Biological molecules Flashcards
1
Q
What are biological molecules
A
molecules made and used by organisms
2
Q
Functions of carbohydrates
A
- energy source (glucose in respiration
- energy store (starch in plants, glycogen in animals)
- structure (cellulose in cell wall of plants)
3
Q
What are the building blocks for carbohydrates
A
monosaccharides
4
Q
Name the three monosaccharides
A
- glucose
- galactose
- fructose
5
Q
Difference between a and b glucose
A
on carbon 1, OH on bottom for a- glucose, on top for b- glucose
6
Q
How are monosaccharides joined together
A
condensation reaction (removing water), between 2 OH groups
7
Q
Bond in a carbohydrate
A
1,4 glycosidic bond
8
Q
Name the disaccharides
A
- Maltose (glucose + glucose)
- Lactose (glucose + galactose)
- Sucrose (glucose + fructose)
9
Q
How are polymers separated
A
hydrolysis reaction (add water)
10
Q
What is a polysaccharide
A
many monosaccharides joined together by condensation reaction, forming glycosidic bonds
11
Q
Name the polysaccharides
A
- Starch (long chain of alpha glucose)
- Glycogen (long chain of alpha glucose
- Cellulose (long chain of beta glucose)
12
Q
Function of each polysaccharide
A
- Starch, energy store in plants
- Glycogen, energy store in animals
- Cellulose, makes up cell wall in plants
13
Q
Polysaccharides summary
A
- carbohydrates made up of long chain of monosaccharides joined by condensation reaction, forming glycosidc bonds
- 3 examples: starch, glycogen, cellulose
- Starch + Glycogen used as energy store (starch for plants, glycogen for animals) as they’re made of many a-glucose which are used for respiration
- Cellulose used to form cell wall of plants, made of many b-glucose
14
Q
Structure of starch
A
- made of amylose (1,4 glycosidic bonds) + amylopectin (1,4 + 1,6 glycosidic bonds)
- long unbranched chain of coiled a-glucose (amylose)
- long chain of a-glucose with side branches (amylopectin)
15
Q
Structure of glycogen
A
straight chain of a-glucose 1,4 glycosidic bonds with side branches (1,6 glycosidic bonds)
16
Q
Properties of starch and glycogen
A
- insoluble (don’t affect water potential, don’t diffuse out of cell)
- coiled/branched, more can fit into cell
17
Q
Structure of cellulose
A
- b-glucose arranged in a straight chain
- hydrogen bonds present to form microfibrils
- many microfibrils are cross linked to form macrofibrils
- this forms structure of cell wall
- strong material prevents cell from bursting
18
Q
Test for starch
A
add iodine, turns blue/black
19
Q
Test for reducing sugar
A
heat with benedicts, turns brick red
20
Q
Test for non-reducing sugar
A
- heat with benedicts, no change
- add dilute hydrochloric acid
- add sodium hydrogencarbonate to neutralise solution
- heat with benedicts, turns brick red
21
Q
What are fibrous proteins
A
strong, insoluble, inflexible material; like collagen
22
Q
What are the building blocks for proteins
A
amino acids
23
Q
Structure of an amino acid
A
- central carbon
- carboxyl group to the right (COOH)
- amine group to the left (NH2)
- hydrogen above, R group below
24
Q
How do amino acids differ
A
different R groups
25
How are amino acids joined together
by condensation reaction between carboxyl group of one and amine group of another, forming peptide bonds
26
Describe primary, secondary, tertiary and quaternary structures
- Primary, sequence of amino acids in a polypeptide chain held by peptide bonds
- Secondary, polypeptide chain coils to form alpha helix + beta pleated sheets held by hydrogen bonds
- Tertiary, secondary structure folds again to form 3D shape held by hydrogen, ionic and disulfide bonds
- Quaternary, made up of two or more polypeptide chains
27
Test for protein
add biuret solution, turns purple
28
What is an enzyme
a biological catalyst which speeds up rate of reaction without being used up by lowering activation energy
29
What makes an enzyme specific
- has specific active site shape
- only complementary substrates can bind to active sites to form ES complexes
30
Describe the lock and key model
active site shape is rigid, only complemntary substrates can bind to form ES complexes
31
Describe the induced fit model
active site changes shape, substrate binds to active site; changes shape so substrate becomes complementary, forming ES complex
32
Effect of substrate concentration on enzyme activity
- increasing substrate concentration increases chance of successful collisions, increasing chance of forming ES complexes, increases rate of reaction
- continues until all substrates are used up
33
Effect of temperature on enzyme activity
- temp increase =
- kinetic energy increases
- molecules move faster, increasing chance of successful collisions, increasing number of ES complexes formed, increasing rate of reaction
34
Overly high temperatures vs enzyme activity
- bonds in tertiary structure break
- active site changes shape so substrate no longer complementary
- can't form ES complexes so enzyme denatures
35
Effect of pH on enzyme activity
if pH is changed from optimum, bonds in tertiary structure break, active site changes shape so no longer complementary to substrate, can't form ES complexes, enzyme denatures
36
Role of a competitive inhibitor
substance with similar shape to substrate binds to active site, blocking it, preventing ES complexes from forming
37
Role of a non-competitive inhibitor
substance binds to allosteric site of enzyme, causes active site to change shape, so less ES complexes form
38
3 types of lipids
- triglycerides
- phospholipids
- cholesterol
39
Role of each lipid
- triglycerides, fat for energy store, insulation, protection of organs
- phospholipids, to make membranes
- cholesterol, for membrane stability and make hormones
40
Structure of triglycerides
- made of 1 glycerol and 3 fatty acids
- joined by condensation reactions, forming ester bonds
41
Saturated vs unsaturated chains
unsaturated contain C=C bonds, saturated do not
42
Structure of phospholipids
- made of 1 glycerol, 2 fatty acids and a phosphate group
- phosphate forms hydrophilic head (water loving), fatty acids form hydrophobic tails (water hating)
- forms phospholipid bilayer
43
What are nucleic acids
polymers made from nucleotides (2 types, DNA and RNA)
44
What is DNA
- deoxyribonucleic acid
- found in all organisms
- carries genes
45
What is a gene
section of DNA that codes for a protein
46
Building block of DNA
- DNA nucleotide, made up of phosphate, deoxyribose sugar and nitrogenous base
47
Name the 4 types of nucleotide
- adenine
- thymine
- cytosine
- guanine
48
Describe the structure of DNA
- consists of polynucleotides
- each nucleotide formed from deoxyribose, phosphate group and nitrogenous base
- phosphodiester bonds between nucleotides
- double helix held by hydrogen bonds
- hydrogen bonds occur between adenine, thymine and cytosine, guanine
49
Describe the process of semi-conservative DNA replication
- DNA helicase breaks hydrogen bonds between the complementary bases
- double strand separates, leaving two template strands
- free DNA nucleotides bind to exposed complementary base pairs
- DNA polymerase catalyses the condensation reaction which joins the nucleotides together
- each new DNA molecule contains one strand of original and one strand of new DNA
50
What is RNA made up of
- ribose sugar
- phosphate group
- nitrogenous base (AUCG)
51
2 types of RNA
- mRNA (messenger RNA)
- tRNA (transfer RNA)
52
Similarities between mRNA and tRNA
- both single stranded
- both made of RNA nucleotides
53
What is ATP
adenosine triphosphate, delivers energy for life processes
54
Structure of ATP
- ribose
- adenine
- 3 phosphate groups
55
Describe the formation of ATP
- ADP + Pi + energy used = ATP
- occurs via a condensation reaction using ATP synthase
- carries energy in its bonds
56
Describe the breakdown of ATP
- ATP= ADP + Pi + energy released
- occurs via hydrolysis reaction using ATP hydrolase
- releases energy from its bonds
57
What makes ATP a good energy deliverer
- immediate source, only need to break one weak bond
- manageable source, releases small amounts of energy
58
3 Uses of ATP in organisms
- protein synthesis
- metabolic reactions
- active transport
59
Properties of water
- dipolar, positively charged hydrogen, negatively charged oxygen, so H2O molecules can form hydrogen bonds with each other
60
Role of water in living organisms
- a solvent so allowing transport of substances
- high specific heat capacity so resists changes in temperature
- a metabolite in photosynthesis
- cohesion between water molecules so supports columns of water
- large latent heat of vaporisation so provides cooling effect
61
What are inorganic ions
salts/minerals that don't contain carbon and are charged
