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Module 5- Heredity Inquiry question 1: Reproduction HEREDITY - Evolution requires heredity – the passing of genetic material from one generation to the next. every organism that exists today is the result of ancestorial lineage of individuals that successfully reproduced at least once before they...

Module 5- Heredity Inquiry question 1: Reproduction HEREDITY - Evolution requires heredity – the passing of genetic material from one generation to the next. every organism that exists today is the result of ancestorial lineage of individuals that successfully reproduced at least once before they died. THIS IS HEREDITY, AND WITHOUT IT, THERE IS NO EVOLUTION. Reproduction is essential for all living organisms, occurring through two main processes: sexual and asexual reproduction. Asexual Reproduction Definition: Involves only one parent and produces genetically identical offspring. Types: ○ Unicellular Organisms: Bacteria: Reproduce by simple cell division (mitosis). Eukaryotic Protists: Organisms like Amoeba and Paramecium divide by binary fission. Yeasts: Reproduce through budding, where a small "bud" forms on the parent and separates to grow independently. ○ Multicellular Organisms: Fungi: Release spores produced by mitosis. Plants: Can reproduce through runners, which are outgrowths that develop into new plants. Animals: For example, the Hydra can reproduce asexually by budding. Advantages: ○ Rapid population increase, allowing organisms to capitalize on favorable conditions (e.g., food availability). Disadvantages: ○ Lack of genetic variation can make populations vulnerable to environmental changes, risking extinction. Sexual Reproduction Definition: Involves two parents combining genetic material to produce diverse offspring. Process: ○ Involves the formation of reproductive cells (sperm and egg) through meiosis, a special type of cell division. Advantages: ○ Increases genetic variation, enhancing the survival of a species in changing environments. Disadvantages: ○ More complex, time-consuming, and energy-intensive than asexual reproduction. External & Internal Fertilisation Fertilisation is a key process in sexual reproduction where the egg and sperm fuse to form a zygote, containing genetic information from both parents. Fertilisation can occur in two primary ways: external and internal. External Fertilisation Definition: Fertilisation occurs outside the bodies of the parents, typically in a water environment. Process: Both parents release eggs and sperm into the water, where fertilisation takes place. Strategies: ○ Many species, like fish, have mating rituals and signals to synchronize gamete release. ○ Some organisms, like corals and sponges, spawn in response to environmental triggers (e.g., full moon). Characteristics: ○ Often involves a large number of gametes to increase the chance of successful fertilisation, but many may go to waste. Internal Fertilisation Definition: Fertilisation occurs inside the female’s body, providing protection to the egg and sperm from drying out. Terrestrial Plants: ○ Male gametes are carried in pollen grains, which are delivered to flowers by wind or pollinators (e.g., bees). ○ Pollen grains release sperm that swim down a pollen tube to fertilise eggs in the ovary. Terrestrial Animals: ○ Males deposit sperm directly into the female’s reproductive tract, where sperm can swim to fertilise the eggs. Development After Fertilisation: ○ Egg-laying Species: Birds, most fish, and reptiles lay eggs, with embryos developing outside the mother's body. ○ Live Birth Species: Some fish and reptiles retain fertilised eggs inside their bodies until they hatch. Marsupials: After brief gestation, young are born and continue developing in a pouch. Placental Mammals: The fetus develops inside the mother's body, nourished through a placenta, and is born when fully  developed. Fertilisation Methods and Their Relation to Habitat Sexual reproduction increases genetic variation, enhancing a species' chances of survival during environmental changes. However, achieving fertilisation can be challenging based on habitat: Aquatic Origins: Sexual reproduction likely began in water over a billion years ago, allowing external fertilisation where sperm swim to the egg. Moisture Dependence: Early land plants (like mosses and ferns) and amphibians still require moist conditions for reproduction, returning to water to breed. Internal Fertilisation: This adaptation emerged with conifers and later reptiles, birds, and mammals, allowing reproduction in drier environments without the need for water. Overall, external fertilisation is suited to aquatic habitats, while internal fertilisation enables successful reproduction on land, contributing to the evolution and diversification of terrestrial life. Humans, like all placental mammals, reproduce sexually using meiosis to create gametes (egg and sperm) with half the chromosome number. Fertilisation occurs inside the female, and the developing fetus is nourished through the placenta. After full development, the baby is born and breastfed with the mother’s milk. Male Reproductive System: Primarily a sperm delivery system, relatively simple in structure and function. Female Reproductive System: More complex, designed to produce eggs, support pregnancy, and nourish the fetus throughout development. Male Reproductive System: Structure and Function Testes: - Located in the scrotum, which hangs outside the body. - Kept at a slightly lower temperature, essential for healthy sperm production. Penis: - Contains erectile tissue that fills with blood, causing an erection. Sperm Duct: - Tube through which sperm cells travel from the testes to the penis. Glands: - Several glands add fluids to the sperm along the sperm duct. - These fluids nourish and maintain the health of the sperm. Semen: - The mixture of sperm cells and fluid produced by the glands. - During ejaculation, semen is expelled from the urethra. Ejaculation: - Occurs through muscular contractions. - Typically releases a few milliliters of semen, containing around 200 million sperm cells. Ovaries: Before birth, a girl has about 50,000 immature eggs due to meiosis. Egg Maturation: After puberty, one egg matures and is released into a fallopian tube each month. Fertilisation: Sperm cells swim from the vagina, through the cervix, and uterus to the fallopian tube to fertilise the egg. Zygote Development: The fertilised egg (zygote) begins dividing by mitosis and develops into an embryo. Embryo Implantation: Several days post-fertilisation, the embryo reaches the uterus. Pregnancy & Birth: Embryo Implantation: ○ The embryo implants into the uterine wall, beginning to receive nutrients and oxygen from the mother’s blood. Placenta Formation: ○ A placenta develops, facilitating the exchange of food, oxygen, and waste between the mother and the foetus. The umbilical cord connects the foetus to the placenta. Amniotic Sac: ○ The foetus is enclosed in the amnion, a flexible bag filled with amniotic fluid that supports the foetus and acts as a shock absorber. Gestation Period: ○ Pregnancy lasts about 270 days (approximately 9 months). Birth Process:  ○ Initiated by a hormone from the brain that dilates the cervix and causes contractions in the abdominal muscles. ○ The amnion bursts, releasing amniotic fluid. ○ Stronger contractions expel the baby through the cervix and vagina, followed by the placenta as the "after-birth." Hormones Control Reproduction: Endocrine System: Hormones regulate various body functions, with the reproductive system being particularly hormone-dependent. Puberty: - Hormones from the pituitary gland trigger the production of sex hormones in reproductive organs. In Males: Testosterone from the testes causes changes like a deeper voice, facial and body hair growth, and increased muscle mass. In Females: Oestrogen from the ovaries leads to breast development and changes in hip shape for childbirth. Pregnancy: Hormones from the placenta suppress further egg production and maintain uterine conditions. Hormonal changes prepare breasts for milk production. Birth Process: Triggered by a hormone that causes cervical dilation and contractions. Lactation: After birth, a hormone from the pituitary stimulates breast tissue to produce milk for the baby. Menstrual Cycle: The cycle of egg production and menstrual bleeding is intricately controlled by hormones. The Menstrual Cycle: Overview 1. The Build-Up: ○ Hormonal Regulation: Increasing levels of FSH (Follicle-Stimulating Hormone) from the pituitary gland lead to the release of oestrogen and LH (Luteinizing Hormone). ○ Follicle Maturation: An immature egg in the ovary matures within a cyst-like structure called a follicle. Around days 10-14, the follicle bursts, releasing the egg, marking the fertile window (3-5 days for potential pregnancy). 2. Progesterone Release: ○ After ovulation, the remnant of the follicle produces progesterone. ○ Effects of Progesterone: Thickens the uterine lining and increases blood supply for a potential embryo. Prepares breasts for possible milk production. 3. The Break-Down: ○ Approximately 10 days post-ovulation, the follicle remnant dies, leading to a sudden drop in progesterone. ○ Menstrual Period: The uterine lining breaks down and is shed, resulting in menstrual bleeding for 3-4 days. ○ The cycle restarts with renewed FSH production. Manipulation of Plant & Animal Reproduction through Selective Breeding Selective Breeding: Definition: Human-controlled reproduction to enhance desirable traits in plants and animals. Historical Use: Farmers have practiced selective breeding for thousands of years to improve crop and livestock quality and yield. Examples: Selecting superior rams for meat and wool. Choosing high-yield seeds for planting. Creating diverse breeds of dogs, flowers, and livestock. Case Study: Wheat: Ancestral Wheat: Small seed kernels, shed when mature, flexible stems, high variability in traits. Modern Wheat: Larger kernels, seeds stay attached for easier harvesting, stronger stems, selected for uniform traits like disease resistance. Impact: Modern wheat offers high yields and improved resilience but has less genetic diversity. Concerns:  Reduced genetic variation makes modern wheat vulnerable; it may not survive in the wild without human cultivation. Manipulation of Plant & Animal Reproduction through Cloning Cloning involves creating genetically identical organisms. It includes methods like: Asexual Reproduction: Techniques such as runners, cuttings, and grafting, used in plants for centuries. Tissue Culture: A modern approach to mass clone plants from small tissue samples in controlled lab conditions. Animal Cloning is more complex; the first mammal clone, "Dolly" the sheep, was created in the 1990s. While it's theoretically possible to clone any mammal, ethical concerns have led to bans on human cloning in many countries. Tissue Culture Process: This involves cultivating tissue samples in sterile nutrient media with controlled conditions to promote growth and development into full plants. Purposes of Cloning: 1. Produce many copies of plants with desirable traits. 2. Generate plants with low seed production, like orchids. 3. Conserve rare or endangered species. 4. Create disease-free plant populations. 5. Rapidly increase genetically modified species for farming. 6. Facilitate scientific research on hybrids or new pharmaceutical products. Cloning is essential in agriculture, conservation, and research, enabling the efficient reproduction of beneficial traits and the preservation of biodiversity. Cloning & Genetic Diversity Cloning leads to the production of genetically identical offspring, which reduces genetic diversity. When large numbers of clones are produced from a few or a single parent, the result is a population of closely related individuals. Monocultures in agriculture, such as wheat, rice, and bananas, exemplify this trend. While cloning can yield high-quality and consistent food products, it poses serious risks. Low genetic diversity makes crops vulnerable to environmental changes, diseases, or pests, threatening their survival. The Irish Potato Famine serves as a historical example of these dangers. In the 19th century, Irish farmers relied heavily on a single high-yield potato variety, cultivated through asexual reproduction. When a fungal disease, known as Potato Blight, struck in 1847, it decimated the crops over several years. The lack of genetic variation left the entire potato population susceptible, resulting in the deaths of approximately 1 million people and mass emigration. The Wollemi Pine (Wollemia nobilis) is a critically endangered tree species, with fewer than 100 specimens remaining in the wild. Discovered in 1994 in Wollemi National Park, it is often referred to as a “living fossil” due to its ancient lineage, known from fossils dating back 200 million years. Genetic Vulnerability: Analysis reveals that the existing population has minimal genetic variation and is affected by a virulent fungal disease, threatening its survival. Preservation Efforts: In response to its endangered status, preservation initiatives began shortly after its discovery. Tissue culture techniques have enabled the propagation of many young Wollemi Pines, which are sold commercially and planted in various botanical gardens around the world. While tissue culture has successfully expanded the population and helped create disease-free specimens, the ongoing low genetic diversity poses a long-term risk to the species. Organizations like the Australian Botanic Garden at Mount Annan are actively involved in seed production and tissue culture to further ensure the survival of the Wollemi Pine. Inquiry Question 2: Cell Replication Genes, Chromosomes & DNA Genes: Units of inheritance that determine traits (e.g., eye color, hair texture). Simple principle: one gene influences one characteristic, though complex traits involve multiple genes. DNA: A complex chemical structured as a helix, encoding genetic information via nucleotide sequences. Each gene is represented by a specific DNA sequence that directs protein synthesis. Chromosomes in Eukaryotic Cells: Genes are organized into chromosomes, which are thread-like structures made of DNA and proteins. Humans have 46 chromosomes (23 pairs); the first 22 pairs are identical across individuals, while the 23rd pair are sex chromosomes determining gender. Chromosomes in Prokaryotic Cells: Prokaryotes have one circular chromosome (genophore) and may contain plasmids, small loops of DNA that can replicate independently and facilitate gene transfer. Purposes of Mitosis and Meiosis Mitosis: Purpose: Primary method of cell division in unicellular organisms (binary fission) and crucial for growth and repair in multicellular organisms. Growth: Enables the production of many small cells to overcome limitations of surface area-to-volume (SA/Vol) ratio, allowing organisms to grow larger. Repair: Replaces damaged or worn-out cells, such as the continuous production of new blood cells. Meiosis: Purpose: Cell division for sexual reproduction, crucial for halving genetic material in gametes (sperm and egg cells) to ensure proper genetic contribution from both parents during fertilization. Chromosomes & Genes: Structure: Chromosomes contain thousands of genes along their length and occur in pairs called homologous chromosomes. Homologous Pairs: Correspond to each other but are not identical; they carry allelic genes in corresponding locations. Genotype Example: For genotype AaBbCc, the genes are located on homologous chromosomes, which have been duplicated before division. Each chromosome consists of two identical chromatids (forming an X shape), while the homologous chromosomes are similar but not identical. The Structure of DNA and DNA Replication Structure of DNA: Polymer Composition: DNA is a polymer made of smaller units called nucleotides. Nucleotide Components: Each nucleotide consists of: ○ A phosphate group ○ A sugar (deoxyribose) ○ One of four nitrogenous bases: Adenine (A), Cytosine (C), Guanine (G), Thymine (T). Double-Stranded Structure: DNA consists of two strands of nucleotides, with one strand running in the opposite direction to the other. The strands are held together by complementary base pairing: ○ A pairs with T (A-T) ○ C pairs with G (C-G) DNA Replication: Key Mechanism: The complementary base pairing allows each strand of DNA to serve as a template for the formation of a new complementary strand. Process: 1. The DNA molecule is untwisted and unzipped by enzymes, separating the two strands. 2. Free nucleotides in the cell match with the exposed bases on each strand (A-T and C-G). 3. New complementary strands are formed by connecting these nucleotides. 4. Each new DNA molecule is then twisted back into a double-helix shape, resulting in two identical DNA molecules, ready for cell division. Visual Representation: The DNA structure resembles a twisted ladder, where the sugars and phosphates form the side rails, and the base pairs act as the rungs. DNA Discovery and Its Role in Species Continuity Historical Context: By the 1950s, scientists knew DNA was the genetic material but struggled to understand its structure and function. Key figures in the discovery of DNA's double-helix structure included: ○ Francis Crick: Expert in molecular shapes. ○ Maurice Wilkins: Prepared pure DNA crystals. ○ Rosalind Franklin: Obtained crucial X-ray diffraction images. ○ James Watson: Collaborated to analyze data, leading to the breakthrough. Collaboration in Science: The discovery exemplified teamwork, with each scientist contributing unique skills. Franklin's contributions were often overlooked after her death. DNA Structure: DNA comprises two strands forming a double helix, with pairs of bases (A-T and C-G) bonded by sugar-phosphate chains. Cell Division and Species Continuity: Cell Division: Essential for reproduction and species survival. Genetic Variation: Crucial for evolutionary adaptation. Species with variation can better survive environmental changes. Sources of Variation: Asexual Reproduction: Limited variations arise mainly from mutations. Sexual Reproduction: Increases genetic diversity through: ○ Gene mixing from two parents. ○ Meiosis, which introduces randomness and crossing-over, leading to unique offspring. Conclusion: Sexual reproduction is vital for maintaining genetic diversity, enhancing a species' adaptability and resilience through natural selection. Inquiry Question 3: DNA and Polypeptide Synthesis Protein Structure and Function Protein Basics: Proteins are polymers made of amino acids, forming chains called polypeptides. A polypeptide must fold into a specific 3D shape to function as a protein. DNA and Protein Synthesis: The DNA sequence contains codes (codons) that specify which amino acids are to be added to a polypeptide chain. Each codon consists of three DNA bases, and a gene for a polypeptide (e.g., 1,000 amino acids) comprises 3,000 nucleotide bases. Changing Definition of a Gene: Initially, a gene was viewed as a hereditary unit determining a single trait. Research revealed that multiple genes could affect a single phenotype through a series of enzyme-controlled reactions. The modern definition of a gene is a unit of heredity that specifies a protein. Protein Formation: The sequence of amino acids in a polypeptide determines its final shape. About 20 different amino acids contribute to this sequence, with interactions between them influencing folding. Functions of Proteins: Proteins serve various roles in organisms: ○ Enzymes: Catalysts for biochemical reactions. ○ Structural Molecules: Found in muscles, skin, hair, and bones. ○ Specialized Proteins: Include hemoglobin (oxygen transport), chlorophyll (photosynthesis), and antibodies (immune defense). Importance of Shape: The function of proteins is heavily reliant on their shape, which is determined by the amino acid sequence. Proper functioning is essential for processes like enzyme activity and oxygen transport. Conclusion: DNA controls the amino acid sequence in proteins, highlighting the connection between genetics and protein function. From DNA to Phenotype Part 1: From DNA to Polypeptide 1. Transcription: ○ This initial step occurs in the nucleus, where one strand of DNA serves as a template to produce messenger RNA (mRNA). ○ mRNA is a single-stranded polymer of nucleotides that differs from DNA in its sugar, structure, and one nucleotide (uracil replaces thymine). ○ Each three-base sequence (codon) in mRNA specifies an amino acid for the polypeptide chain. 2. Translation: ○ This process occurs at the ribosome, where mRNA moves and is translated into a polypeptide. ○ Transfer RNA (tRNA) molecules carry amino acids to the ribosome. ○ The ribosome uses mRNA as a guide to connect the amino acids into a polypeptide chain via enzymatic activity. Part 2: From Polypeptide to Phenotype Once synthesized, the polypeptide folds and twists into a functional protein, which can serve various roles in the body, such as: ○ Structural Proteins: Build muscle or skin. ○ Enzymes: Catalyze biochemical reactions (e.g., producing colored pigments). ○ Hormones: Regulate bodily functions (e.g., growth). Example: Eye color is determined by proteins coded in DNA that produce pigments in iris cells. While the gene for eye color exists in every cell, it is only expressed in iris cells. tRNA and Ribosomes tRNA Structure: ○ tRNA molecules are cloverleaf-shaped, with one end attaching to a specific amino acid and the other end featuring an anticodon that pairs with mRNA codons. Ribosomes: ○ Ribosomes are the sites of translation, utilizing the mRNA code to construct polypeptides, aided by various enzymes and tRNA. Conclusion The processes of transcription and translation bridge the gap between genetic information in DNA and the physical expression of traits (phenotype) through proteins. The sequence of bases in DNA ultimately determines the structure and function of proteins, which are vital for various biological processes. Inquiry question 4: Genetic Variation Gregor Mendel's Experiments: Mendel, an Abbot in the Czech Republic, conducted experiments on pea plants to understand inheritance. He bred pure-breeding plants over generations to examine traits like height and flower color. His large sample size revealed consistent results: the first generation (F1) exhibited the dominant trait, while the second generation (F2) showed a ratio of approximately 3:1 (dominant to recessive). Mendel's Explanation: Traits are determined by "factors," now known as genes. Each trait has alleles, with one being dominant and the other recessive. Plants possess two alleles for each trait (homozygous or heterozygous). Only one allele is passed to gametes during reproduction, leading to the offspring inheriting one allele from each parent. Punnett Square: A tool developed by Punnett to visualize genetic crosses, simplifying the calculation of offspring genotypes and phenotypes. For example, in a monohybrid cross between two heterozygous tall plants (Tt), the expected phenotypic ratio in F2 offspring is 3 tall to 1 dwarf. Pedigree Diagrams: Used to trace inheritance patterns in families, helping identify dominant and recessive traits without unethical experimentation on humans. Example: In a pedigree showing tongue-rolling ability, individuals can be analyzed to determine their genotypes based on their offspring's traits. Applications: Pedigree analysis aids in understanding genetic disorders (e.g., hemophilia, color-blindness) and informs family planning decisions. Overall, Mendel's work laid the foundation for modern genetics, illustrating how traits are inherited and providing tools for predicting genetic outcomes. Sex Determination and Inheritance Patterns Sex Determination in Humans: Humans have 46 chromosomes, arranged in 23 pairs. Of these, 22 pairs are autosomes, and the 23rd pair consists of sex chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The sex of a child is determined by the type of sperm that fertilizes the egg: if a sperm carries an X chromosome, the child is female (XX), and if it carries a Y chromosome, the child is male (XY). Thomas Morgan's Experiments: Morgan studied Drosophila fruit flies and discovered that certain traits, such as eye color, were inherited differently between males and females, indicating sex-linked inheritance. In his experiments, he found that red eyes (dominant) and white eyes (recessive) were determined by alleles on the X chromosome. Males (XY) inherit only one allele for eye color, while females (XX) inherit two. Sex-Linked Traits: For eye color in fruit flies: ○ Females: XRXR (red), XRXr (red), XrXr (white) ○ Males: XRy (red), Xry (white) When crossing these flies, Morgan observed a 3:1 ratio of red to white eyes in the F2 generation, reflecting a blend of Mendelian and sex-linked inheritance patterns. Genetic Disorders: Examples of sex-linked disorders in humans include red-green color blindness and hemophilia, both more common in males due to their  single X chromosome. Co-Dominance and Incomplete Dominance: Co-Dominance: Both alleles are fully expressed in the phenotype. For example, in Shorthorn cattle, a heterozygous cross results in roan coats (RW). Incomplete Dominance: The phenotype is a blend of the two alleles. In snapdragons, red (RR) and white (WW) flowers produce pink (RW) flowers when crossed. Multiple Alleles: Some traits, like human blood types, are controlled by multiple alleles. The ABO blood group system includes three alleles: IA, IB, and i. ○ IA and IB are co-dominant; both are dominant over i. ○ Possible blood types are A (IAi), B (IBi), AB (IAIB), and O (ii). Rhesus Factor: The Rh factor (D or d) is inherited independently of the ABO blood group and follows a simple dominant-recessive pattern. Rh+ individuals have the D allele, while Rh- individuals have the d allele. Punnett Squares for Blood Types: Crosses involving blood type and Rh factor can be analyzed using Punnett squares to predict offspring phenotypes. The Effect of Environment on Phenotype Understanding Phenotype and Environment: An organism’s phenotype (observable traits) is influenced by both its genotype (genetic makeup) and environmental factors. For instance: ○ Genotype TT or tt may both result in a dwarf phenotype under poor soil conditions. This illustrates that while genes dictate potential traits, environmental conditions can modify the final appearance. Darwin's Gaps in Evolutionary Theory Charles Darwin acknowledged two significant gaps in his theory: 1. Inheritance of Traits: How do advantageous traits get passed to offspring? 2. Source of Variation: What generates the differences that natural selection acts upon? Mechanisms of Variation 1. Variation from Meiosis: Meiosis is the process of cell division that produces gametes (sperm and eggs). Homologous chromosomes separate randomly and independently, leading to a vast number of possible combinations. In humans, with 23 pairs of chromosomes, meiosis can create approximately 8 million different gametes. 2. Crossing-Over: During meiosis, homologous chromosomes can exchange segments of DNA through a process called crossing-over, further increasing genetic diversity. This mixing of genetic material contributes to the variability among offspring. 3. Sexual Reproduction: Sexual reproduction involves the combination of genetic material from two parents, resulting in offspring with a unique mix of traits. This not only increases variation but also enhances adaptability within populations. Inquiry Question 5: DNA Sequencing Gene Frequency Definition: Measure of how common a particular gene is in a population. Natural Selection: Favored traits increase in frequency over generations. Dominant vs. Recessive Genes Common Misconception: Dominant genes automatically increase in frequency. Example: In Mendel's pea experiment, the phenotype ratio was 75% tall (dominant) to 25% dwarf (recessive), but genotype frequencies were equal (TT, Tt, tt). Hardy-Weinberg Principle Core Idea: In random mating populations, gene frequencies remain constant unless affected by: ○ Migration: Movement of individuals. ○ Genetic Drift: Random changes, especially in small populations. ○ Natural Selection: Traits that enhance survival become more common. Case Study: English Pepper Moth Observation: Shifts in color frequencies due to environmental changes (industrialization). Conclusion: Natural selection was driving the changes, not random chance. The Human Genome Project (HGP) Completion: 2003. Findings: ○ Human genome: 3.3 billion base pairs, 22,000 genes. ○ Only 2% codes for proteins; the rest includes regulatory elements and non-coding DNA. Benefits of HGP Medical Advances: Understanding and treating diseases, including cancer. Personalized Medicine: Tailored treatments based on genetic profiles. Biotechnological Applications: Enhanced agriculture and food production. Single-Nucleotide Polymorphisms (SNiPs) Definition: Variations in a single nucleotide that can affect gene function. Applications: ○ Personalized Treatments: Tailored healthcare based on individual genetics. ○ Forensics and Ancestry: Tracing lineage and ethnic origins. Insights into Human Evolution Fossil Evidence Common ancestor with chimpanzees: 5-10 million years ago. Multiple early human species co-existed (e.g., Neanderthals). Genetic Evidence Mitochondrial DNA: Traces lineage back to "Mitochondrial Eve" (~150,000 years ago). Y-Chromosomal DNA: Traces male lineage back to "Y-Chromosomal Adam" (~130,000 years ago). Migration Patterns Modern humans migrated from Africa in several waves (~60,000 years ago). Evidence of interbreeding with Neanderthals (2-4% Neanderthal DNA in non-African populations) and Denisovans (4-6% in some Asian populations). Summary- Population genetics merges evolutionary theory with genetics, enhancing our understanding of species evolution, genetic diversity, and the impact of genes and the environment. The HGP and SNiP analysis have profound implications for health, ancestry, and the study of human evolution. Module 6: Genetic Change Inquiry Question 1: Mutation What is a Mutation? Definition: A permanent change in the genetic information of an organism. Importance of "Permanent": Frequent accidental changes occur in DNA, but most are repaired by cellular mechanisms. Only a few become mutations. Overview of Mutation Types 1. Genic Mutations: Affect single genes. ○ Point Mutations: Include single base substitutions, deletions, and insertions. 2. Chromosomal Mutations: Involve changes in chromosome number or structure. ○ Types: Chromosome Number: Trisomy: Extra chromosome (e.g., Down Syndrome). Monosomy: Missing chromosome (e.g., Turner Syndrome). Chromosome Structure: Deletion: Missing part of a chromosome. Duplication: Extra copies of a gene or chromosome segment. Inversion: Chromosome segment reversed. Translocation: Part of one chromosome attached to another. Crossing-Over Definition: Exchange of genetic material between homologous chromosomes during meiosis. Impact: Increases genetic variation without changing overall genome content—not a mutation. Changes to Chromosome Number Non-Disjunction Definition: Failure of homologous chromosomes to separate properly during meiosis. Examples: ○ Down Syndrome (Trisomy 21): Extra chromosome 21 due to non-disjunction during egg formation, resulting in 47 chromosomes. ○ Turner Syndrome (45 X0): Missing X chromosome in females, leading to developmental difficulties. Polyploidy Definition: Presence of extra complete sets of chromosomes (e.g., triploidy, tetraploidy). Effects: Generally fatal in humans, but beneficial in plants (e.g., larger fruits, flowers). Common in cultivated crops. Changes to Chromosome Structure 1. Deletion: Loss of a chromosome segment; can affect gene function. 2. Duplication: Extra copies of a chromosome segment; linked to some cancers. 3. Inversion: Reversal of a chromosome segment; usually harmless unless it disrupts genes. 4. Translocation: Movement of chromosome segments between non-homologous chromosomes; can lead to cancers in somatic cells. Summary Understanding mutations, including their types and mechanisms, is crucial for studying genetics and evolution. Mutations can have significant impacts on organisms, from genetic diseases in humans to increased robustness in plants, playing a key role in both health and biodiversity. Understanding Mutations Definition Mutation: A permanent change in the genetic material of an organism. Types of Mutations 1. Genic Mutations: Affect single genes.  ○ Point Mutations: Change a single nucleotide. Substitution: One base is replaced by another. Insertion/Deletion: Adding or removing a base shifts the reading frame (frameshift mutation). 2. Chromosomal Mutations: Affect whole chromosomes or parts of them. ○ Types: Deletion: Loss of a part of a chromosome. Duplication: Extra copies of a part of a chromosome. Inversion: A segment of a chromosome is reversed. Translocation: A piece of one chromosome is transferred to another chromosome. Polyploidy: Having extra sets of chromosomes (common in plants). Effects of Mutations Somatic Mutations: Occur in body cells; not inherited. Can lead to cancer. Germ-Line Mutations: Occur in gametes; can be inherited by offspring. Causes of Mutations Spontaneous Mutations: Random errors during DNA replication. Mutagens: Environmental factors that increase mutation rates. ○ Radiation: X-rays, UV light, etc. ○ Chemicals: Certain pollutants and carcinogens. ○ Biological Factors: Some viruses can integrate their DNA into the host genome, causing mutations. Consequences Mutations can have various effects, from benign to harmful. They can: ○ Alter protein function. ○ Lead to genetic disorders (e.g., sickle-cell anemia). ○ Affect evolutionary processes by introducing new traits. Non-Coding DNA Mutations can also occur in non-coding regions, which might regulate gene expression or have other important roles. Summary Mutations are a fundamental aspect of genetics, playing a key role in evolution and genetic diversity. Understanding their types, causes, and effects helps us grasp their significance in biology. Mutation and Evolution Sources of Genetic Variation 1. Sexual Reproduction: ○ Involves two parents, creating a mix of traits in offspring. 2. Meiosis: ○ Independent Segregation: Random separation of homologous chromosomes during gamete formation results in diverse combinations. ○ Crossing-Over: Homologous chromosomes exchange segments, increasing genetic variation further. 3. Mutations: ○ Random changes in DNA that can create new, inheritable traits. ○ A single mutation can alter a protein's function, potentially providing a survival advantage. Role of Mutations in Natural Selection Mutations introduce new traits into a population, which may be advantageous, neutral, or detrimental. Most mutations are recessive and can remain hidden for generations until two carriers produce offspring that express the trait. Changes in the Gene Pool Gene Pool: The total genetic diversity within a species. Factors Influencing the Gene Pool 1. Gene Flow: ○ Movement of individuals between populations helps stabilize genetic variation. ○ Even minimal migration can maintain gene frequencies across populations.  2. Genetic Drift: ○ Random changes in gene frequencies, particularly impactful in small populations. ○ Can lead to loss of genetic diversity as certain genes may be randomly lost or become more common. 3. Mutations: ○ Introduce new genetic variations. ○ Beneficial mutations can become more common through natural selection, while harmful ones may be eliminated. Interplay of Factors The stability and diversity of a gene pool are shaped by the interaction of gene flow, genetic drift, and mutations, alongside natural selection. Natural selection favors traits that enhance survival, leading to evolutionary changes in the species over time. Summary Mutations are the primary source of genetic variation, providing raw material for evolution. Through processes like gene flow and genetic drift, the gene pool of a population can change, reflecting the ongoing dynamics of natural selection. This interplay drives the evolution of species, enabling adaptation to changing environments. Inquiry question 2: Biotechnology Definition: Biotechnology: Any technology that uses living organisms to create products. Genetic Technology: A subset that involves manipulating genes, often referred to as genetic engineering. Historical Context Ancient Biotechnology: Neolithic Revolution (11,000 years ago): Marked the start of agriculture, leading to settled communities and societal changes. ○ Innovations included seed storage, farming tools, and techniques for harvesting. ○ Agricultural societies faced health issues and social inequalities compared to hunter-gatherers. Early Biotechnologies: Fermentation: Utilized yeast to produce beer, which made water safer to drink and led to the creation of other products like yogurt and bread. Selective Breeding: Early farmers selected the best plants and animals for breeding, improving yields and traits over generations. Modern Biotechnology Key Developments: 1917: Bacteria were first used to produce chemicals for explosives. 1928: Discovery of penicillin from the fungus Penicillium revolutionized medicine by treating infections. 1971: Successful gene splicing experiments marked the beginning of modern genetic technology. Applications of Genetic Technology 1. Medical Supplies: Production of human insulin and other substances by splicing human genes into bacteria. 2. Biofuels and Bioplastics: Use of genetically modified microorganisms for sustainable production. 3. GM Plants: Development of crops with higher yields or resistance to pests. 4. Bioremediation: Genetically engineered organisms used to clean up pollution. Techniques in Biotechnology 1. Selective Breeding: ○ Humans have altered genomes for thousands of years by selecting traits in plants and animals. ○ Example: Modern wheat has been selectively bred for larger seeds, disease resistance, and higher yields compared to ancestral wheat. 2. Artificial Pollination: ○ Involves manually transferring pollen from one plant to another to control breeding. ○ This technique is used to create hybrids, like nectarines (peach + plum), and is widespread in agriculture. 3. Artificial Insemination (A.I.): ○ Collection and freezing of semen from high-quality animals for widespread use.  ○ Used in livestock to improve herds globally and in human reproduction for couples facing infertility. Ethical Considerations The use of biotechnology raises ethical questions, especially regarding genetic modification and human reproduction. Past ideas of eugenics highlight the complexities of applying genetic technology to humans. Conclusion Biotechnology has evolved from ancient agricultural practices to modern genetic technologies, offering significant advancements in medicine, agriculture, and environmental management. The interplay between historical practices and contemporary innovations continues to shape our society, presenting both opportunities and ethical dilemmas. Cloning and Tissue Culture Cloning: A clone is a group of genetically identical organisms. The simplest form of cloning is asexual reproduction, such as: ○ Cuttings: Taking a part of a plant and growing it into a new plant. ○ Grafting: Joining parts of different plants to grow together. Tissue Culture: Tissue culture is a modern method of cloning plants on a large scale. It involves: ○ Taking small pieces of plant tissue and culturing them in nutrient-rich media under sterile conditions. ○ Controlling light, temperature, and using plant hormones to promote growth and differentiation. This method can produce thousands of clones from a single parent plant. Why Use Tissue Culture? 1. To replicate plants with desirable traits (e.g., disease resistance). 2. To quickly multiply rare or endangered species. 3. To create disease-free populations for conservation or commercial purposes. 4. For scientific research into new plant varieties or products. Advantages: High yield of identical plants, particularly beneficial for GM crops, which can significantly increase agricultural productivity. Disadvantages: Genetic uniformity may pose risks to food security and biodiversity. Recombinant DNA Technology Definition: Recombinant DNA technology involves combining DNA from different sources to create new genetic combinations. Insulin Production Example: 1. Restriction Enzymes: Enzymes that cut DNA at specific sequences. 2. Isolate the human gene for insulin and insert it into bacterial plasmids (circular DNA). 3. When bacteria multiply, they produce human insulin, which is purer and more reliable than animal-derived insulin. Genetic Engineering and Transgenic Species Transgenic Species: Organisms created by transferring genes from one species to another. Example: The Bt gene from Bacillus thuringiensis is inserted into crops to make them resistant to insect pests, reducing the need for chemical pesticides. Methods of Gene Transfer: 1. Gene Gun: Shoots DNA into plant cells using tiny particles. 2. Agrobacterium: A bacterium that can transfer its DNA into plants, modified to carry desired genes. Commercial Impact: GM crops have significantly increased agricultural yields and farmer incomes. However, public concerns about their safety persist, even though scientific evidence does not support health risks. Gene Therapy Definition: Gene therapy aims to treat genetic disorders by repairing or replacing faulty genes. Example - Cystic Fibrosis (CF): CF is caused by a defect in a single gene. The therapy involves: 1. Isolating a healthy version of the gene. 2. Using harmless viruses as vectors to deliver the healthy gene into the affected lung cells. Current Status: Clinical trials for various diseases (including CF, Parkinson’s, and hemophilia) are underway, but none have yet been approved for widespread use. Conclusion These biotechnological advancements hold significant promise for agriculture, medicine, and conservation. However, ethical considerations and potential risks associated with genetic modifications and cloning must be carefully evaluated as the technologies continue to develop. Cloning and Gene Cloning Cloning Overview: Cloning involves creating genetically identical organisms. Horticulturists have long used methods like cuttings and grafting to clone plants. Tissue culture allows for mass cloning of plants from a single parent in laboratory conditions. Animal Cloning: Cloning animals, such as the famous Dolly the sheep, was achieved in the 1990s. This process raises ethical and moral concerns, leading many countries to ban human cloning. Gene Cloning: Gene cloning involves copying specific genes rather than entire organisms. An example is the production of insulin using recombinant DNA technology, which involves inserting a human insulin gene into bacteria. Potential Benefits of Cloning 1. Enhanced Food Production: ○ Cloning can efficiently propagate genetically modified (GM) plants with desirable traits, like higher nutritional content. ○ Cloning superior livestock (e.g., bulls) can improve agricultural yields and quality. 2. Organ Transplants: ○ Cloning pigs modified with human genes could provide organs for transplants with fewer rejection issues. Genetic Diversity Concerns Cloning and selective breeding can reduce genetic diversity, making species more vulnerable to diseases and environmental changes. For example, monocultures (like bananas or certain rice strains) can lead to catastrophic failures, as seen during the Irish Potato Famine. Industrial Applications of Genetic Technology 1. Improving Processes: ○ Genetic modifications can enhance traditional fermentation and production methods for various products. 2. Biofuels: ○ Developing GMOs from non-food crops or agricultural waste for biofuel production aims to reduce reliance on fossil fuels. 3. Bioremediation: ○ GM bacteria can be engineered to clean up pollutants, such as oil spills, more effectively. Social and Ethical Implications  1. Historical Context: ○ The shift from hunting and gathering to agriculture (the Neolithic Revolution) allowed for population growth but also led to social issues, inequalities, and conflicts. 2. Modern Concerns: ○ GM Food Controversy: Concerns include health risks, ecological impacts (e.g., cross-pollination with wild relatives), and ethical considerations about patents and ownership of GMOs. ○ Public Perception: Fears about GMOs often stem from misinformation or conspiracy theories, despite scientific evidence supporting their safety. 3. Economic Ethics: ○ The patenting of GMOs raises moral questions, particularly regarding profits made from smallholder farmers in developing countries. Conclusion The advancements in cloning and genetic technology offer numerous benefits in agriculture and medicine but also pose challenges related to ethics, biodiversity, and social equity. Ongoing discussions about these issues are essential as technology continues to evolve. The Fuel vs. Food Debate Biofuels: Ethanol and biodiesel are made from crops like corn and sugar cane to reduce fossil fuel dependence and CO2 emissions. Claims of being "carbon-neutral" may be overly optimistic, as replacing all petroleum fuels with biofuels would require about 75% of arable land, making it impractical. Future Directions: 1. Agricultural Waste: Research focuses on converting plant waste into biofuels to save arable land for food. 2. Non-Arable Land: Exploring GM algae cultivation in non-arable areas for biofuel production. Stem Cell Technology Overview Types of Stem Cells: Totipotent: Can develop into any cell type (found in early embryos). Pluripotent: Can differentiate into three germ layers. Unipotent: Limited to specific cell types (e.g., adult stem cells). Cloning Methods: iPSC (Induced Pluripotent Stem Cells): Reprogramming adult cells; potential tumor risk. SCNT (Somatic Cell Nuclear Transfer): Replacing an egg's nucleus with a somatic cell nucleus for therapeutic cloning. Uses: Current: Bone marrow transplants. Future: Regenerating tissues and organs, minimizing rejection issues. Ethical Concerns 1. Human Cloning: Banned in over 70 countries due to moral objections and fears of "designer babies." 2. Stem Cell Research: Generally accepted for therapeutic use but controversial when involving human eggs, raising ethical questions about embryos. Module 7: Infectious Disease Inquiry Question 1: How are diseases transmitted? How are diseases transmitted? Pathogen: Organism or infective agent living in/ on another living organism causing disease Disease: Condition in an individual, that impairs normal function( infectious/ non-infectiuous) Infectious disease: Caused by a wide range of different organisms + agents - pathogens Non-infectious disease: Caused by factors like dietary, hereditary, environmental- exposure to chemicals Type of pathogen Distingishing features Example Proion - Defective form of protein molecule - Mad cow disease Non living - Does not contain DNA or RNA - creutzfeldt-Jacob disease - Mostly attacks brain/ nerve cells - Molecular level-low nm - Not visible with light microscope Virus - Non cellular - Hepatitis B Non living - Contains DNA, RNA + protective coat - AIDS- HIV - Requires a living host cell to replicate - Small poxs- variola virus - Less than 500nm - Not visible with light microscope Bacteria - Unicellular, Prokaryotic cell - Tuberculosis Living - Cell was surrounding cell - Anthrax - Up to 100um - Visible with light microscope Protozoa - Eukaryotic unicellular organisms - Malaria Living - Usually complet life cycle - Giardiasis - 50-150um - Visible with light microscope Fungi - Eukaryotic cells with cell wall - Tinea Living - Some unicellular, most are multicellular - Thrush - Um to mm Macro-Parasite - Eukaryotic cells- multicellular organism - Tapeworm Living - Mostly arthopods or worms - Paralysis tick - External parasites = ectoparasites - Interal parasites = endoparasites - Mm to meters - Visible with naked eye Transmission in an epidemic Transmission of infectious disease Epidemic: widespread of an infectious disease in a community at a particular time Direct contact: Often spread through direct contact Ebola - EVD, severe fatal disease fatality rate 50% Person -Person Touching or exchanging body fluids, - 2014-16 west Africa epidemic of EVD 11,000 deaths Contact occur before infected person has - Host was a fruit bat, transmitted to a human that symptoms (sexually transmitted diseases) then spread from further human to human contact Factors that affect - How infectious it was Droplet Spread Coughing, sneezing + speaking releases transmission - Population density droplets carrying disease. Transmission - Population mobility happens when droplets are in close - Cultural beliefs (washing the dead) proximity - Poor public health + sanitation Prevention of the - Cooking meat thoroughly Responses of plants to pathogens spread - Wearing PPE + good personal hygiene - Contact tracing Physical- barriers to prevent entry - Laboratory testing - Bark contains lignin - Safe burials - Waxy cuticle on leaves - Limiting movement of individuals - Thick cell wall - Quarantine the infected - Closing of stomata Chemical- plants produce chemical defences Adaptions in Pathogens to Entry and Transmission - Plant cells tighten + cell walls thicken preventing pathogen entry Transmission: Pathogenic bacteria are found in a range of environments + - Chemicals in cell wall cause it to thicken + trap transmitted to the host through water, food, and air. Once inside they have pathogen, the infected cell then self- destructs mechanisms to aid their dispersal  - Staphylococci secrete chemicals to break blood close down or connective - Salicylic acid produced to produced protection tissue against further pathogen invasion Attachment: species with glycocalyx x or fimbriae attach to cells to make removal Named AUS plant: Eucalyptus species difficult Pathogen: Fungus phytophthora cinnamomi Reproduction: species can multiply rapidly under the right conditions, allowing Symptoms: wilted, yellow leaves, stunted growth bacteria to quickly infect + spread in host Chemical protection: They contain oils in leaves with Mobility: flagella allow bacteria to move fast in environments + host to aid anti-microbial properties colonisation Effects + control: Widespread killing off species. Spread can Example: Malaria be controlled by washing + disinfecting shoes containing Facilitate entry into host - infected female mosquito bite + penetrate the skin, P the fungi spores Falciparum exits the mosquitos salivary glands entering human bloodstream Facilitate transmission between hosts - Antigen initiating an effective immune Indirect contact: often spread through the air indirectly + response against the pathogen, P Falciparum produces adhesion proteins, tricks the other mechanisms human immune system so that it does not recognise pathogen + attack it- plasmid remains in the human bloodstream, ready to be ingestsed by another mosquito Physical and chemical changes in host cells Airborne Agents can linger in the air allowing transmission diseases to spread- like measles - For pathogens to cause disease it has to get inside us Contaminated Germs linger on surfaces, touching - The human body has multiple defences to prevent pathogens from causing objects contaminated surfaces can expose you- disease happens when you touch your face Barriers to entry (1st line of defence): structural (physical) + physiological adaptions before washing hands (chemical) to prevent pathogen entry NON SPECIFIC Innate immune system (2nd line of defence): NON SPECIFIC mechanisms try to Food + drinking E.Coli + botulism - spread through destroy pathogens entering the body water contaminated food + water, often from Adaptive immune response (3rd line of defence): SPECIFIC mechanisms that act to mishandled foods destroy specific pathogens entering the body Physical barriers to entry: Diseases can transfer to animals-humans Skin- 3 layers of packed cells make it impenetrable to pathogens. Sebaceous + Animal- person through bites, scratches etc. Toxoplasma sweat glands produce sebum + sweat creating a salty acidic environment and contact gondii, found in cat feces is a risk to making pathogen growth hard people with weak immune systems Mucous membranes- line respiratory, urinary + digestive tracts - cells secrete mucous anti microbial properties - hair cells direct mucous with trapped microbes out of Zoonosis occurs when diseases go from body Animal animals - people. - Anthrax (sheep), Peristalsis- moves mucous + trapped microbes towards anus Reservors Rabies(rodents), West Nile virus (birds) Urinary flow- flushed away unwanted pathogens out of urinary tract Chemical barriers + responses: Zoonotic like malaria transmitted by Saliva- lysosomes in saliva attack + damage bacteria cell walls blood-sucking insects (fleas), fleas get Acid- stomach contains hydrochloric acid pH 1-2, kills most microbes preventing Insect bites infected by feeding on hosts like birds entry then pass it on to another host after Small intestine pH- pH 7-8, kills any microbes that survive the stomach acid bitting Tears- contains lysosomes which inhabit or kill microbes Organisms in soil, water + vegetation transmit disease to people. Hookworm Environmental spreads through contaminated soil. reservoirs Legionnaires disease can be transmitted by water from cooling towers + evaporative condensers Pasteur and Koch - Believed that life arose spontaneously from non-living matter - Louis Pasteur disproved this with the swan-necked flask experiment Swan neck flask experiment - 2 flasks filled with broth, boiled to kill microbes - One flask was broken so that dust + air can go in - Broth in the broken flask turned dark = microbial growth, broth in the unbroken flask was unchanged It was concluded that spontaneous generation could not have occurred as both flasks would have turned dark - Robert Koch 1800s demonstrated that microorganisms cause disease - Differeded from miasma theory - Proposed theory- Germ Theory, Koch’s postulates demonstrated that a particular disease is caused by the specific organism - Isolated bacteria from diseased organism then injected into healthy animals = exhibited same symptoms as first - Demonstrated that specific infectious diseases (Anthrax) was created by specific microorganism - Provided a set of principals whereby other organisms could have shown the cause disease Plant diseases Animal diseases - Caused by various fungi + bacteria, can have large scale - Typically caused by various virus + bacteria (like plant diseases, effects on agriculture production large scale effects on production) Fire blight Foot + Mouth disease  - Contagious disease affecting apples, pears + pome fruit - Highly contagious- cloven hoofed animals (sheep + cattle) AUS (worldwide besides AUS +Japan) considered free of FMD - Attacks blossoms, leaves, shoots, branches, fruit + roots - FMD excluded from AUS by strict quarantine - Results in tissue death + bacteria ooze droplets on - FMD caused by food + mouth disease virus infected tissue which spreads to heathing plants though - Causes fever + blisters in mouth + hooves of sheep + cattle rain, wind, insects + pruning tools - Leads to severe production losses - Difficult to contain, can be prevented by on-farm - Infected animals recover, leaves them weakened + debilitaled = biosecurity- prevents entry, establishment + spread of herds destroyed pests + diseases or by practising on farm hygiene - Outbreak in 2001 in UK caused $19 billion in export losses practices - Countries only import livestock + meat products from FMD free - Pome fruit growing areas in AUS are high risk areas for fire countries like AUS blight - If the outbreak reaches AUS est $7.1 billion will be lost in 3 months- - 1997, found in Melbourne Royal Botanic Gardens coasting essential it stays FMD free the industry $20 million in losses Innate and Adaptive Immune System Immune response - Pathogens can sometimes get through bodies defence Acquired immunity: can be developed naturally or artificially over your barriers lifetime - They act as antients & trigger the bodies immune system Naturally acquired: to respond Active: antigens enter the body naturally, the body produces antibodies - They have markers on their surfaces that we don’t Passive: antibodies pass directly from mother → fetus via placenta or breast recognise as ‘self’, our bodies cells have special markers milk that we recognise Artificially acquired: - Once they enter the body they trigger both the innate & Active: Antigens are injected via vaccines. The body produces antibodies to adaptive immune system become immunised The innate immune response involves: Passive: Pre-formed antibodies injected directly into the body. The body Phagocytosis- does not produce the antibodies (anti-venom serum) - Body has 2 main types of white blood cells neutrophils & Active immunity: is where the immune system responds to exposure to macrophages, they act as phagocytes to carry out microbes phagocytosis. Passive immunity: Gained from pre-formed antibodies without being - Phagocytes can engulf microbes. Chemicals & enzymes exposed to the microbe or pathogen inside the phagocytes destroy the microbes - Some will display an antigen from the pathogen on the surface after phagocytosis has occurred - Helps trigger T-cells to begin attacks on that pathogen (3rd line of defence) Inflammatory system - Injures to body tissues release histamines that can trigger an inflammatory response - Histamines increase blood capillaries to dilate & become more permeable - Allows phagocytes (white blood cells) in the bloodstream to exist the capillaries & enter body tissue to attack pathogen - This response causes pain, fever, redness, swelling & heat Lymphatic system - Takes in dead cells & debris from the phagocytes & carries this fluid towards the lymph nodes for disposal, allowing healing begin Cell death (apoptosis) - Specialised White blood cells recognise body cells that have been infecting with viruses - They release chemicals causing the cell to undergo ‘self-destruction’ or apoptosis - Both the cell & the pathogens inside die Adaptive immune system - B cells: Produced in bone marrow, responsible for antibody-mediated immunity. - T cells: Produced in bone marrow, mature in the thymus, and responsible for cell-mediated immunity. Stages of B and T Cells: - Naive cells: Mature without antigen exposure. - Effector cells: Active after encountering specific antigen. - Memory cells: Circulate post-pathogen elimination, and provide rapid response upon re-exposure. Naive B Cell Characteristics: - Each contains a unique BCR for antigen detection. - Millions of variations ensure comprehensive antigen recognition. B Cell Activation: - Requires: - Antigen binding to specific BCR. - Antigen presentation via APCs and MHC II to Th cells. Outcome of B Cell Activation: - Differentiation into memory B cells or plasma cells. - Plasma cells produce antibodies, which form complexes with antigens. Role of Memory B Cells: - Accumulate in the spleen and lymph system long-term. - Prompt production of specific antibodies upon antigen re-exposure Spread of Disease Hygiene practices Understanding how infectious diseases are transmitted can aid in - To keep control of the spread of disease pathogens must be minimising the spread. As populations increase, travel is more prevented from coming into contact with new hosts affordable and trade in agriculture has increased, these factors Types of hygiene need to be considered in preventing the spreading of diseases. Personal hygiene- Frequent bathing, handwashing with soap Communal hygiene- water purification, sewage infrastructure Influenza A: Food hygiene: keeping cooking & raw food separate, storing food at Local; recommended temps - Easily spread in dense populations (schools, hospitals) Hygiene practices kill pathogens → reduce risk of transfer → reduce the - Spreads quickly in cities compared to rural areas incidence of disease Reginal: Quarantine: strict isolation imposed to prevent spreading of disease or - Can occur through transport (car, aeroplanes) unwanted animals or plants. The quarantine prevents the entry & spread of - Affected people can travel to unaffected individuals and diseases by spread the disease - Inspection - People living in rural areas come into contactless due to - Regulation less population compared to cities - Restrictions of movement Global: - And enforcement of destruction of diseased organisms - Aeroplanes take infected people to different countries Vaccination: causing a massive scale spread - Process of making people resistant to infection caused by specific - Some countries have limited knowledge on the pathogens prevention & spread of disease = quick spread of the - Very effective in preventing future infections disease especially in developing countries. - Immunity provided either active or passive, depending on source of immunity Active immunity: - Vaccines often contain live attenuated or inactivated version of a pathogen - Does not cause disease symptoms, stimulates the immune system to produce antibodies & memory cells offering long term protection (chickenpox) Passive immunity: - injection of antibodies into a person - Antibodies produced in & then isolated from another organism - Passes the immune system & provides immediate protection - No memory cells produced & protection is short term Most effective way to prevent disease spread Public health campaigns: - Effort to persudade community to engage in behaviors that will improve heath or have them refrain from behavours that are unhealthy HPV vaccination: - Common virus affecting both men & women, spreads through sexual contact - Extensive trails demonstated that vaccinating young women with HPV vaccine refuses risk of cervical cancer Use of pesticides: - Chemicals used to prevent spread of infectious animal & plant pathogens & insect vectors - Organophpsphates main class of pesticides used in AUS, work by disrupting the neurological system of insects Genetic engineering: - Modification of organisms genome, by insertion of a transgene - Desired outcome an altered phenotype, expression of a protein or hormone that advantages to the organism - Valuable to agriculature due to growing resistance of pathogen & insect vectors to current pesticides Bt cotton: Antiviral drugs - Cotton have a gene from a soil bacteria, bacillus thuringiensis (Bt) Positives: inserted into genome - Tartget specfic viral pathogens - Gene produces protein that kills insects, when they try and eat the - Improve health outcomes & life expectancy of infected plant the toxin they ingest will kill them person - Bt is effective in killing pests that damage the plant & transmit Negatives: disease - Challenging as host cells are used by virus to reproduce, Prevalence of disease - Immunisation drug targetrs a virus = harm to host cell Incidence: rate at which people develop the disease in the population (new - Drug-resistance cases) - The company that developed the drug increase the $ Prevalence: proportion of the population with a disease (infected) - Mobility of population important when assessing the risk of Effectivness of antibodies spreading the disease, includes all travel Positives: - Incidence & prevalence rates need to be considered when - 200 million lives saved determining the limitations needed to be imposed to reduce to - Different cell walls make bacteria easy target than viruses spread Negatives: - Vaccines = resistance or immune to specific pathogens - Only work on bacterial infections - When >95% is vaccinated the disease is less likely to spread (herd - misuse/oversues = restistance immunity) - Allegies to antibodies - Essential to protect thoses who cant get vaccinated - Side effects= vomiting & nausea) - Reduced mobility & high vaccination rates are successful for reducing transmission & death Control of epidemics and pandemics Epidemic: Outbreak of infectious disease in a defined area Pandemic: spread of new disease across a continent or worldwide - The primary principle of controlling the spread of diseases during these times is preventing infecting individuals from coming in contact with non-infected people Achieved by: Environmental management: - Provision of clean food & water - Sanitation & PPE - Vaccination clinics - Good air quality Quarantine: - Restricted population movement - Isolate infected/exposed person - Destruction of diseased organism (cows) Covid 19: - Lockdowns - Introduction of vaccines - Mask wearing & social distancing - Isolation of infectious, social distancing Prevalence of Disease - Malaria Strategies to prevent disease Malaria: - Proir to germ theory, work of pastier & koch predicted & controlled - Caused by microscopic parasites infecting liver & red disease was based on assocaitaions between environment blood cells conditions & disease outbreaks - Parasites include Plasmodium ovale, P. malariae, P. - Infected people were separted by non-infectious people, but did Knowles, P. vivax, and P. falciparum. not know the cause - Spread through mosquito bites; Australia's mainland is - after development of the germ theory specific pathogens & mode malaria-free but present in the Torres Strait Islands. of transmission liked to particular diseases = improvement in - Australians can contract it in tropical/subtropical areas of provenditing & controllingdeades spreads Asia, Africa, America, Pacific islands & Middle East Historicial: Symptoms: - Lack of knowledge = religion influcned cultural valued & beliefs - Sudden fever, chills, headache, sweating, nausea, (plague was good punishing) vomiting. - Limited success in predicting & controlling outbreaks - Joint and muscle pain; severe cases may include seizures, - John snow mapped cholera cases in london as he thought that the confusion, kidney failure, and coma. water was contaminated causing the outbreak - Symptoms appear 9-14 days post mosquito bite, - Indication that it could be controlled by providing clean water sometimes delayed. Cultural: Transmission: - Ideas, customs & behaviour of people like in west africa involve - Female Anopheles mosquito bite injects parasites into the direct contact with the dead bloodstream. - Main mode of spreading for diseases like ebola, the epidemic was - Rarely through blood transfusion, sharing needles, and brought under control through public education & safe burials mother-to-fetus transmission. Current strategies: Risk Factors: - Development of the germ theory allows for infections to be - Travelers to malaria-endemic regions, especially rural controled areas. - 1880’s we know that diseses were caused by specific pathogens = - High-risk groups: pregnant women (risk of severe malaria), control & prevantaive measure taken to avoid infection young children (