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Biology Y1 > Module 2 - Biological Molecules > Flashcards

Module 2 - Biological Molecules Flashcards

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1
Q

Name some fibrous proteins

A

Collagen
Keratin
Elastin

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2
Q

Name some globular proteins

A

Haemoglobin
Pepsin
Insulin

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3
Q

What are globular proteins?

A

They tend to roll into spherical shapes where hydrophobic R group are inside and hydrophilic groups are outside so they are soluble in water
They have specific shapes, making them good as hormones and enzymes

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4
Q

What are the features of collagen?

A 
Provide mechanical strength to: 
Artery walls, prevents bursting when high pressure blood is pumped
Tensions connecting muscles to bones 
Bones are made of collagen
Cartilage and connective tissue
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5
Q

What are the features of Keratin and Elastin?

A

Keratin:
Rich in cysteine so many disulfide bridges and hydrogen bonds for strength
Nails, hair, horns, fur
Impermeable so barrier to infections/ waterproof

Elastin:
Cross linking and coiling make it stronger
Stretch
Skin stretches and uses elastin to go back to original shape
Blood vessels to stretch

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6
Q

What are the features of haemoglobin

A

Quartinary structure made of four polypeptides: 2 alpha-globin chains and 2 beta-globin chains
Prosthetic group in each chain (haem group) containing iron ions
Is a conjugated protein
Iron ions react with oxygen to help carry it around the body

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7
Q

What are the two approaches regarding computer modelling of protein structures?

A

Ab initio protein modelling: model on physical and electrical properties of atoms within each amino acid

Comparative protein modelling: protein threading which scans the amino acid sequence against a database of solved structures and produces possible models that match it

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8
Q

What are cations?

A

Positive ions

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9
Q

What are anions?

A

Negative ions

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10
Q

Name some cations

A 
Calcium - Ca2+
Sodium - Na+
Potassium - K+
Hydrogen
Ammonium
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11
Q

Name some anions

A

Nitrate

Hydrogencarbonate

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12
Q

PRACTICALS
How to test for Carbohydrates

   STARCH
A

1) Add iodine solution to sample

2) if starch is present you will see the sample change from yellow-brown to BLUE-BLACK

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13
Q

PRACTICAL

Testing for reducing sugars

A

1) heat reducing sugar with benedict’s solution ( alkaline copper II Sulfate)
2) colour change from blue to green to yellow to orange-red

The red indicates reducing sugar is present

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14
Q

What are reducing sugars?

A

They are either monosaccharides or disaccharides that reduce or give electrons to other molecules

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15
Q

Why would the precipitate of a present reducing sugar be red

A

Benedict solution contains copper 2+ ions reduced to copper + ions forming the red precipitate copper oxide

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16
Q

What is an alternative way of testing for reducing sugars?

A

Commercially manufactured test strips : dip into solution and compare colour to calibration card

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17
Q

PRACTICAL

Testing for Non-reducing sugars

A

1) test sample for reducing sugars to ensure there are none
2) take another sample and boil with hydrochloric acid to hydrolyse the sucrose into glucose and fructose
3) cool solution and use sodium hydrogencarbonate solution to neutralise
4) test for reducing sugars again
A positive result (green-red) indicates non reducing sugars present in original sample

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18
Q

When does a condensation reaction occur?

A

It occurs when to molecules joined together with the REMOVAL of water

19
Q

What is meant by ‘polar’?

A

One molecule exerts a greater attraction because it may have a greater number of protons than the other molecule it’s bonded to. This means that molecule will become slightly negative and the other slightly positive

20
Q

What is meant by a hydrogen bond?

A

A hydrogen bond is a weak interaction which happens whenever a molecule contains a slightly negatively charged atom bonded to a slightly positively charged hydrogen atom

21
Q

What is hydrolysis?

A

It’s the splitting apart of two molecules with the addition of water

22
Q

Why are Polysaccharides good energy stores?

A
  • Compact meaning they occupy a small amount of space. Occur in dense granules
  • hold glucose molecules in chains so they can be easily snipped off by hydrolysis for respr
  • branched chains (amylopectin) are more compact, allows many glucose molecules to be snipped off for quick energy
  • 1-4 g linkages (amylase)
  • 1-6 g linkages (glucosidase)
  • less soluble in water
23
Q

What are the features of Amylose?

A
  • Coils into a spiral (hydrogen bonds hold it in place)
  • Hydroxyl group on inner coil so it’s less soluble
  • has 1-4 g bonds
  • a glucose molecule
24
Q

What are the features of Amylopectin?

A
  • coils into a spiral shape
  • has branches
  • 1-4 g bonds and 1-6 g bonds
25
Q

What are the features of cellulose?

A
  • forms cell wall
  • B glucose monomers
  • B glucose is rotated 180 degrees ( prevents spiralling) (additional strength)
  • form microfibrils ( additional tensile strength)
  • form macrofibrils that criss-cross for extra strength
26
Q

What are the features of a lipid?

A
  • contain hydrogen, carbon and oxygen
  • insoluble in water (not polar)
  • they are macromolecules
27
Q

What are the 3 most important lipids?

A
  • steroids
  • phospholipids
  • Triglycerides
28
Q

What is a triglyceride?

A
  • molecule comprised of glycerol and fatty acids

- ‘essential fatty acids’ are fatty acids that are ingested ‘complete’

29
Q

What is a glycerol?

A
  • molecule comprised of 3 carbon atoms

- 3 OH groups are important to the structure of the TRIglycerol

30
Q

What are the features of a fatty acid?

A
  • Carboxyl group (-COOH) attached to hydrocarbon tail
  • carboxyl group ionise into H+ and -COO- group. Therefore an acid
  • If saturated it has no C=C bonds
  • if there are C=C bonds they are unsaturated as no H molecules can bond
  • having more than one C=C bond can change shape of the hydrocarbon
31
Q

What are the functions of Triglycerides?

A
  • Energy source= broken down for Resp
  • Energy store= insoluble so can be stored without affecting water potential of cell
  • Insulation= ‘blubber of wales’, animals in hibernation store extra fat for heat
  • Buoyancy= fat less dense than water, help float
  • Protection= fat around delicate organs, shock absorber
32
Q

How are triglycerides formed?

A
  • OH from the fatty acid and the H from glycerol react through a condensation reaction
  • form ester bond (O-C=O) (covalent bond)
33
Q

Behaviour of phospholipids in water?

A
  • phosphate group is polar so it’s hydrophilic (head)
  • fatty acid is not polar so it’s hydrophobic (tail)
  • this makes phospholipid molecule amphipathic
34
Q

Phospholipid bilayer

A

Amphipathic phospholipids are excellent at forming membranes around cell membranes in aqueous

35
Q

What is cholesterol and what are it’s features?

A
  • Cholesterol is a steroid alcohol (lipid not made from glyercol and fatty acids)
  • small and hydrophobic, sits inside membrane
  • regulates the fluidity of the membrane preventing it from becoming too fluid or stiff
  • made in liver
  • hormones such as testosterone, oestrogen and vitamin D are all made from cholesterol
36
Q

What are proteins and its functions?

A
  • polymer comprised of amino acids
  • form components of animals eg muscles
  • form enzymes, antibodies and some hormones
  • membranes have protein constituents that act as carriers and pores for active transport across membrane and facilitated diffusion
37
Q

What is the structure of amino acids?

A
  • contain carbon, hydrogen, and Nitrogen
  • 500 diff amino acids, only 20 are proteinogenic
  • has an amine group (-NH2) at one end and a carboxyl group at the other (-COOH)
  • has an R group ( different in each amino acid)
38
Q

Peptide bonds?

A
  • amino acids are joined by them
  • involves condensation reaction
  • Enzymes catalyse these reactions (protease)
  • two amino acids is a dipeptide and more is a polypeptide
39
Q

Primary structure?

A

The sequence of amino acids in a protein is called its PRIMARY STRUCTURE

  • function of protein is determined by structure
  • determines shape of protein molecule
  • peptide bonds
  • 20 to the power of 100 ways of ordering 100 amino acids
40
Q

Secondary structure?

A

Chain of amino acids twist into a shape called the SECONDARY STRUCTURE

  • some coil into a- helix (36 amino acids per 10 turns)
  • held by hydrogen bonds
  • can fold into a zig zag structure producing a B- pleated sheet
  • some have more than one structure at either end
41
Q

Tertiary structure?

A

Coils and folds begin to fold in on themselves to form the TERTIARY STRUCTURE

  • precise shape held by bonds between amino acids
  • May adopt a super coiled shape or spherical shape
  • ionic bonds, disulfide bond
42
Q

Quarternary Structure?

A
  • describes how multiple polypeptide chains are arranged to make complete proteins
  • more than one polypeptide
43
Q

CHROMATOGRAPHY

A

AIM: separate a mixture into its constituents

  • stationary phase= chromatography paper (made of cellulose) there are free OH groups in contact with mobile phase
  • Mobile Phase= solvent for biological molecules (water or ethanol)
44
Q

CHROMATOGRAPHY

A
  • solvent travels up paper and molecules with it
  • by the time the solvent reaches the top, some molecules moved slowly some faster
  • Calculate Rf by measuring distance from pencil line to one molecule (x) and distance from pencil line to solvent front (y)
  • Rf= x/y

Biology Y1 (12 decks)

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