Understanding Antibiotics and Resistance

Antibiotics

• Antibiotics like penicillin are drugs to treat bacterial infections by destroying the cell wall of the bacteria to prevent replication.
• Antibiotics are ineffective against viruses, which reside inside host cells and are not living cells.
• Specific antibiotics are prescribed by medical doctors for specific diseases.
• The number of deaths from infectious bacterial diseases has reduced with use of antibiotics.

Antibiotic Resistance

• Some bacteria strains are resistant to specific antibiotics, rendering them ineffective.
• To prevent the development of resistant bacteria, antibiotics should only be prescribed when necessary (not for minor or viral infections), and patients should complete their full course of antibiotics.
• Bacteria can become resistant due to random DNA mutations.
• Mutated bacteria survive and reproduce while non-resistant bacteria die.
• Resistant bacteria rapidly reproduce, creating genetically-identical resistant copies due to the destruction of competition, with each copy resistant to antibiotics.

Drug Discovery

• Historically, drugs were extracted from plants and microorganisms.
• Today, pharmaceutical industries synthesize most drugs.
• However, the ingredients may be extracted from plants.
• Digitalis, a heart drug, comes from foxgloves and William Withering first used it 200 years ago.
• Aspirin, a painkiller, comes from willow trees and Alexander Fleming discovered Penicillin, which is made from the Penicillium mold.

Developing Drugs

• New antibiotics are trialled for resistant bacterial strains.
• Antiviral drugs treat viral infections by targeting viruses inside cells without harming body cells and tissues.
• Painkillers, like Aspirin, relieve pain from infections but do not cure diseases or kill pathogens.

Drug Testing in Laboratories

• Preclinical testing involves early-stage testing on human cells/tissues in the lab and on live animals to determine toxicity.
• In the UK, new medicines must undergo tests on two different live mammals, and many drugs fail if they damage cells or don't work.
• Clinical testing involves clinical trials on healthy volunteers and patients using low doses to ensure safety, and more clinical trials to discover optimum dosage.

Double-Blind Trials

• During clinical trials, some patients receive a placebo randomly, and neither the patient nor the doctor knows who received it.
• Double-blind trials ensure unbiased results, and the outcomes of the trial could be skewed if either party knew who had received what.
• Identical conditions ensure the drug’s impact on health by eliminating other contributing factors.

Monoclonal Antibodies

• They are produced from clones (genetically identical copies) of cells (white blood cells) and are identical and complementary to one type of antigen (proteins on pathogen surfaces).
• Monoclonal antibodies target chemicals or cells in the body by targeting one binding site on an antigen.

Producing Monoclonal Antibodies

• Injection of antigen into a mouse causes the mouse immune system to produce lymphocytes to produce antibodies against the antigen.
• Extracted lymphocytes are fused with myeloma (tumor) cells to produce hybridoma cells.
• The tumor cells grow rapidly, creating lots of identical cells.
• All the hybridoma cells produce the same antibody.
• Monoclonal antibodies collected and purified to target specific cells and chemicals.

Use of Monoclonal Antibodies

• Monoclonal antibodies can cause side effects (fevers, low blood pressure, vomiting), leading to less common use.
• In pregnancy tests, monoclonal antibodies bind to HCG hormone antigens: if the urine contains HCG, the antibodies show a positive result; if the urine does not contain HCG, a negative result.
• They can identify specific chemicals in blood by being designed to find specific antigens, identify molecules in tissues/cells using fluorescent dyes, monitor hormone levels, and test for pathogens (HIV).
• For treating diseases, specific monoclonal antibodies attach to target cells (cancer cells) and deliver anti-cancer drugs directly to tumors without harming normal body cells because normal cells will ont have complementary antigens.

Plant Diseases

• Pests (greenflies, black flies or aphids) feed on pholem sap and divert sugars away from the plant.
• Fungal diseases (rose black spot, or barley powdery mildew) cause spores to spread in the wind and cause white spots.
• TMU (Tobacco Mosaic Virus) is a common plant pathogen.

Ion Deficiencies in Plants

• Plants need many mineral ions for growth.
• Poor soul quality leads to ion deficiencies/disorders: Plant leaves turn yellow because magnesium deficiency causes chlorosis by preventing proper photosynthesis.
• Nitrate deficiency causes stunted growth since nitrates are needed for creating proteins.

Plant Defenses

• Physical defenses include bark (dead cells that forms barrier against pathogens/pests), waxy cuticles (barrier on leaf/stem to stop pathogens invading leaf tissue), and cell walls (physical barrier against pathogens).
• Chemical defenses includes antibacterial chemicals like mint, garlic and witch hazel (prevent bacteria growth) and poisons like foxglove and deadly nightshade that deter herbivores.
• Mechanical defenses include thorns or hairs to discourage animals and leaves that close rapidly when touched decrease surface area and dislodge smaller herbivores.
• Plants use mimicry, with leaves that resemble the presence of insect eggs, which deters insects from laying eggs to avoid competition.

Signs of Plant Diseases

• Stunted growth, spots on leaves, areas of decay, growths, malformed stems/leaves, discoloration, presence of pests.

Identifying Plant Disease

• Gardening manual and Testing kits that use antibodies can be refered to identify plant disease.
• A laboratory test can also identify the pathogen.

Photosynthesis

• Photosynthesis is an endothermic reaction that requires energy and takes place inside chloroplasts found in plants and algae.
• The energy comes from sunlight, which is trapped by chlorophyll inside chloroplasts.
• Photosynthesis Equation: 6CO2 + 6H2O --> C6H12O6 + 6O2

Rate of Photosynthesis

• Key factors affecting the rate of photosynthesis include: Temperature, light intensity, carbon dioxide concentration, and chlorophyll concentration.
• Increasing temperature increases the rate of photosynthesis due to increased energy, but temperatures above 45° cause enzymes to denature and stop working, causing the reaction to drop sharply and stop.
• Greater light intensity increases the rate of photosynthesis, but above a certain threshold, the rate will not increase because another factor (temperature) limits the reaction.
• Increasing the carbon dioxide concentration increases the rate of photosynthesis because carbon dioxide is a reactant, but above a certain threshold, the rate will not increase because another factor like light intensity will limit the reaction.
• High chlorophyll concentration increases the rate of photosynthesis.
• A limiting factor restricts the rate of a reaction.

Limiting Factors

• In winter, temperature is typically a limiting factor.
• At night, light intensity is a limiting factor.
• In warm and bright conditions, carbon dioxide concentration is the limiting factor.
• Mineral deficiency leads to less chlorophyll, in which case chlorophyll concentration can be the limiting factor.

Photosynthesis in Farming

• Understanding limiting factors is critical for plant production in greenhouses.
• Farmers must balance lighting, heating costs, and the rate of photosynthesis to increase yield by lighting and heating greenhouses, which increases rate of photosynthesis.
• However, high lighting and heating costs must be considered.

Use of Glucose

• Glucose produced by photosynthesis is used for respiration, or it can be converted into starch (insoluble and stored in stems, leaves, or roots) and cellulose (to strengthen cell walls).
• Photosynthesis can also produce fats and oils (stored in seeds), and proteins (needed for cell growth and repair), which require nitrogen absorbed from nitrate ions in the soil.

Organisms and Energy

• Organisms need energy for growth, to make macromolecules from smaller molecules, and to contract the muscles of animals for movement.
• Homeostasis is needed to keep internal temperatures constant, and to provide energy by respiration.
• Respiration an exothermic process that occurs continuously and supplies all the energy needed by organisms.
• Respiration is either aerobic (with oxygen) or anaerobic (without oxygen).
• In aerobic respiration, glucose reacts with oxygen in the mitochondria of cells to give carbon dioxide, water, and energy (C6H12O6 + 6O2 → 6CO2 + 6H2O (+ energy).
• In animals, anaerobic respiration breaks down glucose less efficiently, converting it to lactic acid (Glucose → lactic acid) during insufficient oxygen like intense activity.
• In plant and yeast cells, anaerobic respiration converts glucose into ethanol and carbon dioxide (Glucose → ethanol + carbon dioxide) called fermentation, which is a critical stage for brewing alcohol and making bread via yeast cells.

Metabolism

• Metabolism includes all the chemical reactions that happen in an organism, creating new molecules with enzymes.
• Metabolic reactions include processes like converting glucose into starch (plants), glycogen (animals), and cellulose (plants), combining glycerol and fatty acid chains to make lipid molecules, and making amino acids by using glucose and nitrate ions.
• Metabolic reactions also break down excess proteins to form urea, which is excreted.
• Exercise increases energy demands, and respiration must increase to meet these new demands.
• Responses to increase the rate of respiration are increase in heart rate to deliver more blood (containing glucose and oxygen) to the muscles, an increase in breathing rate to increase gas exchange (more oxygen and carbon dioxide), an increase in breath volume which increases the rate of gas exchange, and dilated blood vessels to ensure more blood reaches the muscles.

Oxygen Debt

• If muscles do not get enough oxygen, they will respire anaerobically, resulting in oxygen debt.
• Lactic acid is a by-product of anaerobic respiration, which is toxic and causes muscular pain and fatigue when accumulating.
• Lactic acid also prevents muscles from contracting efficiently.
• Oxygen debt involves the extra oxygen that is needed to oxidize and remove lactic acid.
• Blood transports lactic acid to the liver, reacting with oxygen to produce carbon dioxide and water.
• Heavy breathing after exercise repays oxygen debt by increasing oxygen in the lungs.

Cell Biology

• Living organisms are made of cells that provide structure and carry out functions.
• Two main cell types: Eukaryotic and Prokaryotic.
• Eukaryotic cells contain a nucleus and are found in plants, animals, fungi, and protists, and measure 10-100 micrometers .
• Prokaryotic cells do not contain a nucleus, measure 0.1-5.0 micrometers in size, and include bacteria.

Prokaryotic Cells

• Small DNA rings called plasmids: can replicate and move between cells so that genetic information can be shared.
• They do not contain mitochondria or chloroplasts.
• Instead, their genetic material is stored in a single DNA loop in cytoplasm.

Animal Cells

• The cell membrane separates the interior of the cell from the external environment and is selectively permeable to control which substances enter and will leave.
• The nucleus contains chromosomes with the cell's genetic material.
• Ribosomes synthesize (make) proteins.
• Mitochondria is where aerobic respiration takes place.
• Cytoplasm is a jelly-like fluid that fills the cell and where chemical reactions take place.
• Skin, muscle, blood, nerve, and fat cells are common animal cells.

Plant Cells

• They contain a permanent vacuole (fluid-filled sac for water storage enclosed in a membrane) can make up as much as 90% of a plant cell's volume.
• Chloroplasts contain chlorophyll needed for photosynthesis.
• The cell wall (made of cellulose), which is surrounding the cell, increases structural strength.

Differentiation in Plants and Animals

• Cell differentiation occurs when cells acquire different sub-cellular structures.
• Cell differentiation happens at various stages of development in animals and plants.
• Many plant cells can differentiate throughout their lives allowing plants to create new tissues.
• Most animal cells differentiate early in their development.
• In mature animals, cells mostly divide to replace and repair tissues.
• New tissues are rarely created.

Bacterial Cells

• Cell wall and cell membrane providing cells within the structure.
• Cytoplasm (jelly-like fluid for chemical reactions).
• Flagella (whip-like structures used for movement).
• Plasmids (small rings of DNA).

Cell Differentiation

• Cell differentiation is the process where a cell develops new sub-cellular structures to perform a specific function.
• Cell differentiation occurs during an organism’s development in the embryo (where cells divide to form specialized cells) and continues in plants throughout their life.
• Cell differentiation is rare in mature (adult) animals, and cells mostly divide for replacement and repair.

Sperm Cells

• The sperm cells specializes to fertilize eggs, through traveling long distances, and contain a Head (with the nucleus and half the genetic information), an Acrosome (contains digestive enzymes to penetrate the egg), a Middle section (filled with mitochondria to provide the sperm with extra energy for traveling long distance), and a Flagellum (tail) used to travel to the egg.

Nerve Cells

• They transmit electrical messages, called axon (part of the cell that electrical signals travel along), they are long which increases the distance electrical signals can travel, they have a myelin sheath (surrounds the axon to prevent electrical nerve signals from leaking out), and dendrites (branches of a nerve cell that transfer electrical messages to other neurons).

Muscle Cells

• They are specialized (perform a specific function), produce force and motion, and contain mitochondria to generate lots of energy for motion and have Protein fibres (that contract to allow the muscle to move).

Cell Specialisation- Root Hair Cells

• They absorb water/minerals with a structure that includes no chloroplasts because they are located underground .
• They use long projections (to increase surface area for water and mineral absorption).

Cell Specialisation- Xylem

• Specialized to transport water up the stem into leaves include opened-ended cells, xylem vessels ( series of connected dead xylem cells for water to move through), and lignin (strengthens xylem cell walls).

Cell Specialisation- Phloem

• Specialized to transport food products to needed areas, and made up of columns of living cells, Small holes (allow food products to move up and down the phloem vessels.

Magnification vs. Resolution

• Magnification tells us how many times larger an image seen through a microscope is compared to the real object.
• Resolution is the ability to distinguish (tell apart) two or more objects that are close together.
• Magnification= image size/actual size

Developments in Microscopy

• Light microscopes have lenses pass light through a specimen and increases the resolution compared to the human eye, allowing scientists to see bacteria, plant cells and animal cells but did not have enough resolution to tell cells structures from other cells.
• Electron Microscopes using electrons instead of light, have a better resolution ×500,000, this improved the high level of detail and allowing scientists to study how structures function.

Growing Microorganisms

• Microorganisms are grown in a lab can test the effects of antibiotics/disinfectants using Agar gel plate (colonies) and Nutrient broth (containing carbohydrates, minerals, chemicals).

Contamination

• Growing cultures of bacteria provides conditions for bacteria that are not being investigated.
• Contamination leads to a waste of results and opens the doors for health risk.
• Potential sources are skin, air, soil, and water.

Avoiding Contamination

• Use of aseptic (free from contamination by removing unwanted bacteria) techniques, such as flames (pass inoculation loops and using heat).

Cell Division

• Use boiling for Agar and keeping the Lids on Petri test tube.
• Store cultures at a temperature no higher than 25 degrees Celsius to minimize the risk of harmful growth.

Chromosomes

• Chromosomes, found in the cell nucleus, are made of DNA molecules and carry genes.

The Cell Cycle

• The cell cycle include initial growth stage of extra ribosomes and mitochondira, then the cell's chromosomes copy DNA from replication.

Mitosis

• Pulling chromosome and causing the Nucleus divids.

Cell Division

• The cell divides the Cytoplasm by pulling the membrane result in the Production of two sets of daughter chromosomes.

Mitosis

• It is part of the cell cycle that ensuring both daughter cells have the same chromosomes as each other and the parent cell, this is a crucial for processes that are for to tissue growth, repair, and asexual reproduction.

Stem Cells

• They can be found in Embryos (where stem cells are that are not specified) or bone marrow (but not as specified).
• There is potential for a Use of stem cells of treatments related to transplant.

Medical Science

• Plant clones help protect rare plant species and increase disease resistance.
• Thearputial Clonong allows patients with damaged body cells to produce cells that will not be rejected.

Disadvantages of stem cells

• Viral infections
• Ethical beliefs

Diffusion

• The net movement of particles from an area of higher concentration to an area of lower concentration.
• Some example of this is the gas being exchanged in the lungs.
• Can be depended on Concentration gradient and Temperature, and higher the concentration gradient, the higher the rate of speed.

Membrane surface area

• Larger the surface means a higher the rate.

Exchange Surface

• Exchange surfaces are surfaces that maximize gas and solute exchange.
• Some example is Large surface area (allows more of a substance to diffuse at the same time), a Thin membrane (reduces the diffusion distance), and Blood supply (blood pressure vessels bring in new blood as blood starts to even out the concentrations). Ventilation in animals maintains a high concentration gradient by breathin.

Osmosis

• Osmosis is the diffusion of water across a partially permeable membrane from a dilute to a concentrated solution of water.
• This involves Water movement, where is that water will move to make the concentrations the same on both sides of the membrane.
• It is useful to keep in mind that water molecule's move in both direction, but only one has a net effect.

Active Transport

• Is found in may contexts such as, Sugar absorption in human gut, or the Root (where plants gain nutritions.

Types of transports

• Diffusion, Osmosis and Active Transport.
• Active transport is the one transport that requires energy.