BIOLOGY HSC 2024 NOTESGood luck on your HSC.Asexual and sexual reproduction:Asexual reproduction - Production of offspring from one parent.Sexual reproduction - Production of offspring through different parent gametes.Animal sexual and asexual reproduction:Internal fertilisation - The release of gametes into the female body.Pros and Cons = Takes more time, more energy, there is more variation and is safer.External fertilisation - The release of gametes into open environments.Pros and Cons = More offspring, dangerous for eggs, less time and energy consuming, has to be an aquatic environment.Hormones in pregnancy:Oestrogen - Regulates growth, development and physiological aspects of the human reproductive system.Prostregon - Creates uterus lining.Female reproductive system:Vagina → Cervix → Uterus ⇒ Fallopian tube → Ovary.Mitosis:Occurs in somatic (non sex) cells.IPMATC ⇒ Interphase, introphase (preparation), prophase, metaphase (middle), anaphase, telophase, cytokinesis (end).Interphase - Chromosomes duplicate and nutrients prepare.Prophase - Spindle fibres form, chromosomes condense and nuclear membrane breakdown.Metaphase - Chromosomes align in the middle, ready for separation.Anaphase - Spindle shortens and chromatids separate.Telophase - New nuclei form and chromosome decondense. Cytokinesis - Two new daughter cells are formed.Meiosis 1:Occurs in sex cells.Prophase 1 - Spindle fibres form, crossing over occurs and chromosomes condense.Metaphase 1 - Spindle fibres attach to cetromes, chromosomes line up in homologous pairs.Anaphase 1 - Sister chromatids stay together, homologous pairs are pulled apart, cell enlarges.Telophase 1 - Two nuclei form, spindle shortens, cell separation.Meiosis 2:Prophase 2 - Chromosomes condense, spindle fibres form.Metaphase 2 - Chromosomes align in the middle.Anaphase 2 - Cell elongates, sister chromatids are pulled apart.Telophase 2 - Two new nuclei form, gametes are formed in cytokinesis.DNA and RNA:DNA structure - Nucleotide = Nitrogenous base → Sugar → Phosphate.Nitrogenous bases = Guanine, Cytonine, Adenine, Thymine. A T, C G.RNA structure - Nucleotide = Ribose sugar → Phosphate group → Nitrogenous base.Nitrogenous bases = Guanine, Cytosine, Adenine, Uracil. A U, C G.DNA Replication:DNA is semi-conservative (reduces incompatibility).DNA helicase unzips the double helix.DNA polymerase pairs free bases with the open single strand.Dna polymerase acts as a catalyst for the chemical reaction causing a polymer to attach to the phosphate and sugar.Protein Synthesis:Gene - Portions of DNA which specifically code for a protein.Codon - The bases which code for a certain amino acid (Such as start and stop codons).Transcription:Occurs in the nucleus.RNA polymerase separates DNA of a gene.The template is made into MRNA:Bases pair with complementary bases.RNA polymerase adds RNA nucleotides one at a time.DNA strands close up behind this.MRNA has been created.MRNA leaves the nucleus through nuclear pore to go into cytoplasm.MRNA attaches to the ribosome for translation.Translation:Occurs in the ribosome.TRNA attaches complementary codons to create a specific amino acid.RIbosome catalyses peptide bonds between amino acids.TRNA lets go of the amino acids.Stop codon releases the polypeptide chain.Inheritance:Sex linked - Inherited through expression of sex genes (XX (Male) or XY (Female) ).Autosomal - Code for non sex traits such as eye colour, blood type, etc.Infectious Diseases:BacteriaProkaryotic and unicellular.E.g Tuberculosis is caused by Mycobacterium tuberculosis.Enters through infectious droplets.Multiplies when eaten by macrophage.FungiEukaryotic and non-photosynthetic.Fungi secrete digestive enzymes to break down organic matter.E.g. Athletes foot → Microsporum.Chemicals breakdown cherotin on foot.Itchy and inflammation.ProtistsEukaryotic and unicellular.E.g. Malaria → Plasmodium.Floats in human blood and feeds on haemoglobin causing red blood cells to pop.Fever, nausea and weakness.VirusesNucleic acid (DNA or RNA), non-cellular.Needs a host cell.Hijacks host enzymes to make viral proteins.Host becomes a new virus.E.g. InfluenzaDamages lung tissue, body system releases cytokines.Fever, cough.PrionsNoncellularAbnormally infectious protein (folded protein).Effects of brain or neural tissue.E.g. Kuru, found in contaminated brain tissue.Spreads through by “eating” brain tissue.Macro ParasitesMulticellular organismsFeed off host nutrients and can produce toxins.E.g. Ticks suck human blood for nutrients.PlantsE.g. Fire BlightEffects pome fruit (apple, pears, etc) causing rapid browning.Kills plant tissue by attacking roots, fruits and shoots.E.g. Panama DiseaseEffects bananas by a fungi - Fusarium oxysporum.Fungus blocks plants' vascular system stopping movement of water and nutrients.Infectious Disease Transmission:Direct contactPerson to person such as through intercourse.Droplet spread such as talking, sneezing and coughing.E.g. Ebola can spread through saliva.Indirect ContactInfectious diseases travel such as by air, water, food and certain vectors.Active immunity:Antigen stimulates the body to make T cells, B cells and antibodies.Natural - Happens by naturally getting a disease.Artificial - Vaccination gives the weakened pathogen, creating immunity.Passive Immunity:Natural - Given during birth (via placenta and breast milk)Artificial - Given by another person's antibodies.No memory cells.Human Defense System - First line of defence:Physical - Skin (Barrier, Acidic pH, Constant Shedding), Mucus (Sticky layer, Extracts Pathogen).Human Defense System - Innate vs Adaptive:Innate - Immediate defence which does not remember the pathogen.Adaptive - Attack specific antigens and remember the pathogen for its next attack.Human Defense System - Second line:Second line of defence kills pathogens and involves white blood cells.Macrophage, dendritic cells, neutrophils - All contain phagocytes which enable the process of phagocytosis.Human Defense System - Third line:Third line of defence involves T and B cells.T cells - Help in alerting other cells of the pathogen.Cytotoxic T cells - Kill infected cells.Memory B cells - Remember the pathogen for the next attack.Koh’s Postulates:A 4 step experiment which identified infectious microbes.A diseased host and a healthy host is identified.The microbes from diseased host are extracted and placed on culture for growth.Cultured microbes are placed into healthy organisms to allow the same disease to occur.Microbe of the 1st organism and 2nd are compared to recognise the disease causing agents.Louis Pasteur:Germ theory - Disproved spontaneous generation of bacteria and proved invisible bacteria existed.Swan neck experiment - Broth → Nutrient rich → Bacterial growth. Broth is placed in a swan neck flask (exposed to air).Broth is boiled to kill any preexisting microorganisms. Broth becomes foggy indicating bacterial growth.Same experiment with closed neck showed no fogginess, proving that air had bacteria and didn’t allow for spontaneous generation.Mutagens - Electromagnetic radiation:UV, X-Rays and Gamma Rays carry high amounts of energy.They give their energy to atoms in cells, charging them up. This causes them to disperse from the cell.Chemical bonds in DNA break, or mutate.Mutagens - Chemicals:Chemicals are accidentally incorporated into the DNA instead of nucleotides.E.g. 5BDU looks like thymine to the DNA polymerase.Mutagens - Naturally occurring:Chemicals released by microbes, plants and animals, viruses and transposons.Non coding DNA:Makes functional RNA - Mutation will occur to RNA, disabling the function of protein, killing the entire cell.Controls amount of proteins produced - Gene manipulation will change causing too much of too little protein production (for example, lung cancer in which regulatory sequences create too many cancer cells).Point Mutations:Insertion - Extra nucleotide is added.|→ Frameshift point mutation.Deletion - Nucleotide is not included.Substitution - Wrong nucleotide added.Mis-sense - Change in one nucleotide which changes amino acid.Non-sense - Creates a stop codon.Silent - Nucleotide changes but the same amino acid occurs.E.g. Sickle cell anaemia → Substitution, blood cells are unable to carry the proper amount of oxygen.Haemoglobin’s nucleotide is changed from GAG to GTG, changing the haemoglobin's role.Chromosomal Mutations:Deletion - A section is broken off.Inversion - Breaks off and attaches inverted.Translocation - attaches to the wrong chromosome.Duplication - Section is copied more than once.Nondisjunction - Chromosome doesn’t separate properly.Chromosomal Mutation effects:Deletion, inversion and translocation - Genres are moved to a new location.Duplication - Change in amount of proteins produced.Nondisjunction - Not distinct (Down syndrome (Trisomy 21) ).Gene pools:Gene pool - Total collection of alleles for all genes in a population.Can be used to compare living environments.Constantly changing due to allele frequency.Gene flow - Movement of alleles between populations due to movement of individual organisms.E.g. When an organism from the allele frequency of X2 changes down and X1 rises as it’s alleles are in another gene pool.Gene flow can alter crossbreeding overtime in species that stay vacant.Genetic drift - Events in a population causing change in gene pool.X1 are majorly killed, leaving X2 majority. X2 are lucky alleles as they now have higher frequency and will continue to.Mutation - Change in organism DNA, causing gene pool to expand.X1 or X2 has mutated to X3, causing an addition of a new allele → Greater genetic diversity.Selection pressure - External factors affecting an organism's ability to survive in an environment.Organisms with advantageous alleles are likely to survive.Founder and Bottleneck effect:Bottleneck effect - Species experiences an event which significantly reduces population in the gene pool. |→ Genetic Drift.When a small group of individuals are separated from its original population, hence create a new population to start another gene pool.Biotechnology, PCR:Polymerase Chain Reaction - Used to amplify specific DNA regions.Biotechnology, DNA sequencing:Nucleotides are altered to change DNA function.Biotechnology, DNA profiling:DNA profile is created through various DNA regions.Biotechnology, Transgenic:Organisms with another species' genes.Reproductive Technology (RT):Artificial insemination - Deliberately introducing male sperm into the female reproductive tract without intercourse.Artificial pollination - Transfer of pollen from the stamen (male) to stigma (female) of the flower. Can be mechanically dumped by plane or done by hand using a small pollen brush.Whole Organism Cloning (WOC):PlantsCutting - a cutting of a plant is taken and placed in soil to allow it to grow into a plant.Grating and fusing of a cut stem to another stem with roots which grows into a new organism.Tissue Culture - Parent plant is pulverised, releasing individual cells. These are cultures to small sprouts then planted.AnimalsArtificial embryo twinning - Unspecialised clump of cells are taken after fertilisation, these cells are then split to grow into embryos.The embryos are placed into different mothers.The same organisms will be grown from different mothers.Recombinant DNA:Following points are created when 2 or more parts of DNA are joined together.Isolation - DNA fragments are extracted from natural sources → Target gene → scaffold gene.Plasmid → code for genes.Digestion - DNA fragments are cut using the same restriction enzyme. Cuts DNA and plasmid.Specific restriction enzymes cut specific DNA sequences.Insertion - Sticky ends bind, so that the target gene is inserted into scaffold DNA.Target gene plasmid = recombinant plasmid.Ligation - DNA ligase pastes backbone in recombinant plasmid.Recombinant DNA, Bacterial transformation:Recombinant plasmid - growth through bacteria.Enters calcium, calcium DNA, disrupting cell membrane.Heat shock is also used.Antibody resistance gene on plasmid proves transformation.Transgenics:The transfer of genes from one organism to another.Social (human) considerations of biotechnology:Cost - Unaffordable for the general population.Health and safety - Toxic effects on a person, viruses can mutate.Privacy - DNA profiling → Profile kept forever, can be misused by insurance (possible health risks).Homeostasis:The process of maintaining aspects of the body in order to ensure healthy function.Stimulus - Something changes in the outside environment → Receptor (chemo and thermo) - Pick up the change →Control centre - Brain or spinal cord regulates the change →Nervous system or endocrine sends the message (neural or hormone) →Effector - Fixes the imbalance (muscles or glands).Homeostasis Thermoregulation:Stimulus ±~37°C → Thermoreceptor →Hypothalamus (control centre) →Neurons →Effector →Response (perpetuary gland), vasoconstriction / shivering / polorection (goosebumps).Homeostasis Osmoregulation:Dry or Wet environment.Stomata - stomata allows for gas exchange, if open will allow for water vapour to escape (transpiration). Stomata can close by decreasing water in guard cells (abscisic acid hormone causes this).Maximises photosynthesis, minimises water loss.Homeostasis Osmoregulation:Salinity (in plants).Salt exclusion - Special tissues in root inhibit the entrance of salt.Salt excretion - Salt is concentrated then excreted through special glands. Salt crystallises and blows away.Salt accumulation - Deposits salt into old leaves which are shedded off.Homeostasis high blood glucose:Blood GLucose Level (BGL) rises →Pancreas Beta cells release insulin →Blood glucose is taken by body cells →Liver stores glucose as glycogen →BGL declines →Homeostasis (BGL 90mg/100ml).Homeostasis low BGL:BGL is low →Pancreas Alpha cells release glucagon →Liver breaks down glucagon into glucose →Glucose is released →Homeostasis (BGL 90mg/100ml).Nervous System (NS):System which takes information from the environment and passes it through the body (brain and spine). Central nervous system - Gathers information from all over the body and coordinates responses.Peripheral NS - Neurons connecting central NS to the rest of the body.Nervous System, PNS Somatic:Voluntary, conscious portions of NS.Nerves connecting to skin, sensory organs and skeletal muscles.Function is to process information arriving via external stimuli (touch, sight, etc). Control skeletal movement (walking, lifting, etc).Nervous System, PNS Automatic:Involuntary, unconscious portion of the nervous system.Function is to control cardiac muscle contraction, sweating, pupil dilation, etc.Nervous System, Autonomic:Parasympathetic - Nervous system releases acetylcholine which rests heart and digests food.Sympathetic - Nervous system releases danger and releases adrenaline which speeds up heart to pump blood and supply oxygen.Stops digestion.Endocrine System:Hormones - A small chemical which causes a response in another region of the body.Produced by different glands.Secreted by the glands, directly into blood vessels, taken around by the circulatory system and binds target cells.Endocrine difference to Nervous system = Hormones (instead of electrical impulses), slow and is widely distributed to tissues.Endocrine System:Neural - Nerve impulsesHormonal - Change in hormone concentration.Change in the concentration of substance in blood.Endocrine System, glands:Hypothalamus - found in the brain.Controls metabolic processes.Determines control of optimal condition.TRH - triggers release of TSH causing T3 and T4 to release.ADH - Increases water absorption from blood in the kidneys.Endocrine System, pituitary glands:Found in the brain.Release hormones to control the release of other hormones.Posterior - ADH (antidiuretic hormone).Anterior - TSH growth hormone FSH.Endocrine System. Endo Glands; Pineal:Found in the brain.Melatonin (hormone) - controls circadian rhythms (24hr body cycle) / regulates reproductive hormones.Endocrine System. Endo Glands; Thyroid Gland:Controlled by pituitary.Found around the neck (with parathyroid).Hormone - T3, T4 → Thermoregulation.Parathyroid hormone - triggers calcium into blood.Endocrine System. Endo Glands; Thymus:Responsible for immune system development.Hormone - Thymosin → T-cell development. Endocrine System. Endo Glands: Pancreas:BGL control,GLucagon and insulin control BGL.Endocrine System. Endo Glands; Adrenal:Responds to stress and blood pressure.Hormone - Aldosterone, noradrenaline. Endocrine System. Endo Glands; Gonad:Ovaries and testes - Responds to stress and blood pressure.Progesterone and oestrogen - Healthy development of female sex aspects.Testosterone - Masculine development.