Biological molecules Flashcards

Question

POLYSACCHARIDES: amylose structure

Answer 1

-a long chain of alpha glucose molecules coils into spiral shape, with hydrogen bonds holding spiral in place -hydroxyl groups on carbon 2 are situated on inside of coil, making molecule less soluble and allowing hydrogen bonds to form to maintain coiled structure

Answer 2

-amylopectin also coils into spiral shape, held together with hydrogen bonds but with branches emerging from spiral

Answer 3

-1-4 glycosidic chains -glycogen has less tendency to coil -have more branches meaning more compact -easier to hydrolyse monomer units as more ends

Answer 4

-cellulose is found in plants, forming the cell walls -it is a tough, insoluble and fibrous substance -its a polysaccharide made from long chains of B glucose molecules bonded together through condensation reactions to form glycosidic bonds

Answer 5

-hydrogen and hydroxyl groups on carbon 1 are inverted in B glucose - this means that every other B glucose molecule in the chain is rotated by 180 degrees -this and the B1-4 glycosidic bond helps prevention of chain spiralling -hydrogen bonding between the rotated B glucose molecules in each chain also gives the chain additional strength and stops it spiralling -hydrogen bonding between the rotated B glucose molecules in different chain gives whole structure additional strength - the hydroxyl groups on carbon 2 sticks out enabling hydrogen bonds to be formed between the chains -when 60-70 cellulose chains bound together they form microfibrils which are 10-30nm in diameter -these bundle together into macrofibrils containing up to 400 microfibrils which are embedded in pectins to form plant cell walls -macrofibrils run in all directions, criss crossing the wall for extra strength

Answer 6

-microfibrils and macrofibrils have very high tensile strength due to glycosidic bonds and because of hydrogen bonds between chains -macrofibrils are stronger than steel wire of same diameter -macrofibrils run in all directions, crisscrossing the wall for extra strength -it is difficult to digest cellulose because the glycosidic bonds between the glucose molecules are harder to break

Answer 7

-plants do not have a rigid structure therefore each cell needs strength to support the whole plant -there is space between macrofibrils for water and mineral ions to pass in and out of the cell -cell wall is fully permeable -high tensile strength prevents plant cells from bursting when they are turgid giving support - turgid cells press against each other, supporting plant structure as a whole -macrofibril structure can be reinforced with other substances for extra support or to make walls waterproof e.g. cutin and suberin are waxes that block spaces in the cell wall to make it waterproof

Answer 8

-bacterial cell wall - peptidoglycan made from long polysaccharide chains that lie in parallel, cross linked by short peptide chains -exoskeletons - insect and crustacean exoskeletons are made from chitin -it differs from cellulose as had acetylamino group (NH.OCCH3) rather than a hydroxyl group on carbon 2 -it forms cross links between long parallel chains of acetlyglucosamine in a similar way to cellulose

Answer 9

-cotton is 90% cellulose -cellophane and celluloid are derived from cellulose -one of main components of paper is cellulose -rayon is a semi-synthetic fibre produced from cellulose

Answer 10

-lipids contain large amounts of carbon and hydrogen and smaller amounts of oxygen -they are insoluble in water because they are not polar and so do not attract water molecules, but do dissolve in alcohol -3 most important lipids - triglyceride, phospholipid and steroid - these are not polymers but do have different components bonded together - they are examples of macromolecules

Answer 11

-glycerol has three carbon atoms -it is an alcohol which means it has free -OH groups -there are three -OH groups which are important to the structure of triglycerides

Answer 12

-fatty acids have a carboxyl group COOH on one end attached to a hydrocarbon tail made of only carbon and hydrogen atoms -the carboxyl group ionises H+ and a COO group- this structure is therefore an acid as it can produce free H+ ions -a single C=C bond makes a fatty acid monounsaturated e.g. oleic acid -more than one bond makes it polyunsaturated e.g. linoleic acid -having one or more C=C bonds changes the shape of the hydrocarbon chain giving it a kink where the double bond is -because these kinks push the molecules apart slightly it makes them more fluid -animal lipids contain lots of saturated fatty acids which are often solid at 20 degrees -if there are more unsaturated fatty acids the melting point is lower

Answer 13

-if a fatty acid is saturated this means there are no C=C bonds in the molecule -if a fatty acid is unsaturated there is a double bond between two of the carbon atoms instead, meaning fewer hydrogen atoms can be bonded to the molecule -an unsaturated fatty acid will have a kink in its tail -unsaturated fatty acids result in a more fluid membrane as the kinks create larger gaps between the heads and therefore cell membrane more permeable

Answer 14

-a triglyceride consists of one glycerol molecule bonded to 3 fatty acids -a condensation reaction happens between the COOH group of fatty acid and the OH group of glycerol and 3 H2O is released -because there are 3 OH groups, 3 fatty acids will bond hence the name triglyceride -because it is a covalent bond formed and a condensation reaction with water molecule produced, it is an ester bond

Answer 15

-triglycerides can be broken down in respiration to release energy and generate ATP -the first step is to hydrolyse the ester bonds and then both glycerol and fatty acid can be broken down completely to carbon dioxide and water -respiration of a lipid produces more water than respiration of a sugar

Answer 16

-because triglycerides are insoluble in eater they can be stored without affecting the water potential in the cell -mammals store fat in adipose cells under the skin -1kg of fat releases 2x as much energy as 1kg of glucose -this is because lipids have a higher proportion on hydrocarbon atoms than carbohydrates and almost no oxygen atoms

Answer 17

-adipose tissue is a storage location for lipid in whales acting as a heat insulator -lipid in nerve cells acts as an electrical insulator around neurones -animals preparing for hibernation store extra fat

Answer 18

-because fat is less dense than water, it is used by aquatic mammals to help them stay afloat

Answer 19

-humans have fat around delicate organs such as kidneys to act as shock absorber -the peptidoglycan cell wall of some bacteria is covered in lipid rich outer coat -also waxy cuticle on leaf -used in membranes e.g. phospholipids

Answer 20

-phospholipids have the same structure as triglycerides except that one of fatty acids is replaced by a phosphate group -a condensation reaction between an OH group on a phosphoric acid molecule (H3PO4) and one of three OH groups on glycerol forms on ester bond -most of fatty acids found in phospholipids have even number of carbon atoms -commonly one of these chains is saturated and one unsaturated

Answer 21

-when surrounded by water, the phosphate group has a negative charge making it polar (attracted to water) -the fatty acid tails are non polar so repelled by water -the head is hydrophilic and tail is hydrophobic which means phospholipid is amphipathic -membrane lipids tend to be amphipathic whereas those involved in storage are not -the phospholipids that are amphipathic have very distinct properties in water -they may form a layer on the surface of water with heads in water and tails sticking up out -they may also form micelles - tiny balls with tails tucked away inside and hearts pointing outwards into water

Answer 22

-amphipathic phospholipids are excellent at forming membranes around cells and organelles -inside and outside a cell membrane is an aqueous solution -the phospholipids form a bilayer with two rows of phospholipids tails pointing inwards and heads pointing outwards into solution -between 20-80% of membranes of plants and animal cells are made of phospholipids

Answer 23

-individual phospholipids are free to move around their layer but will not move into any position where their hydrophobic tails are exposed to water. This gives the membrane some stability -the membrane is selectively permeable. It is only possible for small and non polar molecules to move through tails in bilayer such as oxygen and carbon dioxide. This lets membrane control what foes in and out of the cells and keeps functioning properly

Answer 24

-cholesterol is a steroid alcohol - a type of lipid which is not made from glycerol or fatty acids -it consists of four carbon based rings or isoprene units -cholesterol is a small and hydrophobic molecule which means it can sit in the middle of the hydrophobic part of the bilayer -it regulates the fluidity of the membrane preventing it from becoming too fluid or stiff

Answer 25

-cholesterol is mainly made in the liver in animals -plants also have a cholesterol derivative in their membranes -it is called stigmasterol and different from cholesterol in only one respect; it has a double bond between carbon 22 and carbon 23

Answer 26

-the steroid hormones testosterone, oestrogen and vitamin D are all made from cholesterol -because they are all small and hydrophobic part of the cell membrane which is hydrophobic can pass through and any other membrane inside the cell -steroids are also abundant in plants and on ingestion and absorption some can be converted to animal hormones

Answer 27

-proteins are large polymers compromised of long chains of amino acids -they form structural components of animals in particular e.g. muscles made of proteins -their tendency to adopt specific shapes makes proteins important as enzymes, antibodies and hormones -membranes have protein constituents that act as carriers and pores for active transport across the membrane and facilitated diffusion

Answer 28

-each amino acid contains the elements carbon, hydrogen, oxygen and nitrogen -some amino acids contain sulfur -there are over 500 different amino acids but only 20 of them are proteinogenic which means that they are found in proteins -each protein chain of amino acids has an amino group NH2 at one end and a carboxyl group at the other COOH -they have an R group which can vary in size, charge and polarity

Answer 29

-amino acids are joined together by covalent bonds called peptide bonds -making a peptide bond involves a condensation reaction and breaking a peptide bond involves hydrolysis -enzymes catalyse these reactions -protease enzymes in the intestines break peptide bonds during digestion -they also break down protein hormones so their effects are not permanent -amino acids join together in same way, whatever R group they have -two amino acids join together by a dipeptide and longer chains form polypeptides -a protein may consist of a single polypeptide chain or more than one chain bonded together -polypeptides have a repeating backbone of N-C-C-N-C-C-N-C-C-N -sequence of amino acids determines shape of polypeptide

Answer 30

-structural= keratin, actin, collagen -catalytic = enzymes -signalling= hormones and receptors -immunological=antibodies -transport = haemoglobin

Answer 31

ABSORBED -nitrates absorbed from soil to make amine group -amino acids come from diet for animals -soya contains all essential amino acids REMOVAL -animals cannot store excess amino acids -amine group make them toxic -amino group removed via deamination in liver -ammonia - urea - urine

Answer 32

-the sequence of amino acids found in a protein chain -number and order of amino acids can change shape and function of the protein

Answer 33

-the chain of amino acids is not straight but twists into a shape called secondary structure -some chains coil into an alpha helix with 36 amino acids per 10 turns of helix -the helix is held together by hydrogen bonds between the NH group and the CO group -other chains fold very slightly in zigzag structure -when one such chain folds over on itself this produces a B pleated sheet -hydrogen bonds between NH and CO further down strand hold the sheet -although hydrogen bonds are relatively weak, many formed which makes both Alpha helix and B pleated sheet stable structures at optimal pH and temperature

Answer 34

-when these coils and pleats start to fold, along with areas of straight chains of amino acids, this forms tertiary structure -the tertiary structure is a very precise shape held firmly by close together bonds between amino acids -the tertiary structure may adopt a supercoiled shape (fibrous) or spherical shape (globular) -has hydrogen, disulphide bridges, ionic, hydrophilic/phobic interactions

Answer 35

-many proteins are made up of more than one polypeptide chain - the quaternary structure describes how multiple polypeptide chains are arranged to make the complete protein molecule

Answer 36

-the primary structure of proteins, the chain of amino acids, is held together by peptide bonds which are very strong covalent bonds -other types of bonds form between amino acids in different parts of the polypeptide chain -these hold together the secondary, tertiary and quaternary structures

Answer 37

-hydrogen bonds form between hydrogen atoms with a slight positive charge and other atoms with a slight negative charge -in amino acids these form in hydroxyl, carboxyl and amino groups

Answer 38

-ionic bonds can form between those carboxyl and amino groups that are part of R groups -these ionise into NH3+ and COO groups -positive and negative groups like this are strongly attracted to each other to form an ionic bond

Answer 39

-the R groups of the amino acid cysteine contains sulfur -disulfide bridges are formed between R groups of two cysteines -these are strong covalent bonds

Answer 40

-hydrophobic parts of the R group tend to associate together in the centre of the polypeptide to avoid water -the same way, hydrophilic parts are found at the edge of the polypeptide to be close to water -hydrophobic and hydrophilic interactions cause twisting of amino acid chain which changes the shape of protein -these interactions can be very important influence given most proteins found to be surrounded by water in living organisms

Answer 41

-has a relatively long thin structure -insoluble -long chains -high tensile strength -structural proteins

Answer 42

-function of collagen is to provide mechanical strength -in artery walls layer of collagen prevents artery from bursting when withstanding high blood pressure -tendons are made of collagen and connect muscles to bones allowing them to pull on bones -bones are made from collagen and reinforced with calcium phosphate which makes them ahrd -cartilage and connective tissue made from collagen

Answer 43

-keratin is rich in cysteine so lots of disulfide bridges form between polypeptide chains -alongside hydrogen bonding, this makes molecule strong -keratin is found wherever a body part needs to be hard and strong -it is found in fingernails, hair, hooves, claws etc -it provides mechanical protection but also provides an impermeable barrier to infection and being waterproof prevents entry of water born pollutants

Answer 44

-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 like processes -skin can stretch around bones and muscles due to 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 bladder helps hold urine -elastin helps our blood vessels to stretch and recoil as blood pumped through them and maintains pressure

Answer 45

-has molecules relatively spherical shape -often have metabolic roles -soluble in water -complex 3D spherical shape -specific shape for enzymes -functional

Answer 46

-the quaternary structure of haemoglobin is made up of four polypeptide - 2 alpha globin chains and 2 beta globin chains -each of these has its own tertiary structure but when fitted together, form haemoglobin molecule -shape of molecule held together and interactions between polypeptides -on outside of each chain there is space in which haem group held -this group is a prosthetic groups - essential part of molecule that could not function without -the haem group contain an iron ion and therefore they are known as a conjugated protein

Answer 47

-function of haemoglobin is to carry oxygen from lungs to tissues - in lungs an oxygen molecule binds to iron in each of four haem groups in haemoglobin molecule -when it binds, turns from purple red to bright red -oxygen released by haemoglobin when reaches tissues

Answer 48

-insulin is made of two polypeptide chains -The A chain begins with a section of alpha helix and B chain ends with a section of B pleat -both chains fold into a tertiary structure and are then joined together by disulfide links -amino acids with hydrophilic R groups are on outside of 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 blood and to increase rate of consumption of glucose

Answer 49

-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 its folds into a symmetrical tertiary structure -pepsin has very few amino acids with basic R groups whereas it has 43 amino acids with acidic R groups -this helps 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 enzymes structure -the tertiary structure is also held together by hydrogen bonds and 2 disulfide bridges

Answer 50

a non protein component that forms a permanent part of a functioning protein molecule

Answer 51

-e.g. to identify binding sites on a protein and develop medicines to block pathogens -sequencing of amino acids allows us to predict shape 1) Ab initio - model properties of atoms and predict shape, often give too many possibilities 2) comparative - allows us to compare sequences to known examples

Answer 52

-potassium - nerve impulse, muscle contraction -chlorine - production of hydrochloric acid in stomach -sodium - helps with nerve impulses -calcium - bones -phosphorus - DNA and ATP -magnesium- processing ATP for bones

Answer 53

-iron- required for proteins e.g. haemoglobin and enzymes -zinc - required for enzymes -manganese - cofactor in enzyme function

Answer 54

-in humans and plants some ions are required in large amounts (macronutrients) and some in small amounts (micronutrients or trace elements) -both humans and plants can display deficiency symptoms if they do not consume enough of ions -for example deficiency of trace element cobalt causes anaemia whilst copper causes young shoots to die

Answer 55

-increases rigidity of bone, teeth and cartilage and is component of exoskeleton -important in clotting blood and muscle contraction -activator for several enzymes -stimulates muscle contraction and regulates transmission of nerve impulses -regulates permeability of cell membranes -important for cell wall development in plants and formation of middle lamella between cell walls

Answer 56

-involved in regulation of osmotic pressure, control of water levels in body fluid and maintenance of pH -affects absorption of carbohydrate in the intestine and water in the kidney -contributes to nervous transmission and muscle contraction -constituent of vacuole in plants which helps maintain turgidity

Answer 57

-involved in control of water levels in body fluid and maintenance of pH -assists active transport of materials across cell membrane -involved in synthesis glycogen and protein and breakdown of glucose -generates health leaves and flowers in plants -contributes to nervous transmission and muscle contraction -component of vacuoles in plants, helping maintain turgidity

Answer 58

-involved in photosynthesis and respiration -involved in transport of oxygen and carbon dioxide -involved in regulation of blood pH

Answer 59

-a component of amino acids, proteins, vitamins, chlorophyll -some hormones are made of protein e.g. insulin -an essential component of nucleic acids -involved in maintenance of pH in body -component of nitrogen cycle

Answer 60

-a component of amino acids, proteins, vitamins, chlorophyll -an essential component of nucleic acids -some hormones made of proteins which contain nitrogen -component of nitrogen cycle

Answer 61

-involved in regulation of blood pH -involved in transport of carbon dioxide into and out of blood

Answer 62

-helps in production of urine in kidney and maintains water balance -involved in transport of carbon dioxide in and out -regulates affinity of haemoglobin to oxygen through allosteric effects on haemoglobin molecule -involved in regulation of blood pH -used to produce hydrochloric acid in stomach

Answer 63

-increase rigidity of bone, teeth and exoskeletons -helps root growth in plants -involved in regulation of blood pH

Answer 64

-involved in regulation of blood pH

Answer 65

-draw line in pencil and put tiny dot on line to show where place solution mixture -do not draw in ink as pigments in ink will also separate -spot solution mixture onto pencil do several times by using capillary tubing -wait for spot to dry in between each and make spot as thin as possible -when it is completely dry put it into solvent -ensure level of solvent is below pencil line -cover beaker with watch glass or glass plate let apparatus run until solvent has reached point just underneath top of TLC -remove it from solvent and lay on white tile to dry

Biological molecules Flashcards

(89 cards)