2024 VCE Biology Revision Lecture PDF

VCE Biology Revision Lecture 2024 Ms. Trist  Plan for today... 1. Recap some content from units 3 & 4 2. Practice Questions 3. Tips for success during the examination Unit Recap3 You can be asked to draw this  DNA Vs RNA DNA...

VCE Biology Revision Lecture 2024 Ms. Trist  Plan for today... 1. Recap some content from units 3 & 4 2. Practice Questions 3. Tips for success during the examination Unit Recap3 You can be asked to draw this  DNA Vs RNA DNA RNA Double Stranded. Single Stranded. Deoxyribose sugar. ‘Ribose’ sugar. Adenine – Thymine Adenine – Uracil Cytosine – Guanine Cytosine – Guanine. One Type Three Types: DNA Only mRNA; tRNA; rRNA Protein Synthesis: Transcription & Translation Transcription (DNA – Translation (mRNA – mRNA) LOCATION - Nucleus Protein) LOCATION - Ribosome 1. RNA Polymerase (RNA pol) unwinds 1. mRNA binds to the ribosome & double helix 2. mRNA’s codons are read 2. RNA pol binds to promotor 3. tRNA carries specific amino acid 3. RNA moves down the DNA producing a 4. If tRNA anticodon is complementary complementary of the gene as pre-mRNA mRNA’s codon, amino acid is released 4. RNA pol detaches from DNA which recoils 5. Amino acids are joined by peptide bonds 5. Pre-mRNA prepares for export 6. To produce polypeptide chain / protein Protein Modification and Export Rough Endoplasmic reticulum – folding and modification Golgi – Final modifications and prep for export Vesicle – Transport protein from RER to Golgi or from Golgi to Plasma Membrane Plasma Membrane – Releases via Exocytosis Mitochondria– provides energy (ATP) for modification and export  Gene Structure Prokaryotic Eukaryotic Promotor Region (RNA Pol Binds) Promotor Region (RNA Pol Binds) Operator Region (Repressor Binds) No operator regions Only Exons – NO Introns Introns and Exons Operons – multiple genes behind No Operons, One gene per a single promotor promotor Regulated by Attenuation and Regulated by supercoiling and repression transcription factors Trp Operon Trp Open is found in some prokaryotes as a way of regulating the amount of Trp (amino acid) produced by the cell. Repression Attenuatio Both 1. Trp binds to n 1. 2x Trp bind to the Regulate the amount leader sequence of Trp produced by repressor protein 2. Forming a terminator the cell 2. Active repressor hairpin loop Conserves cells binds to operator 3. Ribosome is energy / resources region detached from the When Trp is high both 3. RNA polymerase attenuated mRNA repression and cannot produce 4. No Trp produced attenuation can genes E - A occur DNA Modification Enzymes Restriction Enzymes – Cut Phosphodiester Endonucl (sugar-phosphate) bonds in DNA Sticky and Blunt end can ease be produced. Sticky Ends have Ligase Repairs broken Phosphodiester (sugar- overhanding ends and phosphate) bonds in DNA allow for easier insertion of target gene (correct orientation) Polymer DNA polymerase builds DNA (eg Taq Polymerase) Blunt Ends no overhang RNA Polymerase builds RNA ase  Gel Electrophoresis 1. DNA samples are cut with restriction enzymes to expose STR sites 2. DNA samples are loaded in the wells 3. Electronic current is used to separate samples from largest (travel least distance) to smallest (travel the furthest distance) 4. Samples are compared for DNA Profiling What is added: DNA Samples (cut with the same Restriction enzymes) Dye to observe the movement of the DNA DNA ladder for comparison / reference Buffer solution for current to flow through DNA is negatively charged and travels towards the positive electrode - Larger fragments remain closer to the wells - Smaller fragments travel further Polymerase Chain Reaction (PCR) 1 2 3 Denaturation – Annealing – Denaturation – 90°C - 100°C 50°C - 60°C 72°C Sample heated to Sample cooled to Optimum for Taq break Hydrogen allow Polymerase to bonds between complementary synthesize new adjacent nucleotides primers to attach complementary DNA strands CRISPR-Cas9 complex CRISPR Cas9 is a system in prokaryotes which provides immunity for subsequent infections. The CRISPR system has been adapted by scientists for gene editing 1. CRISPR in 2. CRISPR in bacteria Spacers are segments of DNA cut from Biotech Cas9 (endonuclease) capable of precisely invading viruses cutting both strands of DNA (Target Cas9 (endonuclease) capable of precisely sequence) cutting both strands of DNA (Target sgRNA – Produced in a lab from a target sequence) gene and is used to modify the gene PAM sequence plays an essential role in Gene knockout – disrupts the functioning of distinguishing self from non-self & tells Cas- a gene (eg a gene causing cancer) 9 where to cut Gene knockin – new gene is knocked in to gRNA – Produced from a spacer sequence genome (eg a gene to improve crop productivity) Production of Human Insulin Diabetics (type 1) do not produce functional insulin thus rely on synthetic insulin to regulate their blood sugar levels. This process is done in TWO separate bacteria by two separate plasmids. Process Diagram 1. Insulin gene and bacterial plasmid are cut with the same restriction enzyme 2. Recombinant plasmid is produced with B-gal gene & insulin gene 3. Plasmid is heat shocked into bacteria to produce transformed bacteria 4. Bacteria are cultured and insulin protein is produced, harvested and purified (joined to additional insulin chain)  Genetically Modified and Transgenic All Transgenic are GM not all GM are Transgenics Transgenic organisms contain one or more genes from a different species. All transgenic organisms are GMO Genetically modified organisms (GMO) have had their genomes modified by external tools. Enzyme Inhibition Competitive Inhibition Substrate and inhibitor are similar in size, shape and chemical nature, thus COMPETE for the enzymes active site Non-competitive Inhibition Inhibitor binds to the enzymes allosteric site changing the shape of the enzymes active site, preventing the enzyme from binding to its substrate Photosynt Purpose hesis To use light to convert inorganic molecules (Water and Carbon Dioxide) into Glucose Overview Photosynthesis Light Dependent Light Independent Reaction Light strikes Chlorophyll in thylakoid Reaction Rubisco fixes carbon dioxide to RuBP membrane. In the Stroma Water is photolyzed into oxygen and NADPH produced in the LDR is gives Hydrogen Hydrogen to produce glucose NADP+ becomes NADPH and is used for ATP produced in the LDR supplies energy for the Calvin cycle the production of Glucose / Calvin cycle Oxygen leaves the leaf via stomata RuPB  G3P  TP  Glucose ATP is produced from ADP+Pi via ATP synthase in the electron transport chain  Factors affecting Photosynthesis Light, Carbon Dioxide and Water can produce this same saturation graph  Adaptations of C4 and 1 CAM Plants 2 3 C3 Plants C4 Plants CAM Plants LDR Location – Thylakoid LDR Location – Thylakoid LDR Location – Thylakoid membrane of Mesophyll membrane of Mesophyll membrane of Mesophyll Cells Cells Cells LIR Location – Stroma of LIR Location – Stroma of LIR Location – Stroma of Mesophyll Cells Bundle Sheath Cells Mesophyll Cells C3 have NO In times of water stress, C4 CAM Plants ONLY open Stomata adaptations to plants will undergo a C4 pathway at night time to minimize water prevent and separate the LIR and LDR loss. Photorespiration. into different locations  CRISPR & CROPS CRISPR technology can be used to modify crops to improve their photosynthetic efficiency - Improve rubisco’s affinity to CO2 - Improve chlorophyll’s ability to capture all wavelengths of light / capture green light - Improve the speed of the reactions in photosynthesis CRISPR technology can be used to modify crops to improve their crop yields - Increase the number of harvests per stem - Accelerate the time it takes for the crop to mature Cell Purpose Respiratio To use Glucose (organic energy) to produce ATP from (ADP+Pi) n Aerobic (requires oxygen) & Anaerobic (no oxygen) Overview  Stages of Aerobic 1 Respiration 2 3 Glycolysis Krebs Cycle Electron Transport Inputs – Glucose NAD+ Inputs – 2x Acetyl CoA, Chain Inputs – FADH2, NADH, Outputs – 2x Pyruvate, NAD+, FAD+ ADP+Pi, Oxygen NADH Outputs –CO2, NADH, FADH2 Outputs –NAD+, FAD+, ATP Location – Cytoplasm Location – Matrix of Water Mitochondria Location – Cristae of Net - 2 ATP PRODUCED mitochondria Net - 2 ATP PRODUCED Net – 26 - 28 ATP Glycolysis is ALWAYS the Link Reaction – Pyruvate PRODUCED Coenzymes NADH, FADH2 from first step in both aerobic enters mitochondria and is glycolysis and Krebs travel to ETC and anaerobic respiration converted into Acetyl CoA creating a proton gradient. for Krebs Protons (H+) pass through ATP NADH travels to ETC synthase producing ATP from NADH & FADH2 travel to ADP+Pi. ETC Oxygen is final electron acceptor Anaerobic Respiration Anaerobic respiration occurs in all living things & is ALWAYS the first step in respiration (Glycolysis) Lactic Acid formation in Animals Alcoholic Fermentation in Yeast and Plants Glycolysis is responsible for producing the 2 ATP in anaerobic respiration Factors affecting Cellular Respiration Increasing glucose and increasing oxygen concentration will cause same graph Biofuel Biofuel is sustainable and can be used to make purified ethanol through anaerobic fermentation Process: 1. Organic plant waste is obtained (eg non-consumable pants of plants) & exposed to enzymes. 2. Organic plant waste is broken down into glucose 3. Glucose is supplied to yeast in fermentation chambers (anaerobic environment) 4. Yeast use glucose to undergo anaerobic fermentation 5. Bioethanol is harvested and purified for commercial use. Unit Recap4  Macropha Innate APC – phagocytosis of pathogen and displays foreign antigen as MHCII ge Immunity Dendritic APC – phagocytosis of pathogen and displays foreign antigen as MHCII cell Neutrop APC – phagocytosis of pathogen and displays foreign antigen as MHCII hil Eosinop Responsible for parasite infections hils Natural Attack body cells with defective MHC1 via the release of perforins killer Mast Inflammation & histamine release Allergic responses & histamine release cells Antigen Presentation Innate Location Adaptive Antigen presenting cells Macrophage Migrate to the lymph Activate T-Helper cell Dendritic Cell node Neutrophil.  Inflammatory Response Cytokines are released from damaged tissue Immune cells move to site of damage Mast cells release Histamine Histamine causes: - Leaky capillaries - Vasodilation Site becomes hot / swollen & red due to increased cellular activity Macrophages remove debris Adaptive Immune Response Adaptive immune response provides long term immunity to pathogens and protects the body against reinfection through the production of memory cells Adaptive immune response is coordinated by the T-helper cell after Antigen presentation Humoral (B Cell) Cell Mediated (T T-helper cell is activated by APC Cell) T-helper cell is activated by APC T-helper cell releases cytokines and T-helper cell releases cytokines and activates activates Naïve B-Cell Naïve T-Cell Naïve B cell undergoes clonal selection to Naïve T-cell undergoes clonal selection to produce plasma B cell and Memory B cell produce specific Cytotoxic T-cells Plasma B cell produced specific antibodies Cytotoxic T cells will attack cells with specific which bind to & neutralise foreign antigen defective MHC1, causing apoptosis or the Memory B remains in bloodstream & release of perforins provides long term immunity against Plasma B cells produce specific Antibodies subsequent infections Memory cells provide long term immunity Plant Plants have no adaptive immune responses. Immunity Physical Barrier Physical Barriers prevent pathogen from attacking / gaining access to the plant Thorns Trichomes (hairs) Waxy Cuticle Lignin Walls Chemical Barriers Physical Barriers prevent pathogen from attacking / gaining access to the plant Enzymes Essential Oils Phytoalexins Defensins  Prevent the Spread of pathogens Identify the Pathogen Identify its transmission Develop a vaccine* Direct contact?? Gloves, masks, don’t share items, condoms Vaccines attenuated / (STI) dead forms of pathogens Is it bacterial / viral etc? and are used to Droplet transmission? stimulate the body to How does it replicate? Masks, sneeze into produce memory cells elbows, isolate infected and provide protection What are its symptoms? against subsequent Vector infections Control the spread of vectors, mosquito nets Acquiring Immunity  Vaccinations and Herd Immunity Vaccinations stimulate the body to produce memory cells in Active immunity Vaccinations can assist in providing Herd Immunity in a population (95%) Herd immunity can protect those who are unable to receive a vaccination Herd immunity reduces the transmissible hosts available for the pathogen to spread through  Monoclonal Antibodies Monoclonal antibodies are clones of a single antibody produced in the laboratory setting Process: 1. Mouse injected with antigen to stimulate immune response 2. Mouse spleen harvested 3. Mouse Plasma cell are harvested from the spleen and are fused with tumor cell 4. Hybridoma cell is produced & cultured 5. Large quantities of monoclonal antibodies are produced and purified 6. Monoclonal antibodies are given as a treatment Genetic Drift Genetic drift is a random change event that can cause changes in allele frequencies in populations Genetic Drift is not an example of Natural Selection Bottleneck Founder effect Chance event where randomly some Small number of members branch off to form members of the population survive a a brand new population natural disaster and others do not Only the alleles present in the founding Affects smaller populations more than individuals will be present in the new bigger populations population Can result in the loss of alleles from the Causes a decrease in variation population Decreases variation in population  Natural Selection Natural selection is the driving force for evolution Variation in a population allows for traits to be selected for (fit) or selected against (unfit) Over time the allele frequency changes depending on the organism environment Natural selection can lead to speciation Natural selection reduces genetic variation in a population  Natural Selection example – bacterial resistance VARIATION: in a population of bacteria – some have resistance to antibiotic others do not SELECTION PRESSURE: exposure to antibiotic; only those with resistance survive and reproduce (no resistance = no survival) FUTURE GENERATIONS: higher allele frequency of resistant bacteria NATURAL SELECTION OCCURED Antigenic Shift and Drift Vaccines become ineffective due to the random mutations in virus over time. This can be gradual and minimal changes or can be abrupt. Antigenic Drift Antigenic Shift RANDOM SEASONAL MUTATIONS natural selection process occurring over time RAPID & SEVERE CHANGE Can result in a novel virus unknown to species New sub-virus  Speciation The process of new species diverging from an ancestral species due to environmental selection presses Allopatric Sympatric Speciation (V) - Variation exists in ancestral Speciation (V) - Variation exists in ancestral population population (B) – Barrier to prevent gene flow (S) – Selection pressures cause (S) – Selection pressures vary between reproductive isolation newly separated populations (I) – Isolation leads to accumulation of (I) – Isolation of populations to prevent mutations in the populations (not reproduction leading to accumulation of geographically separated) mutations (S) – Speciation two new species are (S) – Speciation two new species are formed and unable to produce viable formed and unable to produce viable offspring offspring EG Lord Howe Palms Eg Darwins Finches  Fossils Process Examples Dating Absolute Dating Index fossils (used to Carbon Dating relatively date other (>60,000) 1. Rapid burial species Potassium Argon 2. Anoxic Environment (