Biomolecules Flashcards
1
Q
Which biomolecule contains glycosidic bonds?
A
Carbohydrates
2
Q
What type of bond is found joining amino acids?
A
Peptide bonds
3
Q
What biomolecules can be used for energy storage?
A
Carbohydrates and lipids
4
Q
Describe the structure of a phospholipid (triglyceride) molecule
A
- Glycerol
- Three fatty acids
- Ester bond
- Phosphate
5
Q
Describe the two fatty acids in a triglyceride molecule
A
- Unsaturated
- Containing less than the maximum number of H atoms
6
Q
What molecule is this? What does it consist of?
R
|
H2N - C - COOH
|
H
A
Amino acid
- Amino group (H2N)
- Carboxyl group (COOH)
- 20 group ‘H’
7
Q
Lipids are insoluble in H2O because they are:
A
Hydrophobic
8
Q
What is lactose composed of?
A
Glucose and galactose
9
Q
What is cellulose made up of?
A
Unbranched chain of glucose molecules linked by β 1,4 glycosidic bond
10
Q
Which purine base is found in RNA?
A
Guanine
11
Q
Amino acids are produced by:
A
Proteins
12
Q
Name three polysaccharides:
A
Glycogen, cellulose and starch
13
Q
What is the most common monomer of a carbohydrate
A
Glucose
14
Q
Is cholesterol a steroid?
A
Yes, carried in the bloodstream by lipoproteins (LDL and HDL)
15
Q
Which is a linear polysaccharide?
- Glycogen
- Starch
- Cellulose
A
Cellulose
16
Q
What type of test is used in determining the presence of carbohydrates?
A
Benedict’s reagent
17
Q
Glucose is a …..
A
Monosaccharide
18
Q
The three classifications of carbohydrates are:
A
Monosaccharide, disaccharide, and polysaccharide
19
Q
Bad cholesterol refers to?
A
Low Density Lipoproteins, high levels of LDL cholesterol raise your risk for heart disease and stroke
20
Q
Which class of lipids is a major component of cell membrane?
A
Phospholipids
21
Q
What biomolecule do enzymes belong to?
A
Proteins
22
Q
What are monomers and polymers?
A
Monomers are the smaller units from which larger molecules are made. Polymers are molecules made from a large number of monomers joined together
23
Q
When does hydrolysis take place?
A
Digestion of carbohydrates
24
Q
Benedict’s solution consists of:
A
Copper sulphate
25
Joining of two monosaccharides takes place by the process of....
Condensation reaction
26
What elements are organic molecules mainly composed of?
- Oxygen
- Hydrogen
- Carbon
- Nitrogen
27
What is the most abundant organic molecule?
Carbohydrates
28
Functions of carbohydrates?
- Storage form of energy
- Component of the cell membrane
- Structural components of many organisms
- Dietary requirement
29
Monosaccharides are equivalent to:
- 1 saccharide (glucose and fructose)
30
Disaccharides are equivalent to:
- 2 monosaccharides (sucrose, maltose, lactose)
31
Oligosaccharides are equivalent to:
- 3-10 monosaccharides (raffinose, maltotriose, oligofructose
32
Polysaccharides are equivalent to:
>10 monosaccharides (starch - linear, dextrin - branched)
33
What are trioses?
- Consist of 3 carbon atoms
- Glyceraldehyde
- Dihydroxyacetone
34
What are tetroses?
- Consists of 4 carbon atoms
- Erythrose
- Erythrulose
35
What are pentoses?
- Consists of 5 carbon atoms
- Ribose
- Ribulose
36
What are hexoses?
- Consists of 6 carbon atoms
- Glucose
- Fructose
37
Define isomers
Compounds that have same chemical formula but have different structures
38
Chemical formula for glucose, galactose and fructose:
C6H12H06
39
Define epimers
Carbohydrate isomers that differ in configuration around only one specific carbon atom (except carbonyl carbon)
40
What are enantiomers?
Mirror images (monosaccharides)
41
In the cyclization of monosaccharides if the OH group faces down its?
alpha-D-Glucopyranose
42
In the cyclization of monosaccharides if the OH group faces up its?
beta-D-Glucopyranose
43
Glycosidic bond for lactose:
beta (1 --> 4)
44
Glycosidic bond for maltose:
alpha (1 --> 4)
45
Glycosidic bond for sucrose:
alpha (1 --> 2)
46
Importance of glucose:
- The main sugar in the human body
- Important energy source in all cells (can't be stored in this form as it affects osmotic balance)
- Glucose is stored in large polymers (glycogen) which are osmotically inactive
- Ribose in nucleotides and nucleic acids
- Form glycoproteins, glycolipids and lipids
- Present in the plasma membrane
47
Where and how is glucose stored?
- Stored mainly in muscle and liver cells, in the form of glycogen
48
What is starch made of and where is it stored?
- Storage form of glucose in plants
| - Composed of two long polysaccharides of glucose
49
What are the polymers of starch?
- Amylose (linear)
| - Amylopectin (branched)
50
What is cellulose?
- Structural carbohydrate (plant cell walls)
- Most abundant organic molecule on earth
- Commonly known to be a fibre and largely indigestible (mammals lack it)
- Chains of beta glucose joined by beta 1.4 glycosidic bonds
51
How are complex carbohydrates formed?
When glycosidic bonds of carbohydrates are attached to non-carbohydrate structures (including: purine, pyrimidine bases (found in nucleic acids), proteins and lipids
52
Function of proteins
- Enzyme catalysts
- Transport
- Storage
- Motion
- Mechanical support
- Immune protection
- Growth and differentiation
53
How many amino acids are there?
20
54
Function of R group in an amino acid:
The physical and chemical characteristics of the R group determine the unique characteristics of a particular amino acid
55
What is phosphorylation?
A very important regulatory switch in a wide variety of protein signalling pathways, channels, transporters and enzymes
56
In eukaryotes, Proteins may be
| phosphorylated at:
- Serine
- Threonine
- Tyrosine
57
Polypeptides are a chain of amino acids
Amino acids are covalently linked together via peptide bonds - condensation reaction
58
Peptide bond
- Uncharged at any pH
- Partial double bond character (therefore no freedom of rotation
- Not easy to break (requires very high acidic conditions and high temp)
59
Levels of protein structure include:
- Primary (linear structure)
- Secondary (simple structures)
- Tertiary (complex 3D shape of the protein)
- Quaternary (arrangement of subunits in multi-polypeptide proteins
60
Primary structure of a protein:
- Linear
- Simplest protein
- How they are synthesised
61
Secondary structure of a protein:
- Brought about via hydrogen binding
- alpha helix (intrachain)
- beta sheet (between strands)
62
Tertiary structure of a protein:
- Determines by the interactions of 2nd structure
- H-bonds
- Ionic bonds
- Hydrophobic bonds
- Disulfide bonds
- Van Der Waal's bonds
63
Quaternary structure of a protein:
- Assembly of two or more polypeptide subunits
| - 3D complex
64
How can protein structure be disrupted?
- pH
- Temp
- Chemicals
- Not easily reversed
65
What are lipids?
- Group of water insoluble molecules, that can't be extracted from tissues by non-polar solvents
- Not polymers
- Oxidation of lipids releases large amount of energy
66
List the type of lipids:
- Fatty acids
- Triacyglycerols
- Phospholipids
- Sphingolipids
- Steroids
67
Describe features of fatty acids:
- A long hydrocarbon chain with a carboxyl group
- 4 to 40 carbons
- Saturated or unsaturated fatty acids
68
Saturated fats
- Most animal fats are saturated
| - Solid at room temp
69
Unsaturated fats
- Plants and fish fats, known as oils, are liquid at room temp
- Double bonds cause chain kinks when prevent packing
70
Function of fats
- Energy storage (stores more than twice the energy as polysaccharide eg, starch or glycogen)
In mammals
- Fats stored in adipose tissues
- Cushion vital organs
- Insulation
71
Briefly describe phospholipids
- Major component of cell membrane
| - Glycerol + 2 FA's + Phosphate group
72
Briefly describe sphingolipids
- Based on sphingosine (C18 amine alcohol)
| - FA's and R groups are added
73
Function of sphingosine
- Cell recognition - carbohydrate
- Signalling
- Lipid rafts
74
What are steroids?
They are lipids with a common carbon skeleton consisting of four fused carbon rings
Different steroids are created by varying functional groups attached to the rings
75
What is cholesterol?
- The principle steroid synthesised by mammals
- Component of eukaryotic cell membranes
- Precursor from which all other steroids are synthesised
- Many of these steroids are hormones, including vertebrate sex hormones
76
Summary of lipids
- Class of hydrophobic compounds
- Not biopolymers
- FA's long chain carboxylic acids
- FA's may be saturated or unsaturated
- TAG's are 3 FA's esterised to glycerol
- Sphingolipids use a sphingosine backbone and may have functional R group
- Cholesterol is the major steroid synthesised in mammals
