BIO Course Notes PDF

MOD 5 Heredity Chapter 1 : Reproduction Inquiry question: How does reproduction ensure the continuity of a species? Students: explain the mechanisms of reproduction that ensure the continuity of a species, by analysing sexual and asexual methods of reproduction in a variety of organisms,...

MOD 5 Heredity Chapter 1 : Reproduction Inquiry question: How does reproduction ensure the continuity of a species? Students: explain the mechanisms of reproduction that ensure the continuity of a species, by analysing sexual and asexual methods of reproduction in a variety of organisms, including but not limited to: - animals: advantages of external and internal fertilisation - plants: asexual and sexual reproduction - fungi: budding, spores - bacteria: binary fission - protists: binary fission, budding Asexual Reproduction Sexual Reproduction One parent Two parents Mitosis Meiosis offspring identical offspring NOT identical Advantages: Advantages: - single organism - Genetic variation → increases survival to - Faster + less energy changing environment - Safer Disadvantages: Disadvantages: - Needs to find a partner - Less genetic variation - Slower + more energy - Higher risk Unicellular organisms 1- Bacteria 2 - Protists Asexual (common) Asexual (common) - Binary fission: involves mitosis followed by - Binary fission (typically) cytokinesis, with each daughter cell - Budding: Small bulges/buds form at the receiving an exact copy of the parent cell’s sides of the cell. The new nuclei move into DNA and half of the cytoplasm the buds and cytokinesis occur with the buds separating from the parent cell Sexual - Transfer of genetic material through direct Sexual contact between cells - involves meiosis where offspring have a new genetic combination Multicellular organisms 3 - Fungi Asexual (common) - Spores (common): tiny light and are spread by the wind or moving water, allowing the fungus to germinate in new environments, → offspring won't have to compete for space and resources. - Budding Sexual - Occurs in stressful environmental conditions → genetic variability - Involves two haploid cells from different mycelia fusing forming a diploid cell. This cell then undergoes meiosis producing haploid spores that are genetically different. 4 -Plants Asexual Bulbs: storage organs at the base of a plants Corms: similar to bulbs but solid without layers - New bulbs form as the plant grows each grow into - E.g taro a separate plant - E.g onions and garlic Tubers Rhizomes - stores food underground in tubers attached to the - Underground stems that spread sideways. New plant roots. Their ‘eyes’ are capable of growing into roots grow from nodes to produce new plants new plants. - E.g ginger - E.g potatoes Runners Cuttings - Stems that spread sideways along the ground to - Pieces of a plant, that grow new roots to form a form new plants at their ends new plant - E.g strawberries - E.g certain trees  Layering - Stems touching the soil grow new roots forming new plants - E.g certain rose plants Sexual External fertilisation (need WATER) - E.g mosses and ferns - Damp environment → male gametes can swim and fertilise - Spores instead of seeds Internal fertilisation (NO water) - E.g flowering plants and conifers - Reproductive organs Flowering plants Stamen (male) Pistil / Carpel (female) - Anthers produces male - Ovary contains ovule (contains gametes (enclosed in pollen eggs) grains to prevent drying out) - Style supports stigma - Filament supports anthers - Stigma catches pollen Process: pollen grains land on the stigma and go down through the style to the ovary, where the sperm fertilises the eggs. Ovules containing fertilised eggs develop into seeds and in many species then into fruits. Dispersion: needed to spread seeds to different areas so offspring and parents won't have to compete for resources - Fruits spread seeds through animal droppings - Grasses produce light seeds that can be dispersed by the wind - Others produce seeds that can get carried by animals Conifers (cone producing plants) Male cones produces large amounts of pollen, which is carried by the wind Pollen grain lands on a female cone, goes down through a pollen tube to the ovary, allowing sperm to fertilise the eggs. Ovules containing fertilised eggs later develop into seeds. When the female cones mature, their scales separate to release the seeds. Animals Process: 1. Fertilisation (Meiosis): Sperm cell fuses with an egg cell to producing a zygote 2. Mitosis Zygote undergoes mitosis, growing into an embryo which eventually becomes a foetus External fertilisation (WATER) - AQUATIC animals (fish and amphibians) Both parents release eggs or sperm into the water. Sperm swim to fertilise the eggs (water prevents drying out) Large numbers of gametes and strategies to increase their survival rate Strategies: - Mating rituals and Visual signs - Environmental triggers (e.g full moon or high tides) Internal fertilisation (INSIDE BODY) - TERRESTRIAL animals Male animals use the penis to place sperm inside the female's reproductive tract. A thin film of moisture lines this tract, protecting sperm cells from drying out and allowing sperm to swim to reach and fertilise the eggs. Zygote developing after fertilisation - Birds, Reptiles and Monotremes: Eggs are fertilised internally but are laid by females and develop externally inside an egg, nourished by yolk. - Marsupials: Foetus is born while still very immature and completes development in mother’s pouch, nourished by milk - Placental mammals: Foetus develops inside mothers uterus nourished by a placenta and is born once fully developed Invertebrates External fertilisation in Aquatic invertebrates Internal fertilisation in Terrestrial invertebrates. Many can also reproduce Asexually Internal External Inside Body Outside Body Terrestrial / Land Aquatic / Water E.g Mammals, birds, reptiles E.g Fish, Amphibians Fewer gametes Larger amounts of gametes Higher chance of fertilisation Lower chance of fertilisation Higher survival rate of offspring Lower survival rate of offspring  analyse the features of fertilisation, implantation and hormonal control of pregnancy and birth in mammals Features of fertilisation 1. Physical and Chemical OBSTACLES along the female reproductive tract: ensures only the strongest sperm has a chance of fertilising the egg 2. Species specific receptor proteins on the egg’s membrane: ensures only sperm from the correct species can fertilise the eggs 3. Changes in the egg’s membrane after sperm penetration: locks out other sperm, ensuring only one can fertilise the egg Fertilisation Steps: 1. Sperm reaches an egg in the oviduct - Survive acidic environment of the female reproductive tract - Time of ovulation (protective mucus is thinner making it easier for sperm to enter) - Avoid immune cells protecting the female reproductive tract - Swim against strong currents Along the way: - Sperm matures - Become Hypermotile → tails beating vigorously 2. Sperm penetrates egg Once they reach the egg: - Physically push through the outer layer of follicle cells (corona radiata) - Once they reach the thick outer membrane (zona pellucida) they bind to species-specific sperm receptor proteins - They then have to beat their tails strongly to penetrate and use enzymes to dissolve proteins 3. Only a single sperm can fertilise the egg Ensures zygote has the correct number of chromosomes. The first cell to penetrate the zona pellucida will fuse with the egg’s cell membrane and cause changes that lock other sperm out. The egg and sperm then fuse to form a diploid zygote. Features of implantation Zygote swept by beating cilia and moves to the uterus where it undergoes mitosis forming a blastocyst By the time it reaches the uterus, the blastocyst has started to differentiate forming two layers: - Inner layer → cells that will produce the embryo - Outer layer → trophoblast (surface cells) that implants into the uterine wall and forms the placenta Once the blastocyst touches the uterus lining, the outer layer’s cells multiply forming finger-like projections that attach to the uterine wall, implanting it. These will develop into the placenta and take over the nourishing of the embryo. Hormonal control of pregnancy and birth Hormones act as chemical messengers in the body that regulate and control bodily processes. Different hormones act on specific target tissues to produce specific responses. ❖ Corpus luteum: secretes oestrogen and progesterone, which prepares the uterus for pregnancy by thickening its lining and enriching it with blood ❖ Placenta: Nourishes foetus by allowing nutrients, oxygen and wastes to be exchanged between the blood of the mother and foetus Takes over the corpus luteum by producing high levels of oestrogen and progesterone to maintain the pregnancy. Main Hormones: evaluate the impact of scientific knowledge on the manipulation of plant and animal reproduction in agriculture Methods of manipulating animal and plant reproduction 1. Selective Breeding: 2. Cloning 3. Recombinant DNA: Selecting animals or plants with the Process of producing genetically identical Using recombinant DNA technology to most desirable characteristics for copies of an organism, or part of an alter an organism's genes. breeding organism Cutting a gene from the genome of Advantages ❖ Plants one organism and inserting into the Allows breeders to develop ‘better’ - Asexual methods of reproduction: genome of another, giving the second breeds that reliably produce desirable such as cutting, suckers, bulbs etc organism a new genetic trait characteristics improving agricultural productivity and product quality - Tissue Culture: A piece of tissue is divided and then Disadvantages Disadvantages cultured and planted into soil ❖ Expensive ❖ Gene linkage ❖ Greater regulation required Any gene on the same chromosome ❖ Animals as a desired gene will always be - Embryo splitting inherited with it. An embryo is split and then cultured until each has developed into a new embryo. ❖ Limited Gene Pool New embryos are implanted into separate - Inbreeding surrogate mothers to develop until birth. leading to mutations + health issues Disadvantages - Reduced Genetic variation ❖ Reduced Genetic variation entire population equally susceptible ❖ Expensive to environmental changes (diseases) Chapter 2: Cell Replication Inquiry Question: How important is it for genetic material to be replicated exactly?model the processes involved in cell replication, including but not limited to: - mitosis and meiosis 1. Cell Replication (mitosis and meiosis) Mitosis Process (IMPATC) A diploid parent cell replicates to produce two diploid daughter cells, identical to the parent and each other Meiosis Process: A diploid parent cell divides to produce four haploid daughter cells, each different to the parent and each other. - Produces gametes for sexual reproduction. Unique gene combinations in Gametes Crossing Over Homologous chromosomes pair up, twist together and sometimes exchange sections with each other - Leading to new gene combinations Independent Assortment Occurs when paired homologous are separated randomly into daughter cells during meiosis. - Giving each daughter cell one complete set of chromosomes in a random assortment  - DNA replication using the Watson and Crick DNA model, including nucleotide composition, pairing and bonding 2. DNA Replication DNA Structure - the Watson and Crick model Polymer: a large molecule made up of nucleotides ➔ Nucleotide consists of a sugar molecule, a nitrogen base and a phosphate group Double stranded molecules twisted into a helix shape - The sides are made up of sugar molecules linked to phosphate ions - The rungs that connect to the sugars are made up of complementary nitrogen bases: ➔ Adenine with Thymine, Guanine with Cytosine (AT, GC) DNA Replication 1. A double strand molecule ‘unzips’ into 2 separate DNA strands - with the help of the enzyme helicase that separates paired nitrogen bases 2. Each strand is then used as a template to build a new complementary strand; which forms double strands - with the help of enzymes, DNA polymerases that bind free complementary nucleotides to the exposed bases 3. The new double strands are identical to each other and to the original double chromosome assess the effect of the cell replication processes on the continuity of species Effect of DNA Replication Effect of Mitosis Effect of Meiosis Reproduction Asexual reproduction Sexual reproduction Growth and repair Growth and repair Increases genetic variation Ensures offspring have similar Without mitosis, a zygote - which allows evolution to occur or the same traits as parents, would never be able to → species less likely to go allowing for survival transform into a complete adult extinct organism. Chapter 3 - DNA and Polypeptide Synthesis Students: Construct appropriate representations to model and compare the forms in which DNA exists in eukaryotes and prokaryotes Prokaryotic Similarities Eukaryotic Less DNA DNA is double-stranded Large amounts of DNA Circular chromosome helix; chemically the same Linear chromosome Single chromosome Similar mechanisms to Multiple chromosomes Simpler produce proteins from More complex DNA found in cytoplasm (non- DNA DNA found in nucleus (membrane membrane bound) Both have additional DNA bound) No associated proteins Associated with histone proteins Plasmids often present No plasmids Shorter DNA sequences Longer DNA sequences Model the process of polypeptide synthesis, including: - transcription and translation Protein synthesis 1. Transcription: In the nucleus, the code in the DNA is transferred to a mRNA molecule 2. Translation: The mRNA strand leaves the nucleus and attaches to a ribosome in the cytoplasm, where its code is translated into a sequence of amino acids by tRNA - assessing the importance of mRNA and tRNA in transcription and translation  - analysing the function and importance of polypeptide synthesis Inquiry question: Why is polypeptide synthesis important? Proteins: large molecules made up of one or more polypeptide chains Polypeptide: long molecule made up of a sequence of amino acids linked by peptide bonds Function + Importance Protein formation - Essential macromolecules that carry out numerous functions in living organisms Cellular Processes - crucial role in various cellular activities - involved in the regulation of gene expression, cell signalling, and maintenance of cell structure Growth and development - Fundamental for the growth and development of organisms - forms products that are necessary to carry out replication, transcription and translation as well - h investigate the structure and function of proteins in living things FIbrous/Structural proteins Globular proteins (Enzymes) Polypeptide chains are arranged Polypeptide chains folded in parallel structures forming long into compact spherical fibres or sheets shapes Tough and insoluble Most are soluble Provides strength and support Involved in carrying out cell Builds Tissues functions ➔ Keratin: strengthens skin and hair ➔ Proteases: digests proteins ➔ Collagen: strengthens connective in the stomach tissues such as ligaments and ➔ Lipase: digests fats in the tendons stomach Protein folding (4 stages): 1. Primary structure: 2. Secondary structure: Starts off as a polypeptide Interactions between amino acids fold the chain into pleated sheets and spirals 3. Tertiary structure: 4. Quaternary structure: Further interactions fold and twists Some proteins consist of separate the pleats and spirals into a 3D polypeptides which interact to build a shape larger protein Correct protein shape: For most proteins correct 3D shape is essential for normal functioning - E.g Enzymes: incorrect folding may change the shape of the active site, affecting an enzyme’s ability to fit its substrate and catalyse its reaction Factors affecting protein shape 1. The order of bases in the DNA determines the order of the amino acid sequence. If the amino acids are not in the correct order, crosslinks needed to create the protein’s correct shape may not form 2. Proteins can become denatured, breaking the crosslinks holding a protein in shape causing it to unravel - E.g heating, strong chemicals (acids, alkalis) Chapter 4 - Genetic Variation Inquiry question: How can the genetic similarities and differences within and between species be compared? Students: conduct practical investigations to predict variations in the genotype of offspring by modelling meiosis, including the crossing over of homologous chromosomes, fertilisation and mutations Variations due to Crossing over, Fertilisation and Mutations: model the formation of new combinations of genotypes produced during meiosis, including but not limited to: - interpreting examples of autosomal, sex-linkage, co-dominance, incomplete dominance and multiple alleles - constructing and interpreting information and data from pedigrees and Punnett squares Autosomal Co-dominance Combination of genes found in autosomes Both alleles are equally dominant, so both will be (chromosomes except for the sex chromosome) expressed in the phenotype which appears as a - autosomal dominant or autosomal mixture of the two recessive. Incomplete dominance Multiple Alleles Both alleles are dominant but none of the alleles More than two alleles are fully expressed, resulting in a different E.g human blood groups phenotype from the parents - A and B are co-dominant, O is recessive E.g a blend of the two colours - Combine to produce blood types: A, B, AB, O  Sex linkage Involves sex chromosomes X and Y - Females: XX - Males: XY A female’s two X chromosomes provides her with two copies of all the X chromosomes genes while a male only has one copy. Without a backup copy, any mutation on the single X chromosome will show in his phenotype which is the cause of a number of disorders - E.g colour blindness and haemophilia Pedigree Charts Dominant or Recessive? Find a couple who share the same phenotype with at least one child whose phenotype is different - Parents = Heterozygous - Gene inherited by the child must be recessive (as it did not show in the parents’ phenotypes) If the parents (heterozygous) show the trait (shaded) = DOMINANT If the parents doesn’t show the trait (unshaded) = RECESSIVE Sex-linked or Autosomal? Autosomal: do not differ between males and females, so traits are inherited in the same way regardless of the sex of the parent or offspring Sex-linked: traits controlled by genes on the sex chromosomes Distinction 1 Distinction 2 Distinction 3 Autosomal = both males and Autosomal = both male and Autosomal = generally females are equally affected female individuals could be appears to affect individuals in Sex-linked = all or mostly carriers every generation males affected Sex-linked = always female Sex-linked = appears to skip carries a generation  collect, record and present data to represent frequencies of characteristics in a population, in order to identify trends, patterns, relationships and limitations in data, for example: - examining frequency data - analysing single nucleotide polymorphism (SNP) SNP (single nucleotide polymorphism) SNP: a DNA sequence altered by one nucleotide and is the most common type of genetic variation SNPs are useful biological markers, as some have important implications for human health. - Locating genes associated with disease - Predicting a person’s risk of developing a certain disease - Tracking the inheritance of disease genes - Predicting a person’s response to certain drugs - Predicting a person’s susceptibility to environmental toxins Limitations Studies are usually carried using subjects free of illness and not taking any other medication (UNRELIABLE) Patient’s responses are affected by numerous factors including genetic factors, metabolic factors etc Chapter 5 - Inheritance patterns in a population Inquiry question: Can population genetic patterns be predicted with any accuracy? investigate the use of technologies to determine inheritance patterns in a population using, for example: - DNA sequencing and profiling DNA sequencing The number of base sequences in common between two species reveals the closeness of their relationship as it indicates the length of time since they diverged from their common ancestor ➔ When two populations become separated and stop interbreeding the mutations occurring in the populations are no longer shared. As time passes these mutations cause so many genetic differences that the populations can no longer interbreed and become two different species DNA profiling Uses biological samples (saliva, hair, blood, semen) to identify individuals based on unique patterns in their DNA ➔ Preparing for DNA profiling: 1. DNA is amplified using a process called PCR (polymerase chain reaction) 2. Then cut into fragments using restriction enzymes, producing a set of DNA fragments 3. Samples placed into wells in a sheet of gel 4. As DNA fragments are negatively charged a positive charge is used to attract them to the other end of the gel, each person’s DNA produces a different patterns of bands, with each band representing a different length of DNA fragment 5. Stain bands to make them visible, the patterns produced by the samples from different people can be compared ➔ Fields Benefited Forensics: identifying possible crime suspects and identify a decomposing body Non-criminal identification: identify the parents of children Medicine: identifying good genetic matches for organ or marrow donation and for personalised cancer treatments Agriculture: identify genetically modified plants and prove pedigree in valuable animals investigate the use of data analysis from a large-scale collaborative project to identify trends, patterns and relationships - the use of population genetics data in conservation management - population genetics studies used to determine the inheritance of a disease or disorder - population genetics relating to human evolution Population genetics data (PGD) for: Conservation Management The use of Population genetics data provides vital info about their genetic diversity adding to the effectiveness of older techniques (eg field observation, sampling, measuring abundance and distribution) in managing endangered populations Determining the inheritance of a disease or disorder Population genetic data is becoming increasingly important in medicine including the use of ‘gene banks’ to identify gene sequences associated with inherited diseases Relating to human evolution PGD can be interpreted to address questions about human evolution through analysis of the fossil and archaeological records, combined with analyses of diversity in living human populations. MOD 6 Genetic Change Chapter 1 : Mutation Inquiry question: How does mutation introduce new alleles into a population explain how a range of mutagens operate compare the causes, processes and effects of different types of mutation - Point mutation Occur at a single point in a gene and involve a change in a single base being either: 1. Substitutions 2. Deltetions, Insertions, Duplications CAUSE/PROCESS CAUSE/PROCESS Caused by various mutagens; UV radiation, base Deltetions analogues, Free Radicals - During replication, the DNA template strand slips, causing a nucleotide to be left out EFFECTS Insertions Silent - Slip occurs in the new DNA strand, which - Affected codon codes for the same amino acid adds an extra nucleotide the sequence - No change in amino acid sequence, no effect Duplications - Extra copy of a nucleotide added to new Neutral strand’s sequence - Amino acid altered but has no effect since it is located in a non-critical region of the protein EFFECTS Frameshift Mutation Missene - Alters the reading frame, affecting the - Amino acid altered at a critical region of the protein, mutated codon and all the following codons which DOES AFFECT its function - Significantly changes the protein, often ➔ Serious: vital protein no longer function, leading to loss of function or severe disrupting normal processes (cystic fibrosis) alterations in function ➔ Negative: minor protein no longer function, slight disruption (lactose intolerance) ➔ Positive: beneficial mutation providing a survival advantage (SCA malaria) Nonsense - Codon is replaced by a ‘stop’ codon, halting polypeptide synthesis - Incomplete non-functional protein - Chromosomal Mutation Change in structure of chromosome/s or the total number of chromosomes STRUCTURAL CHANGE Mutations that alter chromosome structure caused by chromosomes breakage or sections being duplicated or translocated DELETIONS DUPLICATIONS CAUSCE CAUSE chromosome breaks, and broken fragment lost Extra copies of one or more genes are added to - Eg during crossing over in meiosis chromosomes EFFECTS When slippage occurs during DNA replication prior Large deletions almost always fatal to mitosis or meiosis Smaller deletions cause various genetic disorders - ‘Cry of a cat’ Syndrome EFFECTS - Cystic Firborsis Various Cancers - Certain genes responsible for regulating cell division become expressed at a higher rate, speeding up cell division Overproduction of particular Proteins - Duplications in genes that code for proteins INVERSIONS TRANSLOCATIONS CAUSE CAUSE Chromosome breaks and a fragment reattaches Chromosome breaks and broken fragment back to front, reversing base sequence reattaches to the wrong chromosomes Errors occurring during DNA replication prior to cell During crossing over or during DNA replication division or during crossing over in meiosis which is not correctly repaired EFFECTS EFFECTS Within a gene During mitosis - Disrupt normal functioning - Disrupt gene regulation resulting in various Non-coding DNA cancers - Few problems During meiosis - If affected gamete is involved in fertilisation can cause genetic disorders - Eg Down syndrome NUMERICAL CHANGE Mutations altering chromosome numbers, with entire chromosomes either missing or extra copies present ANEUPLOIDY POLYPLOIDY Cells contain an abnormal number of one of the Involves having three or more complete sets of chromosomes either: chromosomes - Monosomy - Trisomy CAUSE Errors during meiosis CAUSE - Producing a diploid gamete when if fertilised Error called non-disjunction which occurs during can produce a triploid zygote meiosis, results in chromosomes failing to separate Fertilisation of an egg by 2 sperm correctly, causing either an extra or missing - Results in a triploid zygote/offspring chromosome in affected gametes Spontaneous duplication of chromosomes Hybridisation of closely related species EFFECTS Usually fatal EFFECTS When non-fatal effect vary depending on which Humans chromosome is affected - always lethal - Down syndrome (trisomy 21) Other Animals - Klinefelter’s syndrome (trisomy of sex - not always fatal but often reduces vigour, chromosome) causing low fertility and sterility - Turner syndrome (monosomy of X chromosome) - Can be limited to certain organs, causing improved functioning, adaptive advantage Plants (common)  - Hybridisation: more robust with larger fruits and flowers - Sterile: seedless fruits, reduced seed size Evolution - Important factor in the emergence of new species distinguish between somatic mutations and germ-line mutations and their effect on an organism Somatic Mutations Germ-line Mutations Occurs during meiosis in a single body cell Occur during meiosis and affects the chromosomes - Cannot be inherited of gametes - Can be inherited / passed to offspring Only tissues and body cells derived from mutated cells are affected Every cell in the gamete affected - If fertilised then mutations present in zygote, Will not alter frequency of alleles in the gene pool affecting entire organism Eg some cancers Can alter frequency of alleles in the gene pool - If mutation is advantageous it can increase survival rates, building up over time Eg SCA assess the significance of ‘coding’ and ‘non-coding’ DNA segments in the process of mutation Coding DNA Non-coding DNA segments play a vital role in the production of Large proportion (98.5%) proteins that control the function of numerous biological processes Varying Roles regulating gene activity which is crucial to cell Changes in coding segments will cause mutations functioning that deviate a protein’s functioning and can also carries instructions for making different types of cause structural modifications RNA molecules including tRNA and rRNA Non-coding segments called ‘telomeres’ are Mutations with varying effects located at the ends of chromosomes to protect from - Various genetic diseases damage - Sometimes chromosomal aberrations - Beneficial mutations Mutation Effects Can disrupt normal development or cause serious damage - Linked with uncontrolled cell division causing cancer - In regions of gene regulation can reduce the production of certain proteins - In regions of RNA instructions can interfere with protein synthesis or other processes causing disease  investigate the causes of genetic variation relating to the processes of fertilisation, meiosis and mutation Fertilisation Meiosis Mutation Two gametes combine forming Creates the gametes for fertilisation Produces completely new a zygote with two sets of introducing variation through: alleles, thus creating new genes from each parent. variations Resulting offspring display a Crossing Over mixture of parent's traits, Homologous chromosomes swap Mutations varying effects creating a unique gene segments, the chromosomes involved Damaging non-fatal combination will each contain a mixture of genes Persist in population, proving variation Silent/Neutral - Various interactions in the Independent Assortment Provide variation without affecting genes (dominant, recessive When pairs of homologous survival etc) can result in production of chromosomes separate, they do so Beneficial traits that neither of the parents independently, ensuring gametes Occur infrequently improving survival, possessed receive a mixture of parent’s increase in frequency over time. chromosomes Aiding in evolution evaluate the effect of mutation, gene flow and genetic drift on the gene pool of populations Mutation All genetic variations in gene pools originated as mutations. - When mutations occur in germline cells they become inheritable and will pass down generations The effect of mutations on a gene pool vary depending on their inheritance pattern and capacity to cause harm Beneficial mutations build up in gene pools as they improve survival, increasing the likelihood of passing on the mutation. Which can drive evolution. Antibiotic resistance in Bacteria - Mutation occurs in these bacterial species and once they are passed over to the next generations, a huge population of bacteria might become resistant to specific antibiotics Decrease in gene pool due to mutation may turn lethal and can cause extinction of a certain population - As a decrease in allele number in one population will gradually increase the possibilities of the same event to occur in the following generations and at some point, the population will not have enough variation to survive Gene Flow The movement of alleles from one population to another, mostly due to migration High rates of gene flow between neighbouring populations increases genetic diversity and reduces genetic variation between them - Theoretically it should increase a population’s health and survival rate due to hybrid vigour - Increased genetic diversity reduces the likeliness of couples having the same defect reducing the chance of genetic disease in offspring Genetic Drift Results from random chance events, removing alleles from a population, thus reducing genetic variation within its gene pool - genes that remain are unlikely to provide survival advantages as they have not been naturally selected by the environment but instead present accidentally Biggest impact on small populations because as the gene pool is smaller, increasing the chances of losing important alleles in the process of evolution Can potentially change the course of evolution negatively. As populations become fragmented into smaller populations they lose genetic diversity increasing the risk of extinction Chapter 2 : Biotechnology Inquiry question: How do genetic techniques affect Earth’s biodiversity? investigate the uses and applications of biotechnology (past, present and future) Traditional/Past Biotechnologies Crop Farming Producing food or other products from plants Animal Farming Producing food or other products from animals Selective Breeding Improving the quality of agricultural organism by controlling their breeding (plants and animals) Modern Biotechnologies Pharmaceuticals Developing new pharmaceutical drugs Vaccines Creating vaccines using dead or inactivated pathogens, to prevent disease Antibiotics Creating antibiotics using microorganisms typically bacteria and fungi, to treat disease Future directions of Biotechnologies Personalised Healthcare that is tailored to an individual/s where their genetic makeup and other factors such medicine as lifestyle and environment is used to select medical treatments Using pharmacogenomics to create drugs for specific genes and diseases Determine how well their body can react to a medication Determine Dosages Cancer treatments Gene Altering of genes to treat or prevent disease in somatic or germline cells Therapy / Editing CRISPR Somatic: gene is changed, is not passed down Germline: gametes are changed for the purpose of passing on the changes to their offspring Stem Cell Use of stem cells to repair or replace damaged tissues or cells Therapies Type 1 Diabetes Injuries Blood disorders: SCA - analysing the social implications and ethical uses of biotechnology, including plant and animal examples Social Implications Affordability / Unequal Access Environmental Harm + Safety Risks Privacy Risks - Medicines and Treatments - GMO capacity to cause harm - Laws covering genetic privacy expensive is still undetermined are too narrow and may not - GM seeds expensive - Potential biodiversity loss due provide protection against to clearing of land for growing improper use of data monocultures - Eg insurance companies - GM crops with inbuilt possibly deny health insurance pesticides cause decline in to someone carrying genes insect populations linked with a disease - Genes transferred to weeds - Ancestry information creating herbicide resistant superweeds - Uncertainty of adaptability to environmental change, impacting food security - Possibility of Bioterrorism Ethical Uses Human Embryos Use Gene Editing Cloning - Range of applications - Creation of designer babies benefiting human health (eg where characteristic and traits stem cell research, therapeutic can be selected cloning) - Potential of human life that some believe should not be used/destroyed - evaluating the potential benefits for society of research using genetic technologies Health Improvements Improved quality and quantity of food Improve the safety and effectiveness of medical Genetic engineering increases food production treatments - Creation of crops and animals that are Correct, Prevent, Treat genetic diseases and higher yielding, faster growing, more fertile, disorders disease resistant, increased adaptability Vaccines and Antibiotics (improved/new) - Improve nutrition of food by adding genes to Extend life of organisms increase nutrients - Greater food security > reducing malnutrition and hunger Production of useful Materials Safe water supplies Genetic engineering allows easy synthesis of a Genetic engineering to produce pest resistant range of materials with biological origins crops and livestock lowers the use of pesticide - Human insulin, antibodies, rubber, vanilla, reducing toxic runoff spider silk - Protects local water supplies - Potential to create organisms to produce more valuable materials - evaluating the changes to the Earth’s biodiversity due to genetic techniques Biodiversity Changes Large Decrease Native species extinctions - Genetic technologies indirectly responsible for human population growth > increased human activity increased land clearing > loss of habitats increased greenhouse gas emissions and other pollutants herbicide use > chemicals enter water supplies affecting plants and animals Increased competition of resources for native species > engineered organisms often dominate Insect resistance crops > decrease insect population > disrupt ecosystems Spread of Engineered Genes - use of GM organisms can potentially introduce exotic genes and organisms into the environment that may disrupt natural communities and other ecosystems Pathogen Adaptation - Bacteria and viruses evolve a resistance to the resistance that is created by the genetic engineering efforts - Causes pathogens to become stronger and more resistant potentially creating future concerns Small Increase Biodiversity has been increased by the addition of new genetically modified organisms - E.g transgenic plants and animals Chapter 3 : Genetic Technologies Inquiry question: Does artificial manipulation of DNA have the potential to change populations forever? investigate the uses and advantages of current genetic technologies that induce genetic change Genetic Engineering Recombinant DNA technologies used to improve an organism’s characteristics by modifying DNA by either altering genes or inserting genes from other organisms into its genome Ensures organisms have desired traits to improve them for use or consumption - Improved agricultural plants and animals higher yields, faster growth rates, improved nutrient content, disease or pest resistant - Transgenic organisms such as bacteria for manufacturing biologics such as human insulin aid in the production of vaccines, hormones, drugs Gene Editing Technology that enables the precise alterations to genes in specific locations in an organism's genome Eg CRISPR (modify genes in animals and plants) (used in human gene therapy in the future) - Accuracy - Affordability - Ease of use Mutation Breeding Technique that involves deliberately causing mutations in plants to produce desirable traits. Seeds, cuttings or leaf tissue are exposed to mutagens, the mutants produced are then grown and are selected for breeding Creates new/improved plant varieties - Fast - Low tech - Affordable/Cheap compare the processes and outcomes of reproductive technologies HUMANS Reproductive technologies used include various techniques that assist couples having difficulty conceiving naturally or who want to avoid passing on a genetic disease IVF (in vitro fertilisation) - Involves mixing eggs and sperm in a petri dish and after a couple of days, implanting one or tow healthy embryo into the mother’s uterus FET (frozen embryo transfer) - Using a frozen embryo from the initial unsuccessful IVF attempt and following the same process ZIFT (zygote intrafallopian transfer) - Similar to IVF but at an earlier stage of development with the transfer of a zygote into the fallopian tube AGRICULTURE Artificial Insemination Artificial Pollination Selecting plants with disable characteristics for Selecting animals with disable characteristics for fertilisation breeding - Pollen from a selected male plant is - Semen from a selected male animal is collected and dusted on a selected female collected and transported to a selected plant, creating a forced fertilisation. When female animal, where it is then inserted to ripe seeds are collected and grown. achieve pregnancy  Advantages Advantages Allows the production of plants with increased Allows for the production of animals with increased frequency of desirable traits frequency of desirable traits - Higher yields, longer shelf life, improved - Improved quality, yields, appearances sensory characteristics, pest/disease resistance Disadvantages Allows creation of new hybrids Loss of genetic diversity Inbreeding Disadvantages Gene linkage Loss of genetic diversity Monoculture susceptibility - Agricultural varieties outcompete older varieties Monocultures have the same susceptibility to unfavourable environmental conditions investigate and assess the effectiveness of cloning WHOLE ORGANISM CLONING Process that creates one or more genetically identical copies of a whole organism Plants Traditional Asexual Reproduction - Many plants clone themselves naturally by reproducing asexually - Eg runners, tubers, bulbs Tissue Culture - Portions of plant tissue are separated into single unspecialised cells, the cells are then grown in laboratories with controlled environmental conditions. Once the growing cell clusters reach a certain size, plant hermes are apple causing the cells to differentiate and produce seedings. - The seedlings are then planted and grown genetically identical to the original parent plant Effectiveness Advantages Disadvantages Cheap Reduces genetic diversity Low tech Increases herd/monoculture susceptibility Highly successful Effective / identical Animals Embryo Splitting (common) - Deliberately causing embryo splitting which can occur naturally - Process 1. Using IVF to produce an embryo with desirable characteristics from the parents gametes 2. Dividing the embryo into two or more 3. Implanting identical embryos into separate surrogate mothers to develop until birth Somatic cell nuclear transfer (uncommon) - Process 1. Taking a body cell from the animal to be cloned and removing its nucleus 2. Inserting the nucleus into an unfertilised egg cell and applying an electrical stimulus, causing it to develop into an embryo 3. Implanting embryo into the uterus of surrogate mother and allowing it to develop until birth Effectiveness (relate mostly to embryo splitting) Advantages Disadvantages Effective / Successful Reduces genetic diversity Obtain embryos of reliable quality Increases herd/monoculture susceptibility Environmental conservation (endangered, extinct) Gene linkage Medicine (animal testing) GENE CLONING Making many identical copies of a gene or gene product Polymerase Chain Reaction (PCR) Process used to clone genes Used to rapidly amplify a DNA segment, enabling a specific target sequence to be isolated for cloning or sequencing PCRs purpose is to increase the sample to a size large enough to use in its many applications - Pathology testing, sequencing, genotyping, mutation detection, forensics Highly effective with a wide range of applications Biopharming Cloning genes to make biopharmaceutics or other biologics for use in medicine A single gene is inserted into the DNA of another cell, the cell is then cultured in controlled conditions, where it produces billions of identical cells. Each cell contains a copy of the gene and produces the protein encoded in it. Allows the creation of new, safer, more effective, or cheaper pharmaceuticals - Eg human insulin, and recombinant proteins for treating various illnesses Highly effective, producing a range of pharmaceuticals describe techniques and applications used in recombinant DNA technology - the development of transgenic organisms in agricultural and medical applications RECOMBINANT DNA TECHNOLOGY The development of transgenic organisms by combining DNA from different organisms - Usually with improved characteristics of the ability to make new substances Recombinant DNA Techniques 1. Locate and cut the required transgene from the donor’s genome, either by using: restriction enzymes CRISPR 2. Insert the transgene into the host’s genome for it to be incorporated into the host’s DNA, either by using: Biological: transporting genes using VECTORS Physical: insert transgenes into cells using force (injection or gene gun) Chemical: use chemicals to bing the DNA to the cell membranes and then enter the cell CRISPR Agricultural Applications Medical Applications GM Crops Biologics and Pharmaceuticals - Improved quality, yields, resistance, - produced by transgenic organisms environmental - Eg insulin, proteins, hormones Transgenic Animals Biologic therapies - Improved quality, thrive, environmental - Creation of genetically engineered proteins Animal Vaccines and Antibiotics that interact with the immune system to treat diseases caused by its component functioning incorrectly - Eg cancers Transgenic Animals for research - mice  evaluate the benefits of using genetic technologies in agricultural, medical and industrial applications AGRICULTURAL MEDICAL INDUSTRIAL Increased food supplies Biologics and Pharmaceuticals Biologics and Pharmaceuticals - Higher productivity - Human insulin - new medical products meets food demands - Hormones Production of various materials more reliably - Biologic therapies - Chemicals, materials Farmer benefits - Vaccines energy sources - Higher productivity Transgenic animals for Bioremediation - Lower costs research - Transgenic microbes Consumer benefits - Mice have been used to - Improved Genetic Testing clean up toxic characteristics - Allows mutations to be chemicals including oil - Nutritional value detected spills and industrial Environment Gene Therapy wastes - Higher yields, thriving - Treat some genetic organism varieties conditions - Lower insecticide/pesticide use reduces toxic runoff evaluate the effect on biodiversity of using biotechnology in agriculture Positives Negatives Increased biodiversity Native species extinctions - New/Increased organism varieties - Loss of habitats - Monocultures - Land Clearing - Domination interpret a range of secondary sources to assess the influence of social, economic and cultural contexts on a range of biotechnologies SOCIAL ECONOMIC CULTURAL What extent are biotechnology Potential of biotechnologies to Different religions and cultures accepted or distrusted? save costs or increase profits have varying attitudes and Who might benefit from their Potential to create financial opinions use? inequalities - Who might Costs of developing and using disadvantaged or biotechnologies harmed  MOD 7 Infectious Diseases Chapter 1 : Causes of Infectious disease Inquiry question: How are diseases transmitted? describe a variety of infectious diseases caused by pathogens, including microorganisms, macroorganisms and non-cellular pathogens, and collect primary and secondary-sourced data and information relating to disease transmission - classifying different pathogens that cause disease in plants and animals CELLULAR PATHOGENS NON-CELLULAR PATHOGENS Pathogen Living or Nucleic acids Cellular or Prokaryotic or Examples Nonliving? present? Noncellular Eukaryotic Bacteria Living Yes Cellular Prokaryotic Cholera, TB Protozoa Living Yes Cellular Eukaryotic Malaria, ASD Fungi Living Yes Cellular Eukaryotic Ringworm, thrush Macro-parasites Living Yes Cellular Eukaryotic Tapeworm Viruses Nonliving Yes Noncellular N/A Covid, Rabies Prions Nonliving NO Noncellular N/A Kuru, Mad Cow -investigate modes of transmission of infectious diseases, including direct contact, indirect contact and vector transmission MODES OF TRANSMISSION - investigating the transmission of a disease during an epidemic Epidemic: a widespread occurrence of an infectious disease in a community at a particular time. Pandemic: over a whole country or the world - design and conduct a practical investigation relating to the microbial testing of water or food samples Method 1. A small amount of the sample is placed onto the surface of the agar plate, using sterile techniques such as swabbing or streaking. 2. The agar plates are then properly sealed and incubated to allow microbial growth 3. After several days, the agar plates are inspected by looking through the clear plastic lids, there should be colonies of microbes be visible  Investigate the work of Robert Koch and Louis Pasteur, to explain the causes and transmission of infectious diseases Pasteur’s experiments Koch’s postulates Developed a process allowing the specific pathogen responsible for a specific disease to be identified assess the causes and effects of diseases on agricultural production, including but not limited to: - plant diseases - animal diseases Risk of disease higher in agricultural ecosystems: Raised as a Monoculture - large numbers of the same or particular variety of species are grown close together - Organisms raised as genetically similar are equally susceptible to the same disease Environmental stresses have a higher impact as these organisms has not adapted to natural ecosystems - Temperature, rainfall, climate change Intensive farming practices with heavy use of chemicals have weakened the health of plants and animals  compare the adaptations of different pathogens that facilitate their entry into and transmission between hosts Chapter 2: Responses to Pathogens Inquiry question: How does a plant or animal respond to infection? investigate the response of a named Australian plant to a named pathogen through practical and/or secondary-sourced investigation, for example: - fungal pathogens - viral pathogens Australian Host plant Banksias, leaves or stems of Eucalyptus, Wattles Pathogen Commonly parasitic insects such as gall wasps, beetles and moths. Which use plants as a food source for either themselves or their larvae. Symptoms Galls are bumps or swellings at the infection site of a parasite or pathogen. Management Galls are the plant’s response to the irritation produced by the parasite or pathogen. This irritation triggers a flow of plant hormones to the infection site, promoting abnormal growth in an attempt to protect the plant’s healthy tissue by isolating the pathogen. Although galls can benefit parasites by providing a safe place to grow with a ready food supply and protection from predators. analyse responses to the presence of pathogens by assessing the physical and chemical changes that occur in the host animals cells and tissues E.g Inflammation Redness of the skin → due to locally increased blood circulation Heat → fever or increased local temperature Swelling of affected tissues → such as the upper throat during the common cold or joints affected by arthritis Mucus → cause runny nose or cough Pain → body aches, headaches, sore throat Chapter 3: Immunity Inquiry question: How does the human immune system respond to exposure to a pathogen? investigate and model the innate and adaptive immune systems in the human body Innate immune system 1st line of defence: A system of physical barriers and chemical secretions that prevents pathogens from entering the body Physical Barriers Skin Tough layer of tightly packed cells covering all external surfaces ➔ Prevents pathogens from entering Dry dead cells on its surface constantly flake off ➔ Environment too dry for microbes to thrive ➔ Carries pathogens away Mucous membranes Cell layer lining all internal surfaces that secretes sticky mucous ➔ traps pathogens entering the body Cilia Microscopic hair-like projections covering the surface of the mucous membrane lining the lungs that beat rhythmically and constantly ➔ Sweep mucous with any trapped pathogens out of the lungs through the throat Blood brain barrier Unique properties of the blood vessels that supply the brain ➔ Provides tight control that regulates the entry of any substances including pathogens to the brain Chemical Barriers Secretions of the Stomach acid: strong acid secreted by cells lining the stomach digestive tract ➔ Kills microbes due to acidity Bile: Alkaline secretion produced by the liver that is excreted into the small intestine ➔ Kills microbes that survived acidic conditions by changing pH to alkaline Tears Watery secretions of the eyes containing mucus and lysozyme ➔ Bacteria is killed by lysozyme ➔ Carries away dead bacteria Saliva and breast milk Contains lysozyme ➔ Kills bacteria Secretions of the Mildly acidic secretions protect these surfaces urinary and ➔ Inhibits growth of pathogens reproductive passages ➔ Can encourage growth of protective microflora and skin Secretions of sweat Oily, antibacterial secretions glands and hair follicles ➔ Creates a favourable environment for microflora 2nd line of defence: The inflammatory response, complement cascade, and non-specific cellular responses Inflammatory responses: Automatic response to injury triggered by the release of histamine causes ➔ Capillary walls dilating, increasing blood flow to the infection site and bringing: Phagocytes → destroys pathogens by engulfing and digesting Clotting factors → seal broken blood vessels, stop bleeding and delay the spread of pathogens Extra Body heat → restricts the growth of some pathogens and speeds up rate of chemical reactions allowing for rapid repair ➔ Capillary walls become more porous, increasing the flow of plasma into damaged tissues causing swelling More space for phagocytes to move and attack pathogens Pressure increases helping to push fluid away from infection site → clears debris so repair can begin Complement Cascade: Activation of complement proteins in a chain reaction triggered by pathogens that causes defence responses to be amplified ➔ Attracts phagocytes ➔ ‘Marks’ pathogens and infected cells → so phagocytes can easily recognise and attack ➔ Clumping pathogen cells together ➔ ‘Lysing’ bacterial cells (dissolving their cell walls) ➔ Recognises and destroys virus infected cells Non-specific cellular responses: Various white blood cells that attack pathogens in a non-specific way. By distinguishing between the body self cells (own) and non-self cells (antigens), through identification markers called MHC molecules. ➔ Phagocytes: white blood cells that identify foreign invaders through antigens and engulfs and digests them. Types: Neutrophils (kill) Attaches to pathogens and then engulf and destroy them Monocytes/Macrophages Start out as monocytes that hunt and kill pathogens in the blood but can squeeze through capillary walls to enter body tissues where they grow into large macrophages. Macrophages also hunt and kill pathogens in body tissues while also: ➔ Displays pathogen antigens to cells of the adaptive immune system to teach them to recognise the invading pathogen Dendritic Cells Also hunts and destroys pathogens as well as: ➔ Displays pathogen antigens to cells of the adaptive immune system Adaptive immune system 3rd line of defence: destroys invading pathogens and prevents them from returning - Lymphocytes distinguish between different pathogens by their antigens and attack them individually and remember every pathogen they encounter explain how the immune system responds after primary exposure to a pathogen, including innate and acquired immunity Chapter 4: Prevention, Treatment and Control investigate and analyse the wide range of interrelated factors involved in limiting local, regional and global spread of a named infectious disease COVID investigate procedures that can be employed to prevent the spread of disease Procedures for preventing the spread of disease  investigate and assess the effectiveness of pharmaceuticals as treatment strategies for the control of infectious disease Antibiotics Pharmaceuticals for treating BACTERIAL infections They speed up recovery from bacterial infections by reducing bacterial numbers by killing or preventing them from multiplying Antivirals Pharmaceuticals for treating VIRAL infections Most antivirals work by inhibiting viral replication inside infected cells to prevent infections from developing. This limits the viral load, making it easier for the body’s immune system to neutralise the virus. Antimicrobial Resistance Exposing bacteria to antibiotics encourages resistance to develop as the weaker bacteria are killed off leaving the stronger (more resistant) strains to spread Resistance is seriously threatening as certain antibiotics will no longer be effective, resulting in the reliance of higher doses of alternative antibiotics that are more expensive, more toxic and more dangerous to patients. investigate and evaluate environmental management and quarantine methods used to control an epidemic or pandemic Environmental Management Quarantine Methods Airborne Pathogens Isolation of infected individuals and potentially - Sterilising surfaces infected individuals - Cleaning of contaminated areas - PPE The thorough screening of plants, animals and - Safe disposal of contaminated materials humans who come from different regions for any - Social distancing trace of a particular pathogen - Lockdowns Vector-borne pathogens - Reducing Vector populations (spraying pesticides, destroy breeding sites) - PPE (clothing, repellents, nets) interpret data relating to the incidence and prevalence of infectious disease in populations - Mobility of individuals and the portion that are immune or immunised - Malaria or Dengue Fever in South East Asia Incidence: rate at which new cases of a diseases appear over time Prevalence: total number of cases at any one time  evaluate historical, culturally diverse and current strategies to predict and control the spread of disease Historical Culturally diverse In the past the lack of proper knowledge and Herbal Medicine traditions understanding of pathogens and the causes of - Strong antibiotic or antiviral properties disease led to disastrous outbreaks and mostly - Properties to boost the immune system ineffective treatments based on theories or religion Some effective treatment methods include: - Quarantine and the burning of infection sites - Treating infections with toxic chemicals (effective against infective wounds) - Boiling of water investigate the contemporary application of Aboriginal protocols in the development of particular medicines and biological materials in Australia and how recognition and protection of Indigenous cultural and intellectual property is important - h Legal solutions to protect Indigenous Australians with intellectual property rights over their ownership of traditional knowledge is essential as it acknowledges their rights to control and benefit from their cultural heritage, fostering economic empowerment and preserving cultural identity. Eucalyptus oils Tea Tree oils - Has antibacterial properties that is effective - Has antibacterial, antiviral and antifungal against bacterial infections of the respiratory properties. Used for treating a wide tract range of conditions. - E.g throat lozenges, mouthwash, disinfectant - E.g disinfectant, insect bites, fungal infections Emu bush Smoke bush - Leaves from the emu bush are used to clean - Group of endemic shrubs in Western wounds, treat colds and heal mouth/throat Australia infections MOD 8 Non-Infectious Diseases Chapter 1 : Homeostasis Inquiry question: How is an organism’s internal environment maintained in response to a changing external environment? construct and interpret negative feedback loops that show homeostasis by using a range of sources - Temperature - Glucose Homeostasis A process that allows organisms to maintain a stable internal environment by constantly monitoring and adjusting internal conditions to the changing external conditions (temperature, glucose, etc) Negative Feedback Loops Feedback systems which counteract changes to normal or homeostatic levels in the body, therefore returning the system to acceptable conditions  investigate the various mechanisms used by organisms to maintain their internal environment - trends and patterns in behavioural, structural and physiological adaptations in endotherms that assist in maintaining homeostasis Behavioural Structural Physiological Staying cool in hot Being active at dawn and dusk Small body size Vasodilation climates while its cooler (Large SA: volume Sweating Sheltering (underground etc) ratio) Licking paws Large ears Large networks of blood vessels for cooling Staying warm in Migrating Large body size Vasoconstriction cold climates Hibernating Small ears Shivering Living underground Thick body covering (fur/feathers) Conserving water Reducing activity during the Water conserving Thirst in dry climates heat of the day kidney structure Adrenal hormones Sheltering Water conserving regulate water loss intestines via kidneys - internal coordination systems that allow homeostasis to be maintained, including hormones and neural pathways Neural Pathways (Nervous System) Central nervous system (brain) Hypothalamus Small part of the brain that controls and regulates many factors including body temperature, blood pressure, heart rate, etc. ➔ Complex set of functions: - Receptor: site of numerous smaller receptors including thermoreceptors for detecting temp change - Control centre: it receives info from receptors all over the body and processes this info to detect imbalances and correct them by communicating with effectors, triggering different responses. - Link between the nervous and endocrine system: indirectly regulates and coordinates the release of hormones from endocrine glands. It determines which specific hormones need to be released to correct the imbalances and releases hormones called ‘releasing factors’ which stimulate the release of pituitary hormones called ‘stimulating factors’. These stimulating factors target different endocrine glands triggering them to release their particular hormones to restore homeostasis Peripheral nervous system (nerves) Sensory Nerves (Receptors) Carries info TO the brain from receptors such as sense organs - Thermoreceptors: monitor temperature - Hypothalamus: monitors blood glucose levels Motor Nerves (Effectors) Carries info FROM the brain to effector organs such as muscles and glands - Muscles: eg muscles in artery walls to control blood flow - Endocrine glands: Releases hormones into the bloodstream triggering various responses (eg pancreas, pituitary, adrenal glands) - Exocrine glands: produces secretions released outside the body (eg sweat glands) Neurons (nerve cells) Highly specialised cells that carry signals for communicating ➔ Structure: cell body with a nucleus, dendrites, axon, myelin sheath - Cell body: contains a nucleus - Dendrites: branching structures which receives messages - Axon: a long cable that passes messages - Myelin sheath: insulates axons, helping speed neural impulses - Axon terminals: connects to other neurons - Synapse: the small space at the end of each neuron that allows a signal to pass onto the next neuron Nerve impulse ➔ A signal transmitted along a chain of neurons. It consists of a wave of depolarisation caused by changes in the cell membrane Process: ➔ A nerve impulse starts with a neuron’s dendrites receiving a signal which it passes along the entire axon to the synaptic terminals which transmit them to the dendrites of the next neuron in the chain. Neurons use active transport to pump sodium ions out and potassium ions in. This ion exchange creates a higher concentration of positive ions outside the neuron resulting in a polarised state. When the dendrites are stimulated, sodium ions rush back in and potassium ions out. Causing depolarisation in that section of the neuron. The depolarisation in one section triggers the same change in the next section, causing a wave of depolarisation to travel along the axon. This travelling wave of depolarisation is the nerve impulse. Hormones (Endocrine System) Endocrine System: Made up of glands throughout the body, its messages are delivered through a network of pathways operating via the bloodstream. Each gland produces its own hormone/s which are released into the blood and carried throughout the body. Hormones act as chemical messengers each with their own target tissue/s where they bind to specific report proteins to produce specific cellular responses Endocrine glands: - Pituitary or Master gland: releases 'stimulating factors’ triggering other endocrine glands to release their own specific hormones - Pancreas: releases insulin when BSL are high, prompting cells to take in glucose. Releases glucagon when BSL are low, prompting cells to release glucose. - Adrenal glands: releases hormones that act on the kidneys which controls blood concentrations of water and salts Comparison Nervous System Endocrine System Delivers messages extremely rapidly Regulates the complex processes involved in Producing fast responses homeostasis Producing slower responses but are longer lasting - mechanisms in plants that allow water balance to be maintained Roots Transporting Water Roots or root hair cells absorb water from the soil The combined effects of adhesion, cohesion and through osmosis and is transported up to the transpiration pull constantly moves water molecules leaves through the xylem up to the leaves in a continuous stream through the xylem Stomata Adaptations The structure of guard cells allows stomata to open Smaller leaves when water is freely available and close when it is - Less SA from which water can be lost not, preventing excess water loss - Guard cells swell up when filled with water Shedding leaves causing them to bend away from each other - Reduces the total leaf SA from which water creating an opening for water to be can be lost absorbed. - When a plant absorbs less water, vacuoles Thick waxy cuticles in its guard cells shrink causing the cells to - Provides a waterproof layer trapping water shrivel closing the stomata inside the lead and reducing evaporation Chapter 2 : Causes and Effects Inquiry question: Do non-infectious diseases cause more deaths than infectious diseases? investigate the causes and effects of non-infectious diseases in humans Genetic Diseases: ★ caused by an alteration or a mutation to a gene or set of genes - These abnormalities can be due to mutations in a single gene, multiple genes, or changes in the structure or number of chromosomes. - Can be inherited or occur spontaneously due to new mutations. Point mutations / Single gene abnormalities Alteration to one specific gene and affecting the protein product of that gene - CAUSES: External mutagens, DNA replication errors, DNA repair system malfunction - EFFECTS: Silent, Missense, Nonsense, Creation of SNPs, Creation of new alleles Sickle cell anaemia Description: Genetic blood disorder characterised by red blood cells that assume an abnormal, rigid, sickle shape. This irregular shape can lead to various health complications. Cause: Mutation in the HBB gene, which provides instructions for making a part of haemoglobin, the protein in red blood cells that carries oxygen. The mutation causes the haemoglobin molecules to stick together, forming rigid structures that distort the shape of the red blood cells. Effect: Affected cells can block blood flow in small blood vessels, causing pain and potential organ damage. These cells also break down prematurely, leading to chronic anaemia and fatigue. Complications can include severe pain episodes, increased risk of infection and delayed growth. Cystic fibrosis Description: Hereditary disorder affecting the exocrine glands, leading to the production of abnormally thick and sticky mucus. This mucus can clog the airways and lead to respiratory and digestive system issues. Cause: Mutations in the CFTR gene responsible for the production of a protein that regulates the movement of salt and water in and out of cells. The most common mutation, ΔF508, leads to the production of a malfunctioning protein that affects mucus consistency. Effect: The thickened mucus obstructs the airways, leading to persistent lung infections and breathing difficulties. It also affects the digestive system by blocking the pancreatic ducts, which hinders the release of digestive enzymes, causing malnutrition and poor growth. Other complications can include liver disease, diabetes, and reduced life expectancy. Chromosomal abnormalities: alteration to chromosome structure or number - CAUSE: Usually caused by errors in meiosis ➔ Crossing over occurs incorrectly ➔ Sister chromatids incorrectly separated during anaphase - EFFECTS: Usually severe, because chromosomal mutations involve large changes to a number of genes Numerical abnormalities - ENTIRE chromosomes either missing or extra present Structural abnormalities - SECTIONS of chromosomes becoming damaged resulting in deletions, duplications, inversions and translocations of chromosome sections Down syndrome Description: Genetic disorder caused by the presence of an extra chromosome 21. It is characterised by developmental delays, intellectual disability, and distinct physical features. Cause: trisomy 21, where an individual has three copies of chromosome 21 instead of the usual two. This extra genetic material affects the development of the body and brain. Effect: Individuals often have intellectual disability, distinct facial features, and may have heart defects, respiratory and hearing problems, and a higher risk of certain medical conditions such as thyroid disorders and leukaemia. They typically have shorter stature and reduced muscle tone. Klinefelter syndrome Description: Genetic condition affecting males, characterised by the presence of an extra X chromosome (XXY). It can result in physical, developmental, and reproductive issues. Cause: Random error in the distribution of sex chromosomes during the formation of egg or sperm cells, resulting in a male having an extra X chromosome. Effect: Males may have reduced testosterone levels, leading to symptoms such as reduced muscle mass, less facial and body hair, and enlarged breast tissue (gynecomastia). They may also have small testes, infertility, and may experience learning difficulties. Social and behavioural issues are also common. Environmental Diseases (caused by environmental exposure) ★ Caused by an over-exposure to environmental factors Lifestyle Factors Type 2 Diabetes Description: Non-infectious disease characterised by insulin resistance, where the body's cells gradually loses the ability to respond effectively to insulin, becoming insulin resistant and unable to take up glucose causing a high concentration to remain in the blood. Cause: Insulin resistance develops when excess fat is stored in the body - Poor lifestyle factors (Obesity, Physical Inactivity, Unhealthy Diet) Effect: Elevated blood sugar levels (hyperglycemia), which over time can lead to serious complications such as - Cardiovascular Disease, Nerve Damage, Kidney Damage Environmental Pollutants Mestholemia Description: Mesothelioma is an aggressive cancer that primarily affects the lining of the lungs but can also occur in the lining of the abdomen and other organs. Cause: Predominantly caused by exposure to asbestos, a group of minerals used in construction, insulation, and other industries. Inhalation of asbestos fibres can lead to their accumulation in the lungs, causing inflammation and genetic damage over time. Effect: Often takes decades to develop after initial exposure. Symptoms include chest pain, shortness of breath, and fluid buildup around the lungs. Typically diagnosed at an advanced stage with limited treatment options. Radiation Melanoma (check cancer section) Nutritional Diseases ★ Caused by either deficiencies or excesses in an individual's diet. These diseases can result from inadequate intake of essential nutrients, overconsumption of certain foods, or poor dietary habits. Dietary deficiencies Anaemia Description: Deficiency in the number or quality of red blood cells, which impairs the ability to carry adequate oxygen to the body's tissues. It can lead to fatigue, weakness, and various health complications. Cause: Anaemia due to dietary deficiencies is most commonly caused by a lack of essential nutrients such as iron, vitamin B12, or folate in the diet. Iron-deficiency anaemia is the most prevalent form, often resulting from inadequate dietary intake, poor absorption, or increased needs. Effect: Chronic fatigue, weakness, dizziness, and shortness of breath. Severe or untreated anaemia can lead to serious health problems such as heart palpitations and developmental delays. It can also impair cognitive and physical performance, reducing overall quality of life. Dietary excesses Obesity Description: Chronic disease characterised by excessive body fat accumulation, which increases the risk of various health issues. Cause: Primarily caused by an energy imbalance between calories consumed and calories expended. Factors contributing to this imbalance include excessive caloric intake, poor diet (high in fats and sugars), physical inactivity, and genetic predisposition. Effect: Significantly increases the risk of developing numerous health conditions, including type 2 diabetes, cardiovascular diseases, hypertension, certain cancers, and musculoskeletal disorders. It can also lead to psychological issues such as depression and low self-esteem. Cancer ★ Group of diseases characterised by the uncontrolled growth and spread of abnormal cells in the body forming tumours. Cancer can develop in almost any tissue or organ and can metastasize (spread) to other parts of the body. - Cause: Carcinogens (radiation, chemicals, pathogens), Lifestyle factors (smoking, alcohol, obesity, exercise, diet) and susceptibility can be increased due to genetics - Effects: Eventually metastasis to key organs preventing normal functioning - Treatment: combination of surgery, chemotherapy, radiation therapy, and targeted therapies. Melanoma Description: Type of skin cancer that develops from the pigment-producing cells known as melanocytes. It is the most serious form of skin cancer due to its high potential to spread to other parts of the body. Cause: Exposure to ultraviolet (UV) radiation from the sun or tanning beds. UV radiation can damage the DNA in skin cells, leading to mutations that trigger the uncontrolled growth of melanocytes. Effect: Melanoma can appear as a new mole or a change in an existing mole, often characterised by irregular shape and multiple colours. If not detected and treated early, melanoma can metastasize to other organs, making it more difficult to treat and potentially fatal. Lung Cancer Description: Cancer that begins in the lungs, primarily in the cells lining t