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Biology A-Level > 1.2 biological molecules 1 > Flashcards

1.2 biological molecules 1 Flashcards

1
Q

what do organic compounds contain

A

all organic compounds contain carbon atoms, they also contain hydrogen, oxygen and less frequently nitrogen, sulphur and phosphorous

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2
Q

what are carbohydrates used for

A

storing energy in plants, fungi and bacteria, and forming an important part of the cell wall

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3
Q

what are the different forms of a molecule called,
and draw the two different structures of glucose and label them

A

-isomers
-alpha glucose - hydrogen at the top on the right hand side
-beta glucose - hydrogen on the bottom on the left hand side

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4
Q

what is a dissaccharide, how is it made and give an example of one

A

a disaccharide is two monosaccharides joined together in a condensation reaction, and a molecule of water is removed. The link between them is a glycosidic bond (covalent bond)

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5
Q

what are the different monosaccharides that make up the following disaccharides:
-sucrose
-lactose
-maltose

A

1.a-glucose + fructose
2.a-glucose + B- galactose
3.a-glucose + a-glucose

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6
Q

what is the difference between monosaccharides and oligosaccharides

A

molecules with 3-10 sugar units are oligosaccharides whilst molecules with 11+ units are monosaccharides

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7
Q

how does the structure of polysaccharides make the ideal storage molecules

A

-they form compact molecules, so many of them can be stored in a cell
-the glycosidic bonds between them can be broken down easily to allow the quick release on monosaccharide units for cellular respiration

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8
Q

what the name of the process of breaking glycosidic bonds, and where it takes place

A

hydrolysis, hydrolysis takes place during digestion in the gut and in the muscle and liver cells when carbohydrate stores are broken down to release sugars for cellular respiration

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9
Q

what is starch made up of, in detail

A

starch is made up of long chains of alpha glucose, and if looked at more closely, it’s made up of a mixture of two compounds

amylose- unbranched polymer, as the chain lengthens, the molecule spirals which makes it very compact for storage

amylopectin- branched polymer of glucose molecules that can be broken off rapidly when energy is needed

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10
Q

what kind of bonds are amylose and amylopectin made up of

A

amylose is made of 1-4 glycosidic bonds, which is why they’re unbranched

amylopectin is made up of 1-4 glycosidic bonds and the occasional 1-6 glycosidic bonds every 25-30 units, that change the properties of the molecule

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11
Q

what is the effect of starch being made up of both amylose and amylopectin

A

the combination explains why carbohydrate foods are good for you when doing sport. The amylose releases sugar for cellular respiration slowly over a long period which allows you to continue going for longer, and the amylopectin releases glucose rapidly when needed.

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12
Q

what is glycogen

A

Glycogen is the only carbohydrate energy store found in animals, it is also an important storage carbohydrate in fungi

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13
Q

why is glycogen an ideal source of glucose for active tissues with a high rate of cellular respiration

A

It is chemically similar to amylopectin, it is compact and has more 1-6 glycosidic bonds, giving it many side branches, so it can be broken down vert quickly, (also made up of alpha glucose)

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14
Q

why are polysaccharides important in plants

A

They are the main energy storage material

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15
Q

why is cellulose important in plants and what is it made of

A

The cell wall gives plant cells their structural strength and support, and is mostly made of insoluble cellulose
It consists of long chains of beta glucose made of 1-4 glycosidic bonds

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16
Q

why is cellulose a material of considerable strength

A

this is because it is made up of beta glucose, so for the monomers to bond, one of the units must be inverted. This means that hydrogen bonds can form between partially positively charges hydrogen atoms and the partially negatively charged oxygen atoms.
This is called cross-linking
cellulose molecules do not coil, they remain straight

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17
Q

State an example of each and state the difference between fats and oils

A

A fat (butter) , is solid at room temperature, whilst an oil (olive oil) is liquid at room temperature

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18
Q

Name the two types of organic chemicals that fats are made up of and the bonds between them

A

they are both joined by ester bonds
-fatty acids
-glycerol

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19
Q

state the types of saturated and unsaturated fats and explain them

A

saturated- each carbon is joined to the neighbouring hydrogen by a single covalent bond
unsaturated- the carbon chains have one or more double bond
monounsaturated- one double bond
polyunsaturated- more than one double bond

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20
Q

describe in detail how fat or oil would be formed

A

it would be the result of glycerol combining with 1, 2 or 3 fatty acids to make a mono, di, or tri -glyceride.
a bond is formed in the condensation reaction between the carboxyl group pf a fatty acid (COOH) and they hydroxyl group of the glycerol (OH), a molecule pf water is removed resulting in an ester bond

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21
Q

what is the condensation reaction to form a fat/oi and glycerol called

A

esterification

22
Q

what does the nature of the fat/oil that has been formed due to a condensation reaction depend on

A

the fatty acids present, e.g if the fatty acids were saturated, then it would more likely form a fat, because it is solid at room temperature

23
Q

which reaction with lipids is used to drive the production of ATP

A

lipids being oxidised in respiration causes the bonds to break down and and produces carbon dioxide and water.

24
Q

what stores more energy between a lipid and a carbohydrate

A

a lipid stores about 3X as much energy as a carbohydrate

25
Q

name the features of lipids and how they may be of use in animals

A

-they are hydrophobic, so they repel water and oils waterproof organisms
-they are good insulators, so a fatty sheath insulates nerves in organisms which allow them to travel faster
-they insulate animals against heat loss
-they dissolve in oragnic solvents, but are insoluble in water so they don’t interfere with water based reactions that go on in the cytoplasm of the cell

26
Q

describe how a fat or oil is formed

A

-a fat or oil is formed when glycerol combines with one, two or three fatty acids
-a bond is formed through a condensation reaction between the carboxyl group of a fatty acid and a hydroxyl group of glycerol

27
Q

at type of condensation occurs when an oil is formed

A

esterification

28
Q

draw a diagram for the formation of a fatty acid (triglyceride)

A

glycerol + 3 fatty acids = triglyceride
DIAGRAM
- propan 1, 2, 3 triol + COOH (R connected to C)
- H20 circled between fatty acids (HO) and glycerol (H)
- arrow pointing towards product (condensation) and reverse arrow (hydrolysis)
- triglyceride labelled product
- reactants joined up to form one molecule with missing H2O

29
Q

when and why are lipids oxidised

A
  • oxidised during respiration to form carbon dioxide and water
  • this done to drive the production of ATP
30
Q

what are the properties of lipids and what are their corresponding roles

A
  • their hydrophobic nature allows them waterproof organisms
  • they have thick layers to trap air they are good insulators for animals, they insulate nerves which allow electrical impulses to travel faster
  • they have a very low density, so body fat of water mammals lets them float easily
31
Q

how are phospholipids formed

A

when one of the hydroxyl groups of glycerol undergo esterification with a phosphate group instead of a fatty acid

32
Q

how does a phospholipid behave in water

A
  • the polar phosphate part is hydrophilic and dissolved readily in water
  • the lipid tails are hydrophobic so they don’t dissolve
33
Q

describe a unit membrane

A

usually when phospholipids come in contact with water on both sides, and they form a bilayer with their hydrophilic heads pointing outwards towards the liquid

34
Q

what is the basic structure of an amino acid

A

(NH2) (CHR) (COOH)

35
Q

how do amino acids join together

A
  • amino acids join with each other through a condensation reaction between an amino group of one amino acid and the carboxyl group of another to form a peptide bond
36
Q

what are the bonds that can be found in proteins

A
  • hydrogen bonds
  • disulfide bonds
  • ionic bonds
  • the peptide bonds between amino acids
37
Q

briefly describe the types of bonds that can be found in proteins

A
  • hydrogen bonds are relatively weak
  • disulfide bonds form when two cysteine molecules join together
  • ionic bonds form between strongly negative and strongly positive amino side chains
38
Q

what is the primary structure of a protein?

A

the sequence of amino acids that form the polypeptide chain held together by peptide bonds

39
Q

what is the secondary structure of a protein

A

the arrangement of the polypeptide chain into a repeating structure held together by hydrogen bonds
a-helix (coiled) b-pleated sheets (layers of jagged lines)

40
Q

what type of structure do fibrous proteins have

A

secondary structure

41
Q

what is the tertiary structure of a protein

A

further folding of the structure into complicated shapes, consist of disulfide, ionic binds and hydrogen bonds

42
Q

what type of structure do globular proteins have

A

tertiary structure

43
Q

what is the quaternary structure of a protein

A

three dimensional arrangement of more than one tertiary polypeptide

44
Q

what type of protein structure does haemoglobin have

A

quaternary structure

45
Q

describe properties and structure of fibrous protein

A
  • long parallel polypeptide chains with occasional cross linkages
  • they are insoluble in water and pretty tough which make them useful for their structural function (connective tissue of tendons)
46
Q

what is the role of collagen

A
  • a fibrous protein that give strength to ligaments, bones and skin
47
Q

describe the role and structure of a globular protein

A
  • complex tertiary and sometimes a quaternary structure that fold into globular shapes
  • their large shape affects how they behave in water because they have ionic properties so they may dissolve in water to form a solution
48
Q

what are conjugated proteins

A

protein molecules that are joined with a prosthetic group

49
Q

what are glycoproteins, what is their function

A

proteins with a carbohydrate prosthetic group, which helps they hold on to water and makes it harder for enzymes to break it down

50
Q

what are lipoproteins and what is their function

A

proteins that are conjugated with lipids and are important in transporting cholesterol in the blood, and the lipid part helps them bond to cholesterol

51
Q

what is a co-enzyme

A
  • it is an organic compound that binds to the active site of enzymes to assist in the catalysis of a reaction
  • they take part in the reaction and are changed by the end
52
Q
A

Biology A-Level (25 decks)

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