UNIT THREE

1. UNIT THREE BIOLOGY AREA OF STUDY #1: MOLECULES OF LIFE EXAM REVISION LECTURE CHP 2: MEMBRANES AND CELL ORGANELLES

2. CHP 2 TOPIC 1: CELLS Cell Types Viruses: not really cells; share some characteristics with living things including; • Genetic material (DNA or RNA) • Protein coat (known as a capsid); some also envelop themselves courtesy of infected host membrane • Enzymes Prokaryotic Cells: • Include bacteria (Monera), archaebacteria and eubacteria • Smallest living cells (most bacteria less than 1 micron i.e. <1/1000mm) • All single celled organisms (but some form colonies) • Have a cell membrane and cytosol • Lack membrane bound organelles • Have no nuclear membrane • Have just one, circular chromosome; may have many small rings of DNA called plasmids • contain ribosomes(organelle not membrane bound) • May contain fimbria(hairline structures used for attachment); flagellum - used for movement

4. Eukaryotic Cells • Larger than prokaryotic cells (ranging from 10 to 150 microns) • Include the Kingdoms: animal; plants; fungi & protista (protozoa) • Some are unicellular (single celled) others are multicellular (with many specialised cells) • All contain membrane bound organelles suspended in a fluid known as cytosol • (membranes, organelle and cytosol together is known as cytoplasm • Membrane is a liquid lipid bilayer (two layers of phospholipids) • Have many linear chromosomes

6. Topic CHP2.1 Questions: • List up to 7 characteristics of all living things: • Which of the following would be not be visible under a low-power light microscope: Guard Cell; White Blood Cell; paramecium; nucleus; ribosome • Which of the following could be used to examine living cells: • Light microscope or Transmission Electron Microscope • List three characteristics of each of the following: • Protozoan Cell: ___________________, ________________________ & ________________________ • Bacteria Cell: : ___________________, ________________________ & ________________________ • Plant Cell: : ___________________, ________________________ & ________________________ • True False: Bacteria, Plant & Fungi cell walls are made of polysaccharides • True False : The cell wall of Fungi is made of chitin • True/ False: Plasmids are circular units of DNA • What name is given to inert viruses (those not infecting a host): _______________ • What name is given to the protein coat around a viruse: _____________________ / 9 Marks

7. CHP 2 TOPIC 2: CELL ORGANELLES Organelle: structural unit in cells that performs a key function in cellular metabolism

8. CHP 2 TOPIC 2: CELL ORGANELLES

9. CHP 2 TOPIC 2: CELL ORGANELLES

10. CHP 2 TOPIC 2: CELL ORGANELLES

11. CHP 2 TOPIC 2: CELL ORGANELLES

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14. CHP 2 TOPIC 2: CELL ORGANELLES

16. Topic CHP2.2 Questions: • The cellular organelles which assemble polypeptides are called? _________________ • Pancreatic cells will incorporate radioactively labelled amino acids into proteins. Proteins can therefore be labelled and tracked within a cell. If we were tracking a pancreatic enzyme that was to be secreted, the most likely pathway of movement of this protein in the cell would be: • Endoplasmic reticulum to golgi body to nucleus • Golgi body to ER to lysosome • Nucleus to ER to golgi body • ER to golgi body to secretory vesicles • The purpose of the cristae in mitochondria is • To provide greater SA within the organelle • To store chemicals • To provide a surface for the process of photosynthesis to occur • To provide structural support • Rough ER are called rough because: ______________ • In what type of plant cells would you expect to find mitochondria? _____________ • Which 4 organelles contain nucleic material? _____________________________________ • Outline the role of the following organelles in protein manufacture: • Nucleus • Ribosomes • Rough ER • Golgi Apparatus • Secretory vesicles • True/ False: Lysosmes are involved in apoptosis? • Which organelles have a double membrane?__________________________________________ • Name three organelles you can see and three you can’t see under a light microscope in an animal cell. ____________________________________, ________________________________, _______________________________ / 10 Marks

17. CHP 2 TOPIC 3 ENZYMES A catalyst is any chemical which speeds up the rate of a chemical reaction without itself being used up in the reaction. Biological catalysts are enzymes. Enzymes are protein molecules manufactured by cells in the ribosomes. • are proteins that act on other molecules • are organic catalysts • are protein molecules that increase the rate of reactions that occur inside the organism. • are generally intracellular (exception: digestive enzymes) • some require a non-protein cofactor (i.e vitamins, CoQ10) before they can act • have a region, known as the active site, that alligns with a particular substrate • the compounds obtained as a result of the enzyme action are called the products • enzymes are highly specific in their action. Each enzyme acts on a particular substrate.

18. Substrate 1 Enzymes are organic catalysts. Active Site Enzyme Product Enzyme-Substrate Complex 3 2 Enzyme Menu

19. Many enzymes lower the activation energy required to get a reaction going • Enzymes are sensitive to pH. They will only work in optimum pH range • Optimum pH differs for different enzymes • Enzymes are denatured if the pH varies from the optimum • Enzymes are temperature sensitive • Most enzymes work best at temps between 35-40 degrees celcius • The rate of any reaction is slower at lower temps • At temps above 40 degrees most enzymes denature • Some bacterial enzymes can exist in hot temps • Enzyme action can be affected by the presence of other molecules which may inhibit the action of the enzyme • Inhibition of enzymes may be reversible or irreversible

20. Cofactors: some enzymes require another chemical component attached to the protein to be active: • Some cofactors are inorganic ions • Organic cofactors are called coenzymes • Most coenzymes are carrier molecules transferring electrons or ions from one reactant to another in a biological reaction: NADH, NADPH and FADH2 are important coenzymes ATP is a coenzyme This complementary fitting of shapes is known as the ‘lock and key’ theory of enzyme action. in some cases, the shape of the active site varies slightly from that of the substrate and the two fit only after the substrate induces a complimentary shape at the active site theory of enzyme action.

21. Rate of reaction will be dependent upon amount of: • substrate concentration • enzyme concentration • cofactors concentration • presence of inhibitors such as poisons

22. Topic CHP2.3Questions: • Name four factors that influence that rate of enzyme action: ________________, _________________, ______________________ & ______________________ • The amount of energy required to initiate a reaction is called what: ___________ ____________ • A biological catalyst is called an: _____________________ • In regards to enzyme inhibition, denaturing is: reversible / irreversible • A molecule which competes with the substrate for binding to the ensymes active site is called what: ___________________ _________________ • The action of enzymes is: random/ dependent upon diploar bonds/ highly specific • With regards to theories of enzyme action, the perfect fit of enzyme and substrate is called the ________________ theory; when the substrate is slightly different to that of the active site, the theory of enzyme action is known as the ___________ & ______________ theory / 7 Marks

23. CHP 2 TOPIC 4 MEMBRANES & MOVEMENT OF MATERIALS • All cells are surrounded by a cellular membrane (also known as plasma membrane) • Cell membranes are selectively/ semi/ partially permeable • Control movement into and out of cell; communication between cells; recognition by other cells • Less than 0.01 microns thick or 1/ 100 000 mm or 10 nanometers (scanning electron can see down to 2 nanometers!) • Cell membranes are composed of a phospholipidbilayer • Proteins are embedded in the bilayer • Carbohydrate chains are involved in cell recognition • Cholesterol (lipid- steroid) also often embedded in membrane- aide fluidity • The phospholipids and proteins allow the movement of substances in and out of cell

24. Channel Proteins These proteins are used in intercellular communication. In this animation you can see the a hormone binding to the receptor. This causes the receptor protein release a signal to perform some action. Receptor Proteins • There are carrier proteins that regulate transport and diffusion

25. Topic CHP2.4 Questions: • List four roles for cell membranes:____________, ______________, __________, ______________ • List 5 molecules found in a typical cell membrane::____________, ______________, __________,______________ & __________________ • True/ false: you can see a membrane under a scanning electron microscope ? _________________ / 3 Marks

26. CHP 2 TOPIC 5 MOVEMENT OF MATERIALS THROUGH MEMBRANES Diffusion is the ‘tendency’ of particles of gases, liquids and solutes to dispense randomly and fill available space • Rate of diffusion increases with: temperature increase/ concentration increase • Particles random movement from where they are in high concentration to were they are in low concentration • This is commonly referred to as moving along a concentration gradient • Diffusion does not require energy – passive transport • Does not have to occur through a permeable membrane

27. CHP 2 TOPIC 5 MOVEMENT OF MATERIALS THROUGH MEMBRANES Osmosis is the net movement of water molecules across a differentially permeable membrane, from an area of low solute concentration to an area of high solute concentration). note: you don’t usually refer to water with the word concentration • Water can only move passively (through osmosis) • Water (H2O)molecules are smaller glucose (C6H12O6) etc and can move readily • The net movement is ‘overall’ as water moves both directions • When water is in solution, solutes often combine (NACl) and reduce ability of water to move • Intercellular fluid surrounding cells is usually isotonic (the same)asthe intracellular fluid (in cell

28. CHP 2 TOPIC 5 MOVEMENT OF MATERIALS THROUGH MEMBRANES High to Low solute High to Low solute

29. Topic CHP2.5 Questions: • Name two factors that can influence the rate of diffusion: _______________, ____________ • Diffusing particles: move along/ against/ up a concentration gradient • True/ False: Diffusion does not require ATP • True/ False: Diffusion take place through a differentially permeable membrane • True / False: Water can be moved against a concentration gradient with the use of ATP • Which of the following is the larger molecule (circle): a monosaccharide/ water • Name three factors that influence the net movement of water molecules through a differentially permeable membrane: _______________, ____________ & _______________ • Fresh water fish cells would be (circle): isotonic/ hypertonic/ hypotonic in comparison to their environment • Cells of a salt water fish placed into freshwater would: expand & burst/ shrivel • Plant cells placed in a hypertonic solution will undergo: plasmolysis/ become turgid • pressure caused by water within the cell is called: ______________ pressure • Active transport requires which of the following: protein channels, ATP Synthase, ATP, concentration gradient • True/ False: Facilitated Diffusion/ Channel mediated diffusion requires ATP • Name two forms of Exocytosis:____________________ & _______________________ • Name four molecules that can move through a phospholipidbilayer by simple diffusion: __________________, _______________________, __________________, _____________ / 15 Marks

30. CHP 2 TOPIC 6 SURFACE AREA TO VOLUME & CELL SIZE • A few types of cells are large enough to be seen by the unaided eye. • The human egg (ovum) is the largest cell in the body, and can (just) be seen without the aid of a microscope. • Most cells are small for two main reasons: a). The cell’s nucleus can only control a certain volume of active cytoplasm. b). Cells are limited in size by their surface area to volume ratio. A group of small cells has a relatively larger surface area than a single large cell of the same volume. This is important because the nutrients, oxygen, and other materials a cell requires must enter through it surface. As a cell grows larger at some point its surface area becomes too small to allow these materials to enter the cell quickly enough to meet the cell's need. (= Fick’s Law – something you need to learn well). • Rate of diffusion α Surface Area x Concentration Difference Distance Chapter 2 - Cells: Structure & Function

31. CHP 2 TOPIC 6 SURFACE AREA TO VOLUME & CELL SIZE Cellular environments and cell size All cells need to exchange materials with their environments. They need to take in gases, water and nutrients and get rid of wastes. Exchange of materials can only occur through the cell’s membrane. The larger a cell becomes, the smaller its surface area becomes in relation to its volume. Look at these cubes to see the difference increasing size has on the ratio between surface area and volume When a cell grows its volume grows at a greater rate than its surface area. If a cell becomes to large they are unable to carry out sufficient exchange of materials with the environment. Q. how would Fick’s Law influence the potential size of Prokaryotic organisms? Chapter 2 - Cells: Structure & Function

32. Topic CHP2.6 Questions: • Name on cell visible with the naked eye? ______________ • List two factors that limit cell size:________________________, ______________ • As a cell grows larger at some point its surface area becomes too small to allow these materials to enter the cell quickly enough to meet the cell's need. This is known as_____________________ Law • Find the SA: V of the following: • Which cube has the greater SA:V?

33. CHP 2 TOPIC 7 CELL SPECIALISATIION -TISSUES ORGANS & SYSTEMS In most multicellular organisms, we find the following organization: • Cellular Level: The smallest unit of life capable of carrying out all the functions of living things. • Tissue Level: A group of cells that performs a specific function in an organism. • Organ Level: Several different types of tissue that function together for a specific purpose. • Organ System Level: Several organs working together to perform a function. The different organ systems in a multicellular organism interact to carry out the processes of life

34. CHP 2 TOPIC 7 CELL SPECIALISATIION -TISSUES ORGANS & SYSTEMS Eukaryotic cells vary a great deal in structure. Variations in cell structure are related to function. Cells vary in the number of each organelle present and in their shape and life cycle.

35. Topic CHP2.7 Questions: • True/ False: cells in an organ are all made of the same tissue and cell type? ______ • How do single celled organisms function without specialised cells and tissues? Explain: _________________________________________________________________________________________________________________________________________________________________________________________________________ • Name two characteristics of: • root hairs that supports its function to absorb materials from its environment: _______________, ____________________ • Microvilli that supports its function to absorb materials from its environment: _______________, ____________________ • Leaf cell to photosynthesise: _______________, ____________________ / 3 Marks

36. CHP 2 TOPIC 8 CONNECTIONS BETWEEN CELLS Although some cells like blood cells, are free to move as individuals around the body, most cells remain as a group. To assist this ‘community’ of cells are three types of junctions (joins) including: • Occluding junctions: simply where one cell comes into contact with another (no movement of material between them) • Communicating junctions (gap junctions): also known as gap junctions. Consist of protein lined pores between the membrane of adjacent cells. The proteins are aligned like a series of rods with a gap (pore) in the middle of them. This bridge between cells enables the passage of ions, sugars, amino acids, other small particles and even electrical signals between the two cells. (example: electrical impulse in the heart) • Anchoring Junctions (desmosomes): most common form of junction in epithelial cells (skin, uterus, lining cells!). Dense proteins protrude from the cytosol of one cell into the other to ‘anchor’ the cells together.

37. Communicating Junctions right .. Anchoring junctions below Chapter 2 - Membranes and cell organelles

38. Connections between plant cells Chapter 2 - Membranes and cell organelles Plasmodesmata (singular: plasmodium) is the name given for the structure that joins plant cells. Because of the way in which cell walls are built, the gap or pore between two cells is continuous and lined with cell membrane. The structure that bridges the gap is continuos with smooth endoplamsic reticulum.

39. Topic CHP2.8 Questions: • List three types of communicating junctions: ____________________, ___________________________, _________________ • What is the name given to the structure that joins plant cells together: __________________ • True/ False: the cytoplasm of one plant cell is continuous with the cytoplasm of another plant cell • Which macromolecule constitutes the gap junction structure: ________________ • Name this structure: Dense proteins protrude from the cytosol of one cell into the other to anchor the cells together: ____________________ /5 Marks