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Biology (Kaycie) > M2C3 - Biological Molecules > Flashcards

M2C3 - Biological Molecules Flashcards

Biological Molecules

1
Q

What are carbohydrates made from?

A

Carbon, hydrogen and oxygen atoms.

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2
Q

Functions of carbohydrates

A

Energy store, energy source and structural uses.

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3
Q

Monosaccharides

A

Simplest carbohydrate. Larger carbohydrates can be made by joining them together.

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4
Q

Examples of monosaccharides

A

Glucose, Fructose, Ribose

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5
Q

Disaccharides

A

Carbohydrates made by joining two monosaccharide units. They’re bonded by glycosidic bonds.

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6
Q

Examples of disaccharides

A

Sucrose (glucose + fructose)
Maltose (glucose + glucose)
Lactose (galactose + glucose)

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7
Q

Polysaccharides

A

Carbohydrates made from a large number of monosaccharide units. They’re bonded by glycosidic bonds.

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8
Q

Examples of polysaccharides

A

Starch, cellulose, glycogen.

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9
Q

Structure of Glucose

A

C6H12O6

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10
Q

Alpha and Beta glucose

A

Alpha - the hydrogen atom is above the carbon
Beta - the hydrogen atom is below the carbon

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11
Q

Starch

A

Starch is a polysaccharide made up of many alpha glucose molecules arranged into two different structural units:
Amylopectin
Amylose

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12
Q

Amylose

A

Straight chains of alpha-glucose molecules
Joined together by a 1-4 glycosidic bond
Forms a helix shape

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13
Q

Amylopectin

A

Branched chain of alpha-glucose molecules
Joined together by 1-4 and 1-6 glycosidic bonds

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14
Q

Starch

A

Starch is the major storage molecules in plants.
Stared as grains in chloroplasts,
Produced from glucose made during photosynthesis
Broken down during respiration to provide energy.

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15
Q

Structure of Glycogen

A

Glycogen has a similar structure to amylopectin. It contains even more alpha 1-6 glycosidic bonds that produce an even more branched structure.
It is stored as small granules.

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16
Q

Cellulose

A

Consists of long chains of beta-glucose molecules joined together by beta 1-4 glycosidic bonds.
Glucose chains form rope-like microfibrils, which are layered to form a network

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17
Q

Water

A

Water is a polar molecule with the formula H2O. A hydrogen bond forms between the slightly negative oxygen and slightly positive hydrogen atoms.

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18
Q

Properties of water

A

Excellent solvent
High latent heat of evaporation
High specific heat capacity.

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19
Q

Functions of lipids

A

Energy storage, insulation and protection, hormones and water storage.

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20
Q

Structure of a triglyceride

A

Glycerol and 3 fatty acids

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21
Q

Main roles of triglycerides

A

Energy store, insoluble in water.

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22
Q

Structure of phospholipids

A

Glycerol, 2 fatty acids and a phosphate head.

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23
Q

Main roles of phospholipids

A

Cell membrane, hydrophilic and hydrophobic regions

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24
Q

Features of phospholipids

A

Hydrophilic phosphate heads, and hydrophobic fatty acid tails enable the formation of a bilayer.
Centre of the bilayer is hydrophobic so polar molecules cannot pass through it.
Fatty acid tails can be saturated or unsaturated allowing organisms to control the fluidity of the membrane.

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25
Q

Structure of cholesterol

A

Four carbon based rings

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26
Q

Main roles of cholesterol

A

Small molecule that fits into the bi-layer giving strength and stability. Buffer for fluidity

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27
Q

What is a protein

A

Long chains of amino acids (monomers) joined together with peptide bonds

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28
Q

Uses for proteins

A

Structural uses, catalytic uses, signalling uses, immunological uses and carriers.

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29
Q

Structure of proteins

A

Amine group, R-group and carboxyl group.

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30
Q

Primary structure of proteins

A

Sequence of amino acids held together by peptide bonds

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31
Q

Secondary structure of proteins

A

Coiling or folding of amino acid chains due to the hydrogen bonding in between amino acids.

32
Q

Tertiary structure of proteins

A

Folding of the coils/pleats to form a complex 3D shape.

33
Q

What bonds are present in a tertiary structure

A

Disulphide bonds
Ionic bonds
Hydrogen bonds
Hydrophobic and hydrophilic interactions.

34
Q

Quaternary structure of proteins

A

Linking together of a number of polypeptide chins (e.g. haemoglobin)

35
Q

What reaction joins together amino acids

A

Condensation reaction.

36
Q

What are globular proteins?

A

Spherical shaped proteins caused by tightly folded polypeptide chains. Part of quaternary structure. The hydrophobic groups are on the inside and the hydrophilic groups on the outside.

37
Q

Examples of globular proteins

A

Transport proteins - haemoglobin
Enzymes - lipase, catalase and DNA polymerase
Hormones - insulin and oestrogen

38
Q

Insulin

A

Hormone secreted by the pancreas. Involved in regulating blood glucose levels. Quaternary structure consists of two polypeptide chains

39
Q

Haemoglobin

A

Made up of four polypeptide chains. Each chain is wrapped around a group of atoms called a haem group, which holds an iron Fe2+ ion in the centre. Each iron ion is able to bond with two oxygen atoms (one oxygen molecule)

40
Q

Catalase

A

Common enzyme found in nearly all living organism. Catalyses the decomposition of hydrogen peroxide to water and oxygen.

41
Q

Fibrous proteins

A

Parallel polypeptide chains held together by cross links. They form long, rope-like fibres with high tensile strength and are generally insoluble in water

42
Q

Examples of fibrous proteins

A

Collagen, Keratin, Elastin, Silk

43
Q

Collagen

A

Found in connective tissues. Consists of three helical polypeptide chains which twist around each other. One in every three amino acids is a glycerine. The strands are held together by hydrogen bonds, and collagen molecules can form covalent bonds with other parallel collagen molecules to form collagen fibrils.

44
Q

Keratin

A

Found in hair, skin and nails. Contains large proportions of cysteine, which contains sulphur so results in strong disulphide bonds forming.

45
Q

Elastin

A

Found in skin, blood vessels and the alveoli. Allows structures to return to their original shape and size after stretching (like an elastic band)

46
Q

What are the 5 different nucleotide bases

A

Adenine
Guanine
Thymine
Cytosine
Uracil

47
Q

Purine bases

A

Adenine and Guanine which are double carbon rings

48
Q

Pyrimidine bases

A

Thymine, cytosine and uracil which are single carbon rings

49
Q

How are nucleotides bonded

A

Linked together by a condensation reaction between the phosphate of one nucleotide and the sugar of another. This is known as a phosphodiester bond

50
Q

Double helix

A

Held together by hydrogen bonds. Each strand has a phosphate head group (5’) at one end and a hydroxyl group (3’) at the other. The two strands run antiparallel to eachother.

51
Q

DNA vs RNA

A

DNA: Deoxyribose, AT and GC, double stranded, polynucleotide, larger
RNA: RIbose, AU and GC, single stranded, polynucleotide, smaller

52
Q

Key stages of DNA replication

A

1) the double helix unwinds and the DNA ‘unzips’ as hydrogen bonds are broken between the polynucleotide chains.
2) complimentary base pairing occurs between free nucleotides and the exposed bases
3) as the free nucleotides are added, strong bonds form between the phosphate and the sugar groups to form the sugar phosphate backbone.

53
Q

What is the role of DNA Helicase

A

‘unzips’ the DNA

54
Q

What is the role of DNA Polymerase

A

Synthesises the new DNA strand by adding the nucleotides

55
Q

What is the issue with DNA Polymerase

A

It only goes 3 to 5, it cannot go 5 to 3. This is difficult for the antiparallel strand, causing fragments Okazaki fragments

56
Q

Transcription

A

RNA polymerase enzyme attaches to the double helix at the beginning of a gene - the hydrogen bonds between the 2 DNA strands break
Only one side of the DNA molecule is copied - this is the sense strand (template). The other uncopied side is the antisense strand (coding)
The RNA polymerase moves along the DNA adding complimentary mRNA nucleotides to the DNA bases to form a complimentary strand of mRNA

57
Q

Translation

A

mRNA moves out of the nucleus through a nuclear pore and attaches to a ribosome.
tRNA bring amino acids to the mRNA molecule, the order determined by the base codes.
The amino acids are joined with peptide bonds to form the primary structure of the polypeptide

58
Q

What is ATP?

A

Adenosine Triphosphate (ATP) is the universal energy carrier - it is the immediate source of energy for biological processes.

59
Q

Describe the test for starch

A

Add a few drops of iodine to the food. If the colour changed from brown to blue/black starch is present

60
Q

Describe the test for reducing sugars

A

Add Benedict’s solution and heat 80’C in a water bath. If red coloured precipitate forms then reducing sugars is present. The higher the concentration of colour, the higher the concentration of reducing sugars.

61
Q

Describe the test for non-reducing sugars

A

Follow the test for reducing sugars. Then boil with HCl. Cool and neutralise with sodium hydrogen carbonate solution, then repeat the Benedict’s test. The same outcome for reducing sugars test will be present

62
Q

Describe the test for a protein

A

Add Biuret reagent. If the colour changes from blue to lilac, proteins are present.

63
Q

Describe the test for a lipid

A

Add ethanol and shake. White emulsion layer will form near the top if lipids are present

64
Q
A
65
Q

How do you calculate the Rf value

A

distance from start to substance stop / distance from origin to solvent front.

66
Q

Calcium ions (Ca2+)

A

Involved in muscle contraction and nerve impulse transmission

67
Q

Sodium ions (Na+)

A

Involved in co-transport, reabsorption if water in the kidney and nerves impulse transmission

68
Q

Potassium ions (K+)

A

Involved in stomatal opening and nerve impulse transmission

69
Q

Hydrogen ions (H+)

A

Involved in chemiosmosis, pH determination and catalysis of reactions

70
Q

Ammonium ions (NH4+)

A

Involved in nitrogen cycle, where by bacteria convert ammonium ions into nitrate ions

71
Q

Nitrate (NO3-)

A

Mineral ion absorbed by plants to provide a source of nitrogen to make amino acids

72
Q

Hydrogencarbonate (HCO3-)

A

Maintains pH of blood

73
Q

Chloride (Cl-)

A

Provide a negative charge to balance to positive sodium ion and potassium ions in cells

74
Q

Phosphate (PO43-)

A

Involved in the formation of phospholipids for cell membranes, nuclei acid and ATP formation and making in bones

75
Q

Hydroxide (OH-)

A

Biology (Kaycie) (5 decks)

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