Bio 211 Anatomy and Physiology I Fall 2024 PDF

Bio 211: Anatomy and Physiology I Fall 2024 Lecture: Tuesday and Thursday, 9:30-10:50am (SLC 120) Lab: Times vary (check your own schedule) (Stark 217) Instructor: Mark Garbrecht, Ph....

Bio 211: Anatomy and Physiology I Fall 2024 Lecture: Tuesday and Thursday, 9:30-10:50am (SLC 120) Lab: Times vary (check your own schedule) (Stark 217) Instructor: Mark Garbrecht, Ph.D. 234 Pasteur Hall [email protected] Phone: 457-2261 Class website: https://mgarbrecht.wixsite.com/garbrechtbio211 Lecture notes, lab handouts, announcements, etc…. CONNECT website: https://connect.mheducation.com/class/m-garbrecht-garbrecht-fall-2024-bio-211 Access to E-book, tutorials, animations, virtual anatomy lab CHECK OFTEN FOR COURSE MATERIALS AND ANNOUNCEMENTS!!!!!  What is the study of Anatomy and Physiology? “Form and Function” Anatomy Physiology “Form” “Function” What is it? What does it do? 1.Scientific name (SPELLING!!) 1.How does it do it? 2.Location 2.How does it affect other organs, structures 3.Relation to other structures 3.What regulates its action/function 4. Association with other structures  How do we study anatomy? Observation See it, feel it, hear it! Palpation- - What does it feel like? - Is it hard, soft, dense, spongy, light, heavy? Auscultation and percussion - What does it sound like, what sound does it make? - Is it hollow, solid? Check for air/fluid pockets in medical exam - Does it sound “normal”? Check heart rhythm, pulse 1. Gross anatomy- study of structures that we can see with naked eye 2. Histology (microanatomy)- study of structures at the microscopic , cellular level using a microscope  How do we study physiology? Experimentation, Measurement, Data Analysis Do something to someone or something under defined circumstances and OBSERVE what happens and compare that to what happens to a CONTROL group Example: 1. 200 people get a pill with Drug A, that is supposed to lower blood pressure (EXPERIMENTAL GROUP) 2. 200 more people get a pill that doesn’t have any Drug A (CONTROL GROUP) 3. OBSERVE blood pressures in all of the people and compare experimental group to control group Were the blood pressures different between the two groups after they took the pill? Yes- Drug A does in fact lower blood pressure No- Drug A has no affect on blood pressure Its important to make sure both groups were treated EXACTLY the same way. i.e., one group didn’t run a marathon prior to taking the pill -this would make the results invalid  Bio 211- Anatomy and Physiology I Today’s Topics: Hierarchy of the human body General orientation of the human body §Anatomical position §Anatomical planes §Directional terms §Body regions §Body cavities Homeostasis §Positive Feedback §Negative Feedback Structural hierarchy in human biology Biggest, most complex Human Body Organ system (cardiovascular system) Organ (Heart) Tissue (cardiac muscle) Cells (cardiomyocytes) Organelles (nucleus, mitochondria) Macromolecule (Protein, DNA) Molecule (amino acid) Atom (nitrogen, carbon, oxygen) Smallest  Anatomical Position Standing upright Feet flat on ground Arms at side Palms facing forward Eyes and face forward Important in anatomy because it provides a universal frame of reference that ALL anatomists use when talking about location  Anatomy Directional Terms Allows you to describe the location of one structure in relation to another when the body is in the ANATOMICAL POSITION!  Anatomical Planes Frontal: Extends vertically and divides body into dorsal and ventral regions (i.e., front and back) Sagittal: Extends vertically and divides body into left and right halves Transverse: Extends horizontally and divides body into superior and inferior regions (i.e., top and bottom)  Anatomical Planes Looking Looking anteriorly/posteriorly laterally/medially Understanding these planes is essential in radiology X-rays, MRI, CT-scans, etc Looking inferiorly/superiorly  Body Cavities Primary body cavities Secondary body cavities Posterior cavity Cranial cavity - Brain Vertebral canal – Spinal cord Anterior cavity Thoracic cavity : Mostly occupied by lungs and pleural membranes surrounding lungs Mediastinum- Contains esophagus, trachea, larynx, and heart and pericardial membranes surrounding heart Abdominopelvic cavity: Abdominal cavity – digestive organs, spleen, kidneys Pelvic cavity – Bladder, rectum, reproductive organs  Body Cavities Pleural, pericardial, peritoneal membranes are DOUBLE layers of membrane ü Parietal layer -lines a cavity (i.e., parietal pleura) ü Visceral layer –lies on the surface of an organ (i.e., visceral pleura) ü Membranes secrete lubricating fluid called SEROUS FLUID ü Infection of membranes or accumulation in cavities of fluid is a serious concern!!  Homeostasis Concept that the body will react to INTERNAL or EXTERNAL changes in order to maintain the status quo or a “normal” state and meet body’s metabolic demands 1. Body is constantly monitoring and making adjustments to temperature, blood pH, blood sugar levels, blood pressure, etc…… Loss of homeostasis Pathology and Disease! 2. Large focus of physiologists is to understand how this happens How does the body respond to changes and regulate itself? Positive and negative feedback mechanisms  Negative Feedback 1. Process by which the body detects a change (BAD!) and then tries to reverse those changes 2. Primary mechanism that the body uses to maintain homeostasis Example : Body temperature maintenance 1. Body temp rises on a hot day 2. Body reacts by causing vasodilation (blood vessels expand) and sweating 3. Excess heat escapes through skin, evaporation of sweat 4. Body temp falls and returns to normal Often times changes in many organ systems are required to maintain homeostasis  Positive feedback 1. Process by which the body detects a change and causes a GREATER change in the SAME DIRECTION (i.e., more of the same) A self-amplifying response 2. Less common than negative feedback, but still very important! Example: Uterine contractions during childbirth 1. Pressure of baby against cervix activates stretch receptors 2. Body releases hormone that INCREASES contractions 3. Contractions increase and forces baby towards cervix, causing more pressure 4. Also seen in function of digestive system, cardiovascular system, immune system etc…  Positive and negative feedback loops Feedback loops utilize receptors, integrating centers in brain/spinal cord, and effectors to bring about change Integrating centers in brain/spinal cord Control centers for respiration, cardiovascular function, etc… Effectors Receptors and sensors Structure (heart, lung, glands, etc…) that gets signal Structures found in blood vessels, organs that from brain and CAUSES change to restore monitor and detect changes homeostasis  Bio 211- Anatomy and Physiology I Today’s topics Atomic structure, charge Polarity Chemical bonds Solubility pH Chemical reactions and enzymes  Why do we need to understand chemistry to understand biology? Essentially, the human body is one big chemistry experiment At any one time there are BILLIONS of chemical reactions are taking place Your ability to see, hear, breathe, and think are all dependent on chemistry Chemical reactions involved in the production of tryptophan (an amino acid)  Atomic Structure and Charge Surround the nucleus like a cloud Electrons: - charge Protons : + charge Neutron: no charge Nucleus of an atom IONS ATOMS Atoms can give up or take electrons from other atoms in a process called ionization If an atom has UNEQUAL numbers of protons and electrons it is an ION Positively charged ion = CATION Negatively charged ion = ANION  Polarity When two atoms form a bond, electrons are often shared between the two atoms When two identical atoms form a bond, the electrons are equally shared Ø Creates a NON-POLAR MOLECULE When two different atoms form a bond, the electrons are not shared equally Ø Electrons (-) are “pulled” towards one atom Ø Results in one end of the molecule being (+) and one end being (-) Ø Creates a POLAR MOLECULE  Chemical bonds Chemical bonds allow atoms to get together and form molecules and allows molecules to come together to form larger macromolecules 1. Hydrogen bonds – Very weak, easily made and broken - no transfer or sharing of electrons - VERY important in biology!!! 2. Ionic bonds – Pretty weak - involves transfer of electrons from one atom to another 3. Covalent bonds – Very strong, not easily broken - involves sharing of electrons between atoms  Ionic Bonds 1. Formed by attraction of a cation to an anion 2. Easily broken 3. Important for the chemistry of electrolytes Dissociation occurs because ions are more attracted to water (a polar molecule) than to each other Important because Na+, Cl-, Mg2+, Ca2+ need to be IONS in the human body – required for nerve, muscle, bone function  Hydrogen bonding Weak interaction between the slightly positive charge of a H+ atom and the slightly negative charge of O, N, or P very important in physiology – H, O, N, P make up almost 80% of your body!!! allows molecules to be built up and broken down relatively easily works sort of like a magnet Important for structure of protein, DNA, RNA - +  Solubility General rule is that “like dissolves like” Polar molecules are soluble with other polar molecules Nonpolar molecules are soluble in other nonpolar molecules Since water makes up ~60% of our bodies, solubility in water (polar) is an important consideration (drugs, hormones, waste products, etc….): Hydrophilic molecules dissolve in water….because they are typically polar (or have a polar region) Hydrophobic molecules do not dissolve well in water - typically nonpolar (oils and fats) Oil vs Alcohol Oil is hydrophobic Ethanol (alcohol) ü Doesn’t mix is hydrophilic well in water ü Mixes easily in water  Acids, bases, and the pH scale Acids are molecules that can give up H+ ions Bases are molecules that can accept H+ ions pH is a measurement of the relative concentration of H+ ions as compared to pure water Adding an acid to water will increase H+ concentration making the solution acidic Adding a base to water will decrease the H+ concentration making it basic pH scale ranges from 0 (very acidic) to 14 (very basic) -----Water pH = 7.0  Acids, bases, and the pH scale pH is very important to human physiology blood pH MUST be near 7.4 for normal health if blood pH is altered, that means the H+ concentration is too high or too low changes in pH affect hydrogen bonding and therefore affect the function of many enzymes, hormones, and drugs low pH (acidic) environment DENATURES proteins, DNA, RNA and prevents cells from functioning Alkalosis = pH is too high (above 7.45) Acidosis = pH is too low (below 7.35)  Catabolic and Anabolic reactions In living cells, molecules are constantly being broken down into smaller molecules (catabolic reaction) or built up into larger molecules (anabolic reactions) Anabolic reactions often USE energy, catabolic reactions often RELEASE energy üExample: The breakdown of ATP into ADP + P yields energy ATP + H2O ADP + P + ENERGY (to be used by cell) + ENERGY!! anabolic catabolic “What ANA makes, the CAT breaks”  Reaction rates and catalysts Many chemical reactions in the body occur VERY slowly and need to be sped up in order to keep us alive, therefore we need CATALYSTS to speed them up CATALYSTS allow many reactions to occur at physiological temps/pH Biological catalysts are called ENZYMES Enzymes are proteins that help form OR break chemical bonds (often makes reactions occur 1,000s or 1,000,000s times faster!!) üSucrase enzyme breaks down sucrose sugar (bigger) into glucose and fructose (smaller) Enzymes are usually very specific about which molecules they will bind and reactions they carry out  Bio 211- Anatomy and Physiology I Today’s topics Oxidation/reduction Organic chemistry Monomers/polymers Proteins  Oxidation/Reduction Reactions Oxidation – a reaction in which a molecule GIVES UP an electron Reduction – a reaction in which a molecule GAINS an electron Redox reactions are very important in biology and allow the transfer of energy (in the form of electrons) from one molecule to another **** Important for metabolism of nutrients needed for ATP production, metabolism/breakdown of waste products, metabolism/breakdown of hormones and signaling molecules LEO the lion says GER!!!! Loss of Electrons = Oxidation Gain of Electrons = Reduction  Oxidation/Reduction Reactions, cont… When good Redox reactions go BAD (sometimes)! Free Radicals: molecules with an extra electron Ex. : O. (superoxide anion – an oxygen free radical) - 2 Oxygen normally exists as a molecule (O2) but can pick up an extra electron during normal metabolic reactions, or through exposure to radiation (UV light, X-rays) or chemicals Oxygen free radicals do have a useful purpose in the killing of bacteria and viruses by white blood cells (only need a small amount in the right place though) Free radicals are VERY dangerous and can damage DNA, proteins, cell membranes, etc… üDamage from oxidation is linked to heart disease, inflammatory diseases, and CANCER! Free radicals are normally controlled and neutralized by ANTIOXIDANTS üAntioxidant enzymes (made by our body) and vitamins in our food (vitamin A, C, E, etc..)  Organic Chemistry Organic chemistry is the study of carbon containing compounds Organic molecules contain a CARBON BACKBONE (often branched or a ring structure) with a variety of FUNCTIONAL GROUPS attached The type of functional group attached determines the properties of the molecule üMake sure you can identify these by sight C I C I C-C-C-C-C=O Functional group OH Carbon backbone  Monomers/Dimers Many biological macromolecules exist as MONOMERS that combine to form POLYMERS Mono=1, Di=2, Tri=3, Poly=many MONOMERS (one molecule) POLYMERS (many molecules) Amino Acids Proteins Nucleotides DNA, RNA Monosaccharides Polysaccharides (sugars) Fatty Acids Lipids, fats Glycerol Dehydration synthesis: required for polymerization, involves removal of water (H2O) Hydrolysis: addition of H2O required to break polymers into monomers  What do proteins do in our body?? Proteins pretty much “do” everything: 1. Structure: collagen and keratin make up our bones, skin and hair 2. Communication: peptide hormones carry messages from cells in one area of the body to another; receptors needed for all cell signaling molecules 3. Transport: channels and transporters on the cell surface regulate what goes in and what goes out of a cell 4. Catalysis: enzymes speed up normally slow chemical reactions 5. Recognition and protection: proteins on our cell surface specify “self” vs. “non-self” - helps our body recognize our own cells vs. bacteria or viruses 6. Movement: cilia, flagella help move things within an organ. Actin and myosin allow muscles to contract and move the whole body 7. Cell adhesion: proteins allow cells to attach to one another and attach to other structures (i.e., muscle to bone) Amino Acids and protein structure Proteins are polymers of amino acids 20 different amino acids combine in different variations to form ALL the proteins in your body! All amino acids contain a similar “backbone” and then a variable FUNCTIONAL GROUP Our bodies can synthesize most amino acids from other materials (12), but some have to come from food we eat ü8 “Essential Amino Acids” Dehydration synthesis Peptide bond  Amino Acids and protein structure Amino acids are connected to each other by PEPTIDE BONDS 2 amino acid chain = dipeptide 3 amino acid chain = tripeptide Anything longer we just call a POLYPEPTIDE (a.k.a., protein) The CONFORMATION (3D shape) of a protein is critically important to its function The amino acid sequence will determine a protein’s conformation and therefore its function i.e., changes in a.a. sequence lead to changes in protein conformation and function Even a small alteration in conformation or amino acid sequence can alter its function  Amino Acids and protein structure Protein conformation and function is heavily dependent on : pH – changes in pH alter H+ ion concentrations and affect hydrogen bonding. Temperature – high temperatures (lots of kinetic energy) can cause hydrogen bonds to break Redox environment – oxidizing or reducing conditions alter the ability of proteins to maintain disulfide bonds leading to altered tertiary structure. Also affects hydrogen bonding (secondary structure) When a protein loses its normal structure, it is said to be DENATURED - BAD!!! Therefore, it is important to closely monitor and maintain proper the pH, temperature, and oxidation state of tissues in the body---HOMEOSTASIS!!!  Bio 211- Anatomy and Physiology I Today’s topics Carbohydrates DNA/RNA Lipids  Carbohydrates Carbohydrates are organic molecules composed of C,H,O An important molecule the body uses for energy Main source of calories in most diets The oxidation of sugars during metabolism releases a great deal of energy that is used in the production of ATP üOf all the nutrients (carbs, fats, proteins) carbs are easiest to convert to usable energy---SUGAR HIGH! Like proteins, carbohydrates are often large polymers of smaller monomers (monosaccharides)  Carbohydrate Monomers “Monosaccharides” 3 Primary carbohydrate monomers 1. Glucose-main energy source for most cells, brain cells and nerve cells actually demand it Commonly referred to as “blood sugar” 2. Galactose-chemically similar to glucose Body converts galactose to a glucose derivative for use 3. Fructose-common sugar found in fruits Also converted to a glucose derivative before use  Disaccharides 3 Primary Disaccharides 1. Sucrose-common table sugar, cane sugar ü Digested to 1 glucose and 1 fructose 2. Lactose-milk sugar ü Digested to 1 glucose and 1 galactose 3. Maltose-malt sugar that comes from starch digestion ü Digested to 2 molecules of glucose Disaccharides are linked via DEHYDRATION SYNTHESIS reactions and broken down into monosaccharides by HYDROLYSIS All the disaccharides are metabolized to glucose and some “other” sugar The “other” sugar is also eventually converted to glucose as well Obviously, glucose is a very important energy source!  Polysaccharides Large carbohydrate polymers made up of long chains of GLUCOSE monomers 1. Cellulose - Structural carbohydrate in plants ü Can’t be digested by humans ü Also referred to as “dietary fiber” or roughage like lettuce 2. Starch - Energy storage carbohydrate in plants ü The main digestible polysaccharide in our diets ü Potatoes, rice and wheat have a lot of starch 3. Glycogen – Energy storage carbohydrate in HUMANS ü Readily accessible source of energy stored up when we eat excess food ü Primarily stored in liver, but also found in muscle and brain tissues  Nucleic Acids : DNA / RNA DNA – deoxyribonucleic acid ü carries the genetic information of a cell-needed for making proteins ü nucleic acids are extremely long polymers of NUCLEOTIDES ü remains inside the nucleus of the cell RNA – ribonucleic acid ü chemically similar to DNA ü functions as a disposable “copy” of DNA used in the actual production of proteins in the cytoplasm – don’t want to risk damage to DNA!!!! Both nucleic acids are composed of 4 different nucleotides DNA : Adenine, Guanine, Cytosine, Thymine RNA : Adenine, Guanine, Cytosine, Uracil  Nucleic Acid Structure DNA is a double stranded molecule that takes on a DOUBLE HELIX conformation üNucleotides are bound to each other via HYDROGEN BONDS * RNA is single strand of nucleotides HYDROGEN BONDS  Lipids Lipids are organic, hydrophobic molecules that play a large number of roles in human physiology 5 Major types of lipids : 1. Fatty acids: Fairly small molecules which are often precursors to triglycerides 2. Triglycerides: Molecule consisting of glycerol bound to three fatty acids via DEHYDRATION SYNTHESIS. Common type of fat found in foods we eat 3. Phospholipids: Similar to triglycerides except one fatty acid is replaced by a PHOSPHATE group. Very important component of all cell membranes 4. Eicosanoids: 20-carbon lipid derived from arachadonic acid that play an important role in inflammation, cell signaling, blood clotting (prostaglandins) 5. Steroids: 17-carbon, 4-ring lipid. Cholesterol is the “parent” steroid. Hormones like testosterone, estrogen, cortisol are steroids derived from cholesterol. Chemical characteristics of some lipids Saturated fats have fatty acid tails that are “saturated” with hydrogen üCarbon can form 4 chemical bonds üOverconsumption linked to CV diseases Unsaturated fats have fatty acid tails that are not saturated with hydrogen üOne or more carbon atoms have double bonds to other carbon atoms üLiquid at room temp (Oil) üCome from plants (olive oil, corn oil, etc…) Carbon/Carbon double bonds in unsaturated fats causes kinks and bends in F.A. tail, preventing molecules from packing together (stays liquid at room temp.)  Chemical characteristics of some lipids Phospholipids are a major component of all cell membranes (POLAR) Head region is composed of glycerol and a phosphate group üMakes the head region very POLAR AND HYDROPHILIC! Fatty acid tail is largely NONPOLAR AND HYDROPHOBIC Molecules that have a hydrophobic AND hydrophilic regions are called AMPHIPATHIC MOLECULES H2O outside Phospholipid bilayer of a cell (NONPOLAR) membrane H2O inside  Bio 211- Anatomy and Physiology I Today’s topics Introduction to cell structure and function Osmosis and cell transport  Modern Cell Theory Set of generalizations that describe cell structure and its relationship to the organism 1. All organisms are composed of cells and the products of those cells 2. The cell is the simplest structural and functional unit of life 3. An organism’s structure and function is due to the characteristics of its component cells 4. Cells are only derived from other cells 5. Since all cells in an organism share a common ancestry, they all share some similarity in composition and metabolism Ex. All cells in your body have a nucleus and replicate DNA in the same way  General Cell Structure There are over 200 different types of cells in the human body Wide variety of shapes and sizes; although most are in the range of 10-15 microns (1/1,000,000 of a meter) Size and shape of a cell are related to its function Upper limit of size is dictated by relationship between volume and surface area üVery large cells cannot coordinate exchange of nutrients and waste properly (volume increases faster than surface area) General Cell Structure For the most part, all cells in the human body have: 1. Cell membrane (plasma membrane) ü Envelopes the cell and regulates what comes in/out of the cell ü Phospholipid bilayer with many proteins, other molecules 2. Organelles ü Structures that carry out specialized cellular tasks 3. Cytoplasm ü Intracellular environment consisting of cytosol (fluid) and cytoskeleton ü Cytoskeleton provides structural support and coordinates transport of materials within the cell  Plasma Membrane Double layer of phospholipids that envelopes the cell – PHOSPHOLIPID BILAYER Hydrophilic, polar heads face the extracellular and intracellular side (exposed to water) Hydrophobic fatty acid tails are buried in the middle of the membrane (avoiding water) Creates a SEMI-PERMEABLE membrane that surrounds the cell MANY proteins are found embedded in the plasma membrane Ø Regulate movement of solutes in/out Ø Allows for interaction with other cells Ø Allows cell to communicate with other cells, hormones, etc…  Some types of membrane proteins 1. Receptors – receive chemical signals from other cells 2. Enzymes – responsible for breakdown of chemical signals Prevent “overstimulation” 3. Channel proteins – allow solutes and large hydrophilic molecules in/out of cell Can either be open all the time or “gated” and only allow molecules to pass under certain circumstances (ligand-gated, voltage-gated) 4. Cell identity proteins- identify “self” vs. “non-self” (important for immune system) 5. Cell-adhesion molecules – help cells attach to one another or to extracellular material  Osmosis and Transport Across Cell Membranes Solution – Any particulate matter (SOLUTE) dissolved in a liquid (SOLVENT) In biology, solutes are often ions, proteins, hormones, etc… dissolved in water (the solvent) Osmosis = the diffusion of water down its concentration gradient Water is free to move across cell membranes and will move from an area of LOW solute concentration to an area of HIGH solute concentration Water is attracted to many solutes Cell membranes are SELECTIVELY PERMEABLE, some things pass freely (water, some small, uncharged molecules), while others cannot (proteins, large molecules, ions)  Tonicity and Osmosis Hypertonic – when concentration of solute is greater outside than inside Isotonic – when concentration of solute is the same inside and out Hypotonic – when concentration of solute is lower outside THAN INSIDE We normally use these terms to describe a solution that is outside of a cell Example : A hypertonic solution has a HIGHER concentration of a solute than what is found inside the cell Example: Red blood cells in solutions of varying ion concentration Hypotonic Isotonic Hypertonic Water (solvent) will travel into or out of a cell until NaCl concentrations are equal inside and outside the cell. ü NaCl is the solute (trapped in cell) Water 0.9% NaCl 5% NaCl (0% NaCl)  Carrier-mediated transport Movement of SOLUTES (ions, proteins, etc…) across a cell membrane When allowed, solutes will diffuse from an area of high concentration to an area of low concentration until equilibrium is reached 2 main types of transport: 1) Facilitated diffusion – describes a situation in which solutes travel across the cell membrane DOWN ITS CONCENTRATION GRADIENT Solute travels across the plasma membrane using a membrane protein (channel or transporter) but DOES NOT REQUIRE ENERGY (ATP) 2) Active Transport – describes a situation when solutes travel AGAINST ITS CONCENTRATION GRADIENT Uses energy (ATP) and creates or maintains a concentration gradient where solute concentrations are higher on one side of the membrane  Types of transporters Transporters are membrane proteins and are VERY SPECIFIC about what solutes they can transport HIGHER CONCENTRATION LOWER CONCENTRATION Facilitated diffusion: membrane proteins either carry or allow movement of solutes Channels or pores allow solute to travel freely Carriers bind solute and then move it across the membrane In both cases solute travels down conc. gradient.  Active Transport Active transport: membrane protein uses energy (ATP) to move solutes from one side of the membrane to the other AGAINST THE CONCENTRATION GRADIENT Solutes are “pushed” from an area of LOW concentration to and area of even HIGHER concentration (i.e., LOW to HIGH; opposite of facilitated diffusion) High Concentration Low Concentration  Vesicular Transport Many molecules can be transported across the P.M. via membrane carrier proteins (active transport and facilitated diffusion). However, very LARGE molecules, large numbers of molecules, and liquids are better transported via VESICULAR TRANSPORT Vesicles – bubble-like structures made up of pieces of the P.M. 1. Endocytosis: process by which particles or liquid are brought INTO the cell Small section of plasma membrane pinches off and forms a vesicle 2. Exocytosis : process that sends particles or liquids OUT of the cell Basically the reverse of endocytosis  Types of Endocytosis Phagocytosis, pinocytosis, receptor-mediated endocytosis 1. Phagocytosis – “cell eating” process by which a cell engulfs particles or debris ü Neutrophils use this to “eat” bacteria and kill them ü Use pseudopodia to “grab” things; not common in many cells 2. Pinocytosis – “cell drinking”; cell takes in droplets of liquid containing solutes ü Fairly non-specific; but very common in many cells 3. Receptor-mediated endocytosis – Very SELECTIVE, and most common form of endocytosis where cells only take in certain solutes in certain quantities ü Involves the use of RECEPTORS on outer surface of P.M  Organelles 1. Nucleus 2. Endoplasmic Reticulum 6 3. Ribosomes (bound to E.R.) 4 4. Golgi Apparatus 5. Lysozomes/Peroxisomes 6. Mitochondria 5 1 2 3 Nucleus Largest of the organelles Sometimes spherical, but often matches shape of cell Surrounded by NUCLEAR ENVELOPE – 2 phospholipid bilayers (inner and outer) Contain NUCLEAR PORES- allow transcription factors and RNA molecules in/out Stores and protects the cell’s DNA (packaged into 23 pairs of chromosomes)  Endoplasmic Reticulum Series of networks adjacent to the nucleus “Rough” E.R. is dotted with ribosomes for protein synthesis “Smooth” E.R. has no ribosomes E.R. plays important role in the synthesis of steroids and lipids, and has enzymes that are responsible for the detoxification of drugs and alcohol Contributes to tolerance of drugs and alcohol Also explains why some GOOD drugs (i.e., medicines) stop working after a while  Ribosomes Found in the nucleolus, rough E.R. and in the cytoplasm Ribosomes are complexes of protein and RNA Function to translate RNA messages (mRNA) into proteins More on protein translation later!! Lysozomes and Peroxisomes 1. Lysozomes Membrane-bound vesicles that contain LYSOZOMAL enzymes Lysozomal enzymes hydrolyze (break down) fats, proteins, DNA/RNA, carbohydrates White blood cells use lysozomes to degrade bacteria, viruses, damaged cells that they have phagocytosed 2. Peroxisomes Similar to lysozomes, but contain oxidative enzymes that produce and utilize H2O2 in order to metabolize organic compounds  Golgi Apparatus Golgi apparatus is system of sacs often found in proximity to the rough E.R. Functions to synthesize carbohydrates and add sugars to glycoproteins Golgi receives newly made proteins from the E.R., modifies them, sorts them, and packages them into GOLGI VESICLES for transport to other parts of the cell. üSort of acts like the cell’s post office! Vesicles leaving the Golgi have “tags” that indicate where the vesicle of newly formed proteins will go…i.e., plasma membrane, storage vesicles, etc…  Mitochondria The “Powerhouse” of the cell – responsible for the production of ATP Also contain their own DNA (small amount) different from nuclear DNA üAllows the mitochondria to make their own proteins and enzymes Many reactions that take place in the mitochondria are oxidative reactions (Redox reactions) üDysfunction or damage to the mitochondria leads to the release of oxygen free radicals (BAD!) and eventually can lead to cell and tissue death üAlzheimer’s disease, Parkinson’s disease and some cardiovascular diseases and cancers are linked to oxidative stress from mitochondrial damage!  Cytoskeleton Cytoskeleton – collection of protein filaments that supply structural support and transport within the cell Made up of microfilaments, intermediate filaments, microtubules ü Gives cell unique shape, rigidity, loosely holds things in place, provides way to move materials from place to place within the cell  Bio 211- Anatomy and Physiology I Today’s topics Protein synthesis RNA Transcription Protein translation Protein processing and secretion  Flow of genetic information DNA How does a cell “know” how to make all the 1,000s of proteins required for life? ü The genetic information is stored as DNA which is found in the nucleus of every cell Transcription ü DNA can be thought of as the blueprint for making proteins ü When a cell wants to make a protein, a copy of the DNA is made, called mRNA ü The mRNA “copy” is then used by machinery in the cell to make the protein mRNA Translation Transcription = process of making a copy of the DNA into mRNA Protein Translation = process of making a protein using information encoded in the RNA DNA and Chromosomes Chromosomes are composed of long strands of DNA (millions of nucleotides) wrapped around stabilizing proteins Ø Most cells contain 23 pairs of chromosomes Ø 22 pairs of autosomes and 1 pair of sex chromosomes DNA molecules are divided into functional units called GENES Each gene possesses the genetic information for the synthesis of one protein üExample: the insulin gene contains the genetic information encoding the insulin protein  RNA Synthesis (TRANSCRIPTION) RNA synthesis (transcription) is carried out by an enzyme called RNA POLYMERASE üRNA polymerase “reads” the DNA and makes an RNA copy called MESSENGER RNA (mRNA) ümRNA is sent out of the nucleus and then used by ribosomes to make proteins out in the cytoplasm GENE #1 GENE #2 GENE #3 DNA ü Double stranded ü Made of millions of nucleotides TRANSCRIPTION GENE #2 mRNA ü Single stranded ü Made of thousands of nucleotides Important process because: ü Allows for selective expression of genes ü DNA stays protected in nucleus ü ~95% of our DNA is “Junk DNA”  Translation Process by which the genetic information encoded in mRNA is used to synthesize proteins üConverts the language of nucleotides into the language of amino acids Major players involved: 1. mRNA – contains the genetic information 2. Ribosome – protein complex that coordinates the assembly of the polypeptide 3. Amino acids – the building blocks of a protein mRNA GENE #2 ü Single stranded ü Made of thousands of nucleotides TRANSLATION Protein (polypeptide) ü Single stranded ü Complex 3D shape ü Made of thousands of AMINO ACIDS  CODON = sequence of three nucleotides that encode one amino acid in a protein Genetic Code = set of rules that determine which codon encodes each amino acid The genetic code is redundant (some amino acids are encoded by more than one codon)  DNA Replication and Cell Division DNA Replication and cell division are closely linked – one cannot happen without the other Both are influenced to topics we talked about earlier 1. Modern cell theory – states that all cells can only arise from other pre-existing cells Needed to replace old, damaged cells and sperm/eggs 2. A cell needs to duplicate ALL of its DNA before it can divide Mutation DNA replication is probably the most important function that a cell carries out üWe know that DNA encodes the proteins that carry out almost every cell process üWhen DNA is replicated, it must result in an exactly perfect replica of the original  Cell cycle and DNA replication Major Steps in DNA replication: 1. Unwinding of DNA from its packaged double helix structure 2. DNA POLYMERASE binds to each of the two exposed strands and “reads” the DNA, incorporating free nucleotides to make a new complementary strand for each DNA Replication is sort of like mRNA transcription, except we are copying both strands  Genetic Mutations Even though DNA polymerase is very good at replicating DNA correctly, mutations DO occur fairly frequently Some mutations are very bad while others may have no detectable affect on the cell Types of mutations: 1. Point mutations ü Simple replacement of one nucleotide for another – i.e., AèT or GèC, etc…. Silent – change in nucleotide doesn’t change amino acid sequence of protein (remember redundancy of genetic code!) AUU, AUC both encode the a.a. leucine, OR mutation occurs in “junk” DNA Missense – change in nucleotide leads to change in a.a. sequence of protein Nonsense – change leads to formation of a STOP codon, shortened protein 2. Insertions/Deletions ü Addition or removal of a nucleotide ü Can alter how a ribosome reads the mRNA → mutant protein!! THE DOG CAN RUN THE HDO GCA NRU N  Genetic Mutations Mutations can also be classified by function Gain of function- mutation leads to protein with new function or activity Loss of function- mutation causes protein to be non-functional It is tempting to think of genetic mutations as always being detrimental….BUT sometimes they are actually beneficial….or Both!!! 1. Deletion of a portion of the gene encoding the CCR-5 receptor found on T-cells Found in some Northern European populations Confers resistance to smallpox, Bubonic plague, AIDS (GOOD!) 2. Mutation of hemoglobin gene can cause sickle cell anemia AND/OR confer resistance to malaria Since all of our cells have PAIRS of chromosomes, we have TWO copies of every gene HOMOZYGOUS mutation-both copies of gene are mutated (with hemoglobin, causes sickle cell anemia) HETEROZYGOUS mutation-one copy is mutated, other is good ü Individual has very mild symptoms of sickle cell anemia (may not even know it) AND has some resistance to malaria (GOOD!!)  Cell Cycle Process by which ONE parent cell grows and replicates all of its component structures (plasma membrane, organelles, etc…), undergoes division, and yields TWO daughter cells The length of the cell cycle varies widely between cell types and is usually related to their function ² Some cells divide very rapidly all the time (i.e., skin, GI tract), while some cells divide very slowly or not at all (neurons, muscle)… Two different types of cell division: Mitosis – “normal” cell division where one cell divides to produce TWO genetically identical cells – almost all cells in our body divide this way Meiosis – “special” cell division used to produce gametes (sperm and eggs)… each cell produced contains HALF the normal amount of genetic material  What regulates the timing of the cell cycle?? This is a VERY IMPORTANT question in biology since a cell that has lost control of its cell cycle can divide more often than it should and may not stop CANCER!!! 1. Cell conditions ü Cell division is triggered if a cell has grown large enough to become two cells (cytoplasm, organelles, etc…) ü DNA is duplicated ü Nutrient levels – cells will not divide if sufficient food is not present 2. Growth factors ü Hormones and cell signaling molecules that trigger cell division in other cells 3. Environmental conditions ü Contact inhibition – cells will stop dividing when they “feel” other cells all around them and start dividing if they detect open space Many cancer medicines attempt to inhibit DNA synthesis or block the signals of growth factors  Mitosis The cell cycle is divided into two main periods : 1. Interphase – time when the cell is either quiescent or beginning preparations for cell division - the majority of a cell’s life is spent in interphase ü G1 phase, S phase, G2 phase 2. Mitotic phase – time when the cell is actively dividing (nuclear components are duplicated, DNA is divided up, parent cell pinches off into 2 daughter cells) Almost all cells in human body use mitosis to divide and reproduce ü Some human cells are incapable of division and reproduction Results in the formation of 2 daughter cells that are GENETICALLY IDENTICAL to the parent cell  Meiosis Meiosis is the process of cell division that results in the production of 2 cells with HALF the normal genetic material (one copy of each chromosome) This process is only involved in the production gametes (sperm and egg – 23 chromosomes each) Union of sperm and egg results in offspring with normal complement of chromosomes (23 pairs) Meiosis is characterized by one DNA duplication and two cell divisions (meiosis I and meiosis II) During meiosis I, the chromosomes duplicate AND undergo CROSSOVER RECOMBINATION between chromosomes During meiosis II the cells undergo another cell division WITHOUT duplicating DNA Cells with 23 pairs of chromosomes = diploid cell Cells with 23 chromosomes – haploid cell  Errors in Meiosis NONDISJUNCTION describes a situation where cells do not receive the appropriate chromosomes during meiosis II (i.e., each cell receives 1 copy of chromosome #1, #2, etc…) üUltimately, if this gamete is used in reproduction the resulting offspring will end up with the wrong number of chromosomes o3 copies = TRISOMY o1 copy = MONOSOMY In most cases embryos with monosomy or trisomy of a chromosome are not viable and do not survive Nondisjunction üHowever, there are a few cases where the fetus will survive of a chromosome  Bio 211- Anatomy and Physiology I Today’s topics Heredity  Heredity, Genotype, and Phenotype Since we all have two copies of every chromosome (one each from mom and dad), that also means that we have two copies of every gene Different forms of each gene are called ALLELES Ex.: You might possess two slightly different versions of a given gene (one from mom and one from dad) There might be dozens or even hundreds of different versions of a gene in a population of people Genotype = term that describes the GENETIC makeup of our cells (i.e., which alleles we have) Phenotype = term that describes how those alleles are expressed (i.e., our outward appearance or characteristics)  Dominant and recessive alleles If our genotype dictates that we all have two copies of each gene (alleles), how do we know what our phenotype will be? DOMINANT ALLELES are expressed in our phenotype since they typically encode the “normal” protein and mask the effects of the “abnormal” recessive protein RECESSIVE ALLELES typically encode the “abnormal” protein and are only expressed in our phenotype if a cell contains 2 recessive alleles Mutation in CFTR gene is recessive and can cause the genetic disease cystic fibrosis ü“Carrier” has one dominant and one recessive allele – normal phenotype. If other parent is also a “carrier” then there is a 25% chance their child will develop the disease. CODOMINANCE – Person possesses two DIFFERENT dominant alleles and BOTH are expressed in the phenotype Blood Types: A and B alleles are dominant and O allele is recessive Ø AA - Type A blood Ø AO - Type A blood Ø BB – Type B blood Ø BO – Type B blood Ø OO – Type O blood Ø AB – Type AB blood Incomplete dominance – describes a situation where two different dominant alleles lead to a “middle of the road” phenotype Red flower + White flower results in pink offspring In reality, this is a HUGE reason why humans are 99.9% genetically similar yet WE ARE ALL UNIQUE!!! Polygenic inheritance – when more than one gene contributes to a particular phenotype Eye color, skin tone, etc… Many diseases are polygenic in nature üHeart disease, hypertension, cancer are thought to be caused by the contribution of MANY different genes