Topic 2 2.3 Carbs & Lipids (Source: Biology, Course Companion. 2014 Edition, Allot and Mindorff, Oxford University Press)

CARBS! Carbs = sugar 3 types of carbs: Monosaccharides Disaccharides Polysaccharides Saccharon = Latin for “sugar” Saccharin = brand name for artificial sweetener Saccharomyces = Baker’s yeast (for making bread)

Examples of carbs: (Everything here is full of sugar!)

Understanding: Monosaccharide monomers are linked together by condensation rxns to form disaccharides & polysaccharide polymers. Monosaccharides single sugars Molecular formula = C6H12O6 e.g. glucose, galactose, fructose, ribose

Disaccharides Double sugars Molecular formula = _____________??? e.g.

Polysaccharides Many sugars Polymers e.g.

Condensation = combining smaller molecules into larger ones = anabolism or catabolism?? Energy used or released?? E.g. Glucose + glucose = ______________?? Bond holding 2 sugars together = glycosidic bond For every 2 sugars linked together, ____ waters form??

Why is it called condensation?

How many waters formed from the condensation of this polymer?

Hydrolysis Breaking larger molecules into smaller ones Hydro = water Lysis = to break Catabolism Energy released E.g. Lactose = _________ + __________ ??? For every glycosidic bond broken, _____ H2O is needed.

Comparing: condensation vs hydrolysis

Skills: Use of molecular visualization software to compare cellulose, starch & glycogen Jmol = molecular visualization software so you can see molecules in 3D Used by most scientists in research PDB = protein data base Bioinformatics = the science of collecting and analyzing complex biological data such as genetic codes using computer programs BioMolecular Explorer 3D http://www.umass.edu/molvis/bme3d/ BioTopics http://www.biotopics.co.uk/JmolApplet/jcontentstable.html FirstGlance in Jmol http://bioinformatics.org/firstglance/fgij/ We will practice!!!

Application: Structure & function of cellulose & starch in plants and glycogen in humans Starch, glycogen & cellulose = all made of glucose Structure & function differ Types of glucose & types of linkage differ

Glucose

Maltose Which C’s are linked?

2 kinds of glucose: alpha & beta (this makes a difference when forming polysacc’s!)

Cellulose = -glucose molecules Each -glucose added to chain is at 180° to previous one. Therefore, cellulose is straight unbranched chain.

Cellulose microfibrils = bundles with H bonds linking cellulose molecules; strong plant cell walls that prevent plant cells from bursting with water!

Starch = α-glucose Each alpha glucose is added in same direction Therefore, starch is curved chain

Comparison of cellulose & starch

2 forms of starch

Glycogen

Functions of polysaccharides Cellulose = strength & structure of plant cell walls Starch = the way plants store energy (glucose) – in seeds & storage organs like potatoes Glycogen = the way animals store energy (glucose) – in liver & muscles (Can’t just store hundreds of single glucose molecules in cells – it would mess up osmosis in cell. It’s very easy to add & delete single glucose molecules from the polymers starch & glycogen!)

LIPIDS!

Understanding: Triglycerides are formed by condensation from 3 fatty acids & 1 glycerol Triglycerides = fats & oils FAT = liquid at body temp, solid at room temp e.g. fat in human body cells; butter OILS = liquid at body temp and room temp e.g. olive oil Made up of 3 f.a. & 1 glycerol Linked by “condensation rxn” Number of waters produced in 1 triglyceride = ____ Name of bond between each f.a. & glycerol = ESTER bond Used as energy stores & heat insulation (whale blubber!) Fat is stored in ADIPOSE cells in 3rd layer of skin & around some organs

Application: Lipids are more suitable than carbs for long-term energy storage in humans Carbs = short-term energy storage Lipids = long-term energy storage WHY? Amount of energy released per gram is DOUBLE in lipids compared to carbs Lipids are 6X more efficient in amount of energy that can be stored per gram of body mass (so you don’t have to carry tons of fat around!) Lipids are poor conductors of heat, so make good heat insulators (fat directly under skin) Lipids are liquid at body temp, so make good shock absorbers (fat around kidneys protects kidneys)

Why are carbs better for short-term storage? Carbs stored as GLYCOGEN, in liver (150g) and some muscles (2% glycogen) Glycogen – for short-term storage Glycogen is made up of what monomer? __________ Glycogen is easier to break down than Fats Glucose can be used in aerobic or anaerobic respiration (Fat can only be used in aerobic resp)

Skill: Determination of body mass index (BMI) by calculation or use of a nomogram

Calculating BMI

BMI Results:

BMI using a NOMOGRAM:

BMI using a NOMOGRAM:

Health problems… Underweight: insufficient world food supplies Anorexia nervosa (psychological; loss of body mass) Obesity: Excessive food intake & lack of exercise Increases risk of coronary heart disease & type 2 diabetes Reduces life expectancy & increases costs of health care

Understanding: Fatty acids can be saturated, monounsaturated or polyunsaturated

Saturated (max # of H’s) vs Polyunsaturated (less room for H’s)

Understanding: Unsaturated fatty acids can be cis or trans isomers Understanding: Unsaturated fatty acids can be cis or trans isomers * Double bond in a CIS unsaturated fatty acid produces a kink in the molecule because a double bond cannot rotate. So they can’t line up next to each other in an ordered fashion as the trans isomers, and so don’t solidify as readily as trans fatty acids. CIS = Liquid at room temp – OILS!

Trans fatty acids

Fatty Acids CIS TRANS Kink at every double bond Can’t line up evenly Lower melting point Liquid at room temp OILS Natural fat Good for you! Straight chain Line up evenly Higher melting point Solid at room temp Margarine, butter, processed, fried Produced artificially by partial hydrogenation of vegetable or fish oil Bad for you!

Just Say No to Trans Fats!

Lies!

Leading causes of death in US

Application: Scientific evidence for health risk of trans-fats and saturated fats CHD IS THE #1 KILLER OF MEN AND WOMEN IN THE US!!! Coronary Heart Disease (CHD) = coronary arteries (that supply blood to the heart itself) become partially blocked by fat, leading to blood clot & heart attack! Does correlation imply causation? Studies show POSITIVE correlation between saturated fat intake (and trans fat) and rates of CHD Exceptions – some populations in Kenya eat lots of fat and never get CHD Cause could be low fiber, genetics, many tomato dishes Fatty deposits in CHD patients found to contain high amount of trans fats Therefore there probably is a CAUSAL LINK between Trans fats and CHD https://www.youtube.com/watch?v=ecuCECYhw_M#t=102

Atherosclerosis

Nature of Science: Evaluating claims: health claims made about lipids need to be assessed. Many health claims about food are made – some scientific, some not. Easy to scientifically test lab animals – easier to control diet, exercise, temp, age, sex, health Can’t always relate it to humans tho Harder to test humans in same way… WHY? Epidemiological studies = over long period of time ~ use stats to find out if diet associated with increased frequency of disease; still have to eliminate other factors as cause of disease

Topic 2.4 Proteins (Source: Biology, Course Companion. 2014 Edition, Allot and Mindorff, Oxford University Press)

Understanding: Amino acids are linked together by condensation to form polypeptides Polypeptides = chains of amino acids polypeptides made through condensation rxns occurs on ribosomes Proteins = functional entities made of one or more polypeptides and often non-polypeptide cofactors. Eg. Lysozyme is made of just one polypeptide. Haemoglobin is made up of 4 polypeptides.

Formation of a dipeptide by condensation Draw 2 amino acids side by side. Remove an H from one aa and an OH from another. Redraw the 2 amino acids, this time without the H2O you removed, and with a single bond linking the 2 amino acids together. Label the “peptide bond” (the bond joining the 2 aa’s together).

Dipeptide

Formation of polypeptides: Polypeptide = many amino acids linked together by peptide bonds through condensation rxns Oligopeptide = small chain of 2-20 amino acids Insulin = small protein made of 2 polypeptides; 51 aa total Titin = largest known protein; 34,350 aa

Skill: Draw molecular diagrams to show the formation of a peptide bond Draw an oligopeptide made of these 4 amino acids: How many waters would be removed? 3 What is this rxn called? condensation Serine glutamic acid

Understanding: There are 20 different AA’s in polypeptides synthesized on ribosomes 20 different R groups B/c of differences between R groups, 20 AA’s are very diverse Differences: hydrophobic vs hydrophilic, ring structure vs non, can or can’t become charged, act as acid vs base, polar vs non-polar

Nature of Science: Patterns, trends & discrepancies: most but not all organisms assemble polypeptides from the SAME AAs Besides exceptions: modified amino acids (in collagen) or non-standard AAs (selenocysteine & pyrrolysine) Hypotheses: These 20 AAs were produced BEFORE life began Natural selection – the most ideal AAs were favored over time (survival of the fittest AAs) All life evolved from single ancestor, which used these 20 AAs

Understanding: AAs can be linked together in any sequence giving a huge range of possible polypeptides For a polypeptide of n amino acids, there are 20n possible sequences Example: if polypeptide has 400 AAs, there are 20400 possible AA sequences # of AAs in polypeptide can be anything from 20 to tens of thousands Ribosomes are where amino acid condensation takes place!

Understanding: The AA sequence of polypeps is coded for by genes One GENE codes for one POLYPEPTIDE! Gene = short segment of DNA that codes for a polypep DNA is coded information that contains the instructions for assembling the correct AAs into a specific polypeptide Genes are made of bases A, C, T, G Every 3 bases in a row is the code for a specific AA The sequence of the 3 bases determines which AA E.g. ACT codes for one AA, CTG codes for another E.g. If a polypeptide has 800 AAs, how many bases were needed to code for that? Genes also contain extra bases at the ends and in the middle that don’t code for anything OPEN READING FRAME = base sequence that actually codes for a polypeptide Most DNA does not code for anything!

One Gene, One Polypeptide

Understanding: A protein may consist of a single polypep or more than one polypep linked together

Collagen = structure protein in tendons, ligaments, skin, & blood vessel walls; provides tensile strength, with limited stretching (Tensile strength measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks.)

Understanding: The AA sequence determines the 3-D conformation of protein CONFORMATION = 3-D shape Determined by AA sequence 2 basic shapes: 1) Fibrous = elongated & unfolded, with repeating structure (collagen) 2) Globular = folded, with helixes and pleated sheets, stabilized by bonds between R groups (lysozyme)

Application: Denaturation of proteins by heat or pH extremes DENATURATION = change in conformation (shape) due to bonds between R groups breaking Can be caused by heat or pH extremes Usually permanent Heat causes vibrations which break bonds Exception: Thermus aquaticus in hot springs of Yellowstone pH extremes causes R groups change, ionic bonds break or new ones form Exception: Pepsin in stomach

Understanding: Living organisms synthesize many different proteins with wide range of functions See page 93

Applications: Rubisco, insulin, immunoglobulins, rhodopsin, collagen, & spider silk as examples of the range of protein functions See page 94

Understanding: Every individual has a unique proteome PROTEOME = all the proteins produced by a cell, tissue or organism (variable within organism) GENOME = all the genes of a cell, tissue, or organism (fixed in an organism) Proteome is unique to each individual (except identical twins – which can still become diff with age) Proteome determined by gel electrophoresis – separates proteins in a sample