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module two biology > biological molecules > Flashcards

biological molecules Flashcards

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1
Q

what elements are found in carbohydrates?

A

carbon, hydrogen and oxygen (CHO)

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2
Q

what elements are found in lipids?

A

carbon, hydrogen and oxygen (CHO)

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3
Q

what elements are found in proteins?

A

carbon hydrogen oxygen nitrogen and sulphur (CHONS)

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4
Q

what elements are found in nucleic acids?

A

carbon hydrogen oxygen nitrogen and phosphorus (CHONP)

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5
Q

why is water polar?

A

• it has an unevenly distributed charge

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6
Q

how do hydrogen bonds form in water molecules?

A

• they form in between the oxygen and hydrogen atoms as the positive and negative regions interact with each other.
• they are individually weak but collectively strong

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7
Q

what are the four main properties of water?

A

• solvent
• transport medium
• coolant
• habitat

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8
Q

describe water as a solvent

A

• water is polar so polar molecules dissolve in water
• the slight positive charge on hydrogen atoms attracts negative ions and the slight positive charge in oxygen atoms will attract positive ions in solutes - this allows them to dissolve completely into water

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9
Q

why is it useful water is a solvent?

A

• ions can dissolve into the water in blood and then be transported around the body.

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10
Q

describe water as a transport medium

A

• as polar substances dissolve they are easily transported in water around animals and plants in blood or the xylem in plants
• water is cohesive so water molecules stick together due to the hydrogen bonds

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11
Q

why is water useful as a transport medium?

A

• due to cohesion water can easily be transported around plants in the transpiration stream as a continuous column, as it would be difficult to do this with individual molecules.

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12
Q

describe water as a coolant

A

• water has a high specific heat capacity which means a lot of energy is required to raise the temperature of water due to the energy required to break the hydrogen bonds
• this means temperatures remain relatively constant
• water has a large latent heat of evaporation which is the energy required to change stage

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13
Q

why is it useful that water is a coolant?

A

• the high specific heat capacity means that enzymes do not denature or reduce activity due to temperature fluctuations
• a lot of energy is released when you sweat due to the high latent heat

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14
Q

describe water as a habitat

A

• water buffers temperature
• cohesion provides surface tension to water
• ice is less dense than liquid water due to the hydrogen bonds forming a lattice

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15
Q

why is water as a habitat useful?

A

• the buffer quality provides a stable environment for organisms
• the surface tension provided by cohesion means that invertebrates can live on the surface keeping them away from predators
• as ice is less dense as a liquid, ice floats which acts as a habitat and provides an insulating layer

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16
Q

what is a monomer?

A

• small units which can create larger molecules

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17
Q

what is a polymer?

A

• made from lots of monomers bonded together

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18
Q

what are the polymers of the monomer glucose?

A

• starch
• cellulose
• glycogen

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19
Q

what are some examples of monomers?

A

• glucose
• amino acids
• nucleotides

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20
Q

what is the polymer of amino acids?

A

• protein

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21
Q

what are the polymers of nucleotides?

A

DNA and RNA

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22
Q

what is the formula for glucose?

A

C6H12O6

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23
Q

what is an isomer?

A

• a molecule with the same molecular formula but a different structure
• e.g alpha and beta glucose

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24
Q

describe disaccharides

A

• made of two monosaccharides
• joined together by a glycosidic bond
• formed via a condensation reaction

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25
Q

glucose + glucose =

A

maltose + water

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26
Q

glucose + galactose =

A

lactose + water

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27
Q

glucose + fructose =

A

sucrose + water

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28
Q

describe a condensation reaction

A

• two molecules being joined together by removing water

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29
Q

describe a hydrolysis reaction

A

• splitting apart two molecules through the addition of water

30
Q

describe amylose

A

• made from alpha glucose
• 1-4 bonds
• store of glucose in plant cells e.g chloroplasts
• an unbranched helix structure which is compact allowing a lot of glucose to fit into a small space
• insoluble meaning it won’t effect water potential

31
Q

describe amylopectin

A

• made from alpha glucose
• 1-4 and 1-6 bonds
• store of glucose in plant cells
• has a branched structure which increases the surface area allowing rapid hydrolysis back to glucose when needed
• insoluble which means it won’t effect water potential

32
Q

what polymers make up starch?

A

• amylose
• amylopectin

33
Q

describe cellulose

A

• made from beta glucose
• 1-4 glycosidic bonds
• provides structural strength for cell walls in plants
• forms long straight chains held in parallel to many hydrogen bonds forming fibrils
• many hydrogen bonds form collective strength
• insoluble which means it won’t effect water potential

34
Q

describe glycogen

A

• made from alpha glucose
• 1-4 and 1-6 glycosidic bonds
• store of glucose in animals e.g muscle and liver cells
• highly branched which increases surface area for rapid hydrolysis back into glucose when needed
• insoluble meaning it won’t effect water potential

35
Q

describe lipids

A

• macromolecules (not polymers)
• non-polar molecules
• insoluble in water
• dissolve in organic solvents such as ethanol
• hydrophobic
• made from fatty acids and glycerol

36
Q

describe the structure of triglycerides

A

• one glycerol attached to three fatty acids

37
Q

describe the structure of phospholipids

A

• one glycerol attached to two fatty acids and a phosphate group

38
Q

how are triglycerides formed,

A

• via a condensation reaction between one glycerol molecule and three molecules of fatty acids.
• this forms three ester bonds and three water molecules

39
Q

what is an r group?

A

• a fatty acid
• can be saturated or unsaturated

40
Q

what is the difference between saturated and unsaturated fatty acids/r groups

A

• saturated fatty acids have only single bonds between carbons
• unsaturated fatty acids contain at least one double bond between carbons forming a kink

41
Q

what are the four properties of triglycerides?

A

• can transfer energy
• insoluble
• low in mass
• metabolic water source

42
Q

describe triglycerides energy transferring property

A

• due to the large ratio of energy storing carbon-hydrogen bonds compared to the number of carbon atoms a lot of energy can be transferred when it is broken down

43
Q

describe triglycerides metabolic water source property

A

• due to the high ratio of hydrogen to oxygen atoms they can act as a water source as when they are oxidised they can release water
• this is essential for animals in the desert such as camels

44
Q

why is it useful that triglycerides are low in mass?

A

• a lot can be stored in an animal without it increasing the mass and preventing movement

45
Q

what are the properties of phospholipids?

A

• it has a hydrophilic head which can attract water as it is charged
• a hydrophobic tail which repels water but can mix with fats
• polar as they have two charged regions
• in water they position themselves so the heads are exposed to water but their tails are not which forms the phospholipids bilayer

46
Q

describe cholesterol

A

• a sterol meaning it has four carbon rings and a hydroxyl group at one end
• they have hydrophobic and hydrophilic regions
• embedded within cell membranes to impact fluidity
• help reduce the fluidity of membranes at high temperatures and increase fluidity at low temperatures

47
Q

what are proteins made up of?

A
  • one or more polypeptides
48
Q

where are polypeptide chains made?

A

• at the ribosome

49
Q

describe the primary structure of a protein

A

• the order of amino acids in the polypeptide chain ( a polymer )
• must include sequence/order - you cannot just say a chain of amino acids

50
Q

describe the secondary structure of proteins

A

• the sequence of amino acids causes parts of a protein molecule to bend into alpha helixes or beta pleated sheets
• held by hydrogen bonds

51
Q

describe the tertiary structure of a protein

A
  • the coiled or folded chain of amino acids is coiled and folded further
  • the tertiary structure is the final structure for proteins made from a single polypeptide chain
  • ionic bonds form between negative and positively charged r-groups on different parts of the molecule
  • disulphide bonds form whenever two molecules of the amino acid cystene come together
  • when hydrophobic groups are close together they clump together, and hydrophilic groups are pushed to the outside
  • hydrogen bonds form between polar r groups
52
Q

name a hexose and a penrose monosaccharide

A

hexose - glucose
pentose - ribose

53
Q

describe the quaternary structure of a protein

A
  • only available to proteins made up of more than one polypeptide chain e.g hemoglobin
  • contains all of the different types of bonds found in primary secondary and tertiary structures
54
Q

describe ionic bonds found in the tertiary and quaternary structures of proteins

A
  • attractions between negatively charged r-groups and positively charged r-groups on different parts of the molecule
55
Q

describe disulfide bonds found in the quaternary and tertiary structures of proteins

A
  • whenever two molecules of the amino acid cystene come together the sulphur atom in one cystene binds to the other, forming a disulphide bond
56
Q

describe hydrophobic and hydrophilic interactions in the quaternary and tertiary structures of proteins

A
  • when hydrophobic r groups are close together in the protein they tend to clump together
  • when hydrophilic r groups are close together in the protein they are more likely to be pushed to the outside which effects how the protein folds up into its final structure
57
Q

how is a dipeptide formed?

A
  • when two amino acids join together
58
Q

how is a polypeptide formed?

A
  • when more than two amino acids join together
59
Q

what is an amino acids general structure?

A
  • a carboxyl group and an amino group attached to a carbon atom
60
Q

what is the difference between different amino acids?

A
  • its R group
61
Q

how are amino acids joined together?

A
  • through peptide bonds - a molecule of water is released during condensation and a hydrolysis reaction which breaks a peptide bond adds a molecule of water
62
Q

describe globular proteins

A
  • round and compact proteins where hydrophilic R groups are pushed to the outside of the molecule due to hydrophobic and hydrophilic interactions
63
Q

what are the properties of globular proteins?

A
  • soluble - easily transported
64
Q

what are three examples of globular proteins?

A
  • hemoglobin
  • insulin
  • amylase
65
Q

describe hemoglobin

A
  • a globular protein that carries oxygen around the body in red blood cells
  • its known as a conjugated protein which means its a protein with a non - protein group attached to it (a prosthetic group).
  • each of the four polypeptide chains in hemoglobin has a prosthetic group called haem, this contains iron which oxygen binds to
66
Q

describe insulin

A
  • a globular protein
  • a hormone secreted from the pancreas which helps to regulate blood glucose levels
  • it is soluble, which is important as it needs to be transported around the body through the blood to act on tissues
  • it consists of two polypeptide chains which are held together by disulfide bonds
67
Q

describe amylase in terms of globular proteins

A
  • an enzyme that catalyses the breakdown of starch in the digestive system, it is made of a single chain of amino acids
  • its secondary structure contains both alpha helixes and beta pleated sheets
  • most enzymes are globular proteins
68
Q

describe fibrous proteins

A
  • insoluble and strong proteins which are structural and unreactive
69
Q

what are the three examples of fibrous proteins?

A
  • collagen
  • keratin
  • elastin
70
Q

describe collagen

A
  • a fibrous protein
  • found in animal connective tissues such as bone, skin and muscle. its a very strong molecule which minerals can bind to in order to increase its rigidity - e.g. bone
71
Q

describe keratin

A
  • a fibrous protein
  • found in many of the external structures of animals such as skin, hair nails, feathers and horns.
  • it can either be flexible (in hair and skin) or tough (in nails)
72
Q

describe elastin

A
  • a fibrous protein
  • found in elastic connective tissue such as skin, large blood vessels and some ligaments
  • it is elastic so allows tissues to return to their original shape after they have been stretched

module two biology (7 decks)

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