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A A A Level Biology > the final battle part 2 > Flashcards

the final battle part 2 Flashcards

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1
Q

what kind of reaction forms a glycosidic bond

A

condesation between carbon 1-4

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2
Q

what breaks a glycosidic bond

A

hydrolysis

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3
Q

which two monosaccharides make lactose

A

galactose and B glucose

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4
Q

which two monosaccharides make sucrose

A

fructose and glucose

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5
Q

describe the bonding in amylose

A

alpha glucose molecules joined by 1-4 glycosidic bonds

the angle of these bonds means it is a long chain of glucose which twists into a helix

these are further stabilised by hydrogen bonding within the molecule

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6
Q

why does the bonding of amylose aid its function

A

its function is as a storage molecule in plants

the straight chain with no kinks means it is more compact and takes up less space in the plant and is also
less soluble

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7
Q

describe the bonding of amylopectin

A

glycosidic bonds between carbon 1-4 with alpha glucose BUT ALSO
some glycosidic bonds between carbon 1-6 between two glucose every 25 subunits

this gives it a branched structure so takes up more space than amylose

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8
Q

what is the function of amylopactin

A

another energy source in plants

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9
Q

describe the structure of glycogen

A

animal/fungi equivalent to starch

more branched but is compact and takes up less space so is an ideal storage molecule

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10
Q

how does glycogens structure make it an ideal storage molecule

A

branched mean there are free ends for glucose molecules to be added or removed

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11
Q

describe the structure of cellulose

A

made up of beta glucose monosaccharides
which cant join in same way as alpha as hydroxyl groups on carbon 1-4 too far apart to interact so…..
beta glucose molecules are inverted.

This means Bglucose polysaccharides like cellulose can’t coil or form branches so forms a straight chain molecule

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12
Q

what forms when cellulose molecules make hydrogen bonds with each other

A

forms microfibrils»»>which join to make macrofibrils

macrofibrils make fibres which are STRONG INSOLUBLE and used to make CELL WALLS

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13
Q

are lipids soluble

A

no they are non-polar molecules

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14
Q

what are triglycerides made up of

A

1 glycerol + 3 fatty acids

glyceride is an alcohol
fatty acids belong to carboxylic acids -COOH

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15
Q

what kind of reaction forms triglycerides

A

esterfication reaction which forms an ester bond which forms 3 water molecules

hydroxyl group between glycerol and fatty acid interacts

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16
Q

what is a saturated fatty acid

A

no double bonds and maximum number of bonds with hydrogen atoms

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17
Q

what is an unsaturated fatty acid

A

double bonds
if 1 double bond = monounsaturated
more than 1 is polyunsaturated

double bond causes kink so cant pack densely
this is usually liquid at room temp like oil

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18
Q

what is the structure of phospholipids

A

made up of inorganic phosphate head PO4 3-
two fatty acid tails
one of the fatty acids from a triglyceride molecule is replaced with a phosphate group to make a phospholipid

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19
Q

properties of phospholipids

A

they are surfacants (form layer if on top of water)

they make up membranes in a bilayer structure and separate an aqueous environment in the cells

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20
Q

what are sterols/ steroid alcohols

A

a lipid but not fats or oils
-they are complex alcohols w/ 4 carbon ring structure with a hydroxyl OH group at one end which is hydrophillic, polar and soluble

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21
Q

what is an example of an important sterol

A

choleSTEROL made in liver and intestines
important as its positioned between phospholipids w/ hydroxyl group at periphery of membrane

it maintains membranes stability and fluidity

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22
Q

what is the role of lipids

A 
> membrane formation and creation of hydrophobic barriers
>hormone production
>electrical insulation eg) myelin
>waterproofing
>cushion vital organs
>buoyancy in whales
>thermal insulation in penguins
>long term energy storage (triglycerides)
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23
Q

how do amino acids join

A

when the amine group and carboxylic acid groups connected to central carbon react. (R groups not involved at this point)
>hydroxyl from the carboxyl acid group of one amino acid reacts with a hydrogen from the amine group of another amino acid to form a PEPTIDE BOND.
> water is produced too in this condensation reaction

This compound result is called a DIPEPTIDE

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24
Q

how is a polypeptide formed and which enzyme catalyses this

A

when many amino acids are joined by peptide bonds

catalysed by peptidyl transferase present in ribosomes (the site of protein synthesis)

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25
Q

what is the primary structure of a protein

A

the sequence in which amino acids are joined
which is caused by information carried in DNA

this influences how polypeptides fold
only bonds involved are PEPTIDE BONDS

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26
Q

what is the secondary structure of a protein

A

> hydrogen bonding which may form an alpha helix or beta pleated sheet

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27
Q

what is the tertiary structure of a protein

A

folding of a protein into its final shape
>can include sections of its secondary structure as coiling or folding of sections of proteins into their secondary structures brings R groups of different amino acids close enough to react so further foldig of these sections occurs.
These can be:
-HYDROPHOBIC/HYDROPHILLIC INTERACTIONS-weak interactions between polar and non-polar R groups
-HYDROGEN BONDS- weakest of bonds formed
-IONIC BONDS- stronger than H bonds and form between oppositely charged R groups
-DISULFIDE BONDS/BRIDGES - Strongest and Covalentbut only between R groups with sulfur atoms in

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28
Q

what is the quaternary structure of a protein

A
  • association between 2 or more individual proteins or subunits (can be identical or different)
  • similar interactions to tertiary structure but are between different protein molecules rather than within one molecule.

enzymes have 2 identical subunits
hormones like insulin have 2 different subunits
haemoglobin has 4 subunits with 2 sets of identical subunits

29
Q

example of a globular protein

A

insulin

30
Q

example of a conjugated protein

A

haemoglobin

catalase

31
Q

example of a fibrous protein

A

keratin
collagen
elastin

32
Q

what is the structure and properties of a globular protein like

A
  • compact and water soluble
  • form when tertiary structures folding in a way so hydrophobic R grous on amino acids are on the outside of the protein. (making them soluble)

this aids in their function as insulin needs to be dissolved into the bloodstream
-insulin needs to keep its precise shape too to fit into specific receptors on cell surface membranes.

33
Q

what is the structure of a conjugated protein

A

> globular proteins BUT they contain a non-protein prosthetic group. (proteins without this group are called simple proteins)
different types of prosthetic groups:
lipids/carbohydrates combine with proteins so make
glycoproteins or lipoproteins
also metal ions derived from vitamins can form prosthetic groups like Fe2+

34
Q

describe the structure of haemoglobin

A

> made from 4 polypeptides with 2 alpha and 2 beta subunits
each subunit contains a prosthetic haem group
the Fe2+ ions can combine reversibly with oxygen

35
Q

describe the structure of fibrous proteins

A

> long insoluble molecules due to high proportion of amino acids with hydrophobic R groups in primary structure
quite repetitive amino acid with limited range of A.As
which leads to organised structures which are NOT folded into comlex 3D shapes like globular proteins

36
Q

describe the properties and function of keratin

A

> hair skin and nails
hair has fewer bonds making it more flexible than nails
(bonds being strong disulfide bonds)

37
Q

describe the properties and function of elastin

A

> fibres that are present in walls of blood vessels and alveoli of lungs
structures give them flexibility to expand when needed
but also return to their normal size
quaternary protein made of many stretchy molecules of tropoelastin

38
Q

describe the properties and function of collagen

A

> connective tissue found in skin, tendons, ligaments and nervous system
made up of 3 polypeptides wound together in a long rope like structure
this makes it flexible

39
Q

use of calcium ions in body Ca2+

A

nerve impulse transmission

muscle contraction

40
Q

use of sodium ions Na+

A

nerve impulse transmission

kidney function

41
Q

use of potassium ions K+

A

nerve impulse transmission

stomatal opening

42
Q

use of hydrogen ions H+

A

catalysis of reactions

pH determination

43
Q

use of ammonium ions NH4+

A

production of nitrate ions by bacteria

44
Q

use of nitrate ions NO3-

A

nitrogen supply to plant for amino acid and protein formation

45
Q

use of hydrogen carbonate ion HCO 3-

A

maintainance of blood pH

46
Q

use of chloride ions Cl-

A

balance positive charge of sodium and potassium ions in cells

47
Q

use of phosphate ions PO4 3-

A

cell membrane formation
nucleic acid and ATP formation
bone formation

48
Q

use of hydroxide ions OH-

A

catalysis of reaction

pH determination

49
Q

how are nucleotides joined

A

joined by condensation reactions to form a polynucleotide
-phoshphate joined on 5C of pentose sugar forms a covalent bond with hydroxyl group on 3C of pentose sugar on adjacent nucelotide
THESE ARE CALLED PHOSPHODIESTER BONDS whch form sugar phosphate backbone and are proken by hydroglysis

50
Q

what holds the two strands of the double helix together

A

hydrogen bonds between bases

these 2 parallel strands run in opposite directions and so are antiparallel
each strand in one chain of polynucleotides which coil into a double helix

51
Q

what does complementary base pairng ensure

A

-reduces occurance of mutation
-minimise errors in replication
-allows DNA to be copied and transcribed
T with A and C with G
-allows reformation of hydrogen bonds
-conserving genetic information so it is passed onto next generation with accuracy

52
Q

which enzyme forms phosphodiester bonds

A

DNA ligase

53
Q

describe the structure of ATP

A

-nitrogenous base adenine, pentose sugar and 3 phosphates

54
Q

difference between structure of atp and dna

A

3 phosphate groups

nitrogenous base always adenine

55
Q

properties of ATP and way it acts

A

not long term energy store due to instability of phosphate bonds
formed in phosphorylation reaction (condensation)
good immediate energy store as is rapidly reformed

hydrolysed into ADP and Pi

56
Q

structure of ADP compared to ATP

A

2 phosphates in ADP adenosine DIphosphate

57
Q

why is DNA replication semi conservative

A

consists of one old conserved strand and one newly synthesised strand
origional strand acts as template for new strand

58
Q

what does semi conservative replication ensure?

A

ensure genetic continuity between generations of cells meaning genetic information is passed from one generation to the next

59
Q

what is the role of helicase

A

DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.

60
Q

what is the role of DNA polymerase

A

DNA polymerases are responsible for synthesizing DNA: they add nucleotides one by one to the growing DNA chain, incorporating only those that are complementary to the template.

61
Q

20 different amino acids are commonly used for protein synthesis. in this theory we would only need 20 different base combinations
explain the use of the remaining 44 combinations

A

several triplets/ codons code for 1 amino acid
some codons are used as stop/start

mutations can be silent or not change amino acid

62
Q

whtat does it mean that the genetic code is degenrate

A

because a single amino acid may be coded for by more than one codon.

63
Q

what does it mean that the genetic code is non-overlapping

A

genetic code does not overlap, meaning that each nucleotide is part of only one codon-a single nucleotide cannot be part of two adjacent codons.

64
Q

describe how a nucleotide base sequence in a gene is used to synthesise a polypeptide
(transcription and translation)

A

> DNA/Gene transcribed into mRNA
RNA nucleotides line up with complementary base pairs A-U and C-G on template DNA strand
catalysed by RNA polymerase

translation - where mRNA leaves nucleus to ribosomes
>tRNA molecules bind to mRNA
>anticodons bind to codons
>specific amino acid is attached to tRNA
>there is a formation of a PEPTIDE bond between amino acids (not polypeptide)

65
Q

what is the role of RNA polymerase

A

RNA polymerase is an enzyme that is responsible for copying a DNA sequence into an RNA sequence in transcription

66
Q

what is the role of mRNA

A 
short section of DNA transcribed into messenger RNA which is able to leave the nucleus to be translated at ribosomes
ribonucleic acid (not deoxyribose)
67
Q

what is the role of tRNA

A

involved in translation of mRNA and has anticodon complementary to codon

68
Q

what is the role of rRNA

A

rRNA is in protein synthesis – in binding to messenger RNA and transfer RNA to ensure that the codon sequence of the mRNA is translated accurately into amino acid sequence in proteins.

A A A Level Biology (22 decks)

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