins.

Enzymes are molecules which have a precise 3-dimensional shape.

Enzymes are specific (each enzyme acts on a particular material or

substrate). Why?

Enzymes have a specific “dent” (location/depression) within its

Shape which exactly fits with only one substrate.

This dent on the enzyme into which the substrate binds to is called

The Active Site.

The active site is exactly the same shape and size as the substrate.

That specific substrate is the only molecule that can fit perfectly into

The active site, no other substrate can fit into the same active site.

The active site and the substrate are said to have matching or

Complementary shapes.

Every lock binds with its specific key

Factors affecting enzyme action 1. Temperature:

Low temperature slows down the action of enzymes.

Very high temperatures break down the protein structure of the

Enzyme until it no longer can bind with the substrate as the shape

of the active site will be destroyed – this is when the enzyme

is Denatured.

If we start from low temperature and increase the temperature slowly

, the rate of the reaction will increase as high temperature increases the

kinetic energy of the enzyme and the substrate.

This makes them move faster increasing the chances of them

Colliding (hitting together) hence increasing the rate of the reaction

(The Collision theory).

The Optimum temperature or pH is the best temperature or pH at

Which the enzyme works at its fastest speed.

2. pH - Extremes in pH (very high or very low pH) also denatures

enzymes.

State 2 examples of enzymes and mention which reactions do they catalyze

Amylase enzyme in the mouth – breaks down starch into glucose.

Pepsin/Protease enzyme in the stomach – breaks down proteins into

amino acids.

The pepsin enzyme works best in acidic pH.

- Lipase enzyme breaks down fats into fatty acids & glycerol

Lesson – Drugs A drug is any substance taken into the body that modifies or affects Chemical reactions in the body.

Types of drugs;

1-Medicinal/legal drugs;

•Drugs used in medicine to help our bodies fight illness or cure a disease.

•Drugs taken legally to reduce a symptom such as headache or to treat a

bacterial infection.

2-Recreational/illegal drugs;

•Drugs taken to provide stimulation or induce sleep or create hallucinations (not for medical reasons).

•Drugs are present in many products such as: Tea, coffee and ‘energy

drinks’ (caffeine); tobacco (nicotine); and alcoholic drinks which, although legal,

can cause serious effects when taken excessively or over extended periods of time.

The most common legal drug – Antibiotics

•Harmful bacteria that cause disease are called Pathogens or Parasites.

•Antibiotics kill bacterial pathogens (NOT VIRAL).

•Antibiotics help cure disease.

•The ideal drug for curing disease would be the drug that destroys the

pathogen without harming healthy body tissues.

•In practice, antibiotics come pretty close to this ideal drug criterion.

•No antibiotic is 100 % ideal.

•Most of the antibiotics we use come from bacteria or fungi that live in the

soil.

•The best known antibiotic is Penicillin, which is produced by the fungus

Penicillium

Antibiotics – mode of action

Antibiotics attack bacteria in a variety of ways.

1-They destroy/stop the formation of the bacterial cell wall.

2-Prevent bacteria from reproducing.

3-Cause the bacteria to rapture & die.

4-Interfere with protein synthesis and thus stop bacterial growth.

Side effects of antibiotics

1- Antibiotics may produce allergic reactions example skin rash.

2- Antibiotics kill healthy bacteria as well as harmful bacterial cells

(they are not ideal).

3- Sometimes antibiotics are not effective because bacteria mutate (change

their genes), and form Antibiotic-resistant bacteria (the bacteria are not affected

by the antibiotic).

•Antibiotics and viral diseases

•Antibiotics are not effective against viral diseases.

-This is because antibiotics work by destroying structures in bacteria such

as cell walls and membranes, or processes associated with protein synthesis

Drug examples (Heroin, Alcohol & Smoking)

•Many drugs such as Heroin and Morphine act as powerful Depressants.

Depressants are drugs that reduce the activity of the Nervous system.

Depressants increase reaction time and slow down responses.

Reaction time is the time needed to respond to your surroundings.

•Heroin and Morphine are used in medicine to relieve severe pain for example in

cancer patients.

•But if they are not used for treatment purposes they will be considered illegal as

they have many side effects.

1-They are Addictive, this is when the body cannot function properly without the drug (you become used to the drug & you cannot live without it).

2-They are Depressants and increase your reaction time making it unsafe to drive or use any machinery under the effect of the drug.

3-Affect your behavior and make you do things you do not normally do like stealing to get money to buy the drug (makes you aggressive).

Social Implications of any addictive drug:

-Aggressive behavior. -Person will spend lots of money on the drug and may steal or

do criminal acts to buy the drug. -Lack of personal and oral hygiene. -Reckless driving putting ones life at risk. -Broken relationships. -Lack of proper concentration and judgment. -Affects wok performance, people may loose their jobs and become Homeless

Additional hazards can include;

-Drug overdose: (if too much of the drug is ingested, this will lead to blood

poisoning – this is fatal !!)

Spread of diseases: Sharing needles between drug addicts causes the spread of

blood diseases such as AIDS and Hepatitis C virus.

Alcohol

•Alcohol is a Depressant of the Brain & Nervous System.

- This can greatly increase the chance of car accidents.

•Too much alcohol in the blood results in unconsciousness.

•An overdose of alcohol can cause death because it stops the breathing center

in the brain. Effects of alcohol on the Liver

•Alcohol is broken down in the liver.

•Too much alcohol intake over a period of time (usually years) leads to

liver failure.

Alcohol & Pregnancy

•The placenta cannot stop the alcohol in the blood from reaching the fetus.

•Too much alcohol in the mother’s blood can greatly affect the baby and

cause mental and physical defects.

•Even small amounts of alcohol in the mother’s blood can affect the fetus.

Summary - general affects of alcohol on different organs of the body:

Affects liver, brain, stomach, kidney and heart. Brain - addiction. Liver-causes liver failure / fatty liver / kills liver cells / cancer. Stomach-irritates the lining of the stomach and causes stomach ulcers. Kidney-Damages kidney cells.

Heart - increases risk of heart disease

Alcohol & Behavior

•Alcohol reduces that part of the brain which causes shyness (makes you

feel more courageous).

-This leads to reduction of self control, irresponsible behavior such as vandalism

and aggression.

•Alcohol increases reaction time and makes you unfit to drive or use any machinery or take rational decisions. Smoking

•As smoking affects chemical reactions in the body it is considered a drug.

Effects of Smoking:

1- Heart disease:

•Toxins in cigarettes increases the chance fatty material is deposited in

the inner walls of the coronary arteries leading to a heart attack.

• Smoking increases your blood pressure and affects the health of your heart.

2- Fetal defects:

•Babies born to women who smoke during pregnancy are smaller than average.

•This is a result of reduced oxygen supply caused by carbon monoxide in

the blood

3- Lung diseases:

Substance Effect on body

1-Nicotine -Absorbed into the blood.

-Addictive (body gets used to it).

-Nicotine narrows blood vessels

increasing heart rate & blood pressure,

this eventually leads to heart disease.

2-Carbon monoxide (CO) -CO is absorbed into the blood.

-It combines with hemoglobin inside RBC

instead of Oxygen.

-This reduces the amount of Hb available to

carry O2.

-CO reduces the amount of O2 available in

the blood & inside body cells.

-Smoking mothers usually give birth to

children who are smaller in size than non-

smoking mothers due to the effects of CO

on the baby in the womb.

3-Tar

Causes:

1. Lung cancer

2. Lung infection

3. Emphysema

-Absorbed by the cells in the lungs.

1-Tar is an irritant, irritating the cells in the

lungs.

-The irritated cells cause excessive

coughing that damages the delicate alveoli

in the lungs (continuous coughing may

cause them to burst).

-Damaged alveoli decreases their number

and therefore decreases the surface area

available for gas exchange.

-The person finds it difficult to get enough

oxygen into the body leading to difficulty

in breathing or Emphysema.

2-Tar is a carcinogen;

Causes lung cancer.

3-Tar damages/paralyses the cilia (makes

it stop beating/moving) in the lungs and

causes the goblet cells to produce excess

mucus.

-Excess mucus attracts bacteria,

increasing chances of lung infection.

Passive smoking

•It is not only the smokers themselves who are harmed by tobacco smoke.

•Non-smokers in the same room are also affected.

Performance-enhancing hormones (man-made hormones)

•Some athletes and sports persons take drugs to boost their performance.

•Some of these drugs are manmade hormones example Testosterone.

•Taking testosterone supplements leads to increased muscle and bone mass.

•It therefore has the potential to enhance a sportsperson’s performance.

•There are serious long-term effects of taking those drugs such as;

-sterility (men and women cannot have children)

-masculinization in women

-liver and kidney malfunction.

•Because these drugs enhance performance beyond what could be achieved by normal training, they are considered unfair and banned by most sports organizations.

•These hormones can be detected in the urine and this is the basis of most tests for banned substances