Biological Molecules

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What are the 3 types of bonds for biological molecules?
Ionic, Covalent and Hydrogen.
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What type of reaction joins together monomers?
Condensation
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What type of reaction breaks down polmers?
Hydrolysis
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What is metabolism?
All the chemical processes that take place in living organisms
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What are monosaccharides?
A carbohydrate: Sweet tasting, soluable substance
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What is the general formula for a monosaccharide?
(CH20)n where n can be anything between 3 and 7
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What are some examples of a monosaccharide?
Glucose, fructose and galactose.
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What is the test for reducing sugars?
Add equal amount of benedict's and heat the mixture in a water bath fr 5 minutes. If the solution turns orange-brown then reducing sugars are present.
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What monosaccharides pair to make the disaccharide maltose?
Glucose and glucose
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What monosaccharides pair to make the disaccharide sucrose?
Glucose and fructose
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What monosaccharides pair to make the disaccharide lactose?
Glucose and galactose
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What is the bond that is formed between the monosaccharides to make a disaccharide?
Glycosidic bonds
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When the monosaccharides bond, a molecule of water is formed it is therefore classes as a...?
Condensation reaction
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What do you need to add to break the glycosidic bond and what type of reaction is it called.
Water and hydrolysis
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What are polysaccharides?
Very large molecules, they are insoluble. Making them suitable for storage
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What are examples of polysaccharides?
Starch and cellulose
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What is the test for starch?
Add two drops of iodine and shake, Starch is present if the solution goes black - blue
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What are the main features of the structure of starch that make it good for storage?
It is insoluble so doesn't affect water potential, so water is not drawn into the calls by osmosis. Being large it does not diffuse into cells. It is compact so a lot can be stored in a small space.
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When hydrolysed it forms a-glucose, why is this good?
Because a-glucose is readily available and easily transported for use in respiration
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Starch chains may be branched or unbranched. The branched form has many ends, each of which are acted on by enzymes, why is this good?
This means that glucose monomers are released rapidly.
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Where is starch found?
Only in plant cells
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Where is glycogen found?
Animal and bacteria cells
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Glycogen and starch is similar. What are their differences?
Glycogen has shorter chains and is more highly branched.
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Glycogen has the same reasons for being good for storage as starch. But being more highly branched means...?
It has more ends that are acted on simultaneously by enzymes so therefore it is more broken down to form glucose monomers which are used in respiration
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What makes cellulose different to starch and glycogen?
It is made of beta glucose monomers rather than alpha.
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The structure of cellulose is also different to starch and glycogen. How?
Rather than forming coiled chains it forms straight unbranched chains. They run parallel to each other allowing hydrogen bonds to form cross links to adjacent chains. The sheer overall number of hydrogen bonds adds strength to the structure
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What also strengthens the structure of cellulose?
Cellulose molecules are grouped together to form microfibrils which in turn are grouped to form fibres
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What are the 4 main characteristics of lipids?
1. They are insoluble 2. They contain hydrogen, carbon and oxygen. 3. The proportion of O C and H is smaller than it is in carbohydrates. 4. They are soluble in organic solvents such as alcohols.
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What are the four roles of lipids?
1. insulation 2. protection 3. waterproofing 4. source of energy
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What are the main groups of lipids?
Triglycerides and phospholipids
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What are triglycerides?
3 fatty acids combined with glycerol
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How is a triglyceride formed?
Through an ester bond between the fatty acid and glycerol in a condensation reaction.
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Each fatty acid has a carboxyl group with a hydrocarbon chain attached. If this chain has no carbon-carbon double bond then it is described as? And why?
Saturated. Because all the carbon atoms are linked to the max number of hydrogen atoms.
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Each fatty acid has a carboxyl group with a hydrocarbon chain attached. If this chain has one single carbon-carbon double bond it is...?
Mono-unsaturated
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Each fatty acid has a carboxyl group with a hydrocarbon chain attached. If this chain has more than one carbon-carbon double bond it is...?
Polyunsaturated
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What makes a triglyceride a good source of energy?
They have a high ratio of energy-storing carbon-hydrogen bonds to carbon atoms
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What makes triglycerides good for storage?
They have low mass to energy ratio. This makes them good because much energy can be stored in a small volume.
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Triglycerides are insoluble in water because of?
Being large, non-polar molecules. Because of this, their storage does not affect osmosis in cells or the water potential of them.
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Triglycerides are an important source of water, why?
They have a high ratio of hydrogen to oxygen atoms, triglycerides release water when oxidised.
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What makes phosolipids different to triglycerides?
One of the fatty acid molecules is replaced by a phosphate molecule. A fatty acid repels water where as a phosphate molecule attracts water. This makes a phospholipid polar.
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What two parts is a phospholipid made up of?
A hydrophilic 'head' and a hydrophobic 'tail'
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How is being a polar molecule good in an aqueous environment?
Th molecule forms a bilayer within the cell-surface membranes. As a result , a hydrophobic barrier is formed between the inside and outside of the cell.
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What does the hydrophilic head of the phosphate help with?
It helps to hold at the surface of the cell-surface membrane
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The structure of phospholipids allows them to form glycolipids by combining with carbohydrates within the cell-surface membrane. Why is this important?
The glycolipids are important in cell recognition
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What is the test for lipids?
Add 5cm cubed of ethanol to 2 cm cubed of the food sample. Shake the tube. Add 5cm cubed of water to the test tube and shake. A cloudy colour means lipids are present.
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What monomer units makes up a polypeptide?
Amino acids
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What do polypeptides form to make?
Proteins
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Every amino acid has a central carbon atom to which are attached 4 different chemical groups. What are these groups?
1. Amino group 2. Carboxyl group 3. Hydrogen atom 4. R group
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What is the R group?
A variety of different chemical groups. Each amino acid has a different R group. These 20 naturally occurring amino acids differ only in their R group
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Amino acid monomer combine to form a dipeptide through a condensation reaction. The water is made by combining an -OH from the carboxyl group of one amino acid and the -H from the amino group of another amino acid. This then forms?
The two amino acids then become linked by a new peptide bond between the carbon atom of one amino acid and the nitrogen atom of another amino acid
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What's the primary structure of a protein?
Polypeptides- The order of amino acids in the polypeptide chains . The order of amino acids is determined by genetic coding - the sequence of nucleotides ins DNA
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What's the secondary structure of a protein?
The way the chain is folded. The most common structure is the alpha helix.
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What is the alpha helix?
1. A regular coiled spiral structure 2. Hydrogen bonds form between the NH group and the C=O group. 3. The bonds are weak but in mass they are strong.
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What is other secondary structure of a protein that is not as common?
Beta pleated sheets
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What's the tertiary structure of a protein?
The folding up of the alpha helix give a more complex 3D Shape
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The tertiary structure is maintained by a number of different bonds. What are those 3 bonds?
1. Disulfide bridges, fairly strong & not easily broken 2. Ionic bonds formed between any carboxyl&amino groups that are not involved in forming peptide bonds. Weaker than disulfide. Are easily broken by changes in pH 3. Hydrogen bonds.
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What's the quaternary structure of a protein?
Large proteins are complex & have a number of polypeptide chains.This structure is how the different polypeptide chains are arranged together
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What is the test for proteins?
Add an equal amount of sodium hydroxide solution to the solution to be tested. Add a few drops of very dilute copper sulfate and mix gently. A purple colour indicates the presence of peptide bonds and hence proteins
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Proteins form different roles in living organisms, this depends on their molecular shape which can be two types:
Globular and fibrous
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What is the test for non reducing sugars?
+ 2 cm3 of dilute hydrochloric acid to an equal amount of the solution & boil for 5 min. Allow the tube to cool & neutralize with sodium hydrogen carbonate + benedict's solution & heat for 5. If positive it will be red, orange, brown
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What are enzymes?
Globular proteins that act as catalysts.
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What do catalysts do?
Alter the rate of a reaction without undergoing permanent changes themselves.
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What are catalysts effective in small amounts?
They can reused due to not undergoing any permanent changes in the reaction.
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What is meant by activation energy?
The minimum amount of energy required for a reaction to take place.
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What is the active site made up of?
Amino acids
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What is the molecule, of which the enzyme acts on, called?
The substrate
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What is it called when the enzyme acts on the substrate?
An enzyme-substrate complex
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How is the substrate held in the active site?
There are temporary bonds between the amino acids in the active site and the amino acids of the substrate
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What is meant by the 'induced fit model'?
It proposes that the active site forms as the enzyme and substrate interact. The enzyme is flexible and can changes itself to fit the substrate.
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What are enzyme inhibitors?
Substances that directly or indirectly interfere with the functioning of the active site of an enzyme and so reduces its activity.
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What are the two types of enzyme inhibitors?
Competitive and noncompetitive
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What are competitive inhibitors?
They bind to the active site and have a similar structure to the substrate. It slows the rate of reaction, but still reaches max, as the substrate can no longer bind to the active site as it is occupied. It is not permanently bound.
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What are noncompetitive inhibitors?
They have a different structure to the substrate but binds to the enzyme in another position other than the active site causing the active site to change shape so the substrate can no longer bind to it. The rate of reaction slows & does not reach max
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What is a metabolic pathway?
A series of reactions in which each step is catalysed by an enzyme
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Card 2

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What type of reaction joins together monomers?

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Card 3

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What type of reaction breaks down polmers?

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Card 4

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What is metabolism?

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Card 5

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What are monosaccharides?

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kirsty300669

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really excellent piece of flashcards

em1234

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Wow, this is really helpful

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love this

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