Biological Molecules Flashcards

Question

Describe glycogen structure

Answer 1

Glycosidic bonds between carbon 1 and 4 and branches formed by glycosidic bonds between carbon 1 and 6- with Alpha glucose

Answer 2

It's an energy store do when glucose needs it for respiration

Answer 3

It's more compact with more branches so it allowed more molecules to be snipped off . This is because it needs more access to these molecules as animals are more metabolically active

Answer 4

Tough Insoluble Fibrous substances

Answer 5

Are straight and lie side by side , made of beta glucose Hydroxyl groups on carbon 1 are inverted , this means every other beta glucose molecule in the chain is rotate 180 degrees Hydrogen bonding between the rotated beta glucose in each chain also give the chain additional strength and stops it spiralling

Answer 6

Microfibrils Macrofibils

Answer 7

Because plants do not have a rigid skeleton. Each cell needs to have strength to support the whole plant There is space between macrofibrils for water and minerals ions to pass on their way into and out of the cells. . This makes cells walls permeable Highly tensile strength which prevents cells from bursting when they are turgid again helping to support the whole plant . Turgid cells also press against each other supporting the structures of the plant as a whole . The wall protects delicate cell membranes

Answer 8

Made up of 1 glycerol and 3 fatty acid tails Condensation reaction , 3 lots of water given off Ester bonds formed

Answer 9

Contain large amounts of carbon and hydrogen and smaller amounts of oxygen . They are insoluble in water because they are not polar and do not attract water molecules , but dissolve in alcohol

Answer 10

Triglyceride Phospholipids Steroids

Answer 11

If a fatty acid is saturated , this means that there are no c=c bonds in a molecule . They only have single bonds

Answer 12

There is a double bind between two of the carbon atoms instead which means that fewer hydrogen atoms can be bonded to the molecule Having one or more c=c bonds change the shape of the hydrocarbon chain , giving a kink

Answer 13

Energy source - they can be broken in respiration to release energy and generate ATP Energy store - because they're insoluble in water they can be stored so they don't effect water potential Insulation -adipose tissue is a storage location for lipids in whales , acting as a heat insulated . Buoyancy - because fat is less dense than water it is used to float Protection - humans have fat around delicate organs to act as a shock absorber

Answer 14

Has a phosphate group 1 glycerol 2 fatty acid tails 2?Ester bonds and 1 phosphester bond 3 condensation reactions , 3 lots of water released

Answer 15

The phosphate head Has a negative charge , making it polar However the fatty acid tails are non polar and so repel water Head = hydrophilic -on the outside if the cell towards the solution Tails=hydrophobic

Answer 16

Stigmasterol

Answer 17

Type of lipid Consists of 4 carbon based rings Small and hydrophobic molecule Sit in the middle of the hydrophobic part of the bilayer

Answer 18

It regulates fluidity of the membrane , preventing it from becoming too fluid or stiff Hormones made from cholesterol can diffuse straight through the bilayer

Answer 19

Amino group Central carbon Carboxyl group

Answer 20

Resists changes in PH

Answer 21

The oxygen atom has a greater number of positive protons in its nucleus this exerts a stronger attraction for the shared electrons , this means that oxygen atoms become slightly negative , and the hydrogen atoms become slightly positive, when this happens we call the molecule polar Hydrogen bond

Answer 22

``` Liquid Density Solvent Cohesion and surface tension High specific heat capacity High latent heat of evaporation ```

Answer 23

The hydrogen bonds between water molecules make it more difficult for them to escape to become a gas, water has low viscosity which means it flows easily Provide habitats for living things in rivers lakes and seas Form major component of the tissue in living organisms Provide a reaction medium for chemical reactions Provide an effective transport medium

Answer 24

As in any liquid, water molecules constantly move around. Unlike other liquids, as they move they continually make and break hydrogen bonds (see topic 2.2.1, Figure 4). The hydrogen bonds between water molecules make it more difficult for them to escape to become a gas. By contrast, other less polar, but similarly-sized molecules (e.g. H2S) are gases at room temperature. Even with hydrogen bonds, water has quite a low viscosity, which means it can flow easily Because it is a liquid at room temperature, water can: provide habitats for living things in rivers, lakes and seas • form a major component of the tissues in living organisms provide a reaction medium for chemical reactions provide an effective transport medium; e.g. in blood and vascular tissue. -Provide a reaction medium for chemical reactions - provide an effective transport medium

Answer 25

The density of water provides an ideal habitat for living things. If water was less dense, aquatic organisms would find it very difficult to float. When most liquids get colder, they become more dense. If this were the case with water, then water at the top of a pond would freeze and sink. The water replacing it at the top would do the same, until the pond would be full of ice. But water behaves differently It becomes more dense as it gets colder until about 4 oc. As it goes from 4 oc to freezing point, because of its polar nature, the water molecules align themselves in a structure which is less dense than liquid water Because ice is less dense than water • aquatic organisms have a stable environment in which to live through the winter • ponds and other bodies of water are insulated against extreme cold. The layer of Ice reduces the rate of heat loss from the rest of the pond.

Answer 26

Water IS a good solvent for many substances found in living things. This includes ionic solutes such as sodium chloride and covalent solutes such as glucose. Because water is polar, the positive and negative parts of the water molecules are attractedt( the negative and positive parts of the solute. The water moleculet cluster around these charged parts of the solute molecules or and will help to separate them and keep them apart. At this point they dissolve and a solution is formed. Because water is such a good solvent: • molecules and ions can move around and react together in water Many such reactions happen in the cytoplasm of cells, which is over 70% water. molecules and Ions can be transported around living things whilst dissolved in water

Answer 27

A drop of water on a flat surface does not spread out, but can look almost spherical , this is because hydrogen bonging between the molecules pulls them together , the water molecules demonstrate cohesion can look almost spherical. This is because hydrogen bonding between the molecules pulls them together. The water molecule demonstrate cohesion. This happens at the surface of water as well. The water molect at the surface are all hydrogen-bonded to the molecules beneat them, and hence more attracted to the water molecules beneav than to the air molecules above. This means the surface of

Answer 28

Hydrogen bonds Water consists of two hydrogen atoms, each covalently bonded to one oxygen atom. However, because the oxygen atom has a greater number of positive protons in its nucleus, this exerts a stronger attraction for the shared electrons. This means the oxygen atom becomes slightly negative, and the hydrogen atoms become slightly positive: When this happens, we say the molecule is polar

Answer 29

Water temperature;is a measure of the kinetic energy of the water molecules. Water molecules are held together quite t.ightly by hydrogen bondi. Therefore, you have to put in a lot of heat energy to increase their kinetic energy and temperature. The amount of heat energy required is known as the specific heat capacity (4.2 kJ of energy to raise the temperature of 1 kg of water by 1 OCY. This means that water does not heat up or cool down easily Because the main component of many living things is water, and many organisms live in water, its high specific heat capacity is important: • Living things, including prokaryotes and eukaryotes, need a stable temperaturs for enzyme-controlled reactions to happen properly. Aquatic organisms need a stable environment in which to live

Answer 30

High' latent heat of vaporisation When water evaporates, heat energy, known as the latent heat of vaporisation, helps the molecules to break away from each other to become a gas.\Because the molecules are held together by hydrogen bonds, a relatively large amount of energy is needed for water molecules to evaporate. Therefore, water can help to cool livipg things and keep their temperature stabled For example, mammals are cooled when sweat evaporates, and plants are cooled when water evaporates from mesophyll cells.

Answer 31

Reactant Water is also a reactant in reactions such as photosynthesis, and in hydrolysis reactions such as digestion of starch, proteins and lipidsllts properties as a reactant do not directly draw on its polarity, but its role as a reactant is extremely important for digestion and synthesisof large biological molecules,

Answer 32

Peptide | Condensation

Answer 33

Polypeptide

Answer 34

Primary Secondary Tertiary Quaternary

Answer 35

The sequence of amino vids found in a molecule The order of amino acids in the primary structure will determine the shape of the protein molecule Condensation reaction , peptide bonds

Answer 36

The chain of amino acids is not straight. but twists into a shape called the secondary structure. Some chains coil into an A-helix, with 36 amino acids per 10 turns of the helix. The helix is held together by hydrogen bonds between the —NH group of one amino acid and the —CO group of another four places ahead of it in the chain. Other chains fold very slightly in a zig-zag structure. When one such chain folds over on itself, this produces a "pleated sheet. •Hydrogen bonds between the —NH group of one amino acid and the -CO group of another further down the strand hold the sheet together

Answer 37

Tertiary structure When these coils and pleats themselves start to fold, along with areas of straight chains of amino acids, this forms the tertiary structure. The tertiary structure is a very precise shape which is held firmly in place by bonds between amino acidS which lie close to each other. The tertiary structure may adopt a supercoiled shape (e.g in fibrous proteins) or a more spherical shape (in globular proteins), as you will learn in topic 2.2.10.

Answer 38

quaternary structure - many proteins are made up of more than 1 polypeptide chain -descfibes how multiple polypeptide chains are arranged to make the complete protein moleculf This may also be held together with the same types of bond that hold the tertiary structure together. See the quaternary structure of haemoglobin shown in topic 2.2.10.

Answer 39

Protein bonding The primary structure of proteins, the chain of amino acids, is held together by peptide bond: which are covalent bonds, and hence very strong. Other types of bond form between amino acids in different parts of the polypeptide chain. These hold together the secondary, tertiary quaternary structures. The secondary structure is primarily held together by hydrogen bonds the tertiary structure and quaternary structure are held together by hydrogen bonds and many others.

Answer 40

Hydrogen Ionic disulfide Hydrophobic and hydrophilic interactions

Answer 41

Hydrogen bonds forms between hydrogen atoms with a slight positive charge and other atoms with a slightly negative change - in amino acids these firm hydroxyl , carboxyl and amino groups

Answer 42

Can form between those carboxyl and amino groups that are part of R groups . These ionise into NH+3 and COO- groups . Positive and negative groups like this are strongly attracted to each other to form an ionic bond

Answer 43

The R group of the amino acids cysteine contains sulfur . Disulfide bridges are formed between the R group of two cysteines . These are strong covalent bonds

Answer 44

Hydrophobic parts of the R groups tend to associate together in the centreof the polypeptide to avoid water. In the same way, hydrophilic'parts are found at the edge of the polypeptide to be close to water. iHydrophobic and hydrophilic interactions cause twisting of the amino acid chain, which changes the shape of the protein.frhese interactions can be a very important influence, given that most proteins are to be found surrounded by water inside a living organism.

Answer 45

Fibrous proteins have regular. repetitive sequences of amino acids and are usually Insoluble In water These features enable then to form fibres which tend to have a structural function.

Answer 46

Tend to roll up into almost spherical shape . Any hydrophobic R groups are turned onwards towaards the centre of the molecule , while hydrophilic groups are on the outside , this makes the protein water soluble , they also have specific shapes , which helps them to take up roles

Answer 47

Collagen keratin Elastin

Answer 48

Function is to provide mechanical strength - in artery walls a layer of Collagen prevents the artery bursting when withstanding high pressure from blood being pumped by the heart - tendons are made form collagen and connect muscles to bones allowing them to pull on bones

Answer 49

Keratin Keratin is rich in cysteine so lots of disulfide bridges form between its polypeptide chains. Alongside hydrogen bonding, this makes the molecule very strong. Keratin is found wherever a body part needs to be hard and strong It is found in finger nails, hair, claws, hoofs, horns, scales, fur and feathers. It provides mechanical protection, but also provides an impermeable barrier to infection and, being waterproof, also prevents entry of water-borne pollutants.

Answer 50

Elastin Cross-linking and coiling make the structure of elastin strong and extensible. It is found in living things where they need to stretch or adapt their shape as part of life processes. Skin can stretch around our bones and muscles because of elastin Without elastin, skin would not go back to normal after being pinched. Elastin in our lungs allows them to inflate and deflate, and in our bladder helps it to expand to hold urine. Like collagen, elastin helps our blood vessels to stretch and recoil as blood is pumped through them, helping maintain the pressure wave of blood as it passes through.

Answer 51

Haemoglobin Insulin Pepsin

Answer 52

The quaternary structure of haemoglobin is made up of four polypeptides - two alpha globin chains and two beta chains , held together by hydrogen , ionic and disulfide links . On the outside of each chain there is a space in which a haem group is held (prosthetic groups ) which contains and iron ion . A protein associated with this kind of group is called a conjugated protein The function of haemoglobin is to carry oxygen from the lungs to the tissues

Answer 53

Insulin is made of two polypeptides chains. The A chain begins with a section of a-helix, and the B chain ends with a section of 3-pleat. Both chains fold into a tertiary structure, and are then joined together by disulfide links. Amino acids with hydrophilic R groups are on the outside of the molecule, which makes it soluble in water. Insulin binds to glycoprotein receptors on the outside of muscle and fat cells to increase their uptake of glucose from the blood, and to increase their rate of consumption of glucose.

Answer 54

Pepsin is an enzyme that digests protein in the stomach. The enzyme is made up of a single polypeptide chain of 327 amino acids, but it folds into a symmetrical tertiary structure. Pepsin has very few amino acids with basic R groups (only four), whereas it has 43 amino acids with acidic R groups. This helps to explain why it is so stable in the acidic environment of the stomach, as there are few basic groups to accept H + ions, and therefore there can be little effect on the enzyme's structure. The tertiary structure is also held together by hydrogen bonds and two disulfide bridges.

Answer 55

a Computer modelling of protein structure Being able to predict the shape of a protein molecule from its primary structure can be incredibly useful in biochemistry. For example, predicting the occurrence of biologically active binding sites on a protein molecule can help in identifying new medicines. Scientists can predict protein shapes using computer modelling techniques. As techniques for prediction of secondary structure developed, they were based upon the probability of an amino acid, or a sequence of amino acids, being in a particular secondary structure. Such probabilities were derived from 'already-known' protein molecular structures.

Answer 56

Ab initio protein modelling Comparative protein modelling

Answer 57

• Ab initio protein modellingl In this approach, a model is built based on the physical and electrical properties of the atoms in each amino acid in the sequence. With this technique, there can be multiple solutions to the same amino acid sequence, and other methods sometimes need applying to reduce the number of solutions.

Answer 58

One approach is protein threading, which scans the amino acid sequence against a database of solved structures and produces a set of possible models which would match that sequence.

Answer 59

Add iodine solution to a sample If starch is present , will see a colour change from yellow brown to blue / black

Answer 60

Benedicts test Place a sample of food to be tested in a boiling tube , add Benedicts solution then heat in a water bath at 80 degrees Celsius for 3 mins , orange / red participate indicates a reducing sugar is present When low levels of sugar are present It may appear yellow / green

Answer 61

Non-reducing sugars To test for a non-reducing sugar, we have to hydrolyse the bond first, to 'free up' these 'reducing groups', and then test for reducing • First, test a sample for reducing sugars to check there are none there in the first place. • Take a separate sample and boil it with hydrochloric acid to hydrolyse the sucrose into glucose and fructose. • Cool the solution and use sodium hydrogencarbonate solution to neutralise it. • Test for reducing sugars again. A positive result (green-yellow-orange-red) indicates that non- reducing sugar (e.g. sucrose) was present in the original sample. In some cases, a sample may contain reducing and non-reducing sugars. If you have a positive test for reducing sugars from your first sample, you can go on to test for non-reducing sugars in an equal-sized second sample. If present, the precipitate from this second sample will have more mass than the precipitate from the first sample. You can extract the precipitate from the mixture by filtration.

Answer 62

The emulsion test is used to test for the presence of lipids: • Take a sample and mix it thoroughly with ethanol. Any lipid will go into solution in the ethanol (remember that lipids are not soluble in water). • Filter. • Pour the solution into water in a clean test tube. A cloudy white emulsion indicates the presence of lipids. T} is made up of tiny lipid droplets that come out of solution when mixed with water

Answer 63

For this you use the biuret test. If protein is present, the colour changes from light blue to lilac , you may find the reagents are supplied to you separately as biuret A (sodium hydroxide), which you add first, and biuret B (copper sulfate), which you add next. The colour is formed by a complex between the nitrogen atoms in a peptide chain and Cu2+ ions, which is why this test really detects the presence of peptide bonds. place a sample of food to be tested in a well on a spotting tile lilac colour indicates protein is present

Answer 64

The amount of precipitate will increase The amount of copper ions remaining in solution will decrease

Answer 65

A colorimeter works by shining light through a sample. Using a pipette, we can take the supernatant and place it in a cuvette (a small vial). which is then placed into the colorimeter. The cuvette is commonly made of glass or plastic. Ensure you do not leave a greasy fingerprint on the surface of the cuvette, as it could affect transmission of light. Colour filters are often used for greater accuracy. By using a red filter in this case, we can shine red light through the solution, and detect how much passes through (percentage transmission). The solution reflects blue light but absorbs red light: If there is a lot of unreacted copper sulfate, the supernatant is still quite blue, absorption of red light is high and percentage transmission is low. If there is little unreacted copper sulfate, the supernatant is less blue, absorption of red light is low and percentage transmission is high. When using a colorimeter, the device is usually zeroed between each ree appropnate 'blank' sample to reset the 100% transmission / absorption

Answer 66

1- take a series of known concentrations of reducing sugars 2- using a sample of each , carry out benedicts tests 3- use a colorimeter to record the percentage transmission of light through each supernatant 4- plot a graph to show transmission of light against the concentration of reducing sugars

Answer 67

They take a biological or chemical variable which cannot be easily measured , and convert it into an electrical signal

Answer 68

They can be used to detect contaminants in water , and pathogens and toxins in food. They can even be used to detect airborne bacteria

Answer 69

Is to separate a mixture into its constitutes ( biological molecules )

Answer 70

Stationary phase | Mobile phase

Answer 71

This is either the chromatography paper or a thin layer of chromatography plate . The paper is made of cellulose , the chromatography plate is often sheets of plastic covered with a thin layer of silica gel or aluminium hydroxide - in each case there are free -OH groups pointing outwards in contact with the mobile phase

Answer 72

This is the solvent for the biological molecules , we can use water for polar molecules or ethanol for non polar molecules . The mobile phase flows through and across the stationary phase , carrying the biological molecules with it

Answer 73

As the solvent travels up the paper or plate , the components of the solution mixture travels with it , they travel at different speeds so the pigments end up at different positions on the plate . The speed at which molecules move along the paper or plate depends on their solubility in the Solvent and their polarity. Exposed -OH groups make the surface of the paper or plate very polar and allows it to form hydrogen bonds with the molecules. A highly polar solute will tend to stick to the surface (absorbed ) and hence move more slowly , a non polar solute will travel very quickly up the plate

Answer 74

Rf= x/y X = measuring the distance fro the pencil line to the centre of the spot of pigment Y= distance from pencil line to solvent front

Answer 75

Ultraviolet light Iodine Ninhydrin

Answer 76

Commonly used to monitor the progress of reactions Urine tests if athletes for illegal drugs analysing drugs for purity of components Analysis Of food to determine the presence of contaminants

Biological Molecules Flashcards

(101 cards)