BY1; biological molecules

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monosaccharides general formula
(CH20)n where n is the number of carbon atoms.
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How many carbon atoms does a triose sugar have?
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Compounds that have the same chemical formula but fiffer in the arangement of the atoms.
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What are the two main functions of monosaccharides?
Source of energy in respiration, (carbon hydrogen bonds broken to release energy which is used to make atp from adp and pi), and building blocks for larger molecules,
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What are disaccharides?
two monosaccharides linked together
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what bonds joins to monosaccharides?
A glycosidic bond.
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What is this reaction called?
A condensation reaction
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What do glucose and fructose form
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What do glucose and galactose form
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WHat are disaccharides used for?
storage and transport, e.g. in phloem
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What is used to test for the presence of glucose in a solution?
Benedict's reagent
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What colour is benedicts reagent?
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What colour will it turn if glucose is present
Green to yellow to orange and finally red.
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Give an example of a non reducing sugar
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How can sucrose be detected?
it must be broken down into its constituent monosaccharides by heating with hydrochloric acid.
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How is this solution neutralised, due to the fact benedicts raegent needs alkali conditions to work?
Alkali is added slowly untill any fizzing stops.
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Is the benedicts test qualitative or quantitative>
Qualitative, at best semi quantitative
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What could give a more accurate measurement
a biosensor.
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Is starch soluble or insoluble? why is this important?
insoluble. This means water is not drawn to it via osmosis.
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Where is starch found>
Plant cells in the form of starch grains. It can also be found in seeds and storage organs such as potato tubers.
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Why can starch be stored in a small space?
Becuase it is a compact molecule.
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Which isomer of glucose is starch made of?
Alpha glucose
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what are the two polymers of starch, and their positions
Amylose (linear, coils into helix) and Amylopectin (branched, fits inside the amylose)
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Why are the 1-4 linkages important?
they cause the chain to turn and coil.
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what is the main storage product in animals?
Glycogen (sometimes called animal starch) and is very similar to amylopectin
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how do you test for the presence of starch?
iodine will turn blue-black if it comes into contact with starch.
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Where is cellulose found
plant cell walls
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What is the structure of cellulose?
Many long parallel chains of beta glucose cross linked together by hydrogen bonds. The chain has adjacent glucose molecules rotated by 180 degrees. This allows hydrogen bonds to bbe formed between the hydroxyl groups of adjacent parallel chains.
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What are microfibrils?
Between 60 and 70 celllulose molecules become tightly cross linked to form bundles called microfibrils.
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what are microfibrils held together to form?
bundles called fibres.
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Are cellulose fibres permeable?
Yes they are.
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Where is chitin found?
exoskeleton of insects
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Give 3 qualities of chitin
Strong, waterproof, lightweight
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are lipids polar or non polar? soluble/insoluble?
Non polar, insoluble in water.
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how are triglycerides formed?
One glycerol molecule and 3 molecules of fatty acids.
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What reactions joins the fatty acids and glycerol?
Condensation reaction. (3 molecules of water removed)
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what is the bond that is formed
ester bond.
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what does it mean if the hydrocarbon chain has no carbon carbon double bonds?
the molcule is saturated because all the carbon atoms are linked to the maximum possible number of hydrogen atoms.
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what does it mean if there are double bonds present?
The molecule is non saturated.
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What may cause heart disease?
High intake of fat, particularly saturated fats.
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give 5 functions of lipids
plasma membranes, emnergy reserves in plants/animals, insulator against heat loss, Protection of delicate organs, metabolic water when dissolved, Waterproofing (waxy cuticle of leaves)
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Describe the structure of phospholipids
Lipid part is non polar and insoluble in water (hydrophobic). Phosphate group is polar and dissolves in water (hydrophilic)
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How to proteins differ from carbohydrates and lipids
They also contain nitrogen
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How many amino acids are used to make a protein
Around 20
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What is the basic structure of an amino acid
One carboxyl group (-COOH) and at the other end an amino group (-NH2)
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How are proteins built up from a linear sequence of amino acids?
The amino group of one amino acid reacts with the carboxyl group of another, with the elimination of water.
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What is the bond formed between two amino acids?
A peptide bond.
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What is the resulting compound?
A dipeptide.
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What is a long chain of amino acids called?
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What is the primary structure?
The sequence of amino acids in a polypeptide chain.
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What is the secondary structure?
This is the shape that the polypeptide chain forms as a result of hydrogen bonding.
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What is the 3d spiral shape of a polypeptide known as?
The alpha helix
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What is the less common arrangement of the primary sequence being twisted to form a 3d Shape?
The beta pleated sheet.
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What is the name given to the when the alpha helix is folded and twisted to give a more complex 3d shape?
The tertiary structure.
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What bonds maintain tertiary structure?
Disulphide/ionic/hydrogen bonds.
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What is the quaternary structure?
This is a combination of 2 or more polypeptide chains in tertiary form.
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What is an example of a quaternary structure?
Haemoglobin. (4 polypeptide folded chains, at the centre of which is an iron containing group (haem)
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What functions fo fibrous proteins form
Structural functions.
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what is the structure of fibrous proteins?
Polypeptides in parallel chains or sheets with numerous cross linkages to form long fibres
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What is an example of a fibrous protein?
keratin, in hair.
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What ar 3 characteristics of fibrous proteins?
Strong, insoluble in water, tough
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What are the functions of globular proteins?
Enzymes, antibodies, plasma proteins and hormones.
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What is the shape of a globular protein?
compact and folded as spherical molecules.
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What is the test for proteins?
The biuret test.
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What colour indicates a protein?
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what is water a medium for?
Metabolic reactions
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how does water stick together?
Hydrogen bonds.
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how come water attracts charged particles?
The oxgen end is slightly negative and the hydrogen is slightly positive.
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What does a high specific heat mean?
A high amount of heat energy is needed to raise the temperature of water, beacuse hydrogen bonds restrcit movement.
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Why is this importatn?
prevents large fluctuations in temperature, e.g. aqautic habitat, enzymes in cells
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What does high latent heat mean?
Lots of energy needed to change it from liquid to vapour state.
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What is the sticking together of water molecules called?
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why is a high surface tension important?
body of insect e.g. water skater can be supported
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Why is it important that ice is less dense than water?
So that large bodies of water dont freeze completely
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What is magnesium needed for>
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What is iron needed for?
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What is phosphate needed for?
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What is calcium (together with phosphate)needed for?
BOnes and teeeth
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How many carbon atoms does a triose sugar have?



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Card 4


What are the two main functions of monosaccharides?


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Card 5


What are disaccharides?


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