LIFE SCIENCE EXAM NOTES PDF

GLUCOSE TEST: Solution used: Benedict’s solution Result: + will change from clear blue —> opaque green —> yellow —> brick red Process: Boil all the food to be tested in a test tube with a bit of Benedict’s solution STARCH TEST: Solution used: Iodine Result: + will become...

GLUCOSE TEST: Solution used: Benedict’s solution Result: + will change from clear blue —> opaque green —> yellow —> brick red Process: Boil all the food to be tested in a test tube with a bit of Benedict’s solution STARCH TEST: Solution used: Iodine Result: + will become dark blue Process: Boil the food to be tested in water to cook the starch; let cool; add iodine FAT TEST: Solution used: Ethanol Result: + will show cloudy white emulsion Process: Place the food to be tested in a dry test tube (2 drops of oil/fat to 5cm³) Shake to dissolve fat, pour into test tube containing a bit of water PROTEIN TEST: Solution used: Biuret solution Result: + will turn mauve (purple-ish) Process: Must use liquid food. Place in test tube, add equal volume Biuret solution (equal volume NaOH with 1 drop CuSO₄) MICROGRAPH CALCULATIONS: WHEN SCALE LINE IS GIVEN: ACTUAL SIZE = IMAGE SIZE (mm) X SCALE (VALUE ON LINE) LENGTH OF SCALE LINE (mm) MAGNIFICATION = LENGHT OF SCALE LINE (mm) SCALE (VALUE ON LINE) x10³ x10³ mm µm nm x10⁻³ x10⁻³  EUTROPHICATION: Eutrophication is the process in which nutrients accumulate and cause excess growth of plant life and bacteria in a body of water that may deplete it of oxygen. Overused soil may require synthetic fertilisers to regain its nutrient contents. Nutrients usually come from dead and decaying organic matter. If synthetic fertiliser is not used, nutrients can be brought back by the following: leave the soil fallow, plough back dead plants. Many synthetic fertilisers contain phosphates and nitrates. When is rains, these are washed into bodies of water and cause a rapid plant and algae growth. The algae can grow and cover the surface of the water, the preventing the plants and animals further down from receiving sunlight. These organisms then die and attract bacteria that will help decompose these decaying organisms. However, these bacteria use more oxygen and the oxygen levels become almost depleted (water becomes anoxic), causing almost all living organisms in the water (such as fish, plants, insects, aquatic mammals, etc) to die. definitions: fallow: to leave the soil to go through natural nutrient cycles; to not use the soil anoxic/anoxia: the absence of oxygen; low levels of oxygen synthetic fertilisers: manufactured from minerals, gases, and inorganic materials phosphates & nitrates: inorganic components of synthetic fertilisers that encourage plant growth  CELLS: BASIC INFORMATION: Cells are the smallest living unit. They were discovered by Robert Hooke in the mid 1600s (observed from a sliver of cork with “rows of empty boxes”) CELL THEORY: 1839 — Theodor Schwann & Matthias Schleiden — “All living things are made of cells” 50 yrs later — Rudolf Virchow -- “All cells come from cells” 1. All living things are made up of cells 2. The cell is the smallest living unit of structure and function of all organisms. 3. All cells arise from pre-existing cells (discards idea of spontaneous generation) CHARACTERISTICS OF ALL CELLS: Surrounding membrane protoplasm (thick fluid inside cell) organelles (structures used for cell functions) control centre with DNA and RNA ORGANELLES Make up the “cellular machinery” of the cell. 2 types: Derived from membranes; bacteria- like organelles BACTERIA-LIKE ORGANELLES: derived from ancient symbiotic bacteria Forms part of the endosymbiotic theory: modern cells evolved from cells that formed a symbiotic relationship with bacteria  PROKARYOTIC CELLS: first cell type Bacteria and Archaea no membrane bound nucleus —> nucleoid region (region of DNA concentration) organelles not bound by membranes EUKARYOTIC CELLS: Includes protists, plants, animals, fungi nucleus is membrane-bound many internal organelles  ANIMAL CELL: ANIMAL SPECIFIC ORGANELLES: centrioles/centrosomes lysosomes Vacuoles are less prevalent in animal cells, when found they are very small compared to plant cells  PLANT CELL: PLANT SPECIFIC ORGANELLES: chloroplasts cell wall vacuoles are much more prevalent in plant cells and can make up to 90% of the cell size.  PLASMA MEMBRANE: Surrounds cell, contains all cell contents. Made up of phospholipid bilayer and proteins. PHOSPHOLIPID: made up of phosphoric acid and lipid molecule polar molecules head (phosphoric acid) — hydrophylic tail (lipid) — hydrophobic TRANSPORT some molecules can move freely (water; CO₂, O₂, ammonia) Carrier proteins transport others carrier proteins embedded in bilayer) Fluid mosaic model — describes fluid nature of lipid bilayer w/ proteins Phospholipid + protein create mosaic, all molecules move (fluid) MEMBRANE PROTEINS: 1) Channels/transporters: move molecules in 1 direction 2) receptors: recognise certain chemicals 3) glycoproteins: identify cell types 4) enzymes: catalyse substance production TRANSPORT METHODS: PASSIVE TRANSPORT: eg. Diffusion, osmosis liquid or gas moving from an area of high concentration to an area of low concentration (follows the natural concentration gradient) does NOT require energy ACTIVE TRANSPORT: movement of particles against the concentration gradient requires energy eg. Sodium-potassium pump PASSIVE TRANSPORT METHODS: DIFFUSION: molecules move to equalise concentration passive transport, does not require energy OSMOSIS special form of diffusion: only in water fluid flows from lower solute concentration (can be into or out of cell) FACILITATED DIFFUSION: movement through differentially permeable membrane with channels that are specific to certain molecules/ions channels are usually transport proteins (eg. Aquaporins for movement of water) passive transport process: 1) protein binds with molecule 2) protein changes its shape to fit the molecule 3) molecule moves across the membrane while envelopes in transport protein ACTIVE TRANSPORT METHODS: SODIUM-POTASSIUM PUMP: potassium moves into the cell (2 molecules) and sodium moves out of the cell (3 molecules) movement is against the natural concentration gradient, and therefore is active transport/requires energy energy = ATP (adenosine triphosphate) (the energy is released by the hydrolysis of ATP) process: The pump is open toward the inside of the cell. 3 sodium molecules enter the pump, and 1 phosphorous from the ATP bonds to the pump. (ATP —> ADP [adenosine diphosphate]). The pump closes with the sodium inside and opens again toward the outside of the cell. The phosphorus is released back and ADP —> ATP. DIAGRAM SHOWING THE SODIUM-POTASSIUM PUMP AND MOVEMENT OF MOLECULE AND ATP —> SOLUTION DIFFERENCES AND CELLS: solvent + solute = solution HYPOTONIC more solutes inside cell solvent flows INTO cell ISOTONIC solutes EQUAL inside and outside of cell HYPERTONIC greater solutes outside of cell fluid flows OUT of cell *must remember that this is in reference to other thing* eg. If there is less solute in the cell, then the cell is HYPERTONIC compared to the solvent. The solvent is therefore HYPOTONIC compared to the cell. ORGANELLE DETAILS: CELL WALLS: found in plants, fungi, protists surrounds plasma membrane, creates cell structure plants: mostly cellulose fungi : chitin CYTOPLASM: viscous fluid that contains all organelles components: interconnected filaments and fibres, fluid (cytosol), organelles (not nucleus), storage substances CYTOSKELETON: made up of filaments & fibres 3 fibre types: microfilaments, microtubules, intermediate filaments 3 functions: mechanical support, anchors organelles down, helps move subsatnces around the cell CILIA & FLAGELLA: provides motility/mobility cilia: short, move substances outside of human cells flagella: whip-like, found on sperm cells basal bodies (like centrioles) (basal body is a protein structure) bundles of microtubules with a plasma membrane CENTRIOLES: pairs of microtubular structures important for cell division MEMBRANOUS ORGANELLES bound by membrane, functional components within cytoplasm NUCLEUS: control centre surrounded by double membrane —> nuclear membrane contains chromosomes and nucleolus NUCLEAR ENVELOPE: separate nucleus from the rest of the cell also known as nuclear membrane has pores —> nuclear pores DNA: deoxyribonucleic acid hereditary information of cells chromosomes: DNA, Proteins, form for cel division chromatin NUCLEOLUS: most cells have 2+ directs the synthesis of RNA forms ribosomes ENDOPLASMIC RETICULUM (ER): network of interconnected membranes that help move substances within a cell 2 types: rough ER, smooth ER ROUGH ER - Has ribosomes attached to outer surface to manufacture proteins - May also modify the proteins that ribosomes produce SMOOTH ER - no ribosomes attached - contains enzymes to help BUILD molecules (carbs, lipids) GOLGI APPARATUS: involved in synthesis of cell wall packaging and shipping PROCESS: 1. molecule arrive in vesicle 2. vesicle fuses with Golgi membrane 3. molecule may be modified 4. molecule is pinched off into a new vesicle 5. the vesicle leave the Golgi body 6. Vesicle may now combine with plasma membrane to secrete contents LYSOSOME: contains digestive enzymes aids in cell renewal, breaking down old cells parts, and digesting invaders or foreign substances VACUOLES membrane-bound storage sacs more common in plant cells contains water, food, waste products BACTERIA-LIKE ORGANELLES store and release energy Mitochondria (release) chloroplasts (store) MITOCHONDRIA have the own DNA (mitochondrial DNA; inherited from mother, though to correlate to intelligence) double-membrane bound break down fuel molecules (glucose, fatty acids) release ATP energy (adenosine triphosphate) CHLOROPLAST derived from photosynthetic bacteria captures solar energy Photosynthesis takes place in chloroplasts (makes cellular food —> glucose)  ENDOCYTOSIS: The movement of large material (particles, organisms, or large molecules) into the cell. 2 types of endocytosis: bulk phase (non-specific); receptor-mediated (specific) Process of endocytosis: 1. plasma membrane surrounds chosen material 2. edges of the membrane meet 3. membrane fuse to for a vesicle 4. vesicle is pinched off and the material travels into the cell Forms of endocytosis: Phagocytosis (cell eating —> usually whole molecules or small organisms) Pinocytosis (cell drinking —> usually a liquid)  EXOCYTOSIS: Exocytosis is the reverse of endocytosis: it is the movement of large molecules or particles out of the cell (discharge of materials) Process of exocytosis: 1. the material in question is surrounded by a vesicle 2. the vesicle moves the the cell surface near the membrane 3. the membrane of the vesicle and the plasma membrane of the cell fuse 4. the contents of the vesicle are expelled/discharged from the cell A micrograph showing the different components of the cytoskeleton (microtubules, intermediate filament) A micrograph showing centrioles  A micrograph showing the positioning of the nucleolus within the nucleus and nuclear membrane (nuclear envelope) A micrograph showing lysosomes within a cell A micrograph of a vacuole in a plant cell (largest organelle visible) A micrograph showing the process of exocytosis (the discharge of materials from within the cell)  ORGANIC COMPOUNDS organic compounds contain the element Carbon 12 (C12). Eg. CarbS, lipids, proteins CARBOHYRDATES: made up of C;H;O H:O —> 2:1 3 groups: monosaccharides, disaccharides, polysaccharides MONOSACCHARIDES: simple sugars glucose: main energy source; monomer of carbs fructose: fruit sugar galactose: dairy sugar DISACCHARIDES: double sugars maltose (malt sugar) = glucose + glucose lactose (milk sugar) = glucose + galactose sucrose (cane sugar) = glucose + fructose synthesis (building up) of disaccharides occurs by condensation (results in a water molecule in addition to the disaccharide) POLYSACCHARIDE: monomer = monosaccharides starch: glucose stored in plants glycogen: energy stored in animals (liver & muscle cells) cellulose: stored to give plant walls strength BIOLOGICAL IMPORTANCE OF CARBOHYDRATES FOR LIVING ORGANISMS primary energy source for plants and animals - stored as starch in plant - stored as glycogen in animals provides structure for organisms - provides plants will cellulose (for their cell wall structure) - provides animals and fungi with chitin (to make up semi-hard structure) LIPIDS: fats and oils made up of C;H;O H:O ratio is much higher than that of carbs greater source of energy than carbs 1 lipid molecule is made up of 3 fatty acids and 1 glycerol insoluble in water (hydrophobic) soluble in ether and alcohol (eg. Ethanol) 2 types: saturated; unsaturated SATURATED FATS VS UNSATURATED FATS -butter, meat, dairy -vegetable oils -solid @ room temp -liquid @ room temp -low-density lipoprotein (“bad” cholesterol) -high-density lipoprotein (“good”) -clogs arteries -HDL grabs LDL, moves to liver, LDL is broken down and removed BIOLOGICAL IMPORTANCE OF LIPIDS: better source of energy -> produces more energy unit per mass than carbs acts as reserve energy (stored fats) heat insulator (warm blooded animals have a layer of fat under their skin as insulation) makes up the waxy coverings on plant (fruit and leaves) that prevent water loss makes up phospholipid that forms the cell membrane (inner layer) covers organs and acts as a shock absorberprotective covering FAT SOLUBLE VITAMINS: Vitamin A: vision, reproduction, bone health, immune system, skin Vitamin D: bone strength, calcium absorption, immune system Vitamin E: immune system , toxin removal Vitamin K: blood clotting, bone health PROTEINS: monomer—> animo acids very large molecules made up of C;H;O;N (sometimes S;P;Fe) 20 different animo acids peptide bonds between limo acids to form proteins dipeptide: 2 amino acids tripeptide: 3 amino acids polypeptide: deoxyribonucleic acid. Serves as a cellular database by storing information about all the possible polypeptides that can be formed within a cell RNA —> ribonucleic acid. (mRNA, rRNA, tRNA —> messenger, ribosomal, transfer) Needed to convert DNA info into polypeptide sequences. Can serve as primary database in some unicellular organisms (eg. Viruses have no DNA involvement)  MITOSIS The process of mitosis combines with cytokinesis to form cell division. This happens in all eukaryotic organisms. maintains number of chromosomes (diploid cell —> diploid cell) MITOSIS IS THE PROCESS BY WHICH A CELL DUPLICATES ITS GENETIC MATERIALS (CHROMOSOMES) AND PREPARES FOR CELL DIVISION CYTOKINESIS IS THE DIVISION OF THE REST OF THE CELL INTO TWO DIFFERENT DAUGHTER CELLS Prokaryotic cells also divide through binary fission (which is NOT mitosis/cytokinesis) In animals, cell division occurs during embryonic development, growth, and wound healing. Errors during the replication of genetic material or splitting of the cell can result in cell death or cell abnormalities such as cancer. SUMMARY OF PROCESS: 1. before mitosis: cell creates an exact copy of its DNA material 2. during mitosis: the copies are reorganised, repackages into 2 sets of chromosomes, and divided to opposite ends of the cell. 3. mitosis is immediately followed by cytokinesis (the cell divides into 2 new cell) 4. the original cell (mother cell) is identical to the two new cells (daughter cells) PHASES OF MITOSIS: 5 phases: interphase; prophase, metaphase, anaphase, telophase (these fall under “KARYOKINESIS”) (telophase includes early-stage and late-stage —> early stage is included in Karyokinesis; late-stage telophase is cytokinesis) during each phase, different protein are involved to perform specific roles to divide the genetic material cytokinesis happens only after mitosis creates the two new cells INTERPHASE no division takes place —> RESTING STAGE cell grows to be fully matured DNA begins to replicate PROPHASE chromatin shortens and thickens to form chromosomes (chromatin network is spaghetti-shaped, has to reorganise) —> chromosomes consist of chromatids and centromere microtubules are organised to from mitotic spindles (Animals: between centrioles; Plants: I the cytoplasm) nucleolus ad nuclear membrane/envelope begin to disappear METAPHASE chromosomes arrange themselves at the equator of the cell (metaphase plate) assisted by the mitotic spindles (pull on the chromosomes) centromeres attach to the mitotic spindles ANAPHASE each pair of chromosomes is pulled apart into chromatids and the centromeres divide chromatids are now called daughter chromosomes and are identical the the mother chromosomes as well as each other spindle fibres contact and shorten (with the use of ATP) —> pulls the chromosomes to opposite poles of the cell TELOPHASE Early telophase: spindle fibres disappear chromosomes deconstruct themselves back into bundles of chromatin (forms a new chromatin network for each of the new daughter cells) a new nuclear envelope begins to form around the chromatin (to form a new nucleus for each of the daughter cells) cell membrane begins to cleave (called CELL CLEAVAGE) in preparation for cytokinesis (cell process of invagination) CYTOKINESIS: the cell membrane is pinched off to form 2 separate compartments (ANIMAL: membrane grows towards middle until pinched off; PLANT: cell plate (made of pectin) forms across cell to from middle lamella) cytoplasm and organelles are divided between the daughter cells at the end, the membrane fuses and cuts the two daughter cells off from each other THE DAUGHTER CELLS HAVE IDENTICAL DNA AND THE SAME AMOUNT OF CYTOPLASM AND THE SAME ORGANELLES MITOSIS DEFINITIONS: nucleus: location the DNA in a cell nuclear envelope: the membrane that separates the nucleus from the cytoplasm DNA: long molecule that contains the genetic blueprints fro cell behaviour chromatin: loosely bundled coil of DNA histones: proteins that hold DNA stand together in the form of chromatin chromosome: highly organised form of chromatin (each chromosome is composed of two identical parts called CHROMATIDS; DNA only exists as chromosomes during mitosis; each chromosome looks like an X) chromatids (singular): 1 half of a chromosome which contain the same genetic information centromere: bundle of proteins that connects the 2 chromatids to form a chromosome microtubules (MT): tubes of protein which pull the chromosomes apart; part of the cytoskeleton; powered by ATP mitotic spindle: how the MTs are organised during mitosis (collection of microtubule fibres) metaphase plate: the line along which the chromosomes are lined up during mitosis (the line is coordinated by the mitosis spindles) FORMULA FOR NUMBER OF CELLS: 2ⁿ 2 = doubling of cells n = number of divisions that took place MITOSIS IN PLANTS: occurs in special MERISTEMATIC CELLS (in the radicle [root], plumule [stem] or buds —> growth in length) (division in the cambium tissue in stem —> growth in thickness [annual rings]) MITOSIS IN ANIMALS: takes place in special organ tissues: embryonic development (continual mitotic division and growth of cells) basal layer of epidermis (lower layer) long bones (femur, humerus, etc) lymph glands BENEFIT OF MITOSIS: growth process (length & thickness; metamorphosis [change in shape], increase in natural aging) repair and replace damaged/worn out cells method of reproduction in unicellular organisms (binary fission)