General Biology Reviewer PDF

INTRODUCTION TO BIOLOGY ======================= **BIOLOGY** - Derived from two greek words - **"bios"** which means **life** - **"logos"** or **"logia"** which means **study or knowledge.** - Branch of science deals with the study of life - Deals also with the study of living...

INTRODUCTION TO BIOLOGY ======================= **BIOLOGY** - Derived from two greek words - **"bios"** which means **life** - **"logos"** or **"logia"** which means **study or knowledge.** - Branch of science deals with the study of life - Deals also with the study of living things or organisms - **Biologist** - a person specialized in the study of biology. **Life** \- --------------- ---- **Organisms** - Life means being alive or existing - \- anything with life. Other term for living thing that made up of cells. - **Cell** - basic unit of living things. - **Three main parts of cell** - Nucleus - Cell membrane - Cytoplasm - **Unicellular** - organisms made up of one cell - **Multicellular** - organisms made up of two or more cell CHARACTERISTICS OF LIVING THINGS ================================ - **Movement or Locomotion** - organisms are capable of movement. Movement is change of position of whole organisms or just part of an organisms. - **Irritability (Sensitivity)** - ability of an organism to respond to a stimulus(plural; stimuli) - **Feeding (Nutrition)** - The process of taking in food, synthesizing it, digesting and oxidizing it to release energy or build the body - **Respiration** - breaking down of food materials within cell to release energy. - **Excretion**- the process of removing metabollic waste products from the body of living organisms. - **Reproduction** - process by which of living things produce new individuals of their own kind. - **Growth and Development** - organisms grow (get larger) and develop and change over their life span. ◼ **Growth** ----------------- ------------ **Cells/Order** - \- organisms are made up of one - **Adaptation** - all living organisms exhibit a "fit" to their environment. - **Fit** - biologist refers fit as adaptation and it is consequence of evolution by natural selection. **Regulation** \- ----------------- ---- **Homeostasis** - systems perform specific function. - \- the ability of an organism to maintain constant internal conditions. - **Thermoregulation** - many organisms regulate their their body temperature. - **Metabolism** - taking in and using energy. BRANCHES OF BIOLOGY =================== - **Botany** - deals with study of plants. **Botanist** - **Zoology** - deals with study of animals. **Zoologists** - **Mycology** - study of fungi. **Mycologists** - **Bacteriology** - study of bacteria. **Bacteriologists** - **Virology** - study of viruses. **Virologists** - **Immunology** - concerned with body defense againsts diseases and foreign substances. **Immunologists** **Entomology** ------------------ **Parasitology** - \- study of insects. **Entomologists** - \- study of parasites and their effect on living organisms. **Parasitologists** - **Dermatology** - concerned with medical study of skin and its diseases. **Dermatologists** - **Ecology** - deals with relationship among living things and between organisms and their surroundings. **Ecologist** - **Anatomy** - deals with structure of living things. **Anatomist** - **Endocrinology** - study of structure of endocrine glands. **Endocrinologists** - **Histology** - study of structure of tissues. **Histologists** - **Cytology** - study of structure, composition and function of cells. **Cytologists** - **Microbiology** - study of organisms that can be seen only with a microscope. **Microbiologists** **Taxonomy** -------------- **Genetics** - \- classification of organisms. **Taxonomist** - \- study of heredity and variation of organisms. **Geneticists.** RELATIONSHIP BETWEEN BIOLOGICAL SCIENCE WITH OTHER RELATED FIELDS ================================================================= - **Veterinary science (Veterinary Medicine)** - branch of medicine that deals with the diseases of animals. **Veterinarians** - **Agriculture**- concerned with the production of useful plants and animal through farming system. - **Forestry** - science managing forest resources for human benefit. - **Pharmacy** - profession concerned with the preparation, distributions and use of drugs. **Pharmacist or Druggists** - **Medicine** - science and art of preserving health and treating illness. - **Nutrition-** science which deals with food and how body uses it. THE ORIGIN AND NATURE OF LIFE ============================= **THEORIES** - **Theory of Special Creation** - all the different forms of life that occur today on planet earth have been created by god. - **Theory of Spontaneous Generation** - assumed that living organism could arise suddenly and spontaneously fron any kind of non-living matter. - **Theory of catastrophism** - it is simply modification of the theory of special creation. Each catastrophe completely destroyed the existing life, each new creation consisted of life form different from that previous ones. - **Cosmozoic theory (Theory of Panspermia)** - life has reached this planet earth from other heavenly bodies such as meteorites , in the form of highly resistance spores of some organisms. **Theory of Chemical Evolution** \- ---------------------------------------------- ---- **Materialistic theory or Physico-chemical** - also known as SCIENTIFIC PROCESSES IN BIOLOGY =============================== - The scientific processes involved in the study of biology include **observation**, **measurement**, and **experimentation.** - **Observation** - made by using our own sense organs - **Eyes** - for vision - **Ears** - for hearing - **Tongue** - to taste various things - **Skin** - to detect heat, temperature, pressure and even pain. - **Nose** - for smelling - **Measurement** - it is use to carry out investigation by using instruments. **Like Beam Balance (Mass), Thermometer (Temperature), Clock/Stopwatch (Time), Ruler (Length), Stethoscope (Pulse Rate).** - **Experimentation** - a series of investigation intended to discover relationship or certain facts that may lead to finding finding a problem. 1. **Identification of a problem (problem statement)** 2. **Hypothesis formulation** - tentative explanation for the observation made. 3. **Observation and Data recording** 4. **Interpretation of Data** 5. **Conclusion**-it must be based on the collected data. BIOLOGY LABORATORY ================== ✓ A room or building specially designed for carrying out biological experiments. WARNING SIGNS ON LABORATORY CHEMICALS AND APPARATUS =================================================== - **Toxic** - substances can cause death. IMG\_256 - **Flammable** - substances which can catch fire easily.  - **Corrosive** - substances attack and destroy living tissues. IMG\_256 - **Oxidant**- chemical or substance which accelerates burning. Where small fires can be made big in the presence of oxiding agent. - **Explosive** - a forceful rapid reaction which involves random throwing of particles. - **Harmful or Irritant** - harmful substances have a long term effect. THE MICROSCOPE ============== - Instrument used for viewing objects which are too small to be seen by our naked eyes - **Two types of Microscope;** - **Compound or Light Microscope** - uses two or more sets of lenses to provide higher magnifications. Uses light to illuminate specimen. - **Electron Microscope**- uses electrons to illuminate the specimen and can reveal much more structures that light microscope can do. ◆ **Types of Electron Microscope** PARTS OF LIGHT MICROSCOPE AND THEIR FUNCTIONS ============================================= - **Eyepiece** - magnify objects, consist of magnifying lenses - **Body tube** - hold eyepiece lens and revolving nose piece. - **Revolving nose piece** - holds objective lenses in place. - **Course adjustment Knob-** it lowers and raises the body tube to obtained clear image - **Fine adjustment Knob** - raises and lowers the body tube to obtain a fine focus. - **Objective lens** - brings image into focus and magnifies it. - **Stage** - place where specimen being observed is placed - \- holds the specimen in position **Stage clips** ----------------- ---- **Mirror** \- - reflects and directs light to the object under observation. - **Iris diaphragm** - regulates the amount of light passing through the condenser to illuminate the specimen. - **Condenser** - concentrates light reflected by the mirror. **Base** ---------- **Arm** - \- supports the whole microscope - \- supports the body tube and stage. Use also to hold the microscope. - **Hinge screw** - raises and lowers the stage - **Magnification** - Magnification power is symbolized by a number and abbreviation X. - **Example** - **Magnification = eyepiece lens x objective lens magnification** SCIENTIFIC METHOD ================= ✓ **Francis Bacon(1561-1626)** - the first to define the scientific method **SCIENTIFIC PROCESS** 1. **Observation** 2. **Hypothesis** - - - 3. **Experiment** - - **Independent V.** - being changed or tested - **Dependent V.** - the thing/s that you are measuring as the outcome of your experiment. - **Constant** - conditiom that is the same between all of the tested groups. - **Confounding V.** - a condition that is not held constant that could affect the experimental results. 4. **Results/Conclusion** - - - BIOLOGICAL MOLECULES ==================== - Referred to as the molecules of life (bio-molecules) - Found in a living cell and categorized as organic and inorganic molecules in general. - **Organic Biomolecules** -- -------------- **Proteins** -- -------------- - Compound made of small carbon compounds called amino acids. - **Amino acids** - small compounds made of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfur. - Proteins make up about **15%** of our total body mass. -- ------------------- **Carbohydrates** -- ------------------- - Made of atoms carbon, hydrogen and oxygen - Source of energy - Found in different form either sugar or many sugars(saccharides) - **Glucose** - most important carbohydrate fuel in human cells - **Galactose** - reacts with glucose to make lactose. Cannot play the same part in respiration as glucose - **Fructose** - example of hexoses. A ketose or non-reducing sugar. Reacts with glucose to form sucrose - **Ribose and deoxyribose**- example of pentoses. -- ------------------------------ **Types of Sugar Molecules** -- ------------------------------ - **Monosaccharides** - Single sugar molecule - Containing aldehyde group are classified as aldoses. Ketone are ketoses. **Aldoses** ------------- **Ketoses** - \- reducing sugars - \- non- reducing sugars - **Disaccharides** - Two sugar molecule - Most sugar found in nature - Form when two monosaccharides react - Soluble in water - **Polysaccharides** - two or more sugar molecule - Form when monosaccharides can undergo a series of condensation reactions - The condensation called **condensation polymerization** - **-** building blocks **Monomers** -------------- ---- **Starch** \- - produced in plants as a way of storing energy. - **Amylose** - unbranched polymer of a-glucose - **Amylopectin** - branched polymer of a-glucose - **Cellulose** - it makes up the cell walls in plant cells. Third polymer made from glucose. Not hydrolized easily or cannot be digested. - **Oligosaccharides** - few monosaccharides covalently linked - **Glycosidic linkage/s** - help sugar to bond together CELL STRUCTURE AND FUNCTION =========================== - The primary function is to store energy - Highly variable group of molecules that **CELL** include fats, oils, waxes, and some steroids. ✓ Smallest unit of living things. - It is called triglyceride. It is stored in the fat ✓ Basic building blocks of all organisms. cells called adipocytes and lipocytes - Fat cells are categorized in **CELLS - TISSUES - ORGAN - ORGAN SYSTEMS** ❖**white fat cells -** store one large lipid -- ------------------------ **Two types of Cells** -- ------------------------ - Lipids occur in the human body ❖ Bacteria ❖**Triacylglycerol** ❖ Archaea ❖**Cholesterol** ❖**Polar lipids (phospolipids, glycolipids** ◼ **Eukaryotic** **and sphingolipids.)** ❖ Animal cells - **Saturated fats** - tail chains with only single ❖ Plant cells bonds between the carbon atoms ❖ Fungal cells - **Unsaturated fats** - have at least one double ❖ Protist cells bond between carbon atoms in the tail chain can accommodate at least one **CELL THEORY** more hydrogen ✓ **Robert Hooke** coined the term **"cell"** (from the latin - **Polyunsaturated fats** - with more than one cella, meaning "small room") double bond in the tail. ✓ **Leeuwenhoek** discovered bacteria and protozoa ✓ **Matthias Schleiden** and **Theodor Schwann** -- ------------------- **Nucleic acids** -- ------------------- -- ------------------------------------------------------------------------- **This theory has three principles which still stand today. They are:** -- ------------------------------------------------------------------------- - Made of smaller repeating subunits called nucleotides. - **Nucleotides-** composed of carbon, nitrogen, **1.** *All living things are composed of one or more cells.* -- ------------ **Lipids** -- ------------ oxygen, phosphorus, and hydrogen atoms. **2.** *The cell is the basic unit of life.* - Six major of Nucleotides that have **3 units 3.** *All new cells arise from existing cells*. -- ----------------------- **Prokaryotic Cells** -- ----------------------- - **Two Types Nucleic Acids** ◼ **Karyon** = **nucleus** ❖**DNA -** deoxyribonucleic acid ◼ Single celled (unicellular) organisms that lacks a ❖**RNA -** ribonucleic acid nucleus or any membrane-bound organelle ◼ **Components of Prokaryotic Cells** -- ------------------------------------------------------- **Five different Bases found in Nucleotide subunits** -- ------------------------------------------------------- - **Plasma membrane** - **Cytoplasm** +-----------------------+-----------------------+-----------------------+ | ❖**Adenine** | | **DNA** | | | | | | ❖**Cytosine** | | **Ribosomes** | +-----------------------+-----------------------+-----------------------+ - **ATP (Adenosine Triphosphate) -** a - **Hydrolysis reaction** - reverse of condensation - **Condensation reaction** - takes place by releasing water. This process requires energy - **Vitamins**- organic compounds that are needed in ------------------------------------------------------------------------ --- ---------------------- small amounts for metabolic activities. Help enzymes to function well. ✓ **Eukaryotic Cells** ------------------------------------------------------------------------ --- ---------------------- **Vitamin D** **.** - --------------------- --------- **Vitamin B and K** - - called organelles - **"true nucleus,"** - -- --------------- ---------------------------------------------- **Cytoplasm** **-** made up of organelles suspended in the -- --------------- ---------------------------------------------- - **Ribosomes** - responsible for protein synthesis. - Synthesis - means to combine things to produce something else - **Cytoskeleton** - to secure certain organelles in specific position and to allow cytoplasm and vesicles to move within the cell. Ions and organic molecules, -- -------------------------------------------------------------- **There are three types of fibers within the cytoskeleton:** -- -------------------------------------------------------------- - **Microfilaments**, also known as **actin filaments** ◼ **Intermediate filaments** ◼ **Microtubules.** - **Centrosomes** - replicates itself before a cell divides - **Centrioles** - play a role in pulling the duplicated chromosomes to opposite ends of the dividing cells. - **Flagella (singular- flagellum)** - a long hair like structures that used to move an entire cell. - **Cilia (singular - cilium)** - short hair like structures that are used to move entire cells. - **Nucleus** - most prominent organelle in a eukaryotic cell. Houses the cells DNA in the form of chromatin. - **Nuclear envelope** - double-membrane structure that constitutes the outermost portion of the nucleus. - **Chromosome or Chromatin** - **Chromosomes** - structures within the nucleus that are made up of DNA, the hereditary materials and proteins. **Chromatin** \- ---------------------------------- ---- **Nucleolus (plural- nucleoli)** - combination of DNA and protein - \- darkly staining area within the nucleus - **Endoplasmic Reticulum** - series of interconnected membranous tubules that collectively modify proteins and synthesize lipids. ◼ **Lumen** - hollow portion inside ER tubules - **Types of Endoplasmic Reticulum** ----------- ----------------- -- **Rough** **Endoplasmic** ----------- ----------------- -- - - - **Golgi apparatus** - where sorting, tagging, packaging and distribution of lipids and proteins take place. - **Vesicles and Vacuoles** - membrane-bound sacs that function in storage and transport - **Central vacuole**- plays a key role on regulating the cells concentration of water - **Lysosomes** - the cells **garbage disposal** - **Peroxisomes** - small, round organelles enclosed by single membranes. They carry out oxidation reactions that breakdown fatty acids and amino acids - **Mitochondria** - **"powerhouses" or "energy factories"** of a cell. They are responsible for making **adenosine triphosphate (ATP)**. - **Cellular respiration** - formation of ATP from the breakdown of glucose - **Chloroplasts** - helps to photosynthesis. Have outer and inner membrane - **Thylakoids** - set of interconnected and stack, fluid-filled membrane sacs - \- stack of thylakoids **Granum (plural - grana)** ----------------------------- ---- **Stroma** \- - fluid enclosed by the inner membrane and surrounding the grana - **Chloropyll** - a green pigment that captures the energy of sunlight for photosynthesis - **Cell wall** - rigid covering that protect the cells, provides structural support and give shape - **Extracellular Matrix** - hold the cells together to form a tissue - **Intercellular junctions** - the ability of cells to communicate with each other by direct contact. ✓ **Four Kinds Of Connection between Cells** - **Plasmodesma** - channel between the cell wals of two adjacent plant cell - **Tight junctions** - join adjacent animal cell - **Desmosomes** - join two animal cells together - **Gap junction**- act as channels between animal cells - **Plasma Membrane** - made up of a **phospholipid bilayer** with embedded **proteins** that separates the internal contents of the cell from its surrounding environment. - A **phospholipid** is a lipid molecule composed of two fatty acid chains, a glycerol backbone, and a phosphate group. - Regulates the passage of some substances  --- -- ✓ --- -- - In 1972 S. J. Singer and Garth L. Nicolson proposed a new model of the plasma membrane. - Describes the structures of the plasma membrane as compromised of many different components - Fluidity of the plasma membrane is necessary for the activities of certain enzymes and transport molecules within the membrane. - Plasma membranes range from 5--10 nm (nanometers) thick. COMPONENTS OF PLASMA MEMBRANE ============================= - Plasma membrane is made up primarily of a **bilayer of phospholipids** with embedded **proteins, carbohydrates, glycolipids, and glycoproteins,** and, in animal cells, **cholesterol**. - Phospholipid molecules have a "head" that is **hydrophilic (water-loving)** and **polar.** - In contrast, the interior of the membrane, composed of the tails of phospholipids, is **hydrophobic (waterfearing)** or **non-polar** IMG\_256 - **Proteins** make up the second major chemical component of plasma membranes. - **Carbohydrates** are the third major component of plasma membranes. - **Cholesterol** - regulates the fluidity of the membrane and changes based on the temperature of the cells environment. MEMBRANES AND MOVEMENT OF MOLECULES =================================== - **Passive Transport** - naturally occuring phenomenon and does not require the cell to expend energy to accomplish the movement. - **Diffusion** - substances move from an area of higher concentration to an area of lower - **Concentration Gradient** - A physical space in which there is a different concentration of a single substance -- --------------------------- **Facilitated Diffusion** -- --------------------------- - Diffusion across a membrane through a protein carrier. - This means that material moves across the plasma membrane with the assistance of a protein carrier down a concentration gradient (from high to low concentration) *without* the expenditure of cellular energy. - **Transport Proteins** - they function as either channel for the materials or carriers -- ------------- **Osmosis** -- ------------- - Diffusion of water through a semipermeable membrane from a high concentration of water to a low concentration of water across the membrane (water is moving down its concentration gradient). - Transports only water - **Tonicity** - describes the amount of solute in a solution. - **Hypotonic** - means that the extracellular fluid has a lower concentration of solutes - **Isotonic** - the extracellular fluid has the same osmolarity as the cell. - **Hypertonic** - refers to the extracellular fluid having a higher concentration of solutes than the cell's cytoplasm IMG\_256 - **Active Transport** - mechanisms require the use of the cell's energy, usually in the form of adenosine triphosphate (ATP). - **Endocytosis** - type of active transport that moves particles, such as large molecules, parts of cells, and even whole cells, into a cell. - - **Phagocytosis** - the cell membrane surrounds the particle and pinches off to form an intracellular vacuole. - **Pinocytosis** - the cell membrane surrounds a small volume of fluid and pinches off, forming a vesicle. - **Receptor- mediated endocytosis** -uptake of substances by the cell is targeted to a single type of substance that binds at the receptor on the external cell membrane. ✓ - Exocytosis - the opposite of the processes discussed above in that its purpose is to expel material from the cell into the extracellular fluid. -  GENERAL BIOLOGY REVIEWER ======================== WEEK 4-5 **Introduction to Evolution** - Evolution is the gradual change of organisms, long period, new forms replacing the old ones. - As Evolution progressed new species are arising, biodiversity of the planet increasing. - Evolution- genetic composition of a population which may cause by: 1. Meiosis 2. Hybridization 3. Natural Selectior or Mutation **WHAT IS THE IMPORTANCE OF STUDYING EVOLUTION?** 1. **It helps to understand the biological forces that cause organisms to develop from simple to more complex organisms to the extent of new species emerging.** 2. **It helps to know how different organisms relate.** **Theories about the origin of life on Earth** - **The theory of evolution describes how the various forms of life on earth (including humans) emerged and developed.** - **There are five main theories of the origin of life on Earth:** 1. **special creationism** 2. **spontaneous generation** 3. **eternity of life** 4. **cosmozoan theory** 5. **biochemical origin** **Special Creationism- Created by God, Supreme Being created in six days. Special Creationism connects to Religion.** **Three Types of Special Creationism** - **Gap Creation-Large gap between the formation of the earth and the creation of all the animals and plants. Billion or Million years.** - **Evolutionary creationism (Theistic evolution)-** **God "invented" evolution and takes** **Gap Creation- Progressive creation accepts the Big Bangs as the origin of the universe.** - **Intelligent design- That life developed (formed) due to a combination of natural forces and the intervention of a supernatural being.** **Spontaneous generation theory- Suggests that life can evolve \'spontaneously\' from non-living objects.** - **Examples of Spontaneous Generation: People believed that rotting meat turned into flies.** **Eternity of life- There is always been life in the universe. There is no beginning and no end to life on earth.** **Cosmozoan Theory- States that life on the earth originally came from elsewhere in the universe.** - **Example of Cosmozoan Theory: Meteorites brought bacterial spores, germs to the earth. This theory did not gain any significant support because it lacks evidence, and it is strongly linked to the "eternity of life" theory of the origin life.** **Biochemical Theory- life on earth originated in biochemical reactions producing organic molecules. This theory is also called abiogenesis** **Two Scientist (Biologist) inventented abiogenesis were:** - **Aleksander Oparin (1924)** **John Haldane (1929).** **They both suggested that:** - **The primitive atmosphere of the earth was a reducing atmosphere -- no free oxygen (no oxygen gas).** - **There was an appropriate supply of energy, such as lightening or ultraviolet light (UV -- rays).** - **This would provide the energy for reactions that would synthesize a wide range of organic compounds (amino acids, sugars and fatty acids).** **Oparin suggested that:** - **Atmosphere contains NH3, H2, water vapor (H2O), and CH4.** - **High temperature (above boiling point), could make chemical reactions and formed colloidal aggregates or coacervates. (collections of droplets that composed of molecules of different types).** **Oparin considered that:** - **Absorb and assimilate organic compounds (DNA, Amino Acids etc.) leading to the first true cells.** **J. Haldane Proposed that:** - **chemical reactions of these gases were occurred in the primitive sea by solar energy and the sea became a "hot dilute soup" of organic monomers and small polymers.** **Stanley Miller tested abiogenesis (1953)** - **He applied electrical sparks repeatedly through a mixture of gases (NH3, water, H2 and CH4) that were represent the primitive atmosphere of the earth (no oxygen) connected a flask of heated water.** **After testing this, Miller find out:** - **amino acids - to form proteins.** - **pentose sugar - to form nucleic acids.** - **hexose sugar - need for respiration and to form starch and cellulose.** - **Hydrogen cyanide (HCN)- starting point for synthesizes of nitrogen containing bases in nucleotides.** - **This experiment gave strong evidence to support the Oparin-Haldane hypothesis.** **Origin of Autotrophy** - **Origin of Autotrophy- First life cell appeared 4 billion years ago** 1. **Anaerobes.** 2. **Heterotrophs.** 3. **Prokaryotes.** **The three consecutive lines of evolution of organisms on earth leading to:** - **Archaebateria(prokaryotes)- First appeared organisms, (high temp. loving), sulphobacteria, methanobacteria and halophilic (salt loving) bacteria.** - **Can survive in a harsh environment.** - **Eubacteria- are true (ordinary) bacteria, ordinary bacteria and cyanobacteria (blue -- green algae).** - **Prokaryotes- evolved into protista, fungi, plants, animals (nearly all are aerobes).** - **(3.5 billion years ago)- First autotrophs (photosynthetic organisms) came into existence:** **Evolution of chlorophyll molecules:** - **Oxygen (O2) was released as a by-product of photosynthesis.** - **Changes the earth\'s atmosphere from the reducing to an atmosphere containing oxygen.** - **Lamarck Theory of evolution (19^th^ century, 1809)- published a paper entitled Philosophic "Zoologique".** **Lamarck proposed a "theory of transformation" or lamarkism.** **"Zoologique" contains two part of theories:** - **Use and disuse- Structure or process in organism that can be used continuous will become enlarged or more developed but any structure that is not.** **Example of Use and Disuse theory- Giraffe had short neck, but they stretched their neck to reach high branches, developed an elongated neck use theory** - **Inheritance acquired traits- Believed that traits changed acquired during an organism\'s lifetime could be passed on to its offsprings.** **Example of Acquired Traits-Giraffes that had acquired long necks would have offspring with long necks.** **Charles Darwin and Natural Selection** **Charles Darwin and Alfred Wallace (1858)- Published a paper that species were modified of Natural Selection.** **Darwin Studied the finches and find similarities and differences.** **Ancestral finch-Colonized the mainland and able to adapt to the different conditions and evolve into different species.** **Some finches become:** - **Insect eaters (pointed peak).** - **Seedeaters (crushing peak).** **Darwin Summarized his observations into two ideas:** - **All species tend to produce more offsprings than can possibly survive (Fecundity).** - **There is a variation among the offsprings.** **Darwin proposed: - Those members of a species, which are best adapted to their environment, will survive and reproduce in greater number than other less adapted (died out).** **Neo -- Darwinism Theory** - **Neo-Darwinism is a modification of Darwin\'s original theory that takes into account: genetics and ethology (behavioral pattens can also be advantageous or not).** **Example of Neo-Darwinism: Young geese "imprint" upon the first moving object after they are hatched.** **WEEK 6-8 Infectious diseases and Immunity** - **Infectious diseases- caused by living organisms called infectious agents.** **In order to cause a infection disease a pathogen must:** 1. **It must enter the host.** 2. **It must metabolize and multiply on or in the host tissue.** 3. **It must resist host defenses.** 4. **It must damage the host.** **Infection and Disease are not the same.** - **Infection- when a infectious agent (pathogen) enters and begins growing within a host.** - **Disease- when the cells in host body are damaged.** **Sign, symptom and syndrome** - **Sign- A change in body function that is felt by a patient as a result of disease.** - **Symptom-A change in a body that can be measured or observed as a result of disease.** - **Syndrome-A specific group of signs and symptoms that accompany a disease.** **Classifying infectious diseases:** - **Communicable disease: Spread from one host to another.** - **Contagious disease- Easily spread from one host to another.** - **Non-communicable disease-not transmitted from one host to another.** **Classifying infectious diseases by occurrence of diseases** **Severity or duration of infectious disease** - **Acute: disease develops rapidly** - **Chronic: disease develops slowly** - **Subacute: symptoms appear between acute and chronic** - **Latent: disease with a period of no symptoms when the causative agent is inactive** **Extent of host involvement:** - **abscesses** - **Bacteremia: bacteria in the blood.** - **Sepsis: toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection.** - **Septicemia: growth of bacteria in the blood.** - **Toxemia: toxins in the blood.** - **Viremia: viruses in the blood.** **Extent of host involvement:** - **local tooth infection can moves via blood or lymph to set up a new infection at another site - rheumatoid arthritis** **Disease development and stages** **Pathogenicity** 1. **Plague** 2. **Malaria** 3. **Measles** 4. **Influenza** 5. **Diphtheria** 6. **Tetanus** 7. **Tuberculosis** **These pathogenic organisms are called virulent.** **Virulence-refers to a degree of pathogenicity.** **Opportunistic pathogen (opportunist)- causes disease only when body's innate or adaptive defenses are compromised.** **Opportunistic pathogen- Members of normal microbiota or common in environment (e.g., Pseudomonas.** **Normal microbiota (normal flora)- are organisms that routinely reside on body's surfaces and the relationship is delicate balance.** **Individuals are immune-compromised-malnutrition, cancer, AIDS or other disease, surgery, wounds, genetic defects, alcohol or drug abuse, and immunosuppressive therapy following procedures such as organ transplants.** **The spread of infection** **Human reservoirs of infection- carriers of pathogenic microorganisms.** - **Sick people = actively ill** - **Carriers = one who harbors disease organisms in their body without manifest symptoms (healthy).** - **Latent infection carriers = contagious during incubation period or convalescent period.** **Zoonoses- disease that affect wild and can be transmitted to humans.** **Examples:** - **Direct contact with animal or its waste** - **Eating animals** - **Blood sucking arthropods** **Nonliving reservoirs-soil, water, and food can be reservoirs of infection.** **Examples** - **Presence of microorganisms is often due to contamination by feces or urine.** **Types of infectious disease and their causative agent** **Pathogens known as causative agents for different types of infectious diseases are:** 1. **strong antibiotics for a long time** 2. **weakened immune system.** **Types of infectious disease and their causative agent** - **Protozoa** - **Helminths** - **Prions** **Modes of transmission** - **Direct contact** - **Indirect contact** **Host defenses against infectious diseases** **Overview of the immune system** **Immune system- is composed of a number of different cell types, tissues and organs.** **These cells are organized into separate lymphoid organs or glands.** **Nonspecific mechanisms (Innate Immune system)** **Specific mechanisms of host resistance (Adaptive defense)** **The branches of acquired immunity:** **Humoral or Antibody-mediated immunity:** **Cellular or Cell-mediated immunity:**  - **It is important to recognize that they frequently work together.** - **Both systems work together through direct contact with each other, and through interactions with chemical mediators, the cytokines and chemokines.** **Example:** 1. **Macrophages are responsible to phagocytosis the infectious microbes.** **Produce important cytokines that help to induce the adaptive immune response.** 2. **Complement components of the innate immune system can be activated directly by microbes, but can be activated by antibodies, molecules of the adaptive system.**  **Adverse immune reactions (responses)** **Three types of immunological disorders.** **Hypersensitivity reactions-immune response to antigen.** **Hypersensitivity-over reactivity by the immune system to antigens.** **There are four types of hypersensitivity reactions** 1. **Type I** 2. **Type II** 3. **Type III** 4. **Type IV.** **The Types I, II and III are antibody or immune complex mediated.** **Type IV is cell mediated (Delayed type hypersensitivity (DTH)). Occurs days after reencountering the antigen.** **Type I Hypersensitivity** **Atopy-exaggerated IgE-mediated immune response atopic disorders are type I hypersensitivity disorders.** **Allergy- exaggerated immune response to a foreign antigen** **All atopic disorders are considered allergic.** **Type II Hypersensitivity** **Blood transfusion** - **Common practice to give blood transfusions in cases of severe blood loss.** **Type III Hypersensitivity** - **Type III reactions (immune complex disease) cause inflammation** - **Activate the complement system or bind to and activate certain immune cell.** **Type IV Hypersensitivity** **Type IV reactions involves:** 1. **Contact dermatitis (e.g., poison ivy)** 2. **Subacute** 3. **Chronic hypersensitivity pneumonitis.** 4. **Allograft rejection** 5. **Tuberculosis** **And many forms of drug hypersensitivity.** **Autoimmunity and autoimmune disease** - **Autoimmunity- Immune reactivity to self-antigens which lead to tissue damage.** - **Type 1 diabetes** - **Rheumatoid arthritis (RA)** - **Psoriasis/psoriatic arthritis** - **Multiple sclerosis** - **Systemic lupus erythematosus (SLE)** - **Inflammatory bowel disease** - **Addison's disease** - **Graves' disease** - **Sjogren's syndrome** - **Hashimoto's thyroiditis** - **Myasthenia gravis** - **Autoimmune vasculitis** - **Pernicious anemia** - **Celiac disease** **Factors contributing for autoimmune diseases:** - **Age, Auto-antibodies are more prevalent in older people.** - **Gender women have a greater risk than men for developing an autoimmune disease.** **Infections-Many infectious agents have been linked to particular autoimmune diseases and may be important in their etiology.** **Examples of Infectious agents:** 6. **EBV** 7. **Mycoplasma** 8. **Streptococci** 9. **Klebsiella** 10. **Malaria** **Immune Deficiencies** - **Immunological disorders-can be caused by the deficiency of immune response of the host body.** - **Occur when one or more components of the immune system is defective.** - **It is classified as primary or secondary** **Defects in lymphoid lineage: May involve B-cell, T-cell or both. The severity depends on the number and type of immune components involved.** **Defects in myeloid linage: Affect innate immunity, especially phagocytic activity.** **Secondary immunodeficiency** **Tumor Immunology Tumor:** - **Mass of tissue** - **Cell grow even though the body does not need them, and unlike normal old cells, they don\'t die.** - **Cancer is a disease in which cells, almost anywhere in the body, begin to divide uncontrollably.** - **A tumor is when this uncontrolled growth occurs in solid tissue such as an organ, muscle, or bone.** - **Tumors may spread to surrounding tissues through the blood and lymph systems. Evidence for immune reactivity to tumor** **Tumor associated antigens** 11. **Tumor-specific transplantation antigens (TSTA)**- **unique to tumor cells and not** 12. **Tumor associated transplantation antigens (TATA)-** **expressed by tumor cells and** **WEEK 6-8 The Meaning of the Terms Infection and Disease** - **Infection is the invasion of disease-causing micro-organisms into the body.** ❖ **Disease is the disturbance of the normal state of the body.** **Classification of diseases** **Diseases are classified as:** 13. ***Infectious (communicable) diseases*** 14. ***Non-infectious (non-communicable) diseases*** **Infectious (communicable) diseases- These are diseases which can be transmitted from one person to another person. normally caused by micro- organisms like viruses, bacteria, fungi and protozoa, etc.** - **Infectious diseases are transmitted by a way of:** 1. **Droplet of liquid** 2. **Air** 3. **Food or water** 4. **Sexual intercourse** 5. **Touch or contact e.g. ringworm** 6. **An intermediate organism called a vector e.g. malaria by mosquito and bubonic plague by rat flea.** 7. **Diseases causing micro-organisms can enter the body through mouth, nose, skin, vagina, anus, penis, ears, eyes and open wounds.** **Infectious diseases can be:** 1. **Epidemic disease -affects a larger number of people in a short period of time in a region.** 2. **Pandemic disease-communicable disease which is wide spread over a country continent or the whole world.** 3. **Endemic disease - a communicable disease which occurs in an area continuously. Non- infectious (non-communicable) diseases:** **Non-infectious (non-communicable)-** **diseases which can not be transmitted from one person to another.** **Examples of non-communicable diseases include:** 1. **Environmental diseases e.g.** 2. **Lung cncer** 3. **Asbestosis** 4. **Asthma** 5. **Coronary (heart) diseases** 6. **Alcoholism** **Deficiency diseases-due to lack of certain nutrients in the diet.** **Examples:** 1. ***Kwashiorkor:* lack of protein** 2. ***Marasmus:* lack of both carbohydrate and proteins** 3. ***Night blindness:* lack of Vitamin A** 4. **.*Beriberi:* lack of Vitamin B~1~** 5. ***Scurvy:* lack of Vitamin C** 6. **. *Rickets:* lack of Vitamin D, calcium, and phosphorous** 7. ***Anemia:* lack of iron** 8. ***Goiter:* lack of iodine** 9. ***Excessive bleeding (haemophilia):* lack of Vitamin K** **Genetic and congenital disorders e.g.** 1. **Color blindness** 2. **Hemophilia** 3. **Sickle cell anemia** 4. **Albinism** 5. **Down's syndrome** 6. **Klinefelter's syndrome** 7. **Turner\'s syndrome** **Ageing and degenerative diseases e.g.** 1. **Long sightedness due to weakening of eye muscles** 2. **Arteriosclerosis (hardening of arteries)** 3. **Arthritis -- ageing of joint and bone tissues** **Mental illness e.g.** 1. **Schizophrenia** 2. **Senile dementia** 3. **Depression** **Hormonal diseases e.g** 1. ***Diabetes mellitus*** 2. ***Diabetes inspidus*** 3. **Cretinism** **Common Infections and Diseases** **1. CHOLERA-bacterium known as *Vibrio cholerae*** **Symptoms** 1. **Severe watery diarrhea and vomiting** 2. **Body weakness** 3. **Fast and weak pulse** 4. **Low blood pressure** 5. **Wrinkled skin and sunken eyes due to dehydration** 6. **Rapid loss of weight** **Transmission** a. **Food or water borne material contaminated with feces from infected person** b. **Handling of contaminated objects** c. **Vectors e.g. flies moving from human feces to food.** **2. MALARIA-caused by a protozoan called plasmodium.** **Signs and symptoms** a. **High fever. Fever may be continuous, irregular or twice daily.** b. **Vomiting** c. **Lack of appetite** d. **General body weakness** e. **Joint pains** **Transmission** **Malaria is transmitted by a female anopheles mosquito.** a. **Mild fever** b. **Slight abdominal pains** c. **Diarrhea** d. **Vomiting** e. **Ulceration and rupture of intestine** **Transmission** **The disease is spread through** a. **Contaminated water and food** b. **Handling of contaminated objects** c. **Vectors of the disease e.g. houseflies** a. **Loss of weight** b. **Coughing** c. **Fever** d. **Chest pain** e. **Blood in the sputum** **Transmission** a. **Through droplet infection** b. **Through drinking milk from infected cattle** c. **T.B is common in overcrowded areas with poor sanitation** 5. **MENINGITIS** 6. **AMOEBIC DYSENTRY (AMEOBIASIS)** 7. **PLAGUE** 8. **TRYPANOSOMIASIS (SLEEPING SICKNESS)** 9. **BILHARZIA (SCHISTOSOMIASIS)** 10. **ATHLETE'S FOOT** 11. **GONORRHOEA** 12. **SYPHILIS** 13. **CHLAMYDIA** 14. **GENITAL HERPES** 15. **GENITAL WARTS** 16. **HEPATITIS B** 17. **TRICHOMONIASIS** 18. **CANDIDIASIS** **Appropriate Preventive and Control Measures for Common Infections and Diseases** **Prevention of Cholera** a. **Wash hands after visiting toilet or latrine.** b. **Food should be well cooked and drinking water should be boiled and well filtered.** c. **Hands should be washed before and after eating.** d. **Food should be well covered.** e. **Utensils should be washed thoroughly.** f. **Maintain general environmental cleanliness.** **Control of Cholera** a. **The infected person should be isolated.** b. **Special precautions should be taken when handling the infected person.** c. **Vaccination is possible.** **Treatment** a. **The disease can be treated by using antibiotics such as *tetracycline, chloramphenicol.*** b. **Administering rehydration salt solutions.** **Effects** a. **May lead to death.** b. **Extra medical expenses** c. **Failure to perform daily activities.** **Prevention and control of malaria** a. **Spraying insecticides to destroy adult mosquitoes** b. **Introducing fish eating mosquito into stagnant water e.g. *Gambusia* that feed on mosquito larvae.** c. **Draining stagnant water to remove the breeding sites for mosquitoes** d. **Use of mosquito nets to prevent mosquitoes from biting people** e. **Screening the windows with mosquito-proof wire-mesh to prevent entry of mosquitoes in the house through the windows.** f. **Wear long-sleeved shirts and trousers to prevent mosquito bites.** g. **Mosquito larvae and pupa can be killed by spraying oil into stagnant water that cannot be drained.** h. **Taking regular weekly doses of preventive drugs to kill parasites on entry.** i. **Cutting bushes around the houses to destroy shelter for mosquitoes** j. **Using mosquito repellents to flee away the mosquitoes** **Treatment** **Effects** a. **Can cause death.** b. **Can lead to mental confusion in case of cerebral malaria.** c. **Paralysis and unconsciousness** d. **Drowsiness** e. **Anemia** f. **Miscarriage** g. **Inability to participate in economic activities.** h. **Increased medical expenses.**