Carbohydrates, Lipids and proteins

Question 1

What are Monosaccharides?

Answer 1

Are simple sugars and are smallest sugars (monomer)

Act as a source of immediate energy

Examples:
1. Glucose (Glucose in living things D-glucose)
2. Fructose
3. Galactose
(Glucose and fructose have 6 carbons)

Question 2

What are Monomers?

Answer 2

Simple molecules with one or two bonding sites

Used to build big molecules (polymers)

Question 3

What are Polymers?

Answer 3

Large molecules is made of a chain of recurring simple molecules (Monomers)

Question 4

Isomers

Answer 4

Molecule. with the same chemical formula but a different structural formula
(an isomer of glucose —-> galactose)

Question 5

What are Disaccharides?

Answer 5

2 simple sugars attached together (pairs of Monosaccharides linked together) through condensation

Have a double ring structure

Used to transport energy & can be the product of the digestion of starch (Maltose)

Examples

1. Lactose
   (Glucose + Galactose ——> Lactose + H20)
   (keynote: lactose is sugar found in milk & transport energy from mother to offspring)
2. Sucrose
   (Glucose + Fructose ——-> Sucrose + H20)
3. Maltose
   (Glucose + Glucose —–> Maltose + H20)

Question 6

What are Polysaccharides

Answer 6

3 or more simple sugars linked together
(Examples: starch, glycogen, chitin & cellulose)

Used for energy storage & Structural support

Stored as starch for plants. —- (polymer of a-D glucose)
two forms of starch
1. Amylose — has 1,4 linkage (unbranched)
2. Amylopectin — has 1,6 linkage (branched)

Stored as glycogen (within the liver and muscles) for animals —(polymer of a-D glucose)
Gllycogen – (has 1,6 linkage. – branched)

Structural support polysaccharides
Chitin (found exoskeleton of insects) —
Cellulose (found in cell wall) —- unbranched polymer of B-D glucose) – molecules have a parallel arrangement

Question 7

1,4 linkage & 1,6 linkage

glycosidic bonding

Answer 7

1,4 linkage (glycosidic bond) is formed between the carbon-1 of one monosaccharide and carbon-4 of the other monosaccharide.

1,61,4 linkage (glycosidic bond) is formed between the carbon-1 of one monosaccharide and carbon-6 of the other monosaccharide.

Question 8

What are Lipids?

Answer 8

Carbon compounds that are most or entirely hydrophobic

used as long term energy storage
- are six times more efficient in energy stored per gram of body mass than. glycogen or starch

Question 9

Types of Lipids?

Answer 9

1. Triglycerides — three fatty acids linked to glycerol linked by condensation reaction. This condensation reaction results in the formation of three molecules of water. Triglycerides can be either saturated or unsaturated, depending on the composition of the fatty acid chains

(Examples: fats and oils — contain more energy than carbohydrates but difficult to digest)

2. Phospholipids — two fatty acids linked to glycerol with a phosphate group
   (Examples: Phosphilipid bilayer)
3. Steroids — four fused ring molecules
   (examples: cholesterol, progesterone, estrogen, and testosterone)

Question 10

What are fatty acids?

Answer 10

Are components of lipids

are carboxylic acid consisting of an unbranched hydrocarbon chain and end with carboxyl group

Question 11

Types of Fatty acids?

Answer 11

(Hydrocarbon chain determines type of fatty acid)

1. Saturated —- all carbon atoms in hydrocarbon chain linked by single covalent bonds
   (hydrogen atoms bonded to carbon cannot increase)
2. Unsaturated —- contain one or more double bonds between carbon atoms in hydrocarbon chain
   (hydrogen atoms bonded can increase)

Types of Unsaturated fatty acids

1. Monounsaturated — only has one double bond
2. Polyunsaturated — two or more double bonds
3. Cis unsaturated — hydrogen atoms bonded to carbon atoms on same side of double bond
4. Trans unsaturated — hydrogen atoms bonded to carbon atoms on opposite side of double bond

Question 12

Body mass index

Answer 12

body mass can just be measured by just weight

body mass index = mass in kilograms/height in meters squared

Question 13

Evaluate the Health risk of Trans fats and Saturated fatty acids and describe the relationship between correlation and causation

Answer 13

Key note: LDLs raise blood cholesterol levels (‘bad’) while HDLs lower blood cholesterol levels (‘good’)

1) Argument
Trans fats — banned in most countries — are artificially made — associated to coronary heart disease (CHD). Trans fats increase LDL levels and decrease HDL levels within the body, significantly raising blood cholesterol levels. High cholesterol levels in the bloodstream lead to the hardening and narrowing of arteries (atherosclerosis). When there are high levels of LDL in the bloodstream, the LDL particles will form deposits in the walls of the arteries. The accumulation of fat within the arterial walls lead to the development of plaques which restrict blood flow. If coronary arteries become blocked, coronary heart disease (CHD) will result – this includes heart attacks and strokes

Counter argument
Genetic factors may play a role (e.g. blood cholesterol levels only show a weak association to dietary levels).

2) Argument #2
Saturated (fats) fatty acids also increase LDL levels within the body, raising blood cholesterol levels and also have been correlated to CHD.
These health claims are made based on evidence collected in a number of ways:
1) Epidemiological studies comparing different population groups
2) Intervention studies that monitor cohorts following dietary modifications
3) Experimental designs utilising animal models or data based on autopsies

Counterargument
In some populations no correlation was found between high intake Saturated (fats) fatty acids and CHD. (example: Maasi people in Kenya — rare to no CHD yet diets are rich in saturated fatty acids). Furthermore, Validity of intervention studies is dependent on size and composition of cohort, as well as the duration of the study

Conclusion
- shown statistical correlations may not be linked with causation in some instances (positive correlation between CHD & saturated fatty acids doesn’t prove saturated fats cause CHD)

Question 14

What is Emulsion Test for Lipids

Answer 14

1. Alcohol dissolves oils and fats —- mix with ethanol
2. Add a small amount of water to solution
3. Cloudy appearance will show – a positive indication that lipids are present

Question 15

Monomers of Protein

Answer 15

Peptide

Building block of basic structure

Question 16

What is an amino acid?

Answer 16

a simple organic compound containing both a carboxyl (—COOH), an amine (—NH2) group, a hydrogen (H) atom along with an (R group)
(amino acids are linked by condensation reactions)

R group of amino acid is variable —- cause of difference between amino acids (makes them vary)

20 different types of amino acids (naturals types) — (not synthesized in a lab) — (20 different R groups)

9 amino acids (made from food) —– essential
11 amino acids (we make in our body) —– non-essential

Question 17

Dipeptide and Polypeptide

Answer 17

Dipeptide — two amino acids linked together by peptide bond

Peptides —- (chain of 40 or fewer amino acids are called peptides) – anything more in a polypeptide

Polypeptide —- many amino acids (a long chain of unbranched amino acids) linked by peptide bonds (can be as many as 10,000)
- over 2 million polypeptides have been found in living organisms

Question 18

What is a Protein?

Answer 18

single polypeptide or more than one polypeptide linked together

Question 19

What codes an amino acid sequence?

Answer 19

a gene

Question 20

Proteome

Answer 20

all protein produced by a cell, tissue or an organism
(
is variable as different cells in an organism can make different proteins)

Each person has a unique proteome (with the possible exception of identical twins )

Question 21

What are the different levels of Protein Structure?

Answer 21

1) Primary Structure —- linear arrangement of amino acids

(all documented genetic disorders, such as cystic fibrosis, sickle cell anemia, albinism, etc., are caused by mutations resulting in alterations in the primary protein structures, which in turn lead to alterations in the secondary, tertiary structure)

2) Secondary Structure —- recurring arrangement of amino acids with beta-pleated sheets and were alpha helix forms (due to hydrogen bonds between different parts of the protein)

(Examples —Keratin (found in hair)

3) Tertiary Structure — the arrangement of the secondary structures into this final 3-dimensional shape that folds over as a result of disulfide bridges)

(Examples — myoglobin & Hemoglobin)

structures are stabilized by intramolecular bonds

4) Quaternary structure — the arrangement of more than one protein molecule in a multi-subunit complex. Each of the subunits has its own primary, secondary, and tertiary structure. The subunits are held together by hydrogen bonds and van der Waals forces between nonpolar side chains. These proteins often consist of more than one polypeptide chain linked together. Alternatively, proteins may have a quaternary structure if they include inorganic prosthetic groups as part of their structure. Not all proteins will have a quaternary structure – many proteins consist of a single polypeptide chain

(Example — Hemoglobin)

Question 22

Functions of Protein

Answer 22

1. Structural support
   (Collagen –glue of body – holds the body together – bones, muscles etc)
   (used in skin to prevent tearing)

Another example
(Spider Silk — protein that makes web used for catching prey)

2. Hormone production
   (example: Insulin:Protein produced by the pancreas and triggers a reduction in blood glucose levels)
3. Production of Antibodies
   (Immunoglobulins: antibodies involved in immune response that bind to antigens on pathogens)
4. Acts as a Pigment
   (Example: Rhodopsin: A pigment in the photoreceptor cells of the retina that is responsible for the detection of light)
5. Acts as an Enzyme
   (Example: Rubisco: An enzyme involved in the light-independent stage of photosynthesis)
6. Used for transport
   (Example: hemoglobin: A protein found in red blood cells that is responsible for the transport of oxygen

Question 23

How does Denaturation in Protein take place?

Answer 23

Basically, how do they stop functioning

1. Heat (high temperature)
2. High or low PH

Question 24

How do Test for Protein in Food?

Answer 24

Bluret Test

1. Put NaOH and protein into a test tube
   (let the reaction take place for a few minutes)
2. Add copper sulphate into solution (only a drop or a few droplets)
   (if protein is present it becomes purple)