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biology > BIOLOGICAL MOLECULES > Flashcards

BIOLOGICAL MOLECULES Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are monomers ?

A

smaller units from which larger molecules are made

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2
Q

what are polymers ?

A

molecules which are made from a large number of monomers joined together

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3
Q

what is a condensation reaction ?

A

joins two molecules together with a formation of a chemical bond and an elimination of a water molecule.

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4
Q

what is a hydrolysis reaction ?

A

breaks a chemical bond between two molecules and involves the use of a water molecule.

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5
Q

examples of a monomer ?

A

amino acids
monosaccharides
nucleotides

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6
Q

what are monosaccharides and name the most common ones ?

A

monosaccharides are the monomers from which larger carbohydrates are made, examples are :
1) glucose
2) fructose
3) galactose

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7
Q

what are disaccharides and name the most common ones and what they are made from ?

A

it is when 2 monosaccharides join together and the common disaccharides are :
1) maltose :formed from condensation reaction b/w glucose + glucose
2) sucrose : condensation reaction b/w, glucose + fructose
3) lactose : condensation reaction b/w, glucose + galactose

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8
Q

what are polysaccharides and what are the names of the common ones and what are they made of ?

A

polysaccharides are repeating units of monosaccharides, the common ones are :
1) starch
2) cellulose
> starch and cellulose both formed by the condensation of glucose
3 ) glycogen : formed by the condensation of B- glucose.

> all found in plants and animal cells

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9
Q

name the 2 isomers of glucose and the difference between them

A

alpha glucose : has the hydroxide group (OH) at the bottom of the first carbon
Beta glucose : has the hydroxide group at the top of the first carbon and another at the bottom of the second carbon diagnal too each other.

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10
Q

what bond is formed by the condensation between monosaccharides ?

A

glycosidic bond is formed between the condensation of two monosaccharides. condensation between many monosaccharides forms a polysaccharide.

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11
Q

what bond is formed between condensation of 2 nucleotides ?

A

a phosphodiester bond , condensation between many nucleotides forms a polynucleotide.

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11
Q

what bond is formed between condensation of 2 amino acids ?

A

a peptide bond and condensation between many amino acids forms polypeptides.

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12
Q

what are polysaccharides and name the different types ?

A

they are formed from many glucose units joined together and the diferent types of monosaccharides are :
. glycogen
. amylopectin
. amylose
. cellulose

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13
Q

what is the structure and function of glycogen ?

A

it is the main energy storage molecule found in animals and it is a long branched chain of glucose molecules joined together by 1,4 and 1,6 glycosidic bonds. glycogen has many side branches which increase its surface area so allow enzymes to react simultaneously and thus be broken down to release energy. glycogen is a large but compact molecule therefore maximises the energy it can store.
> glycogen has more side branches than amylopectin

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13
Q

what is the structure and function of cellulose ?

A

it is the component which makes up the cell wall within plants and it is a long unbranched chain of glucose molecules joined together by 1,4 glycosidic bonds. the cellulose chains are joined together by hydrogen bonds between the glucose molecules which form a thick fiber called microfibrils. microfibrils allows cellulose to be flexible and strong and therefore provides support too the cell wall and to make the cell turgid. cellulose also has alternating glycosidic bonds.

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13
Q

name the 2 polymers startch is made up of.

A

amylose and amplopectin

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14
Q

what is the function of startch ?

A

starch is a storage carbohydrate found in plants , plants use starch to store excess glucose as its too large to leave cells. starch is also insoluble so thus it does not affect the water potential of cells. starch can be hydrolysed to release glucose for respiration.

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15
Q

what is the structure and function of amylose ?

A

Amylose is a long unbranched chain of glucose molecules joined together by 1,4 glycosidic bonds. amylose is a coiled up molecule , thus it is compact meaning it is good for storage.

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16
Q

what is the structure and function of amylopectin ?

A

amylopectin is a long branched chain of glucose molecules joined together by 1,4 and 1,6 glycosidic bonds. it has side branches which increase surface area for enzymes to react simultaneously and for it to be broken down to release energy for respiration.

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17
Q

what are lipids and its functions ?

A

Lipids are fats and oils which store energy. they are the major source of energy in the human diet. lipids store energy in the body such as adipose tissue which insulates the body and reduces heat loss. lipids are also used for waterproofing. lipids are seen to be the major structure of membranes which form the lipid bilayer.

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18
Q

what are the names of the two different types of lipids ?

A

. triglycerides
. phospoholipids

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19
Q

what is the structure and function of triglycerides?

A

trigylcerides contain a glycerol molecule bonded too 3 fatty acid molecules joined together by an ester bond formed via condensation reaction. Trigylcerides are hydrophobic and non polar so are uncharged this means they are insoluble in water and are used as waterproofing in aquatic birds. trigylecrides contain a high ratio of energy storing carbon- hydrogen bonds to carbon atoms which means they are an excellent energy store. they also have a low mass to high energy ratio meaning lots of energy can be stored in a small volume which is great for animals so they dont need to move with lots of mass. they are large and non polar meaning they are insoluble so their storage does not affect the water potential.

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20
Q

what are saturated lipids ?

A

they are found in animal plants and do not contain any carbon- carbon double bonds.

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21
Q

what are unsaturated lipids ?

A

they are found in plants and contain carbon - carbon double bonds. the presence of the double bond means they can bend and so cant be packed tightly with each other so are liquid at room temperature.

22
Q

what is the structure and function of phosphoplipids ?

A

they contain a glycerol molecule bonded to two fatty acids and a phosphate group. the phosphate group is negatively charged which means it is polar , this allows the head of the phospholipid to be hydrophilic and can therefore attract water molecules. However, the tail of phospholipids is hydrophobic and the tails cluster together away from water molecules allowing them to form a phospholipid bilayer. the heads of phospholipids are positioned upwards to interact with the water molecules . This allows the centre of bilayers to be hydrophobic and create separate conditions on either side of membrane.

23
Q

what are proteins and what are they made from ?

A

proteins are enzymes and are made from monomers called amino acids which combine together to form proteins.

24
Q

describe the structure of an amino acid ?

A

it contains a carbon atom which has 4 chemical groups attached to it , an amine group , a carboxylic group , a hydrogen atom and a R group

25
Q

how many amino acids does every living organism have and what is the one distinguishing difference between them ?

A

every living organism has 20 amino acids , however they all differ only in their side group/ R group.
> the R group is consists of carbon with the exception of glycine.

26
Q

what are dipeptides ?

A

they are formed by the condensation between two amino acids.

27
Q

what does a functional protein contain ?

A

it may contain one or more polypeptides.

28
Q

how is a polypeptide formed from a dipeptide ?

A

when two amino acids join via a condensation reaction a peptide bond is formed and a water molecule is released, the peptide bond forms between the amine group of one amino acid and the hydroxyl group of the other amino acid. the two amino acids joined together is known as a dipeptide. more than two amino acids joined together is known as a polypeptide.

29
Q

what are the 4 levels of protein structure called and what do the levels determine ?

A

. primary
. secondary
. tertiary
. quaternary
> single chain polypeptides only have three levels of protein structure so , primary, secondary and tertiary , however proteins made up of many polypeptides have an additional level the quaternary structure.

30
Q

explain the primary structure of a protein

A

this is the number and sequence of amino acids in the polypeptide chain. it is the initial amino acid sequence which determines the proteins function in the end.

31
Q

explain the secondary structure of proteins

A

hydrogen bonds form between the amino acids in the chain this causes it to coil into alpha helix or fold into b - pleated sheets. the hydrogen bonds are what make these structures stable.

32
Q

explain the tertiary structure of proteins

A

this is the 3D shape of the polypeptide chain and it creates a specific shape due to the sequence of amino acids in the chain as hydrogen bonds , disulphide bridges and ionic bonds form between the R groups.

33
Q

what would happen if their was a change to the amino acid sequence ?

A

this would affect the secondary and tertiary structure as the hydrogen, ionic and disulphide bridges would form in different places.

34
Q

explain the quaternary structure

A

if proteins made up of more than one polypeptide chain are joined together they make a quaternary structure. eg : haemoglobin and antibodies.

35
Q

what is an enzyme ?

A

they are biological catalysts which speed up the rate of reactions without a permanent change.

36
Q

explain the structure of an enzyme

A

enzymes are a type of globular protein which have a 3D structure due to their tertiary structure which gives the active site of an enzyme a specific shape so only the substrate complementary to that active site can bind to it too form enzyme substrate complexes.

37
Q

explain how enzymes speed up metabolic reactions linked to activation energy ?

A

enzymes speed up metabolic reactions by lowering the activation energy, they do this by binding to the reactant molecule and allowing chemical bond forming and bond breaking processes to occur more easily.

38
Q

explain the lock and key model

A

the lock and key model is the old enzyme model which states that the shape of the active site is exactly complementary to the specific substrate molecule and the substrate fits exactly into the active site when forming enzyme substrate complexes.

39
Q

explain the induced fit model

A

the induced fit model is the new model which states that the active site of an enzyme is not exactly complementary to its substrate. when the substrate molecule binds to the active site , the active site changes shape slightly to fit around the substrate and to form a enzyme substrate complex.

40
Q

what happens to the rate of reaction when you increase enzyme concentration ?

A

increasing enzyme conc increases the rate of reaction as more collisions are occurring between enzymes and substrates so more enzyme substrate complexes are being formed. the rate of reaction increases until enzyme conc is no longer the limiting factor and the substrate conc becomes limiting factor so increasing the enzyme conc has no affect.

41
Q

what happens to the rate of reaction when you increase substrate conc ?

A

increasing substrate conc increases rate of reaction as more collisions occur between enzymes and substrates so their is an increase in enzyme substrate complexes . rate of reaction will carry on increasing until the enzyme conc becomes the limiting factor and increasing the substrate conc has no affect as all the active sites are occupied.

42
Q

what happens to the rate of reaction when you increase the temperature ?

A

as the temp increases so does the rate of reaction as this increases the kinetic energy of the molecules so they move at a higher speed and therefore an increase in collisions and an increase in the number of enzyme substrate complexes.

43
Q

what happens to the enzyme if the temperature is too low or too high ?

A

enzymes have an optimum temperature which it works best at if the temperature goes above the optimum temp this will break the bonds holding the enzyme together and will denature the enzyme, therefore this will affect the tertiary structure causing the enzymes active site to change place. as the amino acid sequence is being disrupted this will cause the hydrogen and ionic bonds to form somewhere else causing the active site to change shape.

44
Q

what happens to the rate of reaction when there is an increase in PH ?

A

the rate of reaction will increase as more enzyme substrate complexes will be formed.

45
Q

what happens to enzymes if the PH is too high or too low ?

A

enzymes have an optimum PH ( usually PH 7) and this is the PH enzymes work best at however , if the PH is too high or low this will cause the bonds holding the enzymes together to break and the tertiary structure of an enzyme will be disrupted causing the enzyme to denature , therefore the active site will change shape and enzyme substrate complexes can no longer be formed.

46
Q

what do enzyme inhibitors do ?

A

they slow down enzyme activity or prevent it by using molecules other than substrates that bind to the enzyme.

47
Q

name the 2 different types of inhibitors

A

. competitive inhibitors
. non-competitive inhibitors.

48
Q

what is the role of a competitive inhibitor ?

A

they have a similar shape to a substrate molecule and they compete with substrates to bind to the active site of an enzyme to prevent the substrate from binding to it , therefore preventing enzyme substrate complexes to be formed.

48
Q

what happens to the competitive inhibitor when you increase the substrate concentration ?

A

increasing substrate conc increases the rate of reaction , however increasing substrate conc reverses the effects of a competitive inhibitor as the substrates will out compete the competitive inhibitor for the active site.

48
Q

what happens to the non competitive inhibitor when increasing substrate conc ?

A

increasing substrate conc has no affect on rate of reaction as they cannot bind to the active site.

49
Q

what is the role of a non competitive inhibitor ?

A

they do not bind to the active site of an enzyme as they do not have a similar shape to the substrate, instead they bind to a site away from the active site called the allosteric site. This causes the active site of the enzyme to change shape and so is no longer complementary to its substrate and can no longer form enzyme substrate complexes.

50
Q

what is the test for presence of starch ?

A

when iodine is added to solution if it turns blue or black then starch is present and if it remains orange/brown then it is a negative result.

51
Q

what is the test for the presence of proteins ?

A

place the sample being tested in a test tube and then add equal volume of sodium hydroxide at room temperature . you will then add a few drops of dilute copper sulphate solution. if protein is present the the solution will turn purple, if its a negative result the solution will remain blue.

52
Q

what is the test for presence of reducing sugars
(monosaccharides and disaccharides) ?

A

add 2cm3 of the food sample in liquid form to be tested on . then add the 2cm3 of benedicts solution to the food sample and heat it for 5 minutes in a water bath. if the solution turns brick red then reducing sugar is present if it stays blue their is no reducing sugars present.

53
Q

what is the test for the presence of non reducing sugars ( some disaccharides and polysaccharides ) ?

A

add 2cm3 of the food sample to 2cm3 of the benedicts reagent and then heated for 5 minutes. if solution doesn’t turn brick red then reducing sugar is not present. you will then add 2cm3 of the food sample to 2cm3 of dilute hydrochloric acid , this will hydrolyse the polysaccharides into the monosaccharides they were. you will then add sodium hydrogencarbonate to neutralise the solution as benedicts reagent does not work in acidic conditions. after the PH has been checked you will add 2cm3 of the benedict solution and if the food sample turns brick red then non reducing sugar is present.

54
Q

what is the test for the presence of lipids and fats ?

A

add food sample to the test tube and then add ethanol to the test tube. you will then shake it for a minute. after it has been shaken you will add the water. if lipids and fats are present you will see a milky white emulsion form in the test tube.

biology (9 decks)

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