Water molecules are __(a)__,

therefore __(b)___ do / do not dissolve

Water molecules are polar,

therefore fatty acids do not dissolve

• Hydrogen bonding between molecules makes it a valuable coolant in living organisms.
• Breaking hydrogen bonds needs energy, and removes heat.
• Therefore, hydrogen bonds must break when water evaporates

• Passively, through osmosis. 
• The water goes from areas of low solute concentration to areas of high solute concentration 
• Passes through protein channels in the selectively-permeable membrane

• Water molecules undergo photolysis (split using light energy) and oxygen is formed as a by product.

• Hydrogen bonds form between nucleotides with complementary bases (adenine and thymine and cytosine and guanine). 
• Covalent bonds form within strands between sugar (deoxyribose) and phosphate 

Which diagram best illustrates the interactions between water molecules?

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Which diagram represents the polarity of a water molecule?

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Blood is a water-based transport medium

Which property of water makes blood a good transport medium?

Lactose is a disaccharide 

galactose is a monosaccaride

• A cabohydrate formed when two monosaccharides undergo a condensatoin reaction
• this involves the elimination of a small molecule, such as water

Both: 

• primary sources of energy for organisms

What is this molecule?

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What is this molecule?

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glucose, galactose, fructose

Maltose, lactose, sucrose

Starch, glycogen, cellulose

What is hydrolysis

+ example

a type of chemical reaction, when a chemical compound reacts with water

, example is when lactose is digested into glucose and galactose

What is this?

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A) only I

B) I and III

C) II and III
D) I, II and III

B, 

monosaccharide and cabohydrate

f

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haemoglobin and enzymes

Haemoglobin and enzymes

Primary

secondary

tertiary

quaternary

• ....have α-helices (alpha) and β-pleated sheets (beta). 
• these form as a result of hydrogen bonds between peptide groups of the main chain. 
• Therefore, proteins that contain secondary structures will have regions that are cylindrical (α-helices) and or regions that are planar (β-pleated sheets )

• ...is its three-dimensional conformation, which occurs as a result of the protein folding. 
• This folding is stabilised by hydrogen bonds, hydrophobic interactoins, ionic bonds and disulphide bridges. 
• These intramolecular bonds form between the R groups of different amino acids

• ...is formed when two or more polypeptide chains associate to form a single protein
• (an example is haemoglobin which consists of four polypeptide chains)
• In some cases,proteins can have a non-polypeptide structure called a prosthetic group. These proteins are called conjugated proteins
• The haem group in haemoglobin is a prosthetic group

polypeptide chain

• A polypeptide is formed by amino acids linking together through peptide bonds.
• The information required for making polypeptides is in the genes
• The sequence of bases in a gene codes for the sequence of amino acids in a polypeptide
• The information in the genes is decoded during transcription and translation leading to a protein synthesis

• Amino acids form polypeptide chains by linking together through peptide bonds
• There are 20 different amino acids, so a wide range of polypeptides are possible

Amino acids with hydrophillic R groups are polar

found at the surface of proteins

The distribution of the polar and non-polar amino acids in a protein influences the function and location of the protein within the body.

Amino acids with hydrophobic R groups are non-polar

They are found in the center of water soluble proteins

The distribution of the polar and non-polar amino acids in a protein influences the function and location of the protein within the body.

Polar amino acids are found inside the membrane proteins, and create hydrophilic channels that hydrophilic molecules can pass through

polar amino acids cause portions of the proteins to protrude from the membrane.

If an active site is made up of polar amino acids then the active site is specific to a polar substance

four functions of protein

(name and example)

Structural: collagen strengthens bones, skin and tendons

Movement: mysosin found in muscle fibers causes contraction of the muscle which results in movement

Transport: haemoglobin transports oxygen from the lungs to other tissues in the body

Defense: Immunoglobin acts as an antibody

The solvent properties of water mean that many different substances can be dissolved in it, because of its polarity

Cohesion is the effect of hydroden bonds holding the water molecules together

The hydrogen bonds keep the water molecules sticking together

(Water moves up plants because of cohesion. Long colums of water can be sucked up from roots to leaves without the colums breaking)

Include heat capacity, freezing and bioling points and the cooling effect of evaporation

because of the large heat capacity a considerable amount of energy is required to (break the strong hydrogen bonds) and therefore increase it's temperature. For this reason, water tends to remain relatively stable

How the properties of water relate to its use as a coolant, 

Water can evaporate at temperatures below the boiling point, but hydrogen bonds need to break for this to happen. The evaporation cols the body surfaces (sweat) using the energy from liquid water to break the hydrogen bonds

How the properties of water relate to its use as a medium for metabolic reactions and transport

Because water has solvent properties, many different substances can dissolve in it (because of its polarity)

this means that substances can be carried in the blood or sap because they dissolve in water. it also makes water a good medium for metabolic reactions

Organic compounds are: compounds that are found in living organisms and contain carbon.

Inorganic compounds are: compounds that don’t contain carbon.

Although, there are a few compounds found in living organisms which also contain carbon but are considered as inorganic compounds. These include carbon dioxide, carbonates and hydrogen carbonates. 

• Lipids can be used for energy storage in the form of fat in humans and oil in plants.
• Lipids can be used as heat insulation as fat under the skin reduces heat loss. 
• Lipids allow buoyancy as they are less dense than water and so animals can float in water.

The active site of an enzyme is specific to certain substrates, as it has a very precise shape. This means that enzymes can only catalyze certain reactions, because only a small number of substrates fit into the active site. 

Therefore, for a substrate to be able to bind to an active site of an enzyme,  it must be chemically attracted to, and be able to fit in the active site. 

This can be compared to a lock and key model, where the enzyme is the lock and the substrate is the key

Chains and cycles of enzyme-catalysed reactions

If initially the substrate does not perfectly fit into the enzyme's active site, the active site changes shape when the substrate binds to it so that they fit together perfectly. This explains why some enzymes can bind to several different substates, because the active site changes to accomodate them. 

the activation energy of the chemical reactions that they catalyse

substances that inhibit enzyme activity. There are two types of enzyme inhibitors, competative and non-competative

competative enzyme inhibitors are structurally similar to the substrate of the enzyme, and bind to the active site. This prevents the substrate from binding to the active site, because they are taking the place of the substrate. The substrate can only bind with the active site once the inhibitor is released from the active site. 

The effects of competative inhibitors can be reduced by increasing the concentration of the substrate. More substrates would be able to successfully bind to the active site than the inhibitor, and reduce the effect of the inhibition. This allows the rate of reaction to reach, or achieve a level that is very close to the maximum rate of reaction. 

These are not similar to the substrate, and do not bind to the enzyme's active site. Instead, they bind to a different site on the enzyme and change the active site's conformation. 

The substrate may still be able to bind to the active site, however the enzyme is either not able to catalyse the reaction or can only do so at a slower than normal rate. 

Increasing substrate concentration cannot prevent the inhibitor from binding to the enzyme, as the two bind to diffrent sites. 

A nucleotide is made of the suger deoxyribose, a base (which can be either adenine, guanine, cytosine or thymine) and a phospahte group. 

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A covalent bond forms between the sugar of one nucleotide and the phosphate group of another nucleotide.

DNA is made up of two nucleotide strands, which are connected togeher by covalent bonds within each strand. 

The sugar of one nucleotide forms a covalent bond with the phosphate group of anohter nucleotide. The two strands themselves are connected with hydrogen bonds which are found between the bases of the two nucleotide strands. 

Adenine forms hydrogen bonds with thymine, while guanine forms hydrogen bonds with cytosine. These are complementary base pairings. 

PYRIMIDINES

Smaller, have a single ring

Cytosine

Thymine

PURINES

Larger, double ring, 

Adenine and guanine