Biology part 2

The overall description of enzymes and whatnot

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  • Created by: Katrina
  • Created on: 18-04-12 11:30

Biological catalysts- Enzymes

Chemical reactions are what make you work and enzymes are what make them work

Enzymes are catalysts produced by living things

1)Living things have thousands of different chemical reactions going on inside them all the time.

2)These reactions need to be controlled- to get the right amounts of substances.

3)You can make a reaction happen quicker by raising temp. This would speed up the wanted reactions but also the unwated ones too. There is a limit to how far you can raise the temp in a living creature before its cells become damaged.

4)Living things make enzymes which act as biological catalysts. Enzymes reduce the need for high temps and we only have enzymes to speed up the useful reactions.

A catalysts speeds up a reaction without being used up in the reaction.

5)Enzymes are all proteins

6) All proteins are made up of chains of amino acids which are folded into unique shapes which enzymes need to do their jobs.

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Enzymes and respiration

Enzymes control reactions in respiration,proteinsynthesis and photosynthesis.

Enzymes help build amino acids and proteins

Enzymes are use to synthesise molecules like amino acids- the ones you don't get from your diet. They also catalyse protein synthesis by joining together amino acids. These proteins could be enzymes.

Respiration is NOT breathing in and out

Respiration releases the energy that cells need to do everything.

1)Respiration is the process of releasing energy from the break down of glucose- and goes on in every cell in your body.

2) It happens in plants too, all living things respire. It is how they release energy from their food

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Enzymes and respiration continued...

Aerobic respiration needs plenty of oxygen.

1) Aerobic respiration is respiration using oxygen. It's the most efficient way to release energy from glucose (you can also have anaerobic respiration, which happens without oxygen but that doesn't release as much energy).

2)Most of the reactions in anaerobic respirations happens inside mitochondria.

The word equation for aerobic respiration is:

Glucose + Oxygen -----> Carbon Dioxide + water + ENERGY

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Enzymes and respiration continued...

Respiration releases energy for all kinds of things

1) To build up larger molecules from smaller ones( like proteins from amino acids)

2) In animals to allow the muscles to contract ( which in turn allows them to move about)

3) In mammals and birds the energy is used to keep their body temperature steady ( unlike other animals, mammals and birds are warm blooded)

4) In plants, to build sugars, nitrates and other nutrients into amino acids, which are then built up into proteins.

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Enzymes and digestion

Digestive enzymes break down big molecules into smaller ones.

1)Starch, proteins and fats are big molecules. They're too big to pass through the walls of the digestive system

2) Sugars, amino acids, glycerol and fatty acids are much smaller molecules. They can pass easily through the walls of the digestive system.

Amylase converts starch into simple sugars ( amylase is made in three places, the salivary glands, the pancreas and the small intestines.)

Protease converts proteins into amino acids ( Protease is made made in three places, the stomach- its called pepsin there, the pancreas and the small intestines.)

Lipase converts fats into glycerol and fatty acids (Lipase is made in two places, the pancreas and the small intestines.)

Bile neutralises the stomach acid and emulsifies fats, It is produced in the liver, stored in the gall bladder and released into the small intestine. Bile is alkaline to neutralise stomach acid in the small intestine. It emulsifies fats by breaking into tiny droplets creating a bigger surface area of fat for lipase to work on , making digestion faster.

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Homestasis is the maintenance of a constant internal environment. There are six things needed to be contolled: The first four are things you need at the right level:

1) Body temperature

2) Water contenet

3) ion content

4) Blood sugar level

The next two are waste products- they're constantly produced in the body and you need to get rid of them

1)Carbon dioxide- Product of respiration and is toxic in high quantities, leaves body through lungs 

2) Urea- a waste product made from excess amino acids.

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Homeostasis and kidneys

Kidneys act as filters to clean the blood. Kidneys perform 3 main roles:

Remove urea from the blood , Adjustment of ions in the blood,Adjustment of water content of the blood

Removal of urea- Proteins can't be stored by the body so many excess amino acids are converted into fats and carbs which can be stored. This occours in the liver. Urea is produced as a waste product from the reactions. Urea is poisonous. It is released into the bloodstream via the liver. The kidneys filter it out of the blood and its excreted from the body in urine.

Adjustment of ion content-Ions such as sodium enter the body in food and are absorbed into the blood. If the ion content is wrong , too much or too little water is drawn into the cells by osmosis, which could damage cells. Excess ions are removed by kidneys. Some ions are lost in sweat. Most importantly the balance is always maintained by the kidneys.

Adjustment of water content- Water is taken into body as food and drink and lost from body in 3 ways:urine, sweat and breathing out....

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Water adjustment continued...

The body must constantly balance the water coming in against the water going out. our bodies can't control how much we lose in our breath but we do control other factors. This means the water balance is between:

Liquid consumed, Amount sweated out and amount excreted by the kidneys in the urine.

On a cold day if you don't sweat you will produce more urine which will be pale and dilute. On a hot day you sweat a lot and you produce less urine which will dark and more concentrated. The water lost when it is hot must be replaced by food and drink to restore the balance.

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Controlling Blood Sugar

Insulin controls blood sugar levels

1) Eating food containing carbs puts glucose in the blood from the gut.

2) Normal metabolism (reactions) of cells removes glucose from the blood.

3) vigorous exercise also remove a lot of glucose from the blood.

4) Levels of glucose in the blood must be kept steady. Changes in blood glucose are monited and controlled by the pancreas using the hormone insulin.

Blood glucose level too high- Insulin is added

Blood glucose level too low- Insulin is NOT added

Diabetes (type 1)- the pancreas stops making enough insulin.

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Thanks :) Very helpful!

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