2.1.2 Biological molecules Flashcards
(71 cards)
1
Q
What chemical elements make up carbohydrates
A
Carbon
Hydrogen
Oxygen
2
Q
What chemical elements make up lipids
A
Carbon
Hydrogen
Oxygen
3
Q
What chemical elements make up proteins
A
Carbon
Hydrogen
Oxygen
Nitrogen
Sulfur
4
Q
What chemical elements make up nucleic acid
A
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
5
Q
Example of a hexose monosaccharide
A
glucose
6
Q
Example of a pentose monosaccharide
A
ribose
deoxyribose
7
Q
Draw an alpha glucose molecule
A
8
Q
Draw a beta glucose molecule
A
9
Q
Properties of monosaccharides
A
- sweet
- soluble
- forms crystals
- hydrophilic
10
Q
Give three examples of reducing monosaccharides
A
- glucose
- fructose
- galactose
11
Q
Give one example of a non-reducing monosaccharide
A
sucrose
12
Q
Glucose + glucose
A
maltose
13
Q
Glucose + fructose
A
sucrose
14
Q
Glucose + galactose
A
lactose
15
Q
What bond is formed from two monosaccharides
A
glycosidic bond formed by a condensation reaction
- results in the loss of one molecule of water
16
Q
What is the structure of starch
A
- amylose
unbranched helix-shaped chain with 1,4 glycosidic bonds - amylopectin
1,4 and 1,6 glycosidic bonds
this creates a branched molecule
17
Q
What is the benefit of the helix shape of amylose
A
enables starch to be more compact and thus it is more resistant to digestion
18
Q
What is the function of starch
A
a storage polysaccharide in plants
branched amylopectin means that starch can be easily hydrolysed for use during cellular respiration
19
Q
What is the structure of glycogen
A
made of alpha glucose molecules
both 1,4 and 1,6 glycosidic bonds
similar structure to amylopectin, is more heavily branched
20
Q
What is the function of glycogen
A
storage polysaccharide in animals and fungi
high concentration in liver and muscle cells
21
Q
Why is glycogen more suited to being an energy store than amylopectin
A
glycogen is more heavily branched
- so can be broken down into glucose much quicker for use in respiration
- also more compact so less space needed for storage
22
Q
What is the structure of cellulose
A
long chains of beta glucose joined by 1,4 glycosidic bonds
- no branching
- forms microfibrils
23
Q
Give three properties of cellulose
A
- high tensile strength
- inflexible
- insoluble in water
24
Q
How is beta glucose bonded in cellulose
A
25
Why does cellulose have a very high tensile strength
due to the inversion of alternate beta glucose molecules, hydrogen bonds form between long chains
- this gives them high tensile strength
- allows it to be stretched without breaking, allowing cell walls to withstand turgor pressure
26
What is the function of cellulose
the main structural component of cell walls
cellulose fibres are freely permeable, which allows water and solutes to leave or reach the cell membrane
27
What groups do amino acids have
- amine group
- carboxylic group
- r group
28
Draw an amino acid
29
What bond forms between amino acids
peptide bond
formed through a condensation reaction between the hydroxyl and amine groups
- results in the loss of one molecule of water
30
What are prosthetic groups
non protein parts in proteins
e.g iron in haemoglobin
31
Properties of globular proteins
compact globe structure
hydrophobic R-groups face inwards and hydrophilic R- groups on the outside
- makes them soluble in water
32
Properties of fibrous proteins
form fibres
regular repetitive sequences of amino acids
usually insoluble
33
What is the primary structure of a protein
the sequence of amino acids held together by peptide bonds
- primary structure is specific to each protein
34
What is the secondary structure of a protein
alpha helix shape occurs when hydrogen bonds form between every fourth peptide bond
beta pleated sheet occurs when the protein folds and hydrogen bonds form between parallel peptide bonds
- hydrogen bonds form between the nitrogen, oxygen, and hydrogen atoms
35
What is the tertiary structure of a protein
a complex 3d shape achieved by twisting and folding
R-groups can form bonds with other R-groups
- ionic
- covalent
- disulfide
- hydrogen bonds
- hydrophilic / hydrophobic interaction
36
What is the quaternary structure of a protein
when a protein is made of more than one polypeptide subunit (unusual)
- haemoglobin and antibodies (4 polypeptides)
- collagen (3 polypeptides)
37
What is a lipid
a chemical that dissolves in organic solvents such as alcohol, but not in water (insoluble)
macromolecules - not polymers
- triglycerides
- phospholipids
- steroids
38
What is a triglyceride made of
one molecule of glycerol and 3 fatty acids
39
What groups make up a fatty acid molecule in a triglyceride
a methyl group at one end of the hydrocarbon chain, and a carboxyl group at the other end
40
What is the difference between a saturated fatty acid and an unsaturated fatty acid tail
an unsaturated fatty acid has a double carbon bond
41
Describe a cis-fatty acid
occurs when hydrogen atoms are on the same side of the double bond
- metabolised by enzymes
42
Describe a trans-fatty acid
when hydrogen atoms are on opposite sides of the double bond
- cannot form enzyme-substrate complexes and therefore are not metabolised
43
Give three functions of triglycerides
1) source of energy / energy store
2) insulation
3) buoyancy
44
Why are triglycerides an effective energy store
they store more energy per gram due to their hydrocarbon chains
45
Give two examples of triglycerides use as an insulator
1) part of the composition of the myelin sheath that surrounds nerve fibres
provides insulation which increases the speed of nerve impulse transmission
2) composes part of the tissue layer below the skin which acts as an insulation against heat loss
46
Why do triglycerides help with buoyancy
makes up fat tissue that has a very low density
- increases ability of animals to float more easily
47
How do triglycerides bond
the hydroxyl group of the glycerol reacts with the carboxylic acid group of the fatty acid to form an ester bond through a condensation reaction
48
What is released in the formation of one triglyceride molecule
three molecules of water
49
What is a phospholipid made of
a phosphate group
glycerol
two fatty acid tails
- even number of carbon atoms each (16 or 18), one saturated and one unsaturated
50
How does the composition of the phospholipid contribute to the fluidity of the cell membrane
mainly saturated FA tails - membrane will be less fluid
mainly unsaturated FA tails - membrane will be more fluid
51
What is the structure of a steroid hormone (cholesterol etc)
4 carbon-based ring structures
hydroxyl group at one end (polar and hydrophilic)
rest of the molecule is nonpolar and hydrophobic
52
What are the main functions of cholesterol
- makes up steroid hormones and vitamin D
- prevents phospholipids solidifying at low temps and being to fluid at high temps
- gives mechanical stability as it restricts the movements of the phospholipids (decreases fluidity)
53
Describe the structure of water
polar molecule due to the difference in electronegativity between oxygen and hydrogen
as a result of this polarity, hydrogen bonds form between adjacent water molecules
54
Give five properties of water
1) universal solvent
2) high specific heat capacity
3) high latent heat of vaporisation
55
Why does water act as a universal solvent
as it is a polar molecule, many ions and covalently bonded polar substances will dissolve in it
- allows chemical reactions to occur within cells
56
Why does water have a high specific heat capacity
due to the many hydrogen bonds in water
large amounts of energy are required to overcome these bonds
- means the temperature of water doesn't fluctuate greatly
57
Give two benefits of water having a high specific heat capacity
1) provides a stable habitat for aquatic organisms
2) helps to maintain a constant temperature in the body
58
Give the benefit of water having a high latent heat of vaporisation
provides a cooling effect for living organisms e.g. evaporation of water in sweat from skin
- only a little water is required to evaporate for the organism to lose a great amount of heat
58
Why does water have a high latent heat of vaporisation
large amounts of thermal energy are required to overcome the hydrogen bonds, in order for the water to change state and evaporate
59
Functions of hydrogen ions
H+
- hydrogen bonding
- control of blood pH
- opening stomata (proton pump)
- transported out of companion cells to return with sucrose through co transporter proteins
60
Functions of calcium ions
Ca2+
- bone and enamel structure (calcium phosphate)
- cofactor for enzymes
- synaptic transmission of nerve impulses
- muscle contraction
61
Function of iron ions
Fe2+ / Fe3+
- transport of oxygen via haemoglobin
- transfer of electrons (respiration and photosynthesis)
62
Function of sodium ions
Na+
- generating nerve impulses
- reabsorption of water in the kidneys
- co transporter of glucose and amino acids
63
Function of potassium ions
K+
- generating nerve impulses
- reabsorption of water in the kidneys
- opening of the stomata
- regulating fluid balance
64
Function of ammonium ions
NH4+
- deamination of proteins
65
Function of nitrate ions
NO3-
- source of nitrogen for plants
66
Function of hydrogen carbonate ions
HCO3-
- carbon dioxide transport in the blood
67
Function of chloride ions
Cl-
- maintaining pH balance during carbon dioxide transport
- cofactor for amylase enzyme
68
Function of phosphate ions
PO43-
- components of the cell membrane (phospholipids)
- component of bone (calcium phosphate)
- component of ATP and nucleic acids
69
Function of hydroxide ions
OH-
- determines pH
70
What is the benefit of water having cohesive and adhesive properties
1) enables surface tension which is used by insects as a habitat
2) allows columns of water to move through the xylem of plants and through blood vessels in animals
