Biology Exam Review PDF

Plants Transport in Plants (Water): -Transport of water occurs in XYLEM -Transportation of water and minerals UPWARDS, uni-directional (can’t go back down) through transpiration: the evaporation of water from the leaves as it diffuses through the stomata, creating a negative pressure that pulls wate...

Plants Transport in Plants (Water): -Transport of water occurs in XYLEM -Transportation of water and minerals UPWARDS, uni-directional (can’t go back down) through transpiration: the evaporation of water from the leaves as it diffuses through the stomata, creating a negative pressure that pulls water up through the xylem from the roots (like sucking liquid through a straw). The minerals get sucked up along with the water. -Provides structural support: thick lignin-rich cell walls -Xylem cells are dead at maturity, which means they lack organelle allowing for easier water movement. Water Adhesion and Cohesion (Xylem): -Cohesion: interactions of molecules of the same substance. Due to the polarity of water molecules inside of the xylem vessels, they are stuck together forming a continuous chain, meaning when the chain starts to exit the leaf the whole chain follows. -Adhesion: interactions of molecules between different substances. Water is attracted to the walls of xylem vessels helping to counteract the force of gravity, preventing the water chain from collapsing in the xylem vessels. Transports: -Passive Transport: The movement of molecules along a concentration gradient (does NOT require energy). -Active Transport: The use of energy in the form of ATP to move a molecule or ion against a concentration gradient. Translocation: -Process of how products of photosynthesis are moved from area produced (source) to area required (sink) -Sugars produced in the leaves during photosynthesis are loaded into the sieve tube elements, creating a concentration gradient. This gradient causes water to enter the sieve tubes via osmosis, creating pressure that pushes the sugar solution along the phloem to other parts of the plant where it's needed for growth and metabolism. Companion cells contain mitochondria that help load and unload sugar from the phloem by active transport (against a concentration gradient). Asexual Reproduction: -Product of mitosis (clone: exact genetic replica of parent) -Advantages: well suited for environment, less energy required per reproductive cycle -Disadvantages: poor at adapting to new conditions as there is no diversity for natural selection to work on -Examples: ​ Strawberry Plants: Runners that develop into new plants ​ Dandelions: Return after pulled out because remaining root fragment grows new plant ​ Potatoes: modified underground stem Sexual Reproduction: -Requires meiosis -Flowers are reproductive organs -Advantages: ideal for changing environments and during times of stress -Disadvantages: Energy intensive process (at cellular level) -Example: Flowering plants through pollination. Flower Anatomy: -Sepals (outermost whorl): (not reproductive) usually green and protect the flower bud before it opens. -Petals (second whorl): (not reproductive) attract pollinators. -Stamen (third whorl): anther (male reproductive organ-produces pollen)+ filament -Carpels/pistil (innermost whorl): stigma + style + ovary (female reproductive organ) -All 4 whorls attach at the receptacle Pollination: -Self-Pollination: Transfer of pollen from the male reproductive organ to female reproductive organ of the SAME plant. -Cross-Pollination: Transfer of pollen from the male reproductive organ to female reproductive organ of ANOTHER plant through wind and animals. Seed Dispersal: -If seeds begin growing right beside the parent plant, they will fight for resources, so seeds have various ways of dispersing: -Fruit = costly, but improved dispersal by movement of animals (through ingestion and feces or by burying) -Lightweight seeds = can be carried by wind and water to new locations -Sticky seeds = carried by animals Upper Epidermis/cuticle: Protective barrier against pathogens and water loss. Chloroplast: Forms glucose and energy for the plant. Palisade Mesophyll: The cells I’m in the palisade mesophyll are elongated and columnar and are closely packed together in one or more layers, which maximizes the number of cells exposed to light. Vein: Xylem and phloem tissues. Spongy Mesophyll/Air Space: Facilitates exchanges of gasses between leaf’s internal tissues and the external environment. Guard Cells: Regulate the opening and closing of the stomata to control gas exchange and water loss. Stoma: They allow the exchange of gasses (carbon dioxide in, oxygen out) and transpiration (water vapor out). Osmosis: -The movement of water across a selectively permeable membrane. -Water will move from a high concentration to a low concentration. -A hypertonic solution will have a lower concentration of water than a hypotonic solution, thus water moves across the membrane from the hypotonic to the hypertonic solution Key Terms: -Solute: any dissolved substance in the water, like salt. -Hypertonic: has a higher concentration of solutes -Isotonic: have same concentration of solutes -Hypotonic: Have a lower concentration of solutes ------------------------------------------------------------------------------------------------ Systemes Heart Attack: -Myocardial infarction -Flow of blood from the lungs into the heart is blocked leading to the heart stopping to function properly -Could lead to cardiac arrest, which is when your heart stops pumping and blood cannot reach the rest of the body Circulatory System: -The circulatory system is a network consisting of blood, blood vessels, and the heart. -The system supplies the body with oxygen, nutrients, hormones and removes waste products Main Functions: 1. Transportation: of gasses, nutrient molecules, blood, hormones, and waste materials. 2. Protects: against blood loss from injury and diseases. 3. Regulates: body temperature and pH Types of circulation: 1. Pulmonary Circulation: The movement of blood between the heart and the lungs to oxygenate the blood 2. Cardiac Circulation: The movement of blood within the components of the heart 3. Systemic Circulation: The movement of blood from the heart to the rest of the body Major components: 1. Blood: fluid that transports nutrients, oxygen, carbon dioxide, and many other materials. 2. Blood vessels: system of hollow tubes which carry blood (arteries, veins, capillaries). 3. Heart: Muscular organ that continuously pumps blood through the body and generates blood flow. Components of blood: Blood: Circulates through arteries and veins, carrying O2 and other nutrients to the body’s tissues. Plasma: Yellowish liquid component of blood that carries nutrients, hormones, and waste products. (Erythrocytes) Red Blood Cells: Donut shaped cells that give blood its red color and carry oxygen from the lungs to the rest of the body (survive for 4 months). (Leucocytes) White Blood Cells: Cells that help the body fight off infections and foreign substances. Platelets: Small cell fragments in the blood that help in the clotting process. Hemoglobin: A protein in red blood cells that binds to oxygen and carries it through the bloodstream. High Altitude: -Less oxygen -Body needs more red blood cells to ensure we can uptake more oxygen -After time you will have an increased RBC count and more efficient hemoglobin to bind as much oxygen as possible -People who live in regions of high altitude have less RBC’s so blood is able to travel to extremities quicker. Anemia: -A lack of sufficient oxygen in the body due to a reduction in total amount of red blood cells or low levels of hemoglobin -Results in: Tiredness, weakness, shortness of breath -Causes: Excessive bleeding, Vitamin deficiency, Menstruation (lack of iron), Diet (lack of iron) Sickle Cell Disease: -Caused by a genetic mutation that alters the structure of hemoglobin into rod like structures -This causes the cell to deform into a sickle -Sickle cells are harder and sticker causing them to not flow smoothly through the blood vessels -Stickle cells reduces your risk of getting malaria -Live for 10 to 20 days Blood vessels: Arteries: -Carry high pressure blood away from the heart to the rest of the body -Have thicker and stronger walls than veins due to the fact they deal with higher pressure blood and need to withstand its stress -Arterioles are the smallest form of arteries and are found closest to capillaries Veins: -Carry low pressure blood back to the heart -Valves close behind blood flow ensuring the blood is able to progress through the body and not fall back down due to gravity -Typically located near skeletal muscle groups, which help blood flow by contracting muscles which squeeze the vein and cause the blood to flow from the site of compression -Veins store around 50% of the bodies blood Capillaries: -Very small (< 10 μm diameter) so they can penetrate every tissue in the body -Fine branching blood vessels that form a network between arterioles and venules -The site of fluid and gas exchange between blood and the cells of the body -Never more than 2 cells away from one -Oxygen carried in the blood via the arteries diffuses through capillaries into the cells of the body requiring it -Deoxygenated blood and CO2 from cells diffuses through capillaries and back into the veins which is carried back towards the heart and lungs to become oxygenated Vasoconstriction: -Narrowing or constriction of blood vessels -Smooth muscle cells in the vessel walls constrict causing a decrease in diameter of lumen -The lumen is the passageway through which blood flows and is found in every blood vessel Vasodilation: -Widening or relaxation of blood vessels -Smooth muscle cells in the vessel walls relax causing an increase in diameter Heart: -Located slightly to the left middle of chest -Size of your fist -Composed of cardiac muscle -Special muscle which contracts and relaxes involuntarily Chambers of the heart: -4 Chambers Total -2 ventricles & 2 atria -The left and right chambers are separated by a septum Inferior Vena Cava: -Carries deoxygenated blood from bottom of body to the right atrium Superior Vena Cava: -Carries deoxygenated blood from top of body to the right atrium Right Atrium: -Receives blood returning to the heart via superior/inferior vena cava -Deoxygenated blood from the body Right Ventricle: -Receives blood from the right atrium -Pumps deoxygenated blood to the pulmonary artery Pulmonary Artery: -Carries deoxygenated blood to the lungs (connected to the right ventricle) -Only deoxygenated artery Pulmonary Vein: -Carries oxygenated blood from the lungs to the left atrium -4 valves which prevent backflow of blood Left Atrium: -Receives blood via the pulmonary veins -Oxygenated blood from the lungs Left Ventricle: -Receives blood from the left atrium -Pumps oxygenated blood to the aorta which in turn goes to the entire body Aorta: -Receives oxygenated blood from the left ventricle and moves it to the rest of the body -Biggest artery in the body Tricuspid Valve: -Between right atrium and right ventricle Pulmonary Semilunar Valve: -Between right ventricle and pulmonary artery Bicuspid (mitral) Valve: -Between left atrium and left ventricle. Aortic Semilunar Valve: -Between left ventricle and aorta Heart Beat: -The heart is an involuntary muscle, meaning that our brain does not need to tell it to beat -The heart has coronary arteries which are branches of the aorta that supply the heart with oxygen and nutrients -In the walls of the right atrium there are a group of muscle cells (cardiomyocytes) collectively called the sinoatrial node which control heart beat How the Heart Beats: -The SA node is the heart's primary controller, controlling the rate at which the heart beats -On average the SA node triggers between 60-100 contractions a minute -If the SA node fails to control properly there is a secondary controller called the atrioventricular node (AV node) that maintains around 40-60 contractions a minute -If both fail, a final tertiary controller (Bundle of His) can coordinate around 20-40 contractions a minute Blood Clotting Process: -A blood clot is a plug, which helps stop bleeding from injury. -Our body naturally wants to clot when we undergo an injury. 1. Blood vessel damage 2. Cells release chemicals that cause platelets to bind to damaged areas 3. Platelets bind and help start a series of reactions 4. Prothrombin (inactive enzyme) —--------> Thrombin (active enzyme) 5. Thrombin catalyzes fibrinogen —---------> Fibrin 6. Fibrin is a mesh-like substance that forms the framework for the clot to form. As the fibrin mesh develops, it traps blood cells, platelets, and plasma, forming a solid clot. This clot reinforces the platelet plug, effectively sealing the wound and preventing further blood loss. Bruising: -Bruises occur as a result of damage to the bodies blood vessels -Blood is forced out of capillaries and has nowhere to go -As a result of having nowhere to go the blood pools under the skin -This is why a bruise appears as a dark mark Blood Pressures: -Blood pressure is a measure of the pressure exerted against blood vessels (mainly arteries) -Blood pressure measurements include two readings – a systolic pressure and a diastolic pressure -The systolic pressure is the pressure in the vessel when the heart is contracting (i.e. pulse flow) -The diastolic pressure is the pressure in the vessel when the heart is relaxing -We read blood pressure as systolic over diastolic -A normal blood pressure for a healthy adult is approximately 120 / 80 mmHg High Blood Pressure: Plaque: -Fat, calcium, cholesterol or other materials on and in arterial walls Atherosclerosis: -Hardening of arteries due to buildup of plaque of arterial walls. -The hardening and loss of elasticity of arteries -A loss of elasticity means that arteries are less able to regulate variances in blood pressure Aneurysm: -A bulging or weakened area in the wall of a blood vessel resulting in an abnormal widening greater than 50% of the vessel's normal diameter -An aneurysm may occur in any blood vessel, but is most often seen in an artery rather than veins because of muscles in an artery not able to handle the high blood pressure. It expands to create more room for the blood to flow and in theory, lower the blood pressure. There are four main blood types: A, B, AB, and O -Your blood also contains an additional Rh factor, either positive or negative -Your blood type is inherited from your parents Antigen: A substance in your blood that determines your blood type and what antibodies are produced Antibody: A blood protein produced by the bodies white blood cells in response to a specific antigen, a form of an immune response Given the wrong blood: -Hemolytic Transfusion Reaction leading to hemolysis -Your immune system will respond! -Your white blood cells will realize that there is an invader and move to try and get rid of all your red blood cells -This can be life-threatening Circulatory System: Open: Hemolymph (mixture of blood and tissue fluid) flows freely within the body cavity and makes direct contact with organs and tissues Examples: insects Closed: Blood is kept physically contained within vessels. The blood follows a continuous fixed path of circulation and is confined to a network of vessels that keeps the blood separate Examples: humans Steps of the Respiratory System: Ventilation: -Movement of air into and out of the lungs in two stages: Inhalation and exhalation Gas Exchange: -The process of oxygen diffusing from the blood into our cells that need it and waste products diffusing from the cells into the blood to be removed -There are two sites for gas exchange: Alveoli: Oxygen diffuses into the blood from the alveoli and carbon dioxide diffuses from the blood into the alveoli Tissues: Oxygen diffuses from blood into the cells and carbon dioxide diffuses from cells to the blood Cell Respiration: -Production of ATP at the cellular level -Once the body has oxygen we are now able to use it to create energy through the process of cellular respiration -Glucose + Oxygen —-----> Carbon Dioxide + Water + Energy (ATP) -The breakdown of glucose releases energy and this energy turns ADP into ATP -ATP is used to power the body and its cells -Carbon Dioxide is a waste product and removed via circulatory system and ventilation Nasal Cavity: -Air moves inside the nose and mouth -Air is warmed and moistened, which prevents damage to the thin, delicate tissue of the respiratory membrane -Nasal passages are lined with tiny hairs and mucus that filter out and trap dust and other airborne particles, preventing them from entering the lungs Pharynx: -Air then travels into the pharynx (throat) -Common to both digestive and respiratory systems -At the bottom is the epiglottis which prevents food from going into the trachea (open for breathing/closed for eating) Larynx (voicebox): -At the top of the trachea is the larynx (voicebox) -Made of cartilage -Used for sound production -Vocal cords are pulled together when air is being expelled to cause vibrations/ sound. Trachea: -Flexible tube made of semicircular loops of cartilage -Around 10-12 cm in length -The walls of the trachea are lined with mucus-producing cells and cilia, which further protect the lungs from foreign matter. Cilia are tiny hair-like structures that are found on some cells and move in a wave-like motion to sweep the trapped material upward through the trachea, where it is swallowed or expelled from the body when coughing or sneezing Bronchi -Branch off the trachea and enters each lung -Conducts the air into lungs Bronchioles -Each bronchi branches off into smaller tubes called bronchioles where they lead into the alveoli Lungs: -Right lung has 3 lobes and left lung has 2 lobes (due to heart) -Space between the pleural membrane and the lung is filled with fluid -Pleural membrane surrounds each lung. Allows for maximal and expansion without friction. -Outer layer is attached to the chest wall and inner layer to the surface of the lung Mechanism of Breathing: -Brain -Coordinates breathing movements -Receptors in the brain monitor the pH of the blood. The more CO2 there is, the more acidic the blood is, which causes an increased breathing rate in order to remove the carbon dioxide. -Controlled by the autonomic nervous system, meaning we don’t have to think about breathing Diaphragm and Rib Muscles -Control air pressure in lungs -Inhalation (Air taken into lungs): -The diaphragm contracts and moves downward -The external intercostal muscles contract and the thoracic cage (ribs) moves upward and outward -The volume of the chest cavity increases and the air pressure in the thoracic cavity decreases -The air pressure in the lungs is now lower than air pressure outside the body -Since air moves from regions of high pressure to regions of lower pressure, air rushes into the lungs. Exhalation (Air removed from the lungs) -The diaphragm relaxes and moves up -The external intercostal muscles relax and inner intercostal muscles contract and the thoracic cage moves downward and inward -The volume of the lungs decreases, the air pressure inside the lungs increases, and air moves from the lungs to the lower-pressure environment outside the body -Air is forced out of the lungs by squeezing action of chest cavity and is aided by: ​ i) elastic recoil of tissues ​ ii) thoracic and abdominal wall muscles Diffusion: -Movement of a substance across a membrane from high concentration to low concentration -Diffusion is the process which exchanges gasses for respiration -Diffusion occurs across membranes, which are semi-permeable -Membranes are more permeable to gasses when moist -Moisture allows gasses to turn into liquids as they cross the membrane with the aim of these gasses to be dissolved into the blood (a liquid) Ventilation System: -Unlike many other animals, humans are at a disadvantage when it comes to respiring due to our large bodies -Oxygen is not able to diffuse directly into our cells from the air, and at the same time waste cannot be removed this way -We need specialized organs (lungs and its components) to help bring in oxygen and remove waste -*Gasses also need moist surfaces (membranes) in order to diffuse and our lungs are moist membranes* Alveoli: -Custers at the ends of the smallest bronchioles -They function as the site of gas exchange, and hence have specialized structural features to help fulfill this role: 1. They have a very thin epithelial layer (one cell thick) to minimize diffusion distances for respiratory gasses 2. They are surrounded by a rich capillary network to increase the capacity for gas exchange with the blood 3. They are spherical in shape, in order to maximize the available surface area for gas exchange 4. Their internal surface is covered with a layer of fluid, as dissolved gasses are better able to diffuse into the bloodstream -The ventilation system maintains a large concentration gradient between the alveoli and the blood -Breathing out keeps the CO₂ concentration in the alveoli low, so it diffuses out of the blood -Breathing in keeps O₂ concentration in the alveoli high so it diffuses into the blood Asthma: -Chronic inflammation of the lungs and overproduction of the mucus in the lungs due to airborne substances such as pollen, aerosol sprays, and exercise -Causes narrowing of the air passages of the bronchi and bronchioles which reduces air flow -Experience wheezing, coughing, tightness in the chest and shortness of breath Asthma Attack: -Muscles around the airways contract and cells in the airways may increase mucus production, which further blocks airflow -Hand-held inhaler used to manage asthma by relaxing the bronchial muscles and reducing inflammation, opening up the airway Emphysema: -Protease released by white blood cells and inflamed lung tissue breaks down the connective tissue of the lungs. This results in the destruction of small airways and alveoli. This results in the formation of large air pockets and the breakdown of capillaries. -Large air pockets have a lower surface area to volume ratio than the alveoli which causes insufficient ventilation. When combined with the reduced blood supply this in turn means inefficient gas exchange and hence low blood oxygen levels. -The main cause of emphysema is smoking but it can also develop in people with a long history of chest infections or by air pollution. Bronchitis: -Causes inflammation of the mucous membranes of the bronchi -Classified as: Acute – due to infection, ex: bacteria Chronic – due to an irritant, ex: Cigarette smoke Chronic Obstructive Pulmonary Disease (COPD): A long-term respiratory disease that is a combination of two diseases—bronchitis and emphysema Tumour/Lung Cancers: -Tumors are abnormal growth of tissue that develop at any stage of life in any part of the body. -Cells do not go through planned cell death and multiply rapidly. Cancer is a malignant tumor. -Smoking, passive smoking and exposure to radon, all leads to lung cancer -Starts in the trachea, bronchus or lung tissue Pneumonia: -An infection caused by bacteria, viruses, or fungi -Causes the lungs to be inflamed and filled with fluids -Interferes with gas exchange 3 Types of Pneumonia: 1. Bronchial Pneumonia: Affects patches throughout both lungs 2. Lobar Pneumonia: Affects Lobes 3. Interstitial Pneumonia: Bacteria gets into the lining of the lung Cystic Fibrosis: -Cystic Fibrosis is an autosomal recessive lung disease that is caused by a mutation of the CF gene on chromosome 7 that produces the CFTR protein. -CFTR proteins regulate the flow of chloride ions and water in/out of cell membranes throughout the body. -Traps bacteria, hard to clear foreign particles -Mucus prevents the pancreas from releasing digestive enzymes and insulin GI tract functions: Oral Cavity: -Chewing breaks down food into more digestible pieces -Salivary glands secrete saliva containing enzymes like amylase to break down carbohydrates Esophagus: The esophagus is a muscular tube that connects the pharynx with the stomach. Its main function is to transport food and liquids from the mouth to the stomach through a series of muscular contractions called peristalsis. Stomach: -Primary function is to break down food into smaller pieces, mix it with digestive juices, and then slowly release it into the small intestine for further digestion. -This process is able to be done due to the stomach's muscular walls, which churn and mix the food with gastric juices containing acids and enzymes. -Serves as a temporary storage reservoir for food before it continues its journey through the digestive tract. Small Intestine: -Located between the stomach and the large intestine. -Main function is to further digest food and absorb nutrients into the bloodstream. -Receives partially digested food from the stomach and continues the process of breaking it down using enzymes produced by the pancreas and bile from the liver. -Has specialized structures called villi and microvilli, which increase its surface area for efficient nutrient absorption. Large intestine: -The large intestine is the final part of the digestive system. Its main functions include absorbing water and electrolytes from the undigested food material that passes through it and forming solid waste (feces) for elimination from the body. -The large intestine also houses a large population of beneficial bacteria that help ferment undigested carbohydrates and produce certain vitamins, such as vitamin K and some B vitamins. Rectum: -The rectum is the final part of the large intestine, located just before the anus. Its primary function is to store feces until they are ready to be expelled from the body during defecation. Anal Canal: -The anal canal is the terminal part of the large intestine, connecting the rectum to the outside of the body through the anus. Its main function is to allow the passage of feces out of the body during defecation. Liver: -The liver is a vital organ located in the upper right side of the abdomen, beneath the diaphragm. It performs numerous important functions in the body: The liver metabolizes nutrients from food, filters and detoxifies harmful substances, synthesizes important proteins stores essential nutrients such as vitamins (A, D, E, K) and minerals (iron and copper), as well as glycogen, a form of glucose used for energy, the liver produces bile, a digestive fluid that helps break down fats in the small intestine during digestion. Gallbladder: -The gallbladder is a small, pear-shaped organ located beneath the liver. -Main function is to store and concentrate bile, a digestive fluid produced by the liver. -When we eat a meal, especially one that contains fatty foods, the gallbladder contracts and releases bile into the small intestine through the common bile duct. Pancreas: -The pancreas secretes several digestive enzymes into the small intestine. -Neutralizes the stomach's acidic chyme. --------------------------------------------------------------------------------------------------------------------- Evolution Evolution: The theory of evolution is that all living species are the modified descendents of earlier species, and that we all share a common ancestor in the distant past. Evidence of evolution: -Anatomy: looking at comparisons of today’s very different organisms can show us that they may have been related a long time ago. Example, the bones in our arms: -Biochemical: The chemicals that are used in Metabolism and to make up cells have not changed. Example: ATP, the molecule used to generate energy in cells has not needed to change throughout time. Common ancestors evolved ATP and never changed it, because if the change were to not work, the species would die. Evolution is conservative, meaning that if something is working fine, there is no need for innovation. -Development: Comparisons of the early stages of embryonic development can reveal similarities among species that are not obvious from comparisons of adult organisms. -DNA and Genes: The gene Sonic hedgehog in patterning limbs during embryo development is the same in fish, birds and mammals. Homologous vs analogous: Homologous traits are traits that share a similar embryonic origin. Ex: the limbs of tetrapods. Analogous traits are traits that share the same function but NOT the same origin. Ex: wings of birds and bats. Some features of animals can be both a homologous and an analogous trait. For example the wings of birds and bats, which share a similar embryonic origin and have the same purpose (flight). However, birds and bats do not share an ancestor that flew, as they evolved independently. The bone pattern of 1 - 2 - little bones - digits, is found in both birds and bats. Evolutionary Change: Evolution may be defined as changes in the genetic material of a population over time. These changes could be: Adaptive: Increase in frequency of traits that improve chance to survive and reproduce. Random: Frequency of traits in a population changes due to random events. Mechanisms of Evolution: 1. Natural Selection (VIDA): V - Variation: The genetic variation within a population (eye color, tooth length…) I - Inheritance: Traits are passed down from parents to offspring D - Differential survival/Reproduction: Individuals with certain traits are more likely to survive and therefore reproduce A - Adaptation: Over time, the population becomes better adapted to its environment due to the accumulation of beneficial traits. Natural selection is the most important mechanism of evolution because it is the primary driver of adaptation. It allows populations to become better suited to their environments over time. 2. Gene Flow: The migration of organisms into or out of a population which changes the gene pool of each population. (Ex. A red bird flew into a blue bird only zone and started creating more red birds, changing the gene pool of the blue bird population) 3. Genetic Drift: A drastic decrease in the population size, leaving only those genes present in the remaining individuals in the gene pool. (Ex. A volcano exploded killing 90% of the elk population, the genes of the 10% that survived would be more prominent) 4. Mutation: Random changes to a gene that may result in a new trait. (Ex. A gene code for fur color having a mutation might result in a new fur color). Different versions of genes are called alleles. 5. Non-Random Mating: The likelihood that organisms will select their mate based on certain criteria such as color, size, or other mating behaviors. (Ex. In a species of birds, a female bird selects a mate based on his song) Speciation: -A species is often defined as a group of individuals that actually or potentially interbreed in nature. -Speciation is a process that can result from natural selection acting on multiple heritable traits over time. Two species may be considered the same and not the same if they can: -Reproduce a hybrid in nature (same) -Look different (different) -Eat different things (different) -Behave different (different) Reproductive Isolation: Factor that prevents 2 populations from interbreeding when they live in the same region. When populations become isolated they can evolve into two different species Reproductive isolation could develop in a variety of ways including: Behavioral isolation: the presence or absence of a specific behavior that prevents reproduction between two species from taking place. (Ex: singing birds) Geographic isolation: This happens when populations are separated by geographic barriers. Temporal isolation: Two populations reproduce at different times. (Ex. 2 similar orchids that live in the same forest but pollinate on different days, meaning they can’t pollinate each other.) Types of Cells: Prokaryote: -Organisms contain no nucleus or other membrane bound organelles -DNA is found in circular chromosomes and in a loop called a plasmid Eukaryotic: -Cell contains membrane bound organelles (Ex. Nucleus, chloroplast, mitochondria) -DNA is found in linear chromosomes Both Cell types have: -Cytoplasm -Cell membrane -Ribosomes Classification: Taxonomy: Science of identifying and classifying all organisms. Phylogeny: The study of the evolutionary relationships among species. Limiting Factors: Factors in an environment capable of limiting the growth of a population (Ex: lack of food) Selective Pressure: Causes that reduces or increases reproductive success in a portion of a population. (Ex: Predators) The Linnaean System: -Named after Swedish botanist, Carl Linnaeus -Consists of hierarchy of taxa(groups) -Based on similarity of traits Phylogenetic Trees (Cladogram): -Represent evolutionary relationships among a group of organisms -Tips of tree are descendant taxa -Nodes of the tree represent the common ancestor of the descendants -A clade is a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor. 6 Kingdoms of Life: Bacteria: -Domain: Bacteria -Unicellular -Reproduce: Asexual -Gain energy: Photosynthesis, Inorganic/Organic compounds -Present in every habitat on Earth (including humans) -Vital in cycling nutrients Archaea: -Domain: Archaea -Unicellular -Reproduce: Asexual, Binary fission -Gain energy: Inorganic/Organic molecules -Extreme environments -Broad range of habitats Protists: -Domain: Eukarya -Mostly unicellular -Reproduce: Asexual/Sexual -Gain energy: Sunlight, Organic compounds -Loose grouping of 30-40 phyla (Ex. Algae, diatoms) Fungi: -Domain: Eukarya -Most are multicellular -Reproduce: Asexual/Sexual -Gain energy: Decomposition of organic compounds -Cell wall made of chitin -Form symbiotic relationships with other organisms -Important in brewing, wine making, antibiotics (Ex. Mushroom, mold, yeast) Plants: -Domain: Eukarya -Multicellular -Reproduce: Asexual/Sexual -Gain energy: Photosynthesis -Cell walls made of cellulose (Ex. Ferns, mosses, plants) Animals: -Domain: Eukarya -Multicellular -Reproduce: Asexual/Sexual -Gain energy: Digest organic materials -Contain protein collagen -Are motile during at least one stage of life -Mostly Invertebrates (97%) (Ex. Worms, jellyfish, insects) ------------------------------------------------------------------------------------------------------------------ Diversity Requirements for life: -Body to separate itself from the environment (even just a cell) -Metabolism to obtain and convert energy/resources from environment into growth and repair -Inheritable information (genes) -Move or grow in response to stimuli -Reproduce -Evolve Viruses are in between: -Not living because they have no cellular structures -Strands of DNA or RNA (genetic material) surrounded by protein coat called a capsid -Life is a continuum with viruses in the middle: Non-living Living (crystalline) Viruses (cellular) Virus Classification: -Size and shape -Disease they cause -Nucleic acid core (DNA or RNA) Viral Reproduction: Lytic Cycle: 1. Attachment and entry: Virus attaches to proteins on the cell membrane using the “lock and key” mechanism and enters the cell. 2. Synthesis: Viral DNA or RNA used by host cell machinery to replicate virus components (enzymes, genetic material, capsid proteins) 3. Assembly: Viral parts assemble into new viruses 4. Release: Newly formed viruses are released, killing host cell Examples: Influenza or COVID-19 Lysogenic Cycle: 1. Attachment and entry * Genome Integration: Viral genetic information is incorporated into host cell’s genome When the host cell divides, the viral genome is copied with the host cell’s genome 2. Synthesis 3. Assembly 4. Release Examples: HIV, Herpes (Cold sores) Vaccine: -When an unfamiliar pathogen invades our body, immune cells engulf a few of them to gather intel about them. They then send out a chemical alarm which transmits the enemies information to start the production of specially targeted antibodies to fend off the rest of the attack. After the pathogen is defeated, some of the specialized cells stay around in case the pathogen returns to mount a quicker response. -Vaccination helps us stage a practice version of this battle in advance, so that the immune system can develop antibodies specifically targeted to the enemy. This requires introducing a bit of the enemy pathogen into our bodies, but they are either already killed, breed to be a super weak strain, or dismembered to not be dangerous. -Formaldehyde found in vaccines, alters the structure of pathogens just enough to render them harmless. Adjuvants like aluminum, cause a minor irritation at the injection site summinging immune cells to the scene so they’ll encounter the weakened enemy, putting the immune system on high alert. Archaea: -Biochemically and genetically as different from bacteria as they are from eukaryotic organisms. (Biochemically refers to chemicals used in metabolism and that make up the organism (ex: lipids in cell membrane)) -Discovered in extreme environments (salty, acidic, hot). Halophiles are salt-loving archaea -Not restricted to extreme environments, as they are found in oceans, soils, in and on animals Energy Metabolism: 1. Phototrophs: Source of energy is the sun (Photosynthesis evolved in bacteria) 2. Lithotrophs: Source of energy is inorganic compounds (ex: metal ions) 3. Organotrophs: Source of energy is organic compounds (Organic compounds contain carbon) Carbon Metabolism: Autotrophs: Use inorganic carbon (CO2) Heterotrophs: Use organic carbon sources Inorganic means from non-living as opposed to organic which means from living or once living Facultative anaerobes prefer to live in the presence of oxygen but can survive without it. In contrast, obligate anaerobes cannot live in the presence of oxygen. Reproduction: Bacteria & Archaea reproduce asexually through binary fission: 1. Cell replicates genetic material 2. Genetic material separates to opposite poles 3. Cross-wall forms 4. Daughter cells formed Exchange of Genetic Information: -Conjugation: Transfer of genetic material between bacterial cells by direct cell-to-cell contact. Since conjugation involves only the transfer of genetic material, no new cell is created during the process making it different from sexual reproduction. -Transduction: Process of DNA being accidentally transferred from one bacterium to another by a virus -Transformation: Uptake of DNA from environment that is then incorporated into bacterial DNA Bacterial Classification: Shape: spherical → cocci rod-shaped → bacilli spiral or corkscrew-shaped → spirilla Configuration: in chains → add the prefix strepto- to the shape in clumps → add the prefix staphylo- to the shape Gram Stain: -Based on amount of peptidoglycan in cell wall -Tested with Gram stain -Blue or purple color → Gram positive (has thick layer of peptidoglycan) -Pink color → Gram negative Antibiotic Resistance: Gained from the 3 methods of genetic exchange and mutations: -Resistant gene transferred on a plasmid during conjugation -Acquiring DNA containing resistant gene found in the environment during transformation -Inheritance of resistant gene from parent cell during binary fission -Random mutation of DNA What they do: -Antibacterial agents interfere with specific processes essential for bacterial growth and reproduction. Ex: Prevent building or repairing of cell wall/membrane, disrupt production of RNA or DNA, and prevent bacterial metabolism. How do bacteria protect themselves: Cell Membrane: Functions: -All life requires a body, which a cell membrane provides -Provides a barrier to the environment -Allows selective transport of materials in and out of cell -Allows compartments to be created in cell (nucleus in eukaryotes) -Allows cell to send and receive signals -Provides a site for metabolism and binding -Unlike prokaryotes, eukaryotic cells also possess internal membranes that encase their organelles -Selectively Permeable, maintaining the cell’s internal environment. Whether a molecule or ion can enter or exit the cell depends on its: size, polarity (one side of the molecule is slightly negative and the other side is slightly positive), and charge. Inside of the membrane: -Small nonpolar or polar molecules: In most cases, the concentration of small nonpolar and polar molecules will be greater outside the cell compared to inside the cell. This is due to the selectively permeable cell membrane that only lets in a small amount of these molecules. -Phospholipid: Composed of a hydrophilic head and a hydrophobic tail. The phosphate head is hydrophilic (“water loving”), polar and water soluble. The two fatty acid chain tails are hydrophobic (“water repelling”), non-polar and water insoluble. The separation of electric charge of both ends of the phospholipid makes it a polar molecule. Being the primary molecule making up plasma membranes, it is composed of a phospholipid bilayer whose tails are facing each other. This is because the heads are hydrophilic interacting with the aquatic cellular environment and tails avoid contact with water. -Small surface protein: This peripheral protein is fully on one side or the other of the cell membrane and moves around to let different molecules enter the cell. Membrane-spanning protein: Found in the cell membrane, these proteins carry out many different functions such as: transport glucose molecules in or out of the cell, metabolic activity, Receive Signals and cell recognition. Endosymbiosis: Endosymbiosis is when one organism is living completely inside another organism. Since endosymbiosis is only a theory, here is the evidence: 1. Double membranes: The presence of an inner and an outer membrane suggests that ancient bacteria were engulfed in cell membrane 2. Ribosomes and DNA: Mitochondria and chloroplasts contain their own ribosomes and DNA (separate from rest of cell) 3. Reproduction: Reproduce independently from the rest of the cell The endosymbiotic theory explains how organelles inside eukaryotic cells are descended from ancient unicellular prokaryotic organisms and how simpler organisms combine their different abilities to live together. Mitochondria: The Organelle responsible for producing energy in eukaryotic cells. ATP is the principal molecule for storing and transferring energy in cells, energy is released when the phosphate bond is broken and the molecule turns into ADP. Cellular respiration:​ -The mitochondria in eukaryotes produces ATP via a 4 steps process called cellular respiration. -A 4 step process is necessary due to the sheer amount of energy released in the reaction and because multiple steps can be run at the same time increasing efficiency. Photosynthesis: The process of Photosynthesis occurs entirely in chloroplast which converts the sun’s energy into chemical energy which mitochondria consume to produce ATP which can be used in the cell. Much like mitochondria, chloroplast requires its own DNA and ribosomes to synthesize their own proteins and replicate individually. The inner membrane of chloroplasts is similar to the membrane of an ancient prokaryotic organism that could perform photosynthesis. Photosynthesis is divided into 2 stages: Stage 1 - Photo Stage: Absorbs photons of light using specific pigments (called chlorophyll). The light energy is then used to generate ATP. Stage 2 - Synthesis Stage: Uses ATP generated by photo stage to convert carbon dioxide into glucose through Calvin Cycle. Membrane Bound Organelles (Compartments): -Compartments allow separation of chemical reactions, increasing efficiency -Outer and inner membranes are selectively permeable ensuring molecules required for reactions are present in compartment -Folding of the membrane increases surface area for allowing molecules to flow in and out and more space for cellular machinery -Proteins required to run the reactions are embedded in the inner membrane --------------------------------------------------------------------------------------------------------------------- Genetics Meiosis: -Meiosis is a special form of cell division to form sex cells (gametes) -Two key functions: 1. To form haploid cells (n) with half the normal chromosome number: starting cells (spermatocyte/oocyte) have 46 chromosomes and ending cells (gametes) have 23 chromosomes 2. To re-arrange the chromosomes with a novel combination of genes (genetic recombination) Stages: Interphase: Since we count chromosomes by the number of centromeres present when the 46 chromosomes duplicate, there are still 46 centromeres and thus 46 chromosomes, but there are 92 chromatids, as they have been duplicated. Prophase l: -Chromosomes line up with their homologous pairs (chromosomes that are about the same size, one from paternal origin and one from maternal origin and contain the same types of genes in the same location with different alleles). -Crossing over: Chromosomes lined up in their homologous pairs exchange genetic information between each other creating recombinant chromosomes. Metaphase l: -Chromosomes are in homologous pairs randomly lined up in the middle of the cell (independent assortment). Anaphase l: -Chromosomes are pulled away by the spindle fibers. Telophase l: -Two newly formed nuclei. Cytokinesis: -Splits the cytoplasm into both new cells. Prophase ll: -Spindles start to form. Metaphase ll: -Chromosomes are in a single file lined up in the middle of the cells. Anaphase ll: -Chromatids are pulled away by the spindle fibers. Telophase ii: -Four newly formed nuclei. Cytokinesis: -Splits the cytoplasm into all four cells. Errors in meiosis: Non-disjunction: failure of chromosomes to separate properly: Trisomy: The presence of an extra chromosome Monosomy: The lack of a chromosome Diseases: Mendelian Diseases -A disease caused by mutation in one gene. -Follows Mendel's laws of inheritance; can be either dominant or recessive. -Examples: Cystic fibrosis, sickle cell anemia, hemophilia A, huntington's disease Chromosomal Disease -Caused by alterations in chromosome structure or number -Many be diagnosed by karyotype -Examples: Down’s syndrome, Klinefelter’s syndrome, Turner’s syndrome Karyotype: Image of a person’s chromosomes isolated from an individual cell and arranged in numerical order. May be used to look for abnormalities in chromosome number or structure. Others -Most diseases are the result of multiple genetic changes and/or interactions, as well as environmental influences. -Scientists are devising new ways to identify the different genes that contribute to complex diseases. -Example: breast cancer, coronary artery disease, diabetes.