Section 5: Molecules of Life - Macromolecules Organic molecules contain carbon and hydrogen atoms A) Type of macromolecules 4 types: Name Carbohydrates Lipids Proteins Nucleic acids subunit monosaccharides Glycerol + 3 fatty acids Amino acids nucleotides B) Chemical reactions -forms macromolecules and takes them apart: Subunits + subunit Dehydration synthesis Hydrolysis macromolecule + H2O Dehydration synthesis -making macromolecules from subunits - Water is given off Hydrolysis macromolecules break apart in presence of water to re-form subunits
C) Carbohydrates i. Why group these molecules? Characterized by presence of this molecule grouping H C OH (CHO) Ratio of H to O is approximately 2 to 1 same as with H2O (water) so that s why they are called hydrates of carbon carbohydrates ii. Function used for quick and short term energy storage in cells. iii. Types of carbohydrates 1. Simple carbohydrates a. Monosaccharides 3 to 7 carbons (1 ring) i.e.; glucose 6 carbon sugar b. Disaccharides 2 monosaccharides joined together by dehydration Synthesis ie. Maltose 2. Complex carbohydrates (aka polysaccharides) More than 2 sugar molecules joined together Macromolecules such as starch, glycogen, and cellulose contain many 1000 s of glucose units Starch from plant material, stored glucose units Glycogen from animal material, stored in liver by animals for short term storage of glucose between meals
D) Lipids i. Why group these molecules? Do not dissolve in water - hydrophobic ii. Function Diverse functions Some as hi energy storage molecules -more energy/gram than any other macromolecule Phospholipids cell membranes steroids diverse function including hormones iii. Types of Lipids 1. Fats and Oils 2. Phospholipids 3. Steroids 1. Fats and Oils Composition: Composed of glycerol + 3 fatty acids Lipid Alcohol molecule long chain hydrocarbons with COOH (organic acid) + = also called triglyceride Function: Long term energy storage Insulates against heat loss Protective cushion around major organs
Fatty Acid types in Fats and Oils Saturated No double bonds between carbon atoms Associated with cardiovascular disease because causes plaque buildup in arteries Unsaturated double bonds between carbon atoms in carbon chain (wherever the # of H is less than 2 per carbon) Polyunsaturated fats many double bonds between carbon atoms in carbon chain Trans fats chemically hydrogenated oils - semi solid - unhealthy 2. Phospholipids Composition: **important in forming cell membranes Because polar hydrophilic (water loving) head and nonpolar hydrophobic (water hating) tails: form spontaneous bilayer in water Bilayer (=2 layers) Hydrophobic tails face inward and form hydrophobic interior Hydrophilic heads face outwards towards H2O
3. Steroids Specialized lipids with backbone of 4 fused carbon rings the functional group that is attached to this backbone is what makes each steroid different from each other. Several functions, mainly hormonal ie, testosterone and estrogen Affect 2 o sexual characteristics E) Proteins - essential in the structure and function of our cells. i. Why group these molecules? a name to describe a group of macromolecules with a certain structure (to be described below) with varied functions. ii. Function 1. Support: structural proteins i.e., keratin, collagen, and elastin. Keratins strengthen protective coverings such as hair, quills, feathers, horns, and beaks. Collagens and elastin provide support for connective tissues such as tendons and ligaments. 2. Enzymes: provides location for reactants to come together and speed up chemical reactions in cells: often referred to as catalysts because they speed up chemical reactions. i.e, lactase and pepsin. Lactase breaks down the sugar lactose found in milk. Pepsin is a digestive enzyme that works in the stomach to break down proteins in food. 3. Transport: channel and carrier proteins in plasma membrane allow transport of ions and molecules into and out of cells. i.e., carrier proteins move
molecules from one place to another in the body. i.e hemoglobin carries oxygen in blood 4. Defence: antibodies formed by immune system combine with antigens: involved in defending the body from antigens (foreign invaders). One way antibodies destroy antigens is by immobilizing them so that they can be destroyed by WBC. 5. Hormones: regulatory proteins: messenger proteins which help coordinate certain bodily activities. i.e, insulin, oxytocin, and somatotropin. Insulin regulates glucose metabolism by controlling the blood-sugar concentration. Oxytocin stimulates contractions in females during childbirth. Somatotropin is a growth hormone that stimulates protein production in muscle cells. 6. Movement: contractile proteins in muscle cause movement - responsible for movement. i.e, actin and myosin. -involved in muscle contraction and movement. iii. Video: protein function Youtube...uploaded by mikedolding? Structure of proteins 1. Subunits of proteins = Amino Acid General structure all proteins have this basic structure and an R group that makes each amino acid unique. carboxylic acid (type of organic acid) Amino group Acid group R stands for the functional group this is the part that is different for each amino acid there are 20 different types of aa in humans
2. Peptides: 2 amino acids join together in a dehydration synthesis rxn- the resulting molecule is then called a peptide. Polpeptide = many peptides= many joined amino acids iv. Dehydration synthesis formation of a peptide bond H dehydration Hydrolysis v. Shapes of proteins Protein function depends on it attaining its final 3D shape this shape determines how it binds to other molecules fits like lock and key with other molecules If exposed to extreme heat or ph, proteins become denatured= becomes not natural loses natural 3D shape, so it no longer can fit into the lock and key idea of other molecules so it can no longer function like it should they lose both their secondary and tertiary structure
Bonding between R groups in aa is disturbed in the tertiary structure which is its final shape the bonding between the R groups breaks and therefore the protein loses its shape Causes irreversible change in shape of protein and therefore function: i.e. Boiling eggs If proteins in a living cell are denatured, this results in disruption of cell activity and possibly cell death. vi. Levels of protein organization: Level Shape Bonding Primary 1 o Linear chain of aa Peptide bonds between aa Secondary 2 o Helix (coiling) Pleated sheet (folding) Hydrogen bonds between aa Tertiary 3 o globular Final 3D shape and function: Ionic, covalent, hydrogen bonds btwn R groups Quaternary (rare) 4 o All shapes All bonding 2 or more associated polpeptides 1. Primary = amino acids in a line (linear) joined together by peptide bond H O H H H2N C C N C COOH R OH H R Peptide bond
Acid end of one amino acid bonds to the amine group of the next aa; Acid end is negative, amine end is positive - Therefore polar A Polypeptide = many peptides= many joined amino acids. 2. Secondary =helix coil (right handed spiral) or pleated sheet linear chain takes on 3D shape Hydrogen bonds hold 3D shape in place bond between slightly + H end, and other δ - atoms In an alpha-helix, the protein chain is coiled like a loosely-coiled spring. The "alpha" means that if you look down the length of the spring, the coiling is happening in a clockwise direction as it goes away from you. In a beta-pleated sheet, the chains are folded so that they lie alongside each other 3. Tertiary Structure =globular structure = final 3D shape held in place by covalent or ionic or hydrogen bonding between R groups. held together by interactions between the side chains - the "R" groups Hydrophilic parts are outside and hydropobic parts on the inside *Important for structure The 3 o structure of a protein is the way the whole chain (including the 2 o structures) folds itself into its final 3-dimensional shape. 4. Quaternary structure only for some proteins when several polypeptides with their own 1 o, 2 o, 3 o structure bonds together i.e, haemoglobin and enzymes
F) Nucleic Acids essential in the structure and function of cells. Scientists who first discovered them called them nucleic acids because they found them in the nucleus of the cell i. Why group these molecules? Nucleic acids are either DNA- deoxyribonucleic acid, or RNA ribonucleic acid Both have subunit of a sugar+phosphate+base ii. Function DNA -deoxyribonucleic acid stores genetic information called genes like a code DNA replicates and transmits this genetic info during cell reproduction Genes (the genetic info) specify the sequence of aa in the proteins (if this is faulty will cause genetic faults i.e. sickle cell anemia where red blood cells are misshapen and clog blood vessels leading to all sorts of problems) RNA ribonucleic acid Is the intermediary that transmits the code regarding the aa sequence in a protein RNA is the nucleic acid directly involved in protein synthesis DNA is the keeper of the code, when needed it unravels and passes the code onto a single strand of RNA the RNA uses this code to make a protein. In a later chapter, we describe how this happens. iii. Structure of DNA and RNA Both have nucleotide subunits A Nucleotide is a molecular complex of 3 types of subunit molecules: Phosphate, (Pentose) 5 C sugar, and nitrogen base Linear chains of nucleotides form as phosphate and sugar backbone forms between each nucleotide bonding together RNA and DNA are polymers of nucleotides
DNA RNA Double strand, double helix single strand Sugar = deoxyribose sugar = ribose 4 nitrogen bases 4 nitrogen bases Adenine (A) A Thymine (t) Uracil (U) Guanine (G) G Cytosine (C) C Nucleotides join to form a polynucleotide called a strand In DNA 2 strands twist around each other to form a double helix **Held together by hydrogen bonds between bases Complementary base pairs A with T G with C have shapes that fit together These complimentary base pairs allow DNA to replicate in a way that ensures the sequence of bases will remain the same it is like a code - this is important because it is the sequence of bases that determine the sequence of aa in a protein. it will not function if it isn t correct. iv. Specialized nucleotide ATP Adenosine Triphosphate ATP =adenosine triphosphate special because normal structure of a nucleotide is 1 phosphate, a sugar and a nitrogen base, ATP has 3 phosphates and the base is always adenine. ATP = adenine + ribose (sugar) + 3 phosphate groups ATP is an energy carrier in cells hi energy molecule the hi energy is carried in the phosphate bonds When ATP is broken down you get ADP (adenosine diphosphate) and when the phosphate bond breaks between the ADP and the phosphate group that breaks off, you get energy released.
Energy is used in cellular metabolism to synthesize macromolecules (such as carbohydrates and proteins), in muscle cells the energy is used for muscle contraction, and in nerve cells it is used for conduction of nervous impulses After ATP breaks down it can be recycled by adding phosphate to ADP an input of energy is required to reform ATP ATP is formed from the breakdown of glucose glucose is used as energy storage until required by the cell A glucose molecule contains too much energy to be used as a direct source in cell reactions. Instead the nrg of glucose is converted to ATP.ATP has an amount of nrg that a cell can use to supply chemical reactions in cells.