BIOLOGY TOPIC 2 MOLECULAR BIOLOGY
biological molecules
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BIOLOGY TOPIC 2 MOLECULAR BIOLOGY - Marcador
BIOLOGY TOPIC 2 MOLECULAR BIOLOGY - Detalles
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| What is molecular biology? | Focuses on biological activity at a molecular level which includes the structure and function of chemical substances |
| Biological processes expression is controlled by? | Gene activation (DNA) |
| What is an organic compound? | Compound that has carbon and is found in living things |
| Why is carbon the basis of organic life? | It can form large and complex molecules by covalent bonding |
| How does a structure of a carbon atom allow it to form bonds? | Can share 4 electrons to form 4 covalent bonds |
| What are the 4 principle groups of organic compounds? | Carbohydrates lipids nucleic acids proteins |
| What are exceptions of carbon that aren't considered to be an organic compound? | Carbides (CaC2) Carbonates (CO3 2-) Oxides of carbon (CO, CO2) Cyanides (CN-) |
| How many bonds do carbon atoms form? | 4 covalent bonds with very stable bonds between carbon atoms (catenation) |
| What are carbohydrates? (4) | Made up of C, H, O atoms = (CH2O)n energy source and a short term energy storage recognition molecule (glycoproteins) structural component (part of DNA / RNA ) |
| What are Lipids? (5) | Non-polar, hydrophobic molecules simple, complex or derived forms makes up cell membranes (phospholipids and cholesterol) long term energy storage (fats and oils) signalling molecule (steroids) |
| What are nucleic acids? | Genetic material of all cells for the inherited features of an organism DNA: code for protein making RNA: helps make proteins |
| What are proteins? | Made up of C, H O, N (some S) regulatory molecules in catalysis all enzymes are proteins structural molecule cellular signalling (transduction pathways) |
| What are monomers? (3) | Small, recurring subunits that make complex macromolecules Carbohydrates, nucleic acids + proteins are made of subunits= larger polymers lipids DO NOT contain recurring monomers |
| What are the subunits of carbohydrates? | Recurring monomers: monosaccharides => disaccharides => polysaccharides form ring structures linked with condensation reactions with water as a byproduct |
| Draw a Ribose | Labels |
| Draw a glucose (a or b) | Labels |
| What is lipids made up of? | Fatty acids and glycerol differ in structure so they don't contain a common recurring monomer triglycerides, phospholipids and waxes contain fatty acids chains |
| What are fatty acids? | Long chains of hydrocarbons that may or may not have double bonds (unsaturated vs saturated) |
| What are proteins made up of? | Amino acids which join to form polypeptide chains each amino acid has an amine group (NH2) carboxyl group (COOH) R = different properties (polar / non-polar) |
| What are nucleic acids made up of? | Made up of nucleotides which form polynucleotide chains has: pentose sugar, phosphate group and a nitrogenous base sugar differs in RNA and DNA |
| What are polymers of glucose? | Glycogen (granules) cellulose (cell wall) starch (granules) |
| What are the three main classes of lipids? | Simple (neutral) lipids compound lipids derived lipids |
| What are simple (neutral) lipids? | Esters of fatty acids and alcohol (triglycerides and waxes) |
| What are compound lipids? | Esters of fatty acids, alcohol and additional groups (phospholipids and glycolipids) |
| What are derived lipids? | Substances from simple / compound lipids (steroids and carotenoids) |
| How do proteins join together? | Amino acids join with peptide bonds between the amine and carboxyl groups of amino acids creates a dipeptide = polypeptide chain chain folding depends on the amino acid order |
| How do nucleic acids bond together? | Nucleotides form bonds between the pentose sugar and phosphate group = long polynucleotide chains 2 complementary base pairs bond with hydrogen bonds to form double strands twists = double helix structure |
| What is vitalism? | A belief that said organic molecules can only be made by living systems |
| Why did they believe that only living things could make organic molecules? | Living things has a "vital force" organic compounds were thought to have a non-physical element which inorganic molecules don't have |
| How did the vitalism theory get disproven? | They found that organic molecules could be artificially made heated an inorganic salt (ammonium cyanate) = urea urea is a waste product of nitrogen metabolism and is removed from the kidneys artificial synthesis = organic molecules aren't fundamentally different to inorganic molecules |
| What is metabolism? | The web of all the enzyme catalysed reactions in a cell or organism |
| What do metabolic reactions do? | Provide energy for cellular processes (eg: growth) start the synthesis and assimilation of new materials for use within the cell |
| What is anabolism? | Building up complex molecules from simple molecules by condensation reactions eg: when monomers are covalently joined = water is a byproduct |
| What are monosaccharides joined with? | Glycosidic linkages = disaccharides |
| How is triglycerides formed (what type of linkage)? | Glycerol + fatty acids joined with ester linkage |
| How are nucleotides joined together? | Phosphodiester bonds = polynucleotide chains |
| How are amino acids joined? | With peptide bonds to make polypeptide chains |
| What is catabolism? | Breakdown of complex molecules into simpler molecules by hydrolysis reactions needs water molecules to break bonds within the polymers releases energy oxidation reactions |
| Why are the electrons in H2O not shared equally? | Because oxygen has a higher electronegativity = attracts the electrons more strongly electrons orbit closer to the oxygen atom = polarity =permanent dipole |
| Why is water polar? | Because of the slight charge difference across the different poles oxygen is slightly negative hydrogen atoms are slightly positive |
| What does the charge difference allow water to do? | Form weak polar associations with other polar molecules slightly negative attracts the slightly positive poles of other molecules vice versa |
| When does a hydrogen bond form? | When the slightly positive hydrogen from H2O is attracted to a slightly negative F, O, N atom of another molecule |
| Why are hydrogen bonds stronger than other polar associations? | Because of the high electronegativity of F, O and N |
| How does water bond with other water molecules? | Between a + hydrogen and a - oxygen of two molecules |
| What gives water its special properties? | The intermolecular bonding between water molecules |
| Why can water absorb so much heat before changing state? | Because of extensive hydrogen bonding between water molecules H-bonds need to be broken = needs heat energy |
| What are the 3 properties of water? | Thermal properties - water can absorb a lot of heat before changing state because breaking the hydrogen bonds is needed cohesive / adhesive properties - water sticks to other water molecules (cohesion) and charged substances (adhesion) Solvent properties - water dissolves polar and ionic substances = competing polar associations to draw materials apart |
| Why is water a good place for living organisms? | Temperature changes slowly = maintenance of constant conditions |
| Comparing Methane (CH4) with water | H20 weight = 18 dalton CH4 weight = 16 dalton both have tetrahedral orbital forms but water is bent because of unbonded electron pairs |
| What is sweating? | Evaporation of water to cool down |
| How does sweating work? (4) | Change of water from liquid = vapour needs energy energy comes from the skin's surface when its hot when water evaporates skin is cooled because water has a high SHC = absorbs a lot of thermal energy before evaporating water - highly effective coolant |
| What are the cohesive properties of water? | Same molecules stick together forms hydrogen bonds w other water molecules |
| What are the adhesive properties of water? | Different molecules stick together by forming intermolecular associations with polar and charged molecules |
| How does the cohesive properties explain surface tension? | Hydrogen bonding between water molecules helps the liquid to resist low levels of external force makes the water dense enough for small organisms to move along its surface |
| How does the adhesive properties explain the capillary action? | Attraction to charged or polar surfaces makes water to flow against gravity = capillary action needed for water to be transported up plant stems by transpiration |
| Why can water dissolve so many substances? | Can dissolve any substance that has charged particles (ions) or electronegative atoms (polarity) because the polar attraction of a large amount of water molecules = weaken intramolecular forces (ionic) = disassociation |
| How does hydration occur? | Slightly charged regions of the hydrogen atoms and the oxygen atoms surround atoms with an opposing charge = forms dispersive hydration shells |
| What does hydrophilic mean? | Substances that freely associate and readily dissolve in water all polar molecules and ions |
| What does hydrophobic mean? | Substances that don't dfeely associate or dissolve in water large non polar molecules (fats and oils) |
| What are water soluble substances that travel in our body? | Sodium chloride (NaCl): ionic transported in blood Oxygen: small amounts are soluble in water transported in haemoglobin in red blood cells Glucose: hydroxyl groups (-OH) associates with water so it travels in the blood Amino Acids: transported in an ionized state (either amine or carboxyl group is charged) |
| What are water insoluble substances that travel in our body? | Lipids (fats and cholesterol): non polar and hydrophobic so it does not dissolve in water form complexes with proteins (lipoproteins) = to go through bloodstream hydrophilic parts of proteins, cholesterol and phospholipids shield internal hydrophobic parts |
| What are some examples of monosaccharides (one sugar unit) | Glucose, galactose and fructose usually sweet tasting and is an immediate energy source for cells |
| What are some examples of disaccharides (2 sugar units) | Lactose, sucrose and maltose small enough to be water soluble, transport form of carbohydrates |
| What are some examples of polysaccharides? | Cellulose glycogen and starch used for energy storage or cell structure |
| What does the type of polymer formed depend upon? | Monosaccharide subunits bonding arrangement between them |
| Which polymers can be found in plants? | Cellulose and starch |
| What is cellulose? (3 + 2 examples) | Polysaccharide (structural) found in the cell wall of plants linear molecule made of beta glucose in a 1-4 arrangement b glucose is indigestable to most animals as they lack the enzyme to break it down eg: cows (ruminants) digest cellulose because of bacteria in a specialized stomach eg: rabbits (caecotrophs) will reingest specialized feces that have digested cellulose |
| What is starch (mention amylose) | Polysaccharide (energy storage) in plants a glucose in a 1-4 arrangement found as amylose or amylopectin Amylose is a linear (helical) molecule Amylopectin is branched with 1-6 linkages added amylose is harder to digest and is less soluble = but it takes up less space so it is a better storage form |
| What is glycogen? (3) | Energy storage polysaccharide in the liver made of a glucose linked with 1-4 and 1-6 (branching) similiar to amylopectin because of branching |
| What are fatty acids? | Long hydrocarbon chains in certain lipids (triglycerides and phospholipids) hydrocarbon chain LENGTH can differ and number of DOUBLE BONDS |
| What are saturated fatty acids? | They have no double bonds (max number of H atoms) linear from animal sources (fat) solid at room temp |
| What are unsaturated fatty acids? (level up) | They HAVE DOUBLE BONDS monosaturated = 1 double bond polysaturated = more than1 double bond bent from plant sources (pols) liquid at room temp |
| What are the two different structures of unsaturated fatty acids? | Cis isomers trans isomers |
| What are cis isomers? | Hydrogen atoms attach to the carbon double bond are on the same side |
| What are trans isomers? | Hydrogen atoms attached to the carbon double bond are on different sides |
| Where do TRANS fatty acids come from? (transgender) | Don't happen naturally but are produced by an INDUSTRIAL PROCESS called hydrogenation linear even though they are unsaturated solid at room temp |
| What are triglycerides? | Long term energy storage animals store them as fats (solids) plants store them as oils (liquids) formed when condensation reactions happen between 1 GLYCEROL AND 3 FATTY ACIDS |
| Explain the formation of a triglyceride | Condensation reaction between 1 glycerol and 3 fatty acids hydroxyl group of glycerol joins with the carboxyl group of the fatty acids = ester linkage produces 3 molecules of water can be saturated or unsaturated = depends on the composition of teh fatty acid chain |
| Which fats increase cholesterol levels in the bloodstream? | Saturated and trans fats |
| Which fats lower cholesterol levels? | Cis unsaturated fats |
| Example of unsaturated , saturated and trans fat | Almonds beef cookies |
| How is fat and cholesterol transported and why are they transported this way? | Because they can't dissolve in blood they are packaged with proteins = lipoproteins for transport |
| What do low density lipoproteins do (LDLs)> | Carries cholesterol form the liver to the body = raises cholesterol levels - bad |
| What do high density lipoproteins do (HDL)? | Carry excess cholesterol back to the liver for disposal = lowers cholesterol levels |
| How does a high intake of the different types of fat affect cholesterol levels? | Saturated fats = increase LDL levels = raises blood cholesterol Trans fats = increase LDL levels AND decreases HDL levels = raises blood cholesterol ALOT Unsaturated (cis) fats = increase HDL levels = lowers blood cholesterol |
| What does high cholesterol lead to? | Hardening and narrowing of arteries (artherosclerosis) high levels of LDL = LDL particles forms deposits in the walls fat accumulation = development of plaque which reduces blood flow Coronary Arteries become blocked = CHD which causes heart attacks and strokes |
| What are the two main health claims about lipids in diet? | Diets with too much saturated and trans fats = increase in CHD risk Diets with a lot of mono unsat and poly unsat (cis) = decrease CHD risk |
| What is some evidence that supports that saturated and trans fats increase the risk of CHD? | Positive correlation with intake of sat fats and CHD in people BUT some populations don't fit this ( maasai tribe have a fat rich diet but low rates of CHD) Intervention studies show that lowering sat fat intake reduces factors = CHD development (BP) BUT study's validity depends on sample size and study duration |
| What is some evidence that goes against that saturated and trans fats increase the risk of CHD? | Amount of sat and rans fats in western diets have reduces over last 50 years but CHD cases increases BUT increased carbs causes detrimental health effects as well (eg: diabetes) ALSO CHD depends on other factors as well like exercise |
| Differences in energy storages of carbs and lipids (5) | Storage CARB: short term energy storage LIPID: long term energy storage Osmotic effect CARB: more effect on cell LIPID: less effect on cell Digestion CARB: easily digested LIPID: harder to digest ATP Yield: CARB: stores half as much ATP per gram LIPID: stores 2x as muc ATP per gram Solubility CARB: water soluble as monomers - easy to transport LIPID: not water soluble (hydrophobic) - difficult to transport |
| How is ATP made? | Energy made with cell respiration and can be used in metabolism |
| What is BMI? | Body mass index measures relative mass based on weight and height to see potential weight problems in sedentary adults |
| How is BMI calculated? | BMI = mass in kg / (height in m)2 squared |
| Who are the BMI not accurate for? | Pregnant women professional athletes as they have unrepresentative muscle/ fat ratios used with other measurements SHOULD NOT BE used as a diagnostic tool |
| How many amino acids are there and where are they made? | 20 different amino acids in polypeptides synthesised on ribosomes by translation |
| How do the different amino acids differ so much? (in structure) | The variable side chain (R) has distinct chemical properties (eg: charged) the protein folds and works differently according to its position in the polypeptide chain |
| How are amino acids joined together? | Covalently linked by PEPTIDE BONDS which are formed by condensation reactions = water molecules formed as a byproduct |