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biological molecules Flashcards

1
Q

what are the properties of water

A

“An excellent solvent – many substances can dissolve in water
A relatively high specific heat capacity
A relatively high latent heat of vaporisation
Water is less dense when a solid
Water has high surface tension and cohesion
It acts as a reagent”

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2
Q

why is water a good solvent

A

“As water is a polar molecule many ions (e.g. sodium chloride) and covalently bonded polar substances (e.g. glucose) will dissolve in it
This allows chemical reactions to occur within cells (as the dissolved solutes are more chemically reactive when they are free to move about)
“

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3
Q

why does water have a high specific heat capacity

A

The hydrogen bonds between the water molecules can absorb lots of energy. This means it doesn’t experience rapid temperature changes so its a good habitat.

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4
Q

advantages for water having a high specific heat capacity

A

“Provides suitablehabitats
Is able to maintain a constant temperature as water is able to absorb a lot of heat without big temperature fluctuations
This is vital in maintaining temperatures that are optimal for enzyme activity
Water in blood plasma is also vital in transferring heat around the body, helping to maintain a fairly constant temperature
“

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5
Q

why does water have a high specific latent heat

A

In order to change state (from liquid to gas) a large amount of thermal energy must be absorbed by water to break the hydrogen bonds and evaporate

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6
Q

advantages for water having a high specific latent heat

A

“This is an advantage for living organisms as only a little water is required to evaporate for the organism to lose a great amount of heat
This provides a cooling effect for living organisms, for example the transpiration from leaves or evaporation of water in sweat on the skin”

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7
Q

“why is water very cohesive and advantages 


“

A

It has hydrogen bonds between the molecules so the molecules of water stick together. This helps water to flow making it great for transporting substance in animals and allows columns of water to move through the xylem of plants.

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8
Q

“why is water adhesive and advantage


“

A

Its able to form hydrogen bonds with other molecules which allows water to move up the xylem during transpiration

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9
Q

why is ice less dense then water and state the advantage of this

A

The water molecules in ice are further apart so is less dense so it floats on water. This is useful for living organisms because in cold weathers ice can form an insulating layer above water so the water below doesn’t freeze and living organism in the water don’t freeze and can still move around.

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10
Q

what are monomers

A

Monomers are the smaller units from which larger molecules are made

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11
Q

“what are polymers

“

A

Polymers are molecules made from a large number of monomers joined together in a chain

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12
Q

what is condensation reaction

A

A condensation reaction occurs when monomers combine together by covalent bonds to form polymers (polymerisation) or macromolecules (lipids) and water is removed

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13
Q

What is hydrolysis

A

“Hydrolysis means ‘lyse’ (to break) and ‘hydro’ (with water)
In the hydrolysis of polymers, covalent bonds are broken when water is added “

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14
Q

“What chemical elements make us biological molecules 
”

A

“C, H and O for carbohydrates
C, H and O for lipids
C, H, O, N and S for proteins 
C, H, O, N and P for nucleic acids “

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15
Q

Types of monosaccharides

A

glucose, fructose and galactose Ribose and Deoxyribose

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16
Q

3 type of Condensation reactions to form disaccharide’s and what bond forms and how

A

“Alpha glucose + alpha glucose —> maltose
Alpha glucose + fructose —> starch
Glucose + galactose —> lactose
Glycosidic bond forms as a hydrogen atom from one monosaccharide bonds to a hydroxyl group of another monosaccharide releasing a molecule of water
“

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17
Q

What is starch

A

The main energy storage for plants and is a mixture of two polysaccharides of alpha glucose: amylose and amylopectin

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18
Q

Structure of amylose

A

“10 - 30% of starch
Long unbranched chain of alpha glucose which form 1-4 glycosidic bonds
Coiled structure which makes it compact to store lots of glucose in a small space
Long term storage”

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19
Q

Structure of amylopectin

A

“70 - 90% of starch
Long branched chain of alpha glucose which forms 1-4 and 1-6 glycosidic bonds
It has side branches which means enzymes can break down the glycosidic bond more easily and release glucose quicker
Short term storage”

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20
Q

What is glycogen

A

The main energy storage material in animals and is a polysaccharide of alpha glucose

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21
Q

Structure of glycogen

A

“made up of alpha glucose
1-4 and 1-6 glycosidic bonds
Long and branched
Lots of side branches coming of it so enzymes can break down the glycosidic bond more easily and release glucose quicker
Its very compact so can store lots of glucose in a small space”

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22
Q

Structure of cellulose

A

“long unbranched straight chain of beta glucose forming 1-4 glycosidic bonds
Consecutive beta glucose molecules are rotated 180 degrees to each other
Contain hydrogen bonds which form strong fibres called microfibrils which provides structural support for cells”

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23
Q

structure of a triglyceride

A

“1 glycerol and 3 fatty acids
Fatty acids has COOH and a R group (which is made up of carbon and hydrogen)
Glycerol is an alcohol that contain hydroxyl group
Fatty acid is hydrophobic and non polar so it is not soluble in water “

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24
Q

“structure of phospholipids



“

A

“1 phosphate group (PO43-) and a glycerol and 2 fatty acid
Phosphate group is polar and hydrophilic and is the head and the fatty acids are hydrophobic and are the tail.
They form a double layer with the heads facing out towards water. The centre is hydrophobic so water soluble substances can’t easily pass through it so acts as a barrier to those substances”

25
Q

how do triglycerides form

A

“

By esterification which is when an ester bonds from between the carboxyl group of the fatty acid and the hydroxyl group of the glycerol. It’s a condensation reaction and three molecules of water are formed “

26
Q

what are saturated/unsaturated fatty acids

A

Saturated- contains only single bonds. Straight chain molecules. High melting point Unsaturated- contains carbon carbon double bonds. Its kinked. Lower melting point

27
Q

“why are triglycerides good for energy storage

“

A

“The long hydrocarbon chain in the fatty acid contains lots of chemical energy so a lot of energy is released when they are broken down. So triglycerides store more energy per gram then carbohydrates and proteins
They are insoluble so don’t effect water potential
The triglycerides bundle together as insoluble droplets as the fatty acids are hydrophobic “

28
Q

function of cholesterol

A

Cholesterol has a small size so can fit in between phospholipid molecules in the membrane and bind to the hydrophobic tail causing them to pack more closely together which helps make the membrane less fluid and more rigid

29
Q

structure of amino acids

A

“An amine group -NH2
A carboxylic acid group -COOH

A hydrogen atom
An R group “

30
Q

How do peptide bonds form

A

“to form a peptide bond a hydroxyl (-OH) is lost from the carboxylic group of one amino acid and a hydrogen atom is lost from the amine group of another amino acid
The remaining carbon atom (with the double-bonded oxygen) from the first amino acid bonds to the nitrogen atom of the second amino acid
This is a condensation reaction so water is released “

31
Q

what is the primary structure of a protein

A

The sequence of amino acids bonded by peptide bonds

32
Q

what is the secondary structure of a protein

A

“The secondary structure of a protein occurs when the weak negatively charged nitrogen and oxygen atoms interact with the weak positively charged hydrogen atoms to form hydrogen bonds
There are two shapes that can form within proteins due to the hydrogen bonds:
α-helix - coiled
β-pleated sheet - folded”

33
Q

what is the tertiary structure of a protein

A

“The coil or folded chain of amino acids is coiled and folded further which forms more bonds
Hydrogen bonds (these are between R groups)
Disulphide (only occurs between cysteine amino acids)
Ionic (occurs between charged R groups)
Weak hydrophobic interactions (between non-polar R groups)
For single polypeptide chains this is the final 3D structure”

34
Q

What is the quaternary structure of a protein

A

“When several types of polypeptides bonds are joined together by bonds. Each polypeptide chain in the quaternary structure is
referred to as a subunit of the protein
For proteins made up of more then one polypeptide chain this is the final 3D structure”

35
Q

what is the shape of globular proteins and its functions

A

“compact and spherical in shape
Hydrophilic R group is pushed outside of the molecule due to hydrophobic and hydrophilic interaction in the tertiary structure
This makes the soluble so easily transported in fluids
Has a tertiary and quaternary structure
Involved in biological processes”

36
Q

Structure and function of haemoglobin

A

“Transports oxygen around the body in red blood cells.
Its a conjugated protein and has a quaternary structure
Has four polypeptide chain made up of 2 alpha and 2 glucose subunit
Each of the 4 chains has a prothetic haem group which contain iron which binds to oxygen
Its soluble so can be transported in the blood”

37
Q

structure and function of insulin

A

“its a hormone secreted by the pancreas which helps regulates the blood glucose level.
Its soluble so can be transported n the blood to the tissues where it acts
Consists of 2 polypeptide chains which are held together by disulphide bonds “

38
Q

Structure and function of amylase

A

“an enzyme that breaks down starch in the digestive system
Made up of a single chain of amino acids
Contain both alpha and beta glucose “

39
Q

function of catalase

A

Hydrogen peroxide is produced as a byproduct of many metabolic reactions and its harmful to cells so catalase converts hydrogen peroxide into water and oxygen which prevents any damage to cells or tissue

40
Q

What are conjugated proteins

A

Type of globular proteins which have a non-protein group attached called a prosthetic group

41
Q

fibrous proteins shape and functions

A

“insoluble ands long stands
Little or no tertiary structure
Unreactive
For structural purpose”

42
Q

What is collagen

A

A fibrous protein which is flexible and strong and provides support. It is found in animal connective tissues such as bone, skin and muscle

43
Q

What’s keratin

A

“Keratin makes up hair, nails, horns and feathers (it is a very tough fibrous protein)
It can either be flexible like hair or tough and strong like nails “

44
Q

What’s elastin

A

Found in elastic connective tissue like tendons, skin and ligaments and large blood vessels. Its elastic so allows tissues to return to their original shape after they have been stretched

45
Q

what are calcium ions necessary for

A

Nerve impulse transmission and muscle contractions

46
Q

what are sodium ions necessary for

A

Nerve impulse transmission and kidney function

47
Q

“what are potassium ions necessary for

“

A

Nerve impulse transmission and stomatal opening

48
Q

what are hydrogen ions necessary for

A

Catalysis of reaction and pH determination

49
Q

what are ammonium ions necessary for

A

Production of nitrate ions by bacteria

50
Q

what are nitrate ions necessary for

A

Nitrogen supply to plants for amino acid and protein formation

51
Q

what are hydrogen carbonate ions necessary for

A

Maintenance of blood pH

52
Q

what are chloride ions necessary for

A

Balance positive charge of sodium and potassium ions in cells

53
Q

what are phosphate ions necessary for

A

Cell membrane formation and nucleic acid and ATP formation and bone formation

54
Q

what are hydroxide ions necessary for

A

Catalysis of reaction and pH determination

55
Q

“how to test for proteins

“

A

“Biuret test
Add a few drops of sodium hydroxide solution to make it alkali then add some cooper (II) sulfate solution. If proteins is present the solution will turn purple but if there’s no protein present the solution stays blue “

56
Q

“how to test for reducing sugars

“

A

“Benedict’s test
Add Benedict’s reagent to the sample and heat it in a water bath. If a reducing sugar is present it will form a coloured precipitate with a colour scale from blue to green, yellow, orange and brick-red. This is because the reducing sugar reduces copper (II) sulfate to copper (I) oxide which is insoluble in water. “

57
Q

“how to test for non-reducing sugars

“

A

“Add dilute hydrochloric acid and heat in a water bath and then neutralise with sodium hydrogen carbonate and then carry out the Benedict’s test
“

58
Q

“how to test for starch


“

A

Add a few drops of iodine and if starch is present it will turn from a orange colour to a blue/black colour

59
Q

“how to test for lipids


“

A

Shake the test tube with ethanol and then pour the solution into water. If lipids are present it will turn the solution milky

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