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UNIT THREE

UNIT THREE. BIOLOGY. AREA OF STUDY #1: MOLECULES OF LIFE EXAM REVISION LECTURE CHP 1 . CHP 1 - TOPIC 1 : THE CHEMICAL NATURE OF CELLS. all living things are composed of chemicals Organic Molecules: complex carbon containing molecules Examples: Carbohydrates, Proteins, Lipids, DNA, RNA

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UNIT THREE

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  1. UNIT THREE BIOLOGY AREA OF STUDY #1: MOLECULES OF LIFE EXAM REVISION LECTURE CHP 1

  2. CHP 1 - TOPIC 1: THE CHEMICAL NATURE OF CELLS • all living things are composed of chemicals Organic Molecules: complex carbon containing molecules Examples: Carbohydrates, Proteins, Lipids, DNA, RNA Inorganic Molecules: do not contain carbon in a complex form Examples: water (H20), CO2, Oxygen (O2), mineral ions Cl-, K+, Mg2+, Na+, Ca2+ and NO3-

  3. WATER: A UNIQUE COMPOUND Water is a polar molecule • (part of the molecule is slightly positively charged and the other side is slightly negatively charged. • This polarity allows for formation • of weak bonds between water (and • other charged) molecules… these • bonds are referred to as hydrogen • bonds. • The polarity and ability to form hydrogen bonds gives water some very special • characteristics, many of which are essential for maintaining life on earth as we • know it, including: • as temp falls, water shrinks until it reaches 4 degrees C. it the gets less dense because hydrogen • bonds keep the molecules further apart • Hydrogen bonds cannot form above 100 degrees and therefore the molecules break away from • each other to form its gaseous state, steam. • are highly cohesive • water is able to absorb more heat than most other liquids, therefore it acts as a buffer against • environmental temperature change

  4. Highly Cohesive: The negative oxygen molecule of one water molecule of water is attracted to the positive hydrogen of another water molecule. In fact one oxygen attracts a hydrogen from two other molecules. … although water molecules are attracted to each other, the hydrogen bonds that hold them together are weak and continually break and continually rejoining (causing fluid like form) Why do substances dissolve in water? Water is an excellent solvent for large number of molecules (gases, sugars, and some amino acids) that dissolve in it. The negative charge of the oxygen atom and positive charge of the hydrogen atoms is enough to attract (and sometimes break the bonds) of other molecules

  5. BONDS:

  6. Topic 1.1 Questions: • Water is a: solvent/ solute/ solution/ hydrophobic? • Bonds between water molecules are: covalent/ hydrogen/ ionic • Each Oxygen atom is linked to the oxygen atom by: covalent/ hydrogen/ ionic • Water is: more dense/ less dense at 3 degrees compared to 5 degrees • Substances that dissolve in water are called: hydrophilic or hydrophocbic • True or False: A substance such as Sodium Chloride (NA Cl) dissociates into its parts in water • Water has a pH of: _____ • What name is given to a solution that has many more Hydrogen ions (H+) than hydroxide ions (OH-)? _________________ • Three examples of a organic molecules include: ____________, ______________, _______ • Three examples of inorganic ions include: ____________, ______________, __________

  7. CHP 1 - TOPIC 2: ORGANIC MOLECULES: (BIO)MACROMOLECULES: (complex, naturally occurring organic molecules) Most biomacromolecules (proteins, carbohydrates and nucleic acids) are polymers (molecules made up of many similar base units - monomers) linked together. Lipids are also a group of biomacromolecules. Lipids very rarely form polymers. Macromolecules are created through condensation (synthesis) reactions

  8. Polymers Polymers Monomers/. Subunit Carbohydrates : simple sugars Proteins : amino acids Nucleic acids : nucleotides

  9. CARBOHYDRATES:

  10. PROTEINS

  11. Nucleic Acids

  12. LIPIDS

  13. PROTEIN STRUCTURES

  14. Functional Diversity of Proteins Examples of proteins and their functions include: • collagen: a fibrous protein that provides strength and structural support in bones and tendons • ATP Synthase: an enzyme involved in catalase reactions • myosin: a contractile protein involved in muscle movement • insulin:a hormone that helps regulate blood sugar levels • insulin receptors: which respond to a stimulus from insulin • haemoglobin: a globular protein in red blood cells that transports oxygen in the bloodstream • antibodies:immunoglobins that provide defence against disease

  15. Topic 1.2 Questions: • The sum total of all proteins found in a functioning organism is called what? __________ • Proteins can be divided into two major groups including: ____________ & _____________ • A conjugated protein is one that is? _______________________________________ • Proteins combined with carbohydrates are called: ________________ • In relation to protein shape, HICH refers to: ______________, _________________, ________________ & ________________________ • True/ False: Alpha helices are more elastic than Beta pleated sheets? • Give an example of a protein consisting mainly of alpha helices: ___________________ • List the three basic components of amino acids: _______________, _______________, _______________ • Peptide bonds occur between which two atoms: O & H; O & C; C & C; or C & H? • Which type of nitrogenous bases are double ringed? Purines or Pyrimidines • List the three combinations of DNA/ DNA or DNA/ RNA base pairing: _______________, _______________, _______________ • How many carbons are found in ribose sugar? 3, 4, 5, 7 • Which of the following is not a steroid: vitamin D, bile acids, cholesterol, haemoglobin • Which is the odd one out and why: starch, glycogen cellulose? _______________________ • What molecule is released when amino acids are linked by peptide bonds? ____________ • What is the major component of cell membranes? ____________________________

  16. CHP 1 - TOPIC 3: SCIENTIFIC METHOD Sometimes in the Biology exam, you are asked to assess the design of an experiment; suggest an experiment to carry out; or to suggest hypotheses to be tested! When designing experiments and/ or hypotheses there are a few things to keep in mind: • Any experiment should contain only one variable; all other factors in the setup/ prac, should be constant (this is known as a controlled experiment) • Having chosen one factor to investigate, you make a hypothesis about the effect of varying that factor. Statements should be of the “if… then” type Example#1: If increased temperature raisis the rate of the reaction, then the reaction rate will be higher at higher temperatures than at low temperatures and the products will be produced more quickly… Example #2: If the enzyme works at an optimum rate in acidic environments, the product will be produced more quickly ina solution of pH 4 that in a solution of pH9 • Some experiments require a control. Imagine you are testing the hypothesis that the addition of magnesium to soil improves the growth of plants. You get several plants and addMg to the soil. They grow beautifully! But, compared to what!! ... The control, same plants and soil without Mg added. This is the control. If the control doesn’t grow as well, then you have supported your hypothesis • The results should be repeatable over a number of trials; use a number of samples or; repeat the experiment several times • Not, your hypothesis is only ever supported, never proved (after all there may have been some unknown factor you overlooked). If the results are contrary to your prediction then the hypothesis is disproved.

  17. Topic 1.3 Questions: • What is a controlled experiment?____________________________________ ___________________________________________________________________ • How many variables should you test at any one time? 1, 2, more than 2 • True or False: Hypotheses are only supported, never proven?____________

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