IGCSE Biology: Characteristics of life and organelles

• IGCSE Biology material designed to build confidence for achieving a grade 9.
• Revision guides are available online with questions and answers.
• Website to explore: www.kpbs.org/news/evening.

Characteristics of Living Organisms

• Living organisms exhibit: Movement, Respiration, Sensitivity, Nutrition, Excretion, Reproduction, and Growth, summarized as "MRS NERG".
• Viruses, lacking these characteristics, are considered nonliving.

Organelles Shared by Animal and Plant Cells

• Both animal and plant cells contain cell membranes, cytoplasm, nuclei, ribosomes, and mitochondria.
• Plant cells uniquely possess cell walls, vacuoles, and chloroplasts.

Organelle Functions

• Nucleus: Controls all cell activities.
• Cytoplasm: The location of chemical reactions.
• Cell membrane: Controls the movement of substances in and out.
• Ribosomes: The area where protein synthesis happens.

Plant Cell Specific Organelles

• Cell Wall: Made of cellulose, this offers protection and structural support.
• Vacuole: Filled with cell sap, which is used to maintain cell structure.
• Chloroplasts: The location of photosynthesis, they contain chlorophyll.

Eukaryotes vs. Prokaryotes

• Eukaryotes, such as animal cells, have membrane-bound organelles, including nuclei and mitochondria.
• Prokaryotes, like bacteria and viruses, lack membrane-bound organelles, such as bacteria using DNA or RNA strands.

Bacterial Cell Structure

• Bacteria have a cell wall, sometimes with a slime capsule.
• Some bacteria possess a flagella for movement.
• Nucleoid: Includes a circular chromosome with genetic material, but lacks a nucleus.
• Plasmids: Rings of genetic material used for genetic engineering.
• Both cytoplasm and cell membranes are present.

Bacteria - Pathogenic vs. Non-Pathogenic

• Pathogenic bacteria cause disease.
  • Examples: pneumococcus (pneumonia), tuberculosis (TB).
• Non-pathogenic bacteria are useful.
  • Examples: Lactobacillus bulgaricus (used in yogurt production).
• Bacteria are unicellular, consisting of single cells.

Viruses

• Viruses are smaller and simpler than bacteria, containing a protein coat enclosing DNA or RNA.
• They lack typical organelles.
• Viruses are nonliving and always pathogenic (disease-causing).
  • Examples: Flu virus, cold virus, HIV (causes AIDS), Tobacco mosaic virus (discoloration in plant leaves).

Protists

• Protists are diverse organisms that don't fit neatly into other kingdoms.
• Some protists exhibit animal-like properties, and some plant-like.
  • Algae and Chlorella: Contain chloroplasts, therefore plant-like.
  • Amoeba: Animal-like, lacks chloroplasts and cell walls, obtains nutrients via diffusion.
• Plasmodium: A pathogenic protist that causes malaria, which lives in female mosquitoes and is injected when bitten.
• Protists can be unicellular or multicellular.

Fungi

• Fungi have a cell structure similar to plant cells but are more circular and lack chloroplasts.
• Possess a cell wall made of chitin.
• They also have cell membranes, cytoplasm, and vacuoles.
  • Examples: Mucor, mushrooms, yeast.
• Featuring hyphae (thread-like structures) that form a mycelium network.
• Nutritional mode is saprotrophic nutrition: Extracellularly secrete enzymes onto dead matter to break it down and absorb it via extracellular digestion.

Useful Fungi

• Yeast: Used in beer and bread making.
• During anaerobic respiration, yeast breaks down glucose into ethanol (beer) and carbon dioxide (bread rising).

Five Kingdoms

• Plants, animals, protists, bacteria, and fungi.

Carbohydrate Storage

• Animals: Glycogen.
• Plants: Starch (e.g., potatoes).
• Fungi: Glycogen.

Organization Hierarchy

• Cell: A group of organelles performing a specific function.
• Tissue: A group of cells performing the same function.
• Organ: A group of tissues performing the same function.
• Organ System: A group of organs working together to perform the same function.
• Organism: A group of organ systems working together to perform the same function.

Organ Systems

• Digestive, endocrine, reproductive, circulatory, respiratory, nervous, and excretory systems.

Digestive System Example

• Includes organs such as the stomach, esophagus, pancreas, small intestine, and large intestine.
• The stomach consists of glandular tissue (secretes hydrochloric acid) and muscular tissue (helps channel food).

Zygote

• The cell formed when sperm and egg meet at fertilization.

Enzymes

• Biological catalysts that speed up chemical reactions without being used up.
• Active Site: A special region on the enzyme where substrate molecules bind.
• The active site is the biologically active part of the enzyme.
• Forms an enzyme-substrate complex, which then splits to form the desired product.

Digestive Enzymes

• Amylase:
  • Produced in saliva glands, small intestine, and pancreas.
  • Catalyzes the breakdown of starch into glucose.
  • (Substrate: starch, Product: glucose).
• Protease:
  • Found in stomach, small intestine, and pancreas.
  • Breaks down proteins into amino acids.
  • (Substrate: proteins, Product: amino acids).
• Lipase:
  • Breaks down lipids into fatty acids and glycerol.
  • (Substrate: lipids, Product: fatty acids and glycerol).

Effect of Temperature on Enzyme Activity

• Low Temperatures: Low enzyme activity due to low kinetic energy and infrequent collisions between enzymes and substrates.
• Increased Temperature: Enzyme activity increases with temperature because molecules collide more often.
• Optimum Temperature: The temperature at which enzyme activity is at its peak.
• Above Optimum Temperature: Enzyme denatures, its active site changes shape, and substrate can no longer fit.

Effect of pH on Enzyme Activity

• Enzymes have different optimum pH values; activity decreases if pH is too high or too low.
• Changes in pH outside of the optimum range cause the enzyme to denature.
  • Stomach proteases operate best under acidic conditions (pH ~3), while enzymes in the rest of the digestive system have alkaline optimum pH (around 8).

Transport Types

• Diffusion:
  • Net movement of particles from an area of high concentration to an area of low concentration.
  • Passive process, requires no energy.
  • Key example of diffusion is how perfume particles move across a room after being sprayed.
• Osmosis:
  • Net movement of water from an area of high water potential to an area of low water potential across a partially permeable membrane.
  • Passive process.
• Active Transport:
  • Net movement from an area of low concentration to an area of high concentration (against the concentration gradient).
  • Active process, requires energy.

Amoeba and Diffusion

• Amoeba: Single-celled organism using diffusion to obtain nutrients.
• Oxygen diffuses into the amoeba from an area of high concentration to low concentration because of the ratio of the amoeba making diffusion quicker. Single celled gives amoeba a large surface area.
• Larger multicellular organisms: Have smaller surface area to volume ratio. Which makes diffusion too slow; necessitating circulatory systems.

Photosynthesis

• photosynthesis happens in the chloroplasts of plant cells. Chloroplasts contain chlorophyl
• Uses sunlight to create food.
• Word equation: carbon dioxide + water forms glucose and oxygen.
• Balanced symbol equation: 6CO2 + 6H2O forms C6H12O6 + 6O2.

Limiting Factors

• Limiting Factor: The factor in shortest supply that limits the rate of a reaction.
• Three limiting factors for photosynthesis: carbon dioxide, light intensity, and temperature.

Limiting Factors Scenarios

• Early Morning: Temperature and light intensity are more likely limiting factors.
  • Low temperatures = low kinetic energy, enzymes and substrates can't come together.
• Midday: Carbon dioxide levels.

Leaf Adaptations and Structure

• Large Surface Area: Absorbs more light efficiently.
• Thin Structure: Gases diffuse easier.
• Waxy Cuticle: Prevents transpiration (water loss).
• Upper Epidermis: Transparent, allows light to enter the leaf.
• Palisade Mesophyll: Crammed with chloroplasts for photosynthesis.
• Spongy Mesophyll: Contains air spaces for gas diffusion (carbon dioxide and oxygen).
• Vein (Vascular Bundle): Contains xylem (brings water) and phloem (transports sugar).
• Lower Epidermis: Contains guard cells and stomata.
• Guard Cells and Stomata: Control gas exchange in the leaves.

Stomata Control

• Stomata regulate gas exchange in leaves, enabling carbon dioxide intake and oxygen/water release.

Photosynthesis and Glucose

• Photosynthesis produces glucose, a sugar containing carbon, hydrogen, and oxygen.
• Glucose is a raw material that can be converted into other biological molecules, including lipids (fats) and proteins.
• Glucose is converted into storage compounds like starch, serving as an energy reserve.
• Glucose is used to synthesize cellulose, a major component of plant cell walls providing structural support.

Mineral Ion Uptake

• Plant roots actively transport mineral ions such as magnesium and nitrates from the soil.
• Nitrates are used for protein synthesis within the plant.
• Magnesium is required for chlorophyll production, which is essential for photosynthesis.

Mineral Deficiencies

• Magnesium deficiency leads to yellowing leaves due to insufficient chlorophyll.
• Nitrate deficiency results in stunted growth due of a lack of protein and/or amino acids.

Digestion Definition

• Digestion is the process of breaking down large, insoluble food molecules into smaller, soluble ones that can be absorbed.

Digestion Types

• Chemical digestion involves enzymes altering the structure of food molecules.
• Mechanical digestion physically breaks food into smaller pieces without altering their chemical structure.

Mechanical Digestion Sites

• Mechanical digestion occurs in the mouth through chewing and in the stomach through muscular churning.

Mouth Digestion

• The teeth perform physical digestion.
• Amylase in saliva initiates chemical digestion, breaking down starch into glucose.

Esophagus and Peristalsis

• Food travels down the esophagus (food pipe) via peristalsis.
• Peristalsis are muscular contractions that propel the bolus of food toward the stomach.

Stomach Digestion

• Muscular contractions churn the food.
• Hydrochloric acid breaks down food and destroys pathogens.
• Protease enzymes are secreted to break down proteins into amino acids.

Small Intestine Digestion

• Peristaltic contractions continue to move food.
• Lipase, protease, and amylase enzymes are added, with higher optimum pH levels than stomach protease.

Bile Production and Storage

• Bile, a green substance, is produced in the liver and stored in the gallbladder.
• Bile is released into the small intestine.

Bile Functions

• Bile emulsifies fats, breaking large fat droplets into smaller ones, increasing the surface area for lipase to work.
• Bile neutralizes stomach acid, raising the pH to an alkaline level (around 7 or 8) to prevent enzyme denaturation.

Small Intestine Absorption

• Digested food molecules are small and soluble, which allows them to be absorbed through the small intestine walls into the bloodstream.

Small Intestine Adaptations

• Villi, finger-like structures, maximize the surface area for absorption and increase the area with microvilli.
• Villi also shorten the diffusion distance, have a plentiful supply of blood capillaries, and contain lacteals (for fat absorption).

Large Intestine

• Undigested food passes into the large intestine, where water is reabsorbed into the blood.

Rectum and Egestion

• Feces are stored in the rectum before being eliminated through the anus via egestion.

Egestion vs Excretion

• Egestion is the removal of undigested waste (feces).
• Excretion is the removal of metabolic waste products.

Ingestion Definition

• Ingestion is the process of taking food into the body.

Metabolism Definition

• Metabolism is the rate of chemical reactions in the body.

Assimilation Definition

• Assimilation is the process of building large molecules from small molecules.

Essential Nutrients

• A balanced diet requires carbohydrates, fats, proteins, minerals, vitamins, water, and fiber.

Carbohydrates

• Carbohydrates are found in foods like bread, rice, and pasta, and are a primary source of energy.

Proteins

• Proteins are found in meat like chicken and beef, and are essential for muscle growth and repair.

Kwashiorkor

• Kwashiorkor is a disease caused by protein deficiency, characterized by a distended abdomen.

Fats

• Fats are found in dairy foods like butter and cream, and are a concentrated source of energy and insulation.

Vitamin C

• Vitamin C is found in citrus fruits and helps repair tissues; deficiency leads to scurvy.

Scurvy

• Scurvy, caused by vitamin C deficiency, can cause bleeding gums.

Vitamin D

• Vitamin D promotes strong bones and is produced through sun exposure on the skin or found in fish liver oils.

Rickets

• Rickets, is when a child lacks vitamin D, which weakens their bones

Vitamin A

• Vitamin A ensures good vision in daylight/ at night with lower light settings. Its deficiency leads to night blindness.

Iron

• Iron is found in red meat and spinach, important for healthy blood, and contributes to hemoglobin.

Anemia

• Anemia occurs with iron deficiency, causing fatigue.

Calcium

• Calcium is a mineral that is important for teeth and bones and found in dairy products. A lack of calcium can lead to rickets.

Fiber

• Fiber is essential for digestive health and aids in the movement of food through the digestive system, preventing constipation.

Water

• Water is necessary for supporting chemical reactions in the body.

Nutrient Requirements

• Nutrient needs vary based on age, pregnancy status, exercise levels, etc...

Respiration Overview

• Respiration is a process that occurs in mitochondria and releases energy.
• ATP is produced in respiration and serves as an energy currency for the cell.

ATP Usage

• ATP is used for cell division, building molecules, active transport, and muscle contraction.

Aerobic Respiration Equation

• Oxygen + Glucose → Carbon Dioxide + Water + Energy

Balanced Aerobic Respiration Equation

• C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy

Anaerobic Respiration

• Anaerobic respiration occurs when oxygen supply is limited, leading to the incomplete breakdown of glucose and the production of lactate.

Oxygen Debt

• Oxygen debt is the extra oxygen needed to break down lactate after anaerobic respiration.

Anaerobic Respiration in Yeast

• Yeast anaerobically respires, breaking down glucose into ethanol and carbon dioxide, processes used in bread and beer making.

Breathing System Overview

• Air enters through the mouth, goes to the trachea (windpipe), branches into bronchi, then bronchioles, ending in alveoli.

Alveoli

• Alveoli are surrounded by blood capillaries.

Airway Cleaning

• Goblet cells secrete mucus, and the cilia waft that mucus up to the mouth where it is swallowed and destroyed with stomach acid
• Ciliated cells, with hair-like projections, and goblet cells are both there, to keep the airways healthy.

Ventilation

• Ventilation is the movement of air into and out of the lungs.

Inhalation Steps

• External intercostal muscles contract.
• the ribs move up and out.
• the diaphragm contracts (flattens).
• These processes increase thoracic volume and decrease pressure, drawing air into the lungs

Exhalation Steps

• Internal intercostal muscles contract.
• The ribs move down and in.
• The diaphragm relaxes.
• These events reduce the thoracic volume, increase pressure, and force air out of the lungs

Lung Gas Composition

• Inhaled air has more oxygen than exhaled air because oxygen is absorbed by the blood.
• Exhaled air contains more carbon dioxide because it is a product of respiration.

Alveoli Adaptations

• Large surface area
• thin walls
• moist surfaces

Xylem

• Xylem transports water and mineral ions from roots to leaves, always moving upwards
• Xylem is found in the middle of the root-cross section and is made of dead cells for strength.

Phloem

• Phloem transports glucose from leaves to other plant parts, with a direction that is up and down. Phloem is located in the outer layer of tissue in the stem.
• It transfers food (sugar).

Xylem Structure

• Made of dead cells, lignin reinforce walls

Pholem Structure

• Consists of a sieve plate tube and companion cells that release energy.

Blood Components

• Blood consists of red blood cells, white blood cells, plasma, and platelets.

Plasma

• Plasma is the liquid component of blood, which carries glucose, amino acids, hormones, urea, and carbon dioxide.

Red Blood Cells

• Red blood cells are biconcave and lack a nucleus to maximize space for oxygen transport using hemoglobin, which needs iron for production.

White Blood Cells

• Phagocytes engulf pathogens by enclosing them in vacuoles.
• Lymphocytes use antibodies to target antigens on pathogens.

Antibody Functions

• labeling the pathogen
• neutralizing toxins
• cell bursting

Circulatory System Purpose

• Humans need a circulatory system due to a low surface area from their volume.
• It helps transport oxygen around bodies.

Heart

• Four chambers: left atrium, right atrium, left ventricle, and right ventricle.
• Pulmonary refers to the lungs

Blood Flow

• Oxygenated blood from the lungs enters the left atrium via the pulmonary vein, flows to left ventricle, and then to the aorta, which delivers oxygenated blood around the body.
• Deoxygenated blood returns to the right atrium via the vena cava, flowing through the tricuspid valve into the right ventricle, and out via the pulmonary artery to the lungs.

Ventricle Walls

• Ventricle walls are thicker than atrial walls.
• The wall of left ventricle is also thicker than that of the right.
• They both need to pump harder since the more that they have to pump, the stronger (thicker) they will be.

Coronary

• Blood passes twice into the heart for every once it travels around the body

Artery vs Parma Enemy Meaning

• Arteries carry blood AWAY from the heart.
• "Parma enemy" means relating to the heart.

Hepatic vs Renal Meaning

• Hepatic means relating to the liver.
• Renal means relating to the kidney.

Coronary Heart Disease Risks

• Lifestyle choices increase your chance of getting coronary heart disease.
• There could also be a genetic factor to your risks.

Coronary Arteries

• The heart can not obtain its oxygen/ nutrients from the blood that passes through it; it has its own arteries specifically made to deliver to the heart tissue.

Strenous Heart

• Fatty deposits in the walls of the coronary arteries obstructing blood flow, causing analytic respiration, heart failures, etc.

Medulla Oblongata

• Is triggered during exercise in order to increase the oxygen that is delivered to the muscles and is detected by the Aorta.

Arteries vs Veins

• Arteries carry blood at a high pressure with thick muscle and elastic fiber walls.
• Veins have a wide lumen with thin walls and also contain valves.

Capillaries

• One cell thick capillaries have a narrow lumen that enables a short diffusion distance.

Excretion

• Is the removal of waste products.
• Feces are not excreted.

What Is Homeostasis

• Maintaining a steady internal environment.

Light and Gravity Plant Responds

• Plants respond to light; phototropism, and gravity, geotropism.
• Roots show a positive geotropic response: they grow down in the direction of gravity.
• Stems show negative geotrophic responses: They grow away from gravity.

Auxins

• Plant stems bend towards the sun since auxins concentrate on the side that's Furthest From the Light, causing cell elongation and bending, thus the plant turns toward sunlight.

Nervoua System Communication vs Hormonal Control

• The Nervous System is faster than the hormonal system.
• The Hormonal system has a wider reach since it can affect more than just one place.

Receptors

• The eye receives light and energy.
• Ears receive sound and energy.
• Skin receives both energy and touch.
• Tongue and nose receive chemical energy.

Spinal cord

• The human brain and the spinal cord comprise the central nervous system.

Reflex Action

• An example includes putting your hand on a hot oven shelf: The high temperature is the stimulus, the sensory neurons will bring it to the brain, the impulse comes back, and that is the effect.

Focus From Skin

• Skin helps prevent entry.
• Skin is good for touch and pain.
• Skin helps maintain warmth by using erector pili muscles.

When Your To Hot

• Perspiration (sweating) occurs.
• Hearts will dilate to radiate more heat.
• Hairs will be down since we're not trying to trap the head.

When You're Too Cold

• Hairs will be up, acting like insulators.
• The body will shiver, releasing energy.
• Hearts will bring blood more away from the skin.

Adrenaline

• A fight-or-flight hormone that takes over the body.
• It helps the body prepare for any situations.
• It can provide energy, strength, and heightened senses.
• An example is a cat with dilated pupils.

Sexual vs Asexual

• Sexual reproduction needs 2 parents, and forms a zygote with different genetics, so there is variety in the offspring, which is good for changing conditions.
• Asexual reproduction needs just one parent and produces clones, with no change in genetics: great for quick, large production, which is good for non-changing conditions.

Ferilization

• Sperm meets egg, forming a zygote, which goes through mitotic cell division.

Astrawbarry and potato

• Produce mini plants, which are clones of the original.

Male VS Female Plant parts

• Male: Anther (contains the pollen), filament.
• Female: Style, stigma, and ovary.

Pollanation/ Sede and Fruite formation

• The stigma from the male anther lands on the female.
• A pollen tube grows down, and digestive enzymes break down the ovary wall.
• Pollen meets ovule.
• The ovule becomes the seed.
• The ovule wall becomes the seed coat.
• The ovary wall becomes the fruit.

Self Polanataion vs Transfer

• Pollen is transferred to another plant/stigma.
• if it transfers itself, it is called self-pollination.

Insect vs Wind plant

• Insects are brightly colored for an insect to find.
• Wind disperses pollen (wind doesn't help).

Cermination

• The seed coat bursts, the radicle starts to grow down, and the seed store is used.
• Conditions needed: Warmth, oxygen, and water.

Female repro System

• Includes the vagina, cervix, uterus, fallopian tube, ovaries.

Roles

• Uterus: Where the fertilized egg develops.
• Uterus lining: Supports the fetus with the placenta, (the cervix is just the entrance).
• Ovaries: Make the eggs.

The Male system

• Testicles make sperm.
• Urethra: Connects with the bladder and transfers urine only.
• Sperm duct.

Role of Plessenta

• Provides support with oxygen and nutrients
• Rids the fetus of waist

Estrogen and testo

• Tell the body what to do during puberty.

Protien Synthesis

• The nucleus contains the chromosomes.
• Genes make the proteins.
• Genotype: The genetic makeup of a cell. Example: Bb.
• Phenotype: The expression of letters; for example, black hair and brown are the options.

Homo zigus vs Hetero zigus

• Homozygous: Has 2 of the "same," and the letters will look the same (EX bb).
• Heterozygous: The letters will be different (EX Bb).
• Dominant traits will always be present: ex: BB or Bb, and will have all most the same effect.

Homo receesive

• bb
• No Daminte for it to take over

Punnety squars

• Mother on the top, and the father to the side of the table.

pedigry analysis

• Squares are men.
• Circles are women.
• Shading mean bad guy.

mitois vs miosis

• Mitosis = cloning, identical with offspring (good for unchanged situation).
• Meiosis divides unidentically for a changing environment (better so you can adept).
• Meiosis has 2 cell divisions rather than 1.
• Meosis = 4 daughter cells
• Mitois = 2

How is variation in Species

• Genetics
• Environmental

what is a mutation

• Random change of genetic
• Can be inherited
• Can cause new characteristics

Evolution

• Many organisms that are alive today are derived from the small, simple life.

CH D theory

• Mutation with species and some species adapted so it's better for them.

Antibiotic resistance

• Strong bacteria that has become resistant to antibiotics.

ecoligly

• Environment-(Not living)
• Abiotic Factors is living, while the biotic is not living.
• The community is for all the organs.

Quadrat

• Metal frame
• Quadrat: To get a great feel of the place.

primad numbers and biomass

• The pyramid number shows the number of all organisms at each level and its stage.
• It is hard to show, so it's better to use the biomass pyramids because it shows the mess of all levels.

loss of heat at each chain of life

• Animals move to keep warm, respire, and they poo.

The graph has information to the chart

• Know what level of consumer is in the chart.
• Know what a primary producer is.

Carbon cycle

• CO2 is absorbed by green plants (Photosynthesis) and makes glucose.
• Plants respire, and animals eat those green plants.
• Plants respire, die, and release carbon.

Harm for humans

• Fertilizers and sewage causes lakes and streams to drain the nutrients, which causes plants growing super quick.
• Blocking oxygen to get to the aquatic life form.

water vayor/methine

• Burning of fossal fuels

CFC/Ozone lair

• Damage from aerosol
• Protects us from sunlight harm

Acid

• Rain is nitric acid/sulfuric acid from the air.
• Sulfate impurities are released.

Green houses

• Are for artificial control of temperature.
• They trapped some of the heat energy by an enhanced greenhouse effect.
• Light is a limiting factor.
• Electric lighting.

Perticite

• Is a chemical to kill pest

Biological constorl

• Involves animals that kill the pest.
  • EXAMPLE: Lady bugs KILL AFFERTS.
• Non-toxicity
• Is never fully eradicated
• Slow

Yogurt Production

• Lactobacillus bulgaricus bacteria is used in yogurt production.
• This bacterium carries out anaerobic respiration.
• During anaerobic respiration, lactose (sugar) is broken down into lactic acid.
• Lactic acid gives yogurt its distinctive flavor.
• Yogurt production can be done inside a fermenter.

Fermenters: Structure and Optimization

• A fermenter is a vessel containing microorganisms involved in fermentation reactions.
• Cooling Jacket: Controls temperature by removing excess heat produced by microorganisms during respiration.
• Temperature and pH Monitors: Allows close monitoring, ensuring conditions do not become too extreme.
• Stirring Paddles: Mix the contents to ensure even distribution of nutrients and heat.
• Air Inlet: Allows oxygen into the fermenter for aerobic microorganisms.
• Nutrient Supply: Provides the microorganisms with necessary substances for respiration and growth.

Selective Breeding

• Selective breeding involves humans breeding animals or plants with desired characteristics.
• This process is repeated over many generations.
• In the dairy industry, humans select dairy cows that produce a high yield of milk.
• Selected cows are bred with a bull.
• Female calves likely to produce more milk are selected and the process is repeated.
• Plants can be selectively bred for particular colors via cross pollination.

Genetic Engineering: Insulin Production

• Genetic engineering can be used to create human insulin.
• Type 1 diabetics don't produce insulin and struggle to maintain blood sugar levels.
• Previously pig insulin was used, but this had ethical issues and wasn't ideal.
• Bacterial cells containing plasmids are used in genetic engineering.
• Plasmids are small rings of genetic information within bacterial cells.
• Plasmids are manipulated so that the insulin gene can be inserted.
• Process:
  • The plasmid is cut open using a restriction enzyme to be used as biological scissors.
  • The restriction enzyme cuts the insulin gene away from the rest of the cell.
  • The insulin gene is inserted into the bacterial plasmid using a ligase enzyme.
• The bacterial cell is put into a fermenter with optimum conditions (temperature, pH, oxygen, nutrients).
• The bacteria produces huge amounts of insulin.
• A plasmid with a different gene inserted is called a recombinant plasmid.
• The bacterial cell acts as a vector, transporting biological material from one place to another.

Genetic Modification of Plants

• Plants can be genetically modified to have desired characteristics.
  • Frost resistance
  • Extended shelf life
  • Resistance to weed killers (herbicides).
• Weed killer is called herbicide.
• Herbicide kills weeds, but some often falls on the crops that farmers are trying to grow.
• If they modify it to be herbicide resistant, only the weeds are killed, and the crops survive.

Golden Rice and Other Examples

• Rice has little nutritional value.
• Rice can be genetically modified with vitamin A to stop night blindness.
• Tobacco plants can be modified to produce hepatitis antigens for a potential vaccine.
• Plants can have increased salt tolerance via genetic modification.

Transgenic Organisms

• A transgenic organism has genes transferred from one species to another.
• Goats have had a gene from spiders inserted to produce spider webs in their milk.
• Spider webs are strong, even compared to steel.
• If spider webs are as large as a steel frame, it's much stronger.
• Scientists are interested in artificially manufacturing spider webs.