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Biological molecules Flashcards

1
Q

what role do calcium ions play? Ca2+

A

involved in muscle contraction and nerve impulse transmission

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2
Q

what role do sodium ions play? Na+

A

involved in co-transport, reabsorption of water in the kidney and nerves impulse transmission

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3
Q

what role do potassium ions play? K+

A

involved in stomatal opening and nerve impulses transmission

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4
Q

what role do hydrogen ions play? H+

A

involved in chemioamosis, pH determination and catalysis of reactions

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5
Q

what role do nitrate ions play ? NO3-

A

mineral ion absorbed by plants to provide a source of nitrogen to make aminonacids

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6
Q

what role does the hydrogencarbonate play? HCO3-

A

maintains the pH of the blood

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7
Q

what role do the phosphate ions play? PO4 3-

A

involved in the formation of phospholipids for cell membranes, nucleic acids and ATP formation

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8
Q

describe the structure of a water molecules

A

one atom of oxygen
two atoms oh hydrogen
covalently bonded

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9
Q

what makes water polar?

A

it has a partially negative charge on the oxygen and a partially positve charge on the hydrogen, this is due to the uneven distribution of the shared pair of electrons in the covalent bond.

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10
Q

what is hydrogen bonding?

A

it is when the partial negative charge on an oxygen attract the partial positive charge on a neighbouring hydrogen atom

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11
Q

what are the 4 key properties of water?

A

1- as a solvent in reactions
2- a transport medium
3- as a coolant
4- provides habitat

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12
Q

why is water a good solvent?

A

polar (hydrophilic) or charged molecules dissolve readily in water due to the fact water is polar.

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13
Q

How do hydrogen bonds give water a high specific heat capacity?

A

The hydrogen bonds between water molecules can absorb a lot of energy, so it takes a lot of energy to heat up the water and overcome the bonds

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14
Q

How does having a high specific heat capacity make water a good habitat?

A

It means that the water does not experience rapid temperature changes

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15
Q

Why does water have a high latent heat of evaporation?

A

It takes a lot of energy to break the hydrogen bonds between water molecules, so a lot of energy is used up when it evaporates

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16
Q

Why is it useful that water has a high latent heat of evaporation for living organisms?

A

It means that water is great for cooling things, for example, some mammals sweat when they are hot to cool the surface of the skin

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17
Q

What is cohesion?

A

The attraction between molecules of the same type. eg in water, molecules stick to each other by hydrogen bonds

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18
Q

What are the advantages of water being cohesive?

A

It helps water flow, making it great for transporting substances
It helps water be transported up plant stems in the transpiration stream

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19
Q

Why is it useful that ice floats on water?

A

In cold temperatures, ice forms an insulating layer on top of water and so the water below does not freeze.

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20
Q

Why is water less dense as a solid than a liquid?

A

Water molecules are held further apart in ice than they are in water because each water molecule forms four hydrogen bonds to other water molecules, making a lattice shape

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21
Q

how does cohesion provide habitat?

A

the cohesion provides surface tension to water. this enable small invertebrates to move and live on the surface, providing them a habitat.

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22
Q

give three hexose monosaccharides

A

glucose, fructose and galactose

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22
Q

What are the monomers that make up carbohydrates?

A

monosaccharides

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23
Q

What is the difference between alpha and beta glucose?

A

Alpha glucose hydroxyl group on c1 is below the plane
Beta glucose hydroxyl group on c1 is above the plane

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24
name two pentose monosaccharides
ribose and deoxyribose
25
How do monosaccharides join together?
glycosidic bonds
26
What is a condensation reaction?
a hydrogen atom on one monosaccharide bonds to an OH group on the other, releasing a molecule of water
27
What is a hydrolysis reaction?
When a molecule of water reacts with the glycosidic bond, breaking it apart
28
what is a disaccharide
two monosaccharides joined together by a glycosidic bond in a condensation reaction
29
How is maltose formed?
alpha glucose + alpha glucose
30
how is lactose formed?
alpha glucose + galactose
31
How is sucrose formed?
alpha glucose + fructose
32
what is a polysaccharide?
When more than two monosaccharides are joined together glycosidic bonds by condensation reactions
33
What do plants store excess glucose as?
starch - it is insoluble in water, so does not affect water potential
34
What is the function of starch?
it is the main energy storage material in plants
35
What two polysaccharides make up starch?
amylose and amylopectin
36
Describe amylose
A long unbranched chain of alpha glucose Coiled structure Compact - good for storage Joined by 1-4 glycosidic bonds
37
describe amylopectin
Made by 1-4 glycosidic bonds Some 1-6 glycosidic bonds Branched structure Very compact Free ends where glucose can be added or removed Insoluble
38
What bonds form between two glucose molecules?
alpha 1-4 glycosidic bonds
38
what is glycogen?
it is the main energy storage material in animals. animals store excess glucose and glycogen- another polysaccharide of glucose
39
describe glycogen
its structure is very highly branched , has loads of side branches means that stored glucose can be released quickly via hydrolysis . it is very compact
40
What molecules make up cellulose
Beta glucose molecules
41
How do beta glucose molecules join together?
They join by 1-4 glycosidic bonds Every other molecules is flipped 180 degrees
42
describe cellulose
long, unbranched chains of beta glucose. these chains are held in parallel by many hydrogen bonds to form fibrils. macrofibrils combine to form cellulose fibres. Many hydrogen bonds provide collective strength. It is also insoluble- wont affect water potential
43
what are the three types of lipids?
triglycerides phospholipids cholesterol
44
What are triglycerides composed of?
1 glycerol and 3 fatty acids
45
what are the two types of fatty acid
saturated or unsaturated
46
how are triglycerides formed?
via a condensation reaction (esterification) between one molecule of glycerol and three molecules of fatty acid, forming three ester bonds
47
what are saturated fatty acids
they dont have any double bonds between their carbon atoms. the fatty acid is saturated with hydrogen
48
what are the key properties of triglycerides
1- long hydrocarbon tails of fatty acids contain lots of chemical energy - lots of energy is released when they are broken down 2- act as metabolic water source, triglycerides can release water if oxidised, essential for animals in desert such as camels 3- as lipids are large hydrophobic molecules they are insoluble in water. this means they will not affect the water potential
49
what are unsaturated fatty acids
unsaturated fatty acids had at least one double bond between carbon atoms, which cause the chain to kink
50
What are the functions of triglycerides in the body?
Triglycerides serve as a source of energy for the body. They are stored in adipose tissue and can be broken down to release energy when needed. Triglycerides also help to insulate the body and protect vital organs.
51
what are phospholipids made of
a glycerol with a phosphate group attached and two fatty acid chains (one chain is saturated, one is unsaturated)
52
how are phospholipids made
the two fatty acids also bond to the glycerol via condensation reactions to form two ester bonds
53
why are phospholipids amphipathic
they have both hydrophobic (repelled from water) tails and hydrophilic (attracted to water) head, due to the phosphate group
54
How do phospholipids form the structure of cell membranes?
Phospholipids form the structure of cell membranes by arranging themselves in a double layer, or bilayer, with the hydrophobic tails facing inward and the hydrophilic heads facing outward. This arrangement allows the cell membrane to control the flow of substances in and out of the cell while also maintaining the integrity of the cell.
55
What is the significance of the hydrophobic and hydrophilic properties of phospholipids?
The hydrophobic and hydrophilic properties of phospholipids are significant because they allow the formation of the cell membrane bilayer. The hydrophobic tails are able to interact with each other, creating a barrier that separates the inside of the cell from the outside environment. The hydrophilic heads, on the other hand, allow for the exchange of substances between the cell and its environment, as well as for communication between cells.
56
what is a micelle
is a singe layer of phospholipids with tails pointing inwards eg vesicles and lysosomes
57
what is a cholesterol
it is a sterol, has 4 carbon rings and a hydroxyl group at one end, it has both hydrophobic and hydrophilic (hydroxyl end) regions
58
why is cholesterol important in membranes
1- small size and flattened shape means it can fit between the phospholipid molecules in the membrane 2- at high temps, they bind to the hydrophobic tails of the phospholipids, causing them to pack more closely. this helps the membrane be less fluid and more rigid 3- at lower temperature cholesterol prevents phospholipids from packing too close, so increases the fluidity
58
What are the monomers of proteins?
amino acids
59
What is a dipeptide?
2 amino acids
60
what is a polypeptide
more than 2 amino acids joined together
61
Describe the structure of an amino acid
A carboxyl group an amine group attached to a carbon atom a single hydrogen A variable R group Image: Describe the structure of an amino acid
62
How do amino acids join together?
peptide bonds (condensation reaction)
63
Describe the primary structure of a protein
sequence of amino acids in a polypeptide chain held together by peptide bonds
64
Describe the secondary structure of a protein
Hydrogen bonds form between amino acids in the chain Folds into beta pleated sheet or coils into an alpha helix
65
describe the tertiary structure of a protein
the secondary structure is furhter bent and folded to form a precise 3D shape bonds that hold it: - hydrophobic and philic interactions - more hydrogen bonds - ionic bonds (- & + charged r groups) - disulfide bonds (covalent between cysteine)
66
name three globular proteins
haemoglobin, insulin and amylase
66
describe the quaternary structure
proteins made from more than one polypeptide chain held together by bonds
67
describe haemoglobins structure
- it is made of four polypeptide chains - it is a conjugated protein as it has a non-protein group attached, called the prosthetic group - each of the 4 chains has a prosthetic group called haem - a haem group contains iron, which oxygen binds to
68
what are globular proteins
- polypeptide chains rolled into spherical shape - soluble - metabolic functions - eg enzymes, antibodies, hormones
69
name three fibrous proteins
collagen, keratin and elastin
70
what are fibrous proteins
- long parallel polypeptide chains - cross linkages forming long fibres/sheets - insoluble - have many structural roles
71
where is collagen found
skin tendons, cartilage, bones and teeth
72
where is keratin found
found in hairs, skin and nails, has high proportion of cysteine

OCR Biology (19 decks)

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