topic 1 - biological molecules Flashcards
1
Q
what are the 5 biological molecules?
A
carbohydrates, proteins, lipids, nucleotides, water
2
Q
what is the monomer and polymer for carbohydrates?
A
monomer-monosaccharides, polymer-polysaccharides
3
Q
what is the monomer and polymer for proteins?
A
monomer-amino acids, polymer-polypeptides & protein
4
Q
what is the monomer and polymer for nucleic acids?
A
monomer-nucleotides, polymer-DNA & RNA
5
Q
what is the monomer and polymer for lipids?
A
monomer-fatty acids & glycerol, polymer-isn’t one
6
Q
what is the monomer and polymer for water?
A
monomer-hydrogen & oxygen, polymer- isn’t one
7
Q
are covalent bonds strong or weak?
A
strong
8
Q
what happens in molecules of either OH or NH?
A
a slightly negative charge on nitrogen or oxygen is attracted to the slightly positive charge on the hydrogen on a neighbouring molecule.
9
Q
monomer is glucose what are the polymers?
A
polymers - starch, cellulose, glycogen.
10
Q
monomer is amino acids what is the polymer?
A
protein
11
Q
monomer is nucleotides what is the polymer?
A
DNA & RNA
12
Q
What is a condensation reaction?
A
joining of 2 molecules creating a chemical bond and removing water.
13
Q
what is a hydrolysis reaction?
A
breaks a Chemical bond between 2 molecules and involves the use of water.
14
Q
Everything on starch - monomers, bonds, function, location, structure.
A
monomer - alpha glucose
bonds between monomer - 1-4 glycosidic bonds in amylose. 1-4 & 1-6 in amylopectin.
function - store of glucose
location - plant cells
structure - made of 2 polymers, amylose which is an unbranched helix and amylopectin which is a branched molecule. Overall starch is a branched structure increases surface area for hydrolysis. starch is insoluble.
15
Q
Everything on cellulose - monomers, bonds, functions, location, structure.
A
monomer - beta glucose
bonds between monomer - 1-4 glycosidic bonds
function - structural, strength for cell wall, is rigid
location - plants in the cell wall
structure - polymer forms long straight chains held by many hydrogen bonds to form fibrils. insoluble so won’t affect water potential.
16
Q
everything on glycogen - monomers, bonds, functions, location, structure.
A
monomer - alpha glucose
bonds between monomers - 1-4 & 1-6 glycosidic bonds
function - store of glucose
location - animals - mainly muscle and liver
structure - a highly branched molecules, for rapid hydrolysis back to glucose. insoluble so won’t affect water potential.
17
Q
Carbohydrates - monosaccharides
A
glucose, fructose, galactose.
18
Q
carbohydrates - disaccharides
A
sucrose, maltose, lactose.
19
Q
carbohydrates - polysaccharides
A
starch, cellulose, glycogen
20
Q
structure of triglycerides
A
3 fatty acids, glycerol molecule,
21
Q
What’s the difference between unsaturated and saturated fatty acid?
A
unsaturated - has a double bond so not all carbons are surrounded by hydrogen bonds.
saturated - all carbon atoms are fully surrounded by hydrogens.
22
Q
structure of phospholipids
A
only 2 fatty acids, bonded to the glycerol group and a phosphate group covalently attached to the 3rd hydroxyl group. They also have hydrophobic and hydrophilic regions.
23
Q
what’s the difference between a monomer and polymer?
A
a monomer is a single unit a polymer is many units bonded together.
24
Q
what can carbohydrates be classified as?
A
monosaccharides, polysaccharides and disaccharides.
25
what are the monosaccharides?
glucose, frutose, galactose
26
what is the difference between alpha and beta glucose, drawn out as well?
alpha glucose has hydrogen above of the carbon 1 and hydroxyl below, whereas beta glucose has hydroxyl above carbon 1 and hydrogen below.
27
what is a disaccharide?
2 monosaccharides joined together by a glycosidic bond.
28
what is a condensation reaction?
the joining of molecules through the removal of water
29
how is a disaccharide formed?
created through a condensation reaction
30
what is a hydrolysis reaction?
molecules split apart through addition of water
31
what are disaccharides?
maltose, sucrose, lactose
32
how are polysaccharides created?
created by condensation reaction between many glucose monomers
33
what are the monomers for starch, cellulose and glycogen?
starch - alpha glucose
cellulose - beta glucose
glycogen - alpha glucose
34
what are the bonds between the monomers for starch, cellulose and glycogen?
starch - 1-4 glycosidic bonds in amylose. 1-4 and 1-6 in amylopectin.
cellulose - 1-4 glycosidic bonds
glycogen - 1-4 and 1-6 glycosidic bonds
35
what is the function for starch, cellulose and glycogen?
starch - store of glucose
cellulose - structure and strength for cell wall
glycogen - store of glucose
36
what is the location of starch, cellulose and glycogen?
starch - in plant cells e.g chloroplasts
cellulose - in plants cell wall
glycogen - in animals, mainly muscle and liver
37
what is the structure of starch, cellulose and glycogen?
starch - made of 2 polymers, amylose - unbranched helix, amylopectin - branched molecule
cellulose - polymer forms long straight chains, chains are held in parallel by many hydrogen bonds to form fibrils.
glycogen - a highly branched molecule
38
how does the structure lead to function of starch, cellulose and glycogen?
starch - helix is compact to fit lots of glucose in small space.
has branched structure which increases the surface area for rapid hydrolysis to glucose
is insoluble so won't affect water potential.
cellulose - many hydrogen bonds provide collective strength and is insoluble so won't affect water potential.
glycogen - branched structure increases surface area for rapid hydrolysis back to glucose.
is insoluble so won't affect water potential
39
what is the structure of a triglyceride?
made up of a glycerol and 3 fatty acids.
40
what is the structure of a phospholipid?
made from a phosphate group, glycerol and 2 fatty acids.
41
how are triglycerides formed?
formed via condensation reactions between 1 molecule of glycerol and a molecule of fatty acids (R group)
42
what is the difference between saturated and unsaturated fatty acids?
saturated - the hydrocarbon chain has only single bonds between the carbons making it fully surrounded by hydrogen.
unsaturated - the hydrocarbon chain consists of at least 1 double bond between the carbons so not fully surrounded by hydrogen.
43
what are the properties of triglycerides?
-energy storage - due to large ratio of energy storing carbon
-due to high ratio of hydrogen to oxygen they act as a metabolic water source, triglycerides release water if they are oxidised.
-triglycerides don't affect water potential and osmosis as they are large and hydrophobic making them insoluble.
-lipids have relatively low mass therefore lots can be stored without increasing the mass and preventing movement.
44
how do you test for lipids?
emulsion test
- dissolve the sample in ethanol
- then add distilled water
- if white emulsion appears there is a lipid present
45
how are phospholipids formed?
made of a glycerol and 2 fatty acids chains and a phosphate group.
2 fatty acids also bond to the glycerol via 2 condensation reactions resulting in the ester bond.
46
what are the properties of phospholipids?
-hydrophilic head of a phospholipid can attract with water as it is charged.
-due to the phosphate being charged it repels other fats.
-the fatty acid chain isn't charged so known as the hydrophobic tails and it repels water but will mix with fats.
-they have 2 charged regions
-in water they are positioned so that the heads are exposed to water and tails aren't.
-this forms a phospholipid bilayer membrane structure which makes up the plasma membrane around the cell.
47
how are amino acids joined together to form a dipeptide?
condensation reactions, which means water is removed, a peptide bond is formed between OH of a carboxyl and H or amine group
48
what is a protein?
proteins are polymers made up of the monomer amino acids
49
what is the primary structure of proteins?
the order of amino acids in the polypeptide chain (a polymer)
50
what is the secondary structure of proteins?
the sequence of amino acids causes parts of a protein molecule to bend into alpha helix shapes or folded into beta pleated sheets.
- hydrogen bonds hold the secondary structure
- hydrogen bonds form between c=o groups of the carboxylic group of 1 amino acid and the H in the amine group of another amino acid.
51
what is the tertiary structure of proteins?
the further folding of secondary structure, this forms a unique 3D shape
held in place by ionic, hydrogen and disulphide bonds.
The ionic bonds form between the R groups of different amino acids
disulphide bonds only sometimes occur as they must be a sulfur in the R groups for this bond to occur.
52
what is the quaternary structure of proteins?
a protein made of more than 1 polypeptide chain e.g haemoglobin is made of polypeptide chains
53
what is denaturing?
if a protein dentures this means that the bonds which hold the tertiary and secondary shape break and therefore unique 3D shape is lost
54
what is the importance of the primary structure in proteins?
if even 1 amino acid in the sequence is different then it will cause the ionic, hydrogen or disulphide bonds to form in a different location
this results in a different 3D shape which means the protein becomes non functioning or has a different role.
55
what is the test for starch?
1. add iodine
2. a positive test the solution will turn from orange to blue/black
56
what is the test for reducing sugars?
1. add bendicts reagent and heat
2. a positive test - solution turns from blue to brick red.
57
what is the test for non-reducing sugars?
1. following a negative Benedict's test where the reagent remains blue
2. add the acid and boil
3. cool the solution and then add an alkali to neutralise
4. add benedicts reagent and heat
5. a positive test - solution will turn from blue to brick red
58
what's the difference between reducing and non reducing sugars?
reducing - glucose, fructose, galactose, lactose, maltose.
these can reduce copper sulphate in benedicts reagent to the copper oxide
non reducing - sucrose
involved in the glycosidic bonds in sucrose and therefore sucrose can't reduce copper sulphate to copper oxide
59
what is the test for protein?
1. add biuret
2. postive test - solution turns from blue to purple
60
what is the test for lipids?
1. dissolve the sample in ethanol
2. then add distilled water
3. positive test - a white emulsion will form
61
what is an enzyme?
enzymes are tertiary structure proteins which catalyse a reaction, they are large molecules.
62
what is an active site?
the active site is specific and unique in shape due to the specific folding and bonding in the tertiary structure of the protein.
due to this the specific active site enzymes can only attach to substrates that are complementary in shape.
63
what is the lock and key model?
the model suggests that the enzyme is like a lock and substrate a key, making them complementary.
the model suggests that the enzyme is a fixed shape and due to random collisions the substrate can collide and attach to the enzyme. forming an enzyme substrate complex.
64
what is the induced fit model?
suggests that the enzyme is like a glove and the substrate is like your hand
induced fit is when the enzyme active site is induced or slightly changes shape to mould around the substrate. when the enzyme substrate complex occurs due to the enzyme moulding around the substrate it puts strain on the bonds therefore lowers activation energy.
65
what is a competitive inhibitor?
are the same shape as a substrate and can bind to the active site, this prevents the substrate from binding and the reaction occuring
66
what is a non competitive inhibitor?
binds to the enzyme away from the active site, this causes the active site to change shape and therefore the substrate can no longer bind regardless of how much substrate is added.
67
what is DNA?
deoxyribose nucleic acid codes for the sequence of amino acids in the primary structure of a protein, which determines the final 3D structure and function of a protein.
68
what is a nucleotide?
the monomer that makes up DNA, it is made up of deoxyribose (pentose sugar), a nitrogenous base and 1 phosphate group.
69
what is a polynucleotide?
created via condensation reactions between the deoxyribose sugar and the phosphate group, creating a phosphodiester bond.
it has a sugar - phosphate backbone and covalent bonds.
the DNA polymer occurs in pairs which are joined together by hydrogen bonds between the bases.
adenine and thymine form 2 hydrogen bonds and cytosine and guanine can form 3 hydrogen bonds
70
how does DNA structure relate to its function?
- it has a stable structure due to sugar-phosphate backbone and double helix
- double stranded so replication can occur using one strand as a template
- weak hydrogen bonds for easy unzipping of the 2 strands in a double helix replication.
- large molecule to carry lots of information
- complementary base pairing allows identical copies to be made
71
what is RNA?
is a polymer of a nucleotide formed of a ribose, nitrogenous base and a phosphate group.
- the nitrogenous bases are adenine, uracil, guanine, cytosine.
72
what is the function of RNA?
is to copy and transfer the genetic code from DNA in the nucleus to the ribosomes. Some RNA is also combined with proteins to create ribosomes.
73
what is mRNA?
messenger RNA is a copy of genes from DNA, it is created in the nucleus to carry the copy of the genetic code of 1 gene to a ribosome in the cytoplasm. mRNA is shorter than DNA so can leave the nucleus.
74
what is tRNA?
transfer RNA is only found in the cytoplasm, it is single stranded but folded to create a shape that looks like a cloverleaf held by hydrogen bonds.
function - to attach to 1 amino acid to the ribosome to create the polypeptide chain. specific amino acids attach to specific tRNA molecules which is determined by the codons, these are called anticodons.
75
what is rRNA?
ribosomal RNA is the type of RNA that makes up the bulk of the ribosomes.
76
compare DNA and RNA?
monomers - DNA contains the base thymine whereas RNA contains uracil.
DNA contains the pentose sugar deoxyribose whereas RNA contains the pentose sugar
polymers - DNA is much larger because it contains the entire genome whereas RNA is much shorter as its only the length of 1 gene.
DNA is double stranded but RNA is single stranded.
77
what is semi conservative replication?
step 1 - DNA helicase breaks the hydrogen bonds between the complementary base pairs between 2 strands within a double helix, this causes the helix to unwind.
step 2 - each of the separated parental DNA strands act as templates. Free floating nucleotides within the nucleus are attracted to their complementary base pairs on the template strands of the parental DNA.
step 3 - the adjacent nucleotides are joined together by condensation reactions. DNA polymerase catalyses the joining together of adjacent nucleotides
step 4 - the 2 sets of daughter DNA contains 1 strand of the parental DNA and 1 newly synthesised strands.
78
who discovered DNA?
Watson and crick discovered the structure of DNA in 1953 helped by Rosalind Franklins research on x-ray diffraction.
79
what is the hypothesis on semi conservative replication?
each replicated DNA molecule contains 1 of the original DNA strands snd 1 newly synthesised DNA strand.
80
what is the hypothesis on conservative replication?
the original DNA remains intact following DNA replication and the 2 newly synthesised strands join together.
81
explain meselon and stahl experiment
conducted experiment which proved DNA replication must be semi-conservative
82
what is the structure of water?
is a dipolar molecule and has an unevenly distributed charge due to the fact that the oxygen atom is slightly negative and hydrogen slightly positive.
83
why does water need to be metabolic?
is involved in many reactions e.g photosynthesis so essential that 90% of plasma in blood is water and cytoplasm in cells in largely composed of water.
84
why does water need to be a solvent?
polar or charged molecules dissolve readily in water due to the fact water is dipolar. The slight positive charge on hydrogen atoms will attract any negative ions solutes and the slight negative charge on oxygen atoms will attract any positive ions solutes. the polar molecules are described as hydrophilic. this enables substances to be transported easily around animals and blood or xylem to cells.
85
why does water need to have a large latent heat capacity?
means lots of energy is required to convert water in its liquid state to gas due to hydrogen bonds as energy is needed. it is an advantage to all organisms as it means water provides a cooling affect e.g sweating releasing heat.
86
why does water need to have a high specific heat capacity?
lots of energy required to raise the temperature of water as energy is needed to break the bonds between hydrogen. this means the temperature of water stays relatively stable so if surrounding temperatures fluctuate internal temperature will remain relatively constant. this means enzymes won't denature
87
why does water need strong cohesion?
sticking together by hydrogen bonds, due to water sticking together when water moves up the xylem due to transpiration its a continuous column of water as it is easier to draw up then individual molecules. also provides surface tension to water which enables small invertebrates to move and live on the surface providing them a habitat away from predators.
88
what is the structure of ATP?
contains 3 inorganic phosphate ions for energy transfer which is essential to metabolism. are inorganic as they don't contain phosphate groups
adenine - a nitrogenous base
ribose - a pentose sugar
89
how is ATP made?
made during respiration from ADP, can by hydrolysed into ADP + Pi using enzyme ATP hydrolyse. By breaking bonds between inorganic phosphate groups in hydrolysis reaction a small amount of energy is released to surroundings.
90
what is phosphorylation?
can only transfer energy to different compounds. inorganic phosphate released during the hydrolysis of ATP can be bonded onto different compounds to make them more reactive.
