Biological Molecules Flashcards
(150 cards)
1
Q
What is an electrolyte?
A
An ion in solution
2
Q
What are 2 things calcium ions are necessary for?
A
Nerve impulse transmission
Muscle Contraction
3
Q
What are the 2 things sodium ions are necessary for?
A
Nerve impulse transmission
Kidney Function
4
Q
What are the 2 things potassium ions are necessary for?
A
Nerve impulse transmission
Stomatal opening
5
Q
What are the 2 things hydrogen ions are necessary for?
A
Catalysis of reactions
pH determination
6
Q
What is the key thing ammonium ions are necessary for?
A
Production of nitrate ions by bacteria
7
Q
What is the key thing nitrate ions are needed for?
A
Nitrogen supply to plants for amino acid and protein formation
8
Q
What is the key thing hydrogen carbonate ions are needed for?
A
Blood pH regulation
9
Q
What is the key thing chloride ions are needed for?
A
Balance positive charge of sodium and potassium ions within cells
10
Q
What are the 3 things phosphate ions are needed for?
A
Cell membrane formation
Nucleic acid and ATP formation
Bone formation
11
Q
What 2 things are hydroxyl ions needed for?
A
Catalysis of reactions
pH determination
12
Q
What elements are present in carbohydrates?
A
Carbon, Hydrogen, Oxygen
13
Q
What elements are present in lipids?
A
Carbon, Hydrogen, Oxygen
14
Q
What elements are present in proteins?
A
Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur
15
Q
What elements are present in nucleic acids?
A
Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus
16
Q
What are polymers?
A
Long repeating chains made up of monomers
17
Q
What does polar mean?
A
Regions of positivity and regions of negativity
18
Q
What are 3 unusual properties of water?
A
High boiling point
Cohesive
Solid less dense than liquid
19
Q
What is capillary action?
A
The process of water rising up tubes against the force of gravity
20
Q
What are the two different types of glucose?
A
Alpha and Beta
21
Q
What bond is formed when two glucose molecules join together?
A
1,4 Glycosidic Bond
22
Q
What type of reaction is it when two glucose molecules join together? Why?
A
Condensation reaction, water molecule released
23
Q
How do you create maltose?
A
Alpha Glucose + Alpha Glucose
24
Q
How do you create sucrose?
A
Glucose + Fructose
25
How do you create lactose?
Glucose + Galactose
26
What are pentose monosaccharides?
Sugars that contain 5 carbon atoms
27
What are hexomonosaccharides? Give 3 examples
Sugars with 6 carbons, glucose, galactose and fructose
28
What are hexomonosaccharides? Give 3 examples
Sugars with 6 carbons, glucose, galactose and fructose
29
What bonds are in amylose, what shape does the lead to?
1,4 glycosidic
| Helix shape
30
What are the bonds in amylopectin, what shape does this lead to?
1,4 and 1,6 glycosidic
| Branched monomer
31
What is the equivalent of starch in animals and fungi?
Glycogen
32
Does amylose or amylopectin release glucose faster, why?
Amylopectin, branching leads to more exposed bonds and so is broken down more easily and quickly
33
Describe solubility of amylopectin and glycogen
Insoluble
34
How is glucose released for respiration?
Hydrolysis reactions, breakdown using water into constituent monomers
35
How does cellulose form?
When alternate beta glucose molecules flip 180 so that 1-4 glycosidic bonds can form
36
What is the shape of cellulose?
Straight chain molecule
37
List process of building up from cellulose to cell walls
```
Cellulose,
Hydrogen bonds form,
Microfibrils
Macrofibrils
Cell walls
```
38
How is cellulose important to humans?
Provides roughage as part of diet as it is hard to break down
39
What is the Benedict’s test for and what is it?
Reducing sugars, copper sulfate
40
Explain in 3 steps the Benedict’s reagent test
1) Place sample in boiling tube, if not liquid grind and add water
2) Add equal volume of Benedict’s reagent
3) Heat mixture gently in boiling water Bath for 5 minutes
41
Explain the chemical reaction occurring in a Benedict’s test
Cu 2+ ions react with the reducing sugars, this adds electrons. Cu2+ is reduced to Cu+ forming a red precipitate
42
What is the positive test for the Benedict’s reagent?
Brick-Red precipitate
43
Why does the colour of the solution vary on volume of Benedict’s solution?
The more reducing sugar present, the more precipitate will be formed because less Cu2+ ions are left in solution, so creating a deeper red colour.
44
What are 3 main colours seen during the Benedict’s test? What do they indicate?
Green- low concentration of reducing sugar
Yellow- medium concentration of reducing sugar
Red- high concentration of reducing sugar
45
Is the Benedict’s test qualitative or quantitative?
Qualitative
46
What is the extra step required in the Benedict’s test for non-reducing sugars?
The non-reducing sugar is boiled in hydrochloride acid to hydrolyse into two constituent monomers which are reducing sugars
47
What is the colour change(from and to) in the iodine test?
Yellow/Brown to purple/black
48
What does the iodine test test for?
Starch
49
Explain the method for the iodine test for starch
```
Iodine solution(potassium iodide) added to sample
Wait for colour change
```
50
What are reagent strips used to test for? Why is it beneficial?
Reducing sugars, use of a colour coded chart the concentration of sugar can be determined
51
What is a colorimeter?
A piece of equipment used to quantitatively measure absorbance, transmission or light by a coloured solution
52
Discuss the polarity of lipids, explain why it is this way
Non-polar molecules
Elections in outer orbitals distributed more evenly
No positive or negative areas so non- polar
53
What type of molecule is a lipid? Explain what this term means
Macromolecules
| Large complex molecule built from monomers
54
What is a triglyceride made of?
One glycerol molecule, 3 fatty acids
55
What group of molecules do fatty acids belong to? Why?
Carboxylic acids. Have a -COOH group with a hydrocarbon chain
56
What is an esterification reaction?
Hydroxyl groups on glycerol and fatty acids interact.
3 water molecules are produced
Ester bonds for between glycerol and fatty acid
57
How do you break a triglyceride down?
Hydrolysis reaction using 3 water molecules
58
What is a saturated fatty acid?
Fatty acid chains which contain no double bonds present between carbon atoms, all carbons are taken up with max number of hydrogens
59
What is an unsaturated fatty acid?
A fatty acid with double bonds between some of the carbon atoms
60
What is the result of an unsaturated fatty acid?
Causes kinks in the molecule
Cannot pack so closely
Liquid at room temp rather than solid
61
What lipid do plants contain?
Unsaturated triglycerides
62
What is a phospholipid made from?
2 fatty acids, glycerol and a phosphate group
63
Explain the hydrophilic/hydrophobic nature of a phospholipid bilayer
Due to its length the phospholipid bilayer has a hydrophobic tail and a hydrophilic head
64
Why is a phospholipid called a surfactant?
Forms a layer on the surface of the water with phosphate heads in the water and fatty acid tails sticking out of the water
65
What is the structure of a sterol?
4 ring carbons structure with a hydroxyl group on the end
66
How do sterols have a dual hydrophobic/ hydrophilic nature?
Hydroxyl group is polar so hydrophilic, rest of molecule is hydrophobic
67
What type of molecule is cholesterol? What is its function?
Sterol. Adds stability to membranes and regulates their fluidity
68
What are the 4 biological roles of lipids?
Membrane formation and creation of hydrophobic barriers
Hormone production
Electrical insulation necessary for impulse transmission
Waterproofing
69
Where are lipids stored within the body?
Under the skin and around vital organs
70
What function do lipids provide in the skin and vital organs?
Thermal insulation
Cushioning to protect organs
Buoyancy
71
Explain the method for the emulsion test
Sample mixed with ethanol
Water added and shaken
White emulsion forms a layer on top- lipid present
72
What is a peptide?
A polymer made up from amino acid molecules
73
How many amino acids are found in cells?
20 different amino acids
74
How do two proteins synthesise to form a dipeptide?
Amine and carboxylic acid groups connected to the central carbon atoms react. The hydroxyl in the carboxylic acid group reacts with hydrogen in amine group to form a peptide bond
75
What catalyses the reaction of a polypeptide being formed?
Peptidyl transferase
76
What is the primary structure of the protein?
Sequence in which the amino acids are joined. Only involves peptide bonds.
77
What is secondary structure of the amino acid?
Hydrogen bonds forming within the amino acid chain, pulling into a specific shape.
78
What are the two shapes that can form during secondary proteins? What does this mean?
Alpha helix- hydrogen bonds pull into a coil shape
| Beta pleated sheet- polypeptide chains lying parallel to each other with hydrogen bonds between them
79
What is the tertiary structure of a protein?
Folding of a protein into its final shape, secondary structure pulls R groups close enough that they can interact.
80
What are hydrophobic hydrophilic interactions?
Weak interactions between polar and non-polar R groups
81
What are ionic bonds?
Bonds formed between oppositely charged R groups
82
What are disulfide bridges?
Covalent bonds that form between R groups that contain sulfur atoms
83
How many amino acids are common in the human body?
20
84
How do two peptides join together?
Amine and carboxylic acid group connected to central atoms react. Hydroxyl groups of one amino acid reacts with a hydrogen in the amine group.
85
Why type of reaction is it when two peptides react?
Condensation
86
What enzyme catalyses reaction of formation of polypeptide chains?
Peptidyl transferase
87
What is primary protein structure?
The sequence in which the amino acids are joined
88
What bonds are present in the protein structure?
Peptide bonds
89
What is the secondary protein structure?
The basing repeating structure of amino acids interact and hydrogen bonds are formed within the amino acid chain
90
What two shapes are formed from secondary protein structure? Explain the shapes.
Alpha Helix- coil shape of amino acids with hydrogen bonds between the helix
Beta Pleated Sheet- Polypeptide chains lying parallel to each other with hydrogen bonds between
91
What is the tertiary structure?
The folding of protein into its final shape. Coiling and folding in secondary brings R groups close enough to interact, holding sections together.
92
What are hydrophobic and hydrophilic interactions?
Weak interactions between polar and non-polar R groups
93
What are ionic bonds?
Bonds between oppositely charged R groups
94
What are disulfide bridges?
Covalent bonds between R groups that contain sulfur atoms
95
What is the quaternary structure?
Interaction between 1 or more polypeptide chains
96
How are peptides broken down?
Protease enzyme breaks down the peptide into its constituent amino acids
97
Give 3 features of a globular protein
Compact
Water Soluble
Spherical
98
When do globular proteins form?
Hydrophobic R groups are moved into the middle to be kept around the aqueous environment. So hydrophilic R groups on the outside
99
Why does insulin have to be globular?
Hormone involved with the regulation of blood glucose concentration.
Hormones transported in blood stream so needs to be soluble
Hormones have to fit specific receptors on cell surface membranes so need to have precise shape
100
What are conjugated proteins?
Globular proteins with a prosthetic group
101
What is a prosthetic group?
A non-protein part of a protein
102
Give 4 examples of molecules that make up prosthetic groups
Lipids
Carbohydrates
Metal ions
Vitamins
103
Explain the structure of haemoglobin
Quaternary protein made up of 4 polypeptide chains, two alpha and two beta subunits, 4 haem groups
104
What does haem contain, and what is its role?
Fe II, allows it to combine reversibly with an oxygen molecule
105
What prosthetic group does catalase contain? What does this allow for?
Fe II ions, allow catalase to interact with hydrogen peroxide and speed up its breakdown.
106
What are fibrous proteins made from?
Long insoluble molecules
107
Give 3 examples of fibrous proteins
Keratin, Elastin and Collagen
108
Why do fibrous proteins form?
High proportion of amino acids with hydrophobic R groups, and a limited range of amino acids with small R groups
109
What is the structure of a fibrous protein?
Strong, long molecules which do not fold into 3D molcules
110
Where is keratin found?
Hair, skin and nails
111
What characteristics does keratin have? Why?
Strong, Inflexible and Insoluble
| Due to high proportion of disulfide bridges which decrease flexibility
112
What is elastin made from?
A quaternary protein made of tropoelastin
113
Where are elastic fibres found? Why?
Walls of blood vessels and alveoli
| Give structures flexibility
114
What is collagen and where is it found?
Fibrous protein that is a connective tissue found in skin, tendons, ligaments and the nervous system.
115
Describe the structure of collagen
3 polypeptide chains wound in a long strong rope-like structure
116
What are the 2 roles of nucleic acids?
Storage and transfer of genetic material
| Synthesis of polypeptides
117
What 3 components make up a nucleotide?
A pentose monosaccharide
A phosphate group
A nitrogenous base
118
Explain how two nucleotides join together
Condensation reaction
Phosphate group on 5th carbon forms a covalent bond (phosphodiester) with hydroxyl group on 3rd carbon of the pentose sugar on adjacent nucleotide
119
What type of bond is formed when two nucleotides join together?
Phosphodiester
120
What structure is a polynucleotide said to have?
A long strong sugar phosphate backbone with a base attached to each sugar
121
What are pyrimidines? Give 2 examples
Small bases which contain one single carbon ring
| Thymine and Cytosine
122
What are purines? Give 2 examples
Large bases which contain a double carbon ring structure
| Adenine and Guanine
123
What does it mean for DNA to be 'anti parallel'?
Each strand has a phosphate group at one end and hydroxyl group at the other. The two strands run in opposite direction.
124
In complementary base pairing, describe which pairs join and how many hydrogen bonds they form
Adenine and Thymine- 2 hydrogen bonds
| Cytosine and Guanine 3 hydrogen bonds
125
How do the two strands of DNA remain parallel?
As a purine always binds to a pyrimidine, so there is a constant distance
126
What are 2 structural differences of RNA to DNA?
Ribose rather than deoxyribose
| Uracil rather than thymine
127
Explain the 4 steps in semi conservative replication
1) DNA helicase causes two strands of DNA to separate
2) Free nucleotides activated are attracted to complementary bases
3) Hydrogen bonds formed between nucleotides and complementary bases
4) DNA polymerase catalyses formation of phosphodiester bonds between adjacent nucleotides.
128
What is semi conservative replication?
Two new molecules of DNA produced from one strand. Each one consists of one old strand of DNA and one new strand.
129
What is the role of DNA helicase?
Enzyme that travels along DNA backbone, breaking hydrogen bonds between complementary base pairs. 'Unzipping' them
130
What is the role of DNA polymerase?
Catalyses the formation of phosphodiester bonds between nucleotides
131
What is the genetic code?
The sequences of bases in DNA are the 'instructions' for the sequences of amino acids in the production of proteins.
132
What is a codon?
A sequence of 3 bases coding for 1 amino acid
133
What is a gene?
A section of DNA that contains the complete sequence of bases to code or an entire protein
134
What is the most common start protein?
Methionine
135
Why is genetic code said to be 'degenerate'?
Many amino acids can be coded for by more than one codon
136
Where does protein synthesis occur?
Ribosomes in the cytoplasm
137
What is the process of 'transcription'?
The base sequence of genes being copied and transported on to smaller molecules of RNA so they can move out of the nucelus.
138
What is the sense strand?
Strand of DNA that contains the code for the protein to be synthesised
Runs from 5' to 3'
139
What is the anti-sense strand?
Complementary copy to the sense strand
| Acts as a template strand so complementary RNA strand formed has the same sequence as the sense strand
140
Explain the process of transcription
1) Section of DNA unzips via DNA helicase
2) Free RNA nucleotides pair with complementary bases on anti-sense strand
3) Phosphodiester bonds are formed by RNA polymerase
4) Stops at the end of the gene and mRNA is formed
5) mRNA detaches from DNA template and leaves via nuclear pore
141
What are the two roles of rRNA?
Maintaining structural stability
| Biochemical role in catalysing reaction
142
What is the process of translation?
mRNA binding to a specific site on a small subunit of ribosome
Ribosome holds mRNA in position whilst it is decoded into sequence of amino acids
143
What is an anti codon?
A sequences of 3 bases on the tRNA that is complementary to specific codon on mRNA
144
Where is energy supplied from for translation?
Hydrolysis of ATP
145
Describe 5 step process of translation
1) mRNA binds to ribosome
2) tRNA with specific anticodon and amino acid binds to mRNA
3) another tRNA molecule binds to next complementary codon
4) 1st amino acid binds to 2nd amino acid via peptide bond and peptidyl transferase
5) tRNA leaves mRNA moves along
146
What are the 3 main types of cell activity that require energy?
Synthesis
Transport
Movement
147
What is ATP made up of?
Adenine, Ribose, 3 phosphate groups
148
What is the process of phosphorylation?
Reattaching a phosphate group to a molecule of ADP
149
Explain 5 key properties of ATP
```
Small
Water Soluble
Contains bonds with phosphates with intermediate energy
Releases energy in small quantities
Easily regenerated
```
150
How is energy released by cells?
ATP converted to ADP, the phosphate ion releases energy
