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A Level Biology OCR A > biological molecules > Flashcards

biological molecules Flashcards

chap 3

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1
Q

4 key elements

A

carbon
hydrogen
oxygen
nitrogen

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2
Q

2 key elements in cell biochemistry

A

sulfur
phosphorus

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3
Q

What is a molecule?

A

non metals that are covalently bonded (eg O2)

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4
Q

What elements are specific to proteins and nucleic acids?

A

Proteins: nitrogen, sulfur
Nucleic acids: nitrogen, phosphorus

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5
Q

3 ions for nervous impulse transmissions

A

Ca 2+
Na +
K +

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6
Q

2 ions for determining pH in solutions

A

H +
OH -

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7
Q

2 ions for nitrogen in plants (and names)

A

NH4 + (ammonium)
NO3 - (nitrate)

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8
Q

2 ions for transport of respiratory gases (and names)

A

HCO3 - (hydrogen carbonate)
Cl - (chloride)

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9
Q

1 ion for nucleic acid and ATP formation (and name)

A

PO4 3- (phosphate)

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10
Q

Are the key ions in this module inorganic or organic? Why? Is there an exception?

A

Inorganic
None contain C-H bonds
HCO3 - contains carbon and hydrogen, but the carbon forms a C-O bond

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11
Q

What reaction joins monomers together and releases a water molecule?

A

Condensation

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12
Q

What reaction requires a water molecule to BREAK DOWN polymers?

A

Hydrolysis

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13
Q

When 2 monomers join, what do they form?

A

A dimer

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14
Q

Why is water a polar molecule? (4 points)

A
  • 0 overall charge
  • Oxygen is slightly neg region (d-)
  • Hydrogen is a slightly pos region (d+)
  • Bc oxygen has more protons, it attracts e- closer to it
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15
Q

Where are hydrogen bonds formed? Why? What do they do and what is this similar to?

A
  • Adjacent to water molecules
  • As they are pos and bond to neg oxygen
  • Hold multiple molecules together like IMF
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16
Q

What are the 5 essential properties of water?

A
  • Cohesion, adhesion and surface tension
  • High SHC and LH of V
  • Low density
  • Essential to metabolism
  • Acts as a solvent
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17
Q

What is cohesion? Due to?

A

tendency of water to stick together (due to hydrogen bonds)

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18
Q

What is capillary action? Due to?

A

Ability of water to be pulled up the stem and go against gravity (due to cohesion and adhesion)

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19
Q

What is adhesion? Due to?

A

Ability of water to stick to cell wall (due to hydrogen bonds)

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20
Q

What is surface tension?

A

Where water meets air, the tendency of water to be pulled back into a body of water

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21
Q

What does a high specific heat capacity (SHC) mean?

A

Takes in a lot of energy before getting hotter

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22
Q

What does a high specific latent heat of vaporisation (LH of V) mean?

A

Takes in a lot of energy before evaporating

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23
Q

Why is a high SHC good for water? (2 points)

A
  • Smaller temp range so organisms’ enzymes don’t denature
  • Less ice melts= less habitat loss
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24
Q

Why is a high LH of V good for water?

A

More liquid water available for organisms

25
Q

Why is ice being less dense than water good?

A

Organisms can live on and under ice

26
Q

What 3 processes does water play in metabolism?

A
  • Hydrolysis
  • Photosynthesis
  • Making cell environments aqueous
27
Q

How does ice maintain a stable environment?

A

Surface level ice= insulating layer

28
Q

What kind of solvent is water and what does this mean? (4 points)

A
  • It is a dipolar solvent
  • So neg oxygen can bind to surrounding ions/molecules
  • And pos hydrogen can bind to neg ends of surrounding molecules
  • so it can dissolve lots of substances
29
Q

What is the general formula of a carbohydrate? General ratio?

A

Cx(H2O)y
H:O= 2:1

30
Q

3 roles of carbs (+ examples)

A

energy stores (glycogen +starch)
structural support (cellulose)
DNA (ribose)

31
Q

Isomer

A

molecules with same molecular formula but different structures

32
Q

Water soluble

A

when there are compounds outside the molecule that water can hydrogen bond to

33
Q

What makes a and B glucose isomers? What carbon is this on? What saying can be used to remember this?

A

In a glucose, the hydroxyl group (OH) is below the plane
In B glucose, the hydroxyl group is above the plane
C1
“Beta beats alpha”

34
Q

Why is glucose water soluble?

A

OH is polar and water can hydrogen bond to it

35
Q

Why is water a good transport medium? (3 reasons (so far))

A
  • Polar solvent
  • Cohesion and adhesion
  • Thermal stability
36
Q

What carbohydrate polymers does glucose make up and which types?

A

Alpha:
- glycogen
- amylose starch
- amylopectin starch
Beta:
- cellulose

37
Q

Why does the structure of glycogen differ from the structure of cellulose? Why does it have this structure? What is this due to?

A
  • Glycogen has a higher surface area and is more compact with more extensive branching
  • bc animals need more energy
  • due to 1,4 and additional 1,6-glycosidic bonds
38
Q

How does the structure of cellulose relate to its function? (4 points)

HINT: bonds, shape, solubility, groups

A
  • Hydrogen bonds between chains form microfibrils–> macrofibrils–> high tensile strength fibres
  • doesn’t need branches bc purely structural
  • insoluble, maintaining strength
  • hydroxyl group positioned above C1’, so alternate molecules must be turned upside down so chain is straight and compact
39
Q

What is the structure of a triglyceride? What is the bond? Which is between what groups? (3)

A
  • 1 glycerol + 3 fatty acids
  • ester bonds
  • carboxyl group om fatty acids and alcohol groups on glycerol
40
Q

What is the structure of a phospholipid (3 groups)? What is special about the 2 ends of the phospholipid? Why?

A
  • phosphate group + glycerol + 2 fatty acids
  • phosphate group is hydrophilic (bc it is polar)
  • fatty acids are hydrophobic (bc they’re non polar)
41
Q

Functions of triglycerides (3)

A
  • Energy source
  • Insulation (adipose tissue under skin)
  • Protection (adipose tissue around organs)
42
Q

Function of phospholipid and how?

A

Forms phospholipid bi-layer (hydrophilic head faces outwards and hydrophobic tail faces inwards)

43
Q

Structure of cholesterol and where is it usually?

A

4 carbon rings and hydrophilic hydroxyl group
between phospholipids in the cell membrane

44
Q

Function of cholesterol (2)? What happens if there’s too much of it?

A
  • controls membrane fluidity (stops them bursting open bc they’re too permeable)
  • stabilizes membrane temp
  • membrane becomes too stiff and impermeable so fluids cannot pass thru it
45
Q

Types of bond saturation? (3) What are kinks? What do kinks do?

A
  • saturated (no C=C), monosaturated (1 C=C), polysaturated (>1 C=C)
  • kinks are bends in the chain where double bonds are
  • bend molecule so they cannot pack into solids
46
Q

Why are saturated molecules harder to melt?

A

no kinks=more layers=strong IMF between layers

47
Q

What are 3 types of lipids?

A

Triglycerides
Phospholipids
Cholesterol

48
Q

6 functions of protein

A

enzymes
structural
contractile
hormones
transport
antibodies

49
Q

3 types of proteins + examples

A

globular- insulin
fibrous- collagen
conjugated- haemoglobin

50
Q

What 4 things make up an amino acid?

A
  • amine group (NH2)
  • carboxyl group (-COOH)
  • hydrogen
  • R group
51
Q

What does each structure of protein contain? (excluding tertiary)

A
  • Primary: peptide bonds between amino acids (amino and carboxyl groups)
  • Secondary: hydrogen bonds between amino group on 1 amino acid and carboxyl on another
  • Quaternary: more than 1 polypeptide chain + non-amino components (eg iron)
52
Q

What does the tertiary structure of a protein contain?

A
  • ionic bonds between R groups
  • ionic bonds between carboxyl/amine groups
  • hydrophilic and hydrophobic interactions between polar and non polar R groups (weak)
  • sometimes disulfide bridges
53
Q

Structures of 3 types of protein + 3 properties of each

A

Globular: water soluble, folds into globe/sphere, diverse

Fibrous: elongated (sheet-like), many repeated amino acids, insoluble

Conjugated: 1 alpha and beta polypeptides, quaternary, prosthetic group (non amino component)

54
Q

Functions of 3 types of fibrous proteins

A
  • Keratin: tough (hair, tooth, nails),
  • Elastin: connective tissue (tendons, skin, bones)
  • Collagen: strong support and tensile strength due to hydrogen and covalent bonds (skin, tendons ligaments)
55
Q

Structure + function of catalase

A
  • Fe2+ in 4 haem groups
  • allows it to break down H2O2 which is a toxic by-product of metabolism
  • globular
56
Q

Structure + function of insulin

A
  • soluble and precise shape
  • dissolves in blood and binds to receptors
  • disulfide bridges for stability
  • globular
57
Q

Structure + function of haemoglobin

A
  • 2 alpha and 2 beta polypeptides, 4 haem groups w Fe2+ ions
  • which combine REVERSIBLY w O2 to allow quick pick up and release
  • conjugated
58
Q

True or false- conjugated proteins are entirely separate

A

False- conjugated proteins are just globular and fibrous proteins with prosthetic groups

A Level Biology OCR A (8 decks)

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