Macromolecules Flashcards

1
Q

Roles of sugars and polysaccharides

A

Food molecules and energy store
Structural support
cell protection
cell-cell adhesion and motility
cell signalling

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2
Q

What are D isomers

A

straight chain polyhydroxy alcohols (linear form of cyclic sugars)
either an aldehyde or ketone group
at least three carbon units

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3
Q

What are the two glucose enantiomers

A

alpha and beta glucose

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4
Q

How do the two glucose enantiomers differ, which one is more stable

A

alpha glucose = OH group pointing down
beta glucose = OH group pointing up

beta is more stable as OH groups are further apart in the molecule

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5
Q

What are the polymers of the glucose enantiomers

A

alpha = starch and glycogen
beta = cellulose and chitin

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6
Q

How are sugars linked

A

condensation reaction, removing water forming a 1,4 glycosidic bond

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7
Q

What is the reducing end

A

the end that is free to become linearised

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8
Q

Glycogen

A

highly branched glucose polysaccharide
branching increases the number of ends available to be digested for rapid release of glucose

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9
Q

Structure of a ribosome

A

RNA and protein
active site of ribosome is RNA which is the catalyst for protein synthesis
ribozyme - extra OH on ribose

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10
Q

Structure of a ribosome

A

RNA and protein
active site of ribosome is RNA which is the catalyst for protein synthesis
ribozyme - extra OH on ribose

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11
Q

What is DNA and RNA used for

A

DNA = store of genes
RNA = gene expression

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12
Q

What bonds form when nucleotides are polymerised

A

phosphodiester

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13
Q

What type of pentose is deoxyribose and where is it deoxy at

A

Aldopentose
deoxy at the 2 position

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14
Q

How many hydrogen bonds between A and T, C and G

A

A and T = 2
C and G = 3

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15
Q

What are purine and pyrimidine bases

A

Purine = A and G, two rings
Pyrimidine = T, U, C, one ring

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16
Q

Why does a purine and pyrimidine always complementary base pair

A

keeps the sugar phosphate backbone the same distance apart all the way along the DNA strand

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17
Q

what is a nucleoside

A

ribose and base

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17
Q

what is a nucleoside

A

ribose and base

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18
Q

Which complementary base pair requires less energy to break

A

A and T as there is only two hydrogen bonds between them

18
Q

Which complementary base pair requires less energy to break

A

A and T as there is only two hydrogen bonds between them

18
Q

Which complementary base pair requires less energy to break

A

A and T as there is only two hydrogen bonds between them

18
Q

Which complementary base pair requires less energy to break

A

A and T as there is only two hydrogen bonds between them

19
Q

Levels of protein structure

A

Primary = the order of amino acid residues in the chain
Secondary = localised regular arrangements of the polypeptide backbone to form alpha helices and beta sheets
Tertiary = overall three dimensional fold of the protein
Quaternary = arrangement of multiple amino acid chains

20
Q

Amino acids

A

Chiral carbon molecules
Carboxyl group
Amino group
Hydrogen
R group

Only amino acid that is not chiral = glycine

21
Q

How do amino acids differ

A

Chemical groups within side chains

22
Q

Hydrophobic

A

Water hating
Large and non polar R groups
Cluster away from water in the core of the protein or at interaction interfaces

23
Q

What are the hydrophobic Amino acids

A

Alanine
Valine
Leucine
Isoleucine
Glycine
Cysteine
Phenylalanine
Tryptophan
Proline

24
Q

Which two hydrophobic amino acids contain sulphur

A

Cysteine
Methionine

25
Q

What amino acid can form disulphide bonds and how

A

Cysteine
In an oxidising environment so not in cells as this is reducing

26
Q

Hydrophilic

A

Water loving
Forms hydrogen bonds with water
Can be uncharged but polar, negatively charged, positively charged

27
Q

What are the negatively charged amino acids

A

Aspartic acid
Glutamic acid
(Both carboxylic acids)

28
Q

What are the positively charged amino acids

A

Lysine (primary amine)
Arginine
Histidine

29
Q

What are the uncharged polar amino acids

A

Serine
Threonine
Tyrosine
(Hydroxyl groups)
Asparagine
Glutamine

30
Q

Peptide bond

A

Condensation reaction removing water as the amino and carboxyl groups are joined together forming a linear peptide

31
Q

How are proteins numbered

A

From the N terminus to the C terminus
Residue 1 has a free NH3 +

32
Q

What are the side chains of the polypeptide

A

The R groups

33
Q

What structure is a peptide bond

A

Planar - no rotation
(All in one plane)

34
Q

Why can the peptide bond flick between single and double bonded

A

Delocalisation of electrons from the nitrogen onto the single C-N gives it a partial double bond characteristics
Restricts rotational movement of the polypeptide chain around that bond

35
Q

How is the confirmation of the backbone describe by

A

Torsion angles

36
Q

What are the angles of rotation

A

Phi = angle around alpha carbon and nitrogen
Psi = angle around alpha carbon and carbon

37
Q

How does folding of the polypeptide chain occur

A

Rotation of the phi and psi angles for each residue
Rotation around alpha carbon is not completely free as many combinations of phi and psi angles cause steric clashes of side chains

38
Q

Disaccharides

A

Maltose = alpha glucose and alpha glucose
Sucrose = alpha glucose and alpha fructose
Lactose = alpha glucose and beta galactose
Lactulose = beta galactose and beta fructose

39
Q

Consequences of breaching in starch and glycogen

A

Starch is more densely packed
More exposed end units for access by glycogen synthase/phosphorylase

40
Q

How can C be converted to U

A

Spontaneous deamination

41
Q

Why is DNA double stranded

A

Provide copying mechanism
Enable repair of damaged bases
Stabilise with hydrogen bonds

42
Q

Why is RNA single stranded

A

Allow protein synthesis
Allow internal hydrogen bonding
Allow binding to proteins as well as other RNAs

43
Q

Ramachandran plot shows

A

Most optimal phi and psi angles to avoid steric clashes