Anatomy and Physiology Notes PDF

A & P Lecture \#1 Anatomy - Describes the structure of the body and how the pieces fit together. Physiology - Describes the function of body parts and how they work. Homeostasis - "Maintaining balance" - A condition of equilibrium through regulation and feedback. Feedback Systems -...

A & P Lecture \#1 Anatomy - Describes the structure of the body and how the pieces fit together. Physiology - Describes the function of body parts and how they work. Homeostasis - "Maintaining balance" - A condition of equilibrium through regulation and feedback. Feedback Systems - Receptor: detects the change - Control Center: determines the set point and coordinates an appropriate response. - Effector: carries out the response - Response: feeds back to either reduce or amplify stimulus. Negative Feedback - Response reduces or stops stimulus, preventing severe changes within the body. - The response decreases the difference between current level and set point. Positive Feedback - Amplification of stimulus until change occurs. Homeostatic Imbalance - Occurs when control center cannot properly respond to stimulus. - When negative feedback system becomes overwhelmed or fails, an unintentional loop may occur. Anatomical Terms - Anatomical position - Standing, feet slightly apart, palms forward and thumbs pointing away from the body - Axial Division - Head and torso - Appendicular Division - The limbs Directional Terms - Anterior/Ventral - Towards the front - Posterior/Dorsal - Towards the back - Superior/cranial - Towards the head - Inferior/caudal - Away from head - Medial - Towards the midline of the body - Lateral - Away from the midline of the body - Proximal - Closer to point of attachment - Distal - Further from point of attachment - Superficial - Towards surface of the body - Deep - Away from surface of the body Body Planes - Sagittal - Divides body into left and right. - Frontal/coronal - Divides body into front and back. - Transverse - Divides body into top and bottom. Body Cavities - Dorsal - Cranial Cavity - Vertebral Cavity - Ventral - Thoracic Cavity - Pericardial - Right pleural - Left pleural. - Abdominopelvic cavity - Abdominal - Pelvic Body Cavity Membranes - Body cavities and organs are lined with a think double layered serous membranes or serosa. - Parietal Serosa - Not touching the organ - Visceral Serosa - Touching the organ Abdominopelvic Quadrants - Right Upper Quadrant - Most of your liver, gallbladder, right kidney, parts of small intestine and large intestine. - Right Lower Quadrant - Intestines, right ovary, appendix, cecum, and ascending colon of large intestine. - Lower Upper Quadrant - Stomach, spleen, most of your pancreas, left kidney, parts of small and large intestine. - Lower Left Quadrant - Intestines, left ovary, descending and sigmoid colon and large intestine. Lecture \#2 Matter and Energy - Matter - The 'stuff' of the universe - Energy - Kinetic energy puts stuff in motion. Potential energy is stored. Elements of the Human Body - Carbon, oxygen, hydrogen, and nitrogen make up 96% of the human body. - Calcium, phosphorus, potassium, sulphur, sodium, chlorine, magnesium, and iron are lesser elements that comprise about 3.6% of the body. - Aluminum, boron, chromium, cobalt, copper, fluorine, iodine, manganese, selenium, zinc, and others occur in trace amounts (\>0.4% of body mass) Structure of Atoms - Protons - Positively charged particles found in the nucleolus. - Neutrons - Neutral charged particles found in the nucleolus. - Electrons - Negatively charged particles found in orbitals. - Chemical properties of an atom are primarily determined by its electrons. Electron Shell Model - Atoms are electrically neutral. - Atoms of different elements contain different numbers of protons. - Elements are defined by. - Atomic Number - Number of protons - Atomic Mass - Number of protons and neutrons Isotopes - Atoms that have a different number of neutrons then ''normal'' for that element, they have same atomic number but different atomic mass. Radioisotopes - Isotopes that lose subatomic particles overtime. They do this in a predictable way, which allows us to use them for things like radioisotope dating using carbon-14. Ions - An atom becomes an ion, a charged atom, when it gains or loses an electron. - An atom gains one or mare electrons it becomes an anion. (Negative charge) - An atom loses one or more electrons it become a cation. (Positive charge) Mixtures - Every molecule in a compound will be identical. - Unlike compounds, mixtures do not involve chemical bonding between components. - Mixtures can be separated by physical means, such as straining, filtering or distillation; compounds can. Only be separated by breaking bonds. Chemical Bonds - Valence electrons are least attracted to the nucleolus and most likely to react with other nuclei. These electrons can be involved in chemical reactions. - Shell 1 holds 2 electrons. - Shell 2 holds a mx of 8 electrons. - Shell 3 holds 8 or more electrons. - An atom with full valence electrons is chemically stable or inert. Octet rule. Ionic Bonds - Involve the transfer of valence shell electrons from one atom to another, resulting in ions. Covalent Bonds - Formed by sharing two or more valence electrons between 2 atoms. - Non- polar Covalent Bonds - Share electrons equally - Polar Covalent Bonds - Do not share electrons equally. Hydrogen Bonds - Weak attractive force between 2 a partial positive charge of one molecule and a partial negative charge of another. - This is not a true bond more of a weak magnetic attraction. Chemical Reactions - Occur when chemical bonds are made, broken or rearranged. - Reactants are what you start with. - Products are what you get after the reaction. Types of Chemical Reactions - Synthesis - Two components are combined into more complex molecule. - A+B → AB - Decomposition - These involve breakdown of a molecule into smaller molecules or its constituent atoms. - AB → A+B - Exchange/ Double Displacement - Involve both synthesis and decomp reaction. - Bonds are both made and broken. - AB + CD→AD+CB Redox Reactions - Reduction- Oxidation - Atoms are reduced when they gain electrons. - Atoms are oxidized when they lose electron. - LEO GER/ OIL RIG Rate of Chemical Reactions - Temperature - Increases kinetic energy usually increasing reaction. - Concentration of reactants - Increased concentration usually increases rate. - Particle Size - Smaller particles move faster at the same temperature, increasing rate., - Catalysts - Increase the rate of reaction without being chemically changed or becoming part of the product. Enzymes are biological catalysts. Reversibility of Chemical Reactions - All chemical reactions are theoretically reversible. - Chemical equilibrium occurs if neither forward nor reverse reaction is dominant. - Many biological reactions are not easily reversable. Energy requirements to reverse may be too high, or products may have been removed. Lecture \#3 Biochemistry - The study of chemical composition and reactions of living matter. - Inorganic Compounds - Do not contain carbon. - Water, salt and many acids and bases - Water - is most abundant, accounting 60-80% of volume of living cells. - Hight heat capacity, high heat of vaporization, reactivity, cushioning - Organic Compounds - Contain Carbon - Usually covalently bonded Water - Polar solvent dissolving ionic substances. - Forms hydration layers and large charged molecules - How most substances are carried through the body. Dehydration Synthesis - Covalent bond is created by removing OH from one molecules and H from another, releasing H2O. Hydrolysis - Covalent bond broken by adding OH from water to one molecules and H to another. Salts - ionic compounds that dissociate into separate ions in water. - They separate into cations and anions. Not including OH and H. - Ionic balance is vital to homeostasis. If electrolyte balance is disturbed, all organ systems can cease function. Acids - Proton DONORS - They release H+ ions. Bases - Proton ACCEPTORS - Adsorb H+ ions. pH - Measurement of H+ ions in a solution. - Logarithmic scale (3 pH is 100x more acidic than pH 6) - 1-6 acidic - 7 neutral - 8-10 Basic Neutralization Reaction - Occurs when acids and bases are mixed. - A displacement reaction occurs, forming water and a salt. Buffers - Resists large changes in ph. - Act like weak acid and weak base, releasing H+ ions if pH rises or binding H+ ions if pH falls. - Blood pH is regulated by a bicarbonate buffer. Carbohydrates - Include sugars and starches, contain C, H and O and are main source of chemical energy for metabolism. - Monosaccharides - Singular sugar units made od 3-7 carbons, often in a ring shape. - Disaccharides - Formed through dehydration synthesis of two monosaccharides. - Polysaccharides - Large chains of tens to hundreds of monosaccharaides joint by dehydration synthesis. Lipids - Contain C, H and O, but less than carbs =n and sometimes contain P. - Non-Polar; insoluble in water. - Triglycerides or Neutral fats - Used to store energy. - Joined through dehydration synthesis. - Phospholipids; cell membranes. - Steroids - Consist of four interlocking structures. - Signaling molecules and hormones. - Eicosanoids - Group of unsaturated fatty acids. - Prostaglandins are one type of these molecules, which help regulate blood pressure and inflammation (Ibuprofen reduces prostaglandins which then decrease inflammation) Fatty Acids - Saturated Fatty Acids - All carbons linked via single covalent bonds, resulting in a molecule with the maximum number of hydrogen atoms. - Usually solid at room tempo. - Unsaturated Fatty Acids - Have one or more carbons that are linked in doubles bonds; are not saturated with hydrogen atoms. - Usually liquids. Lecture \#4 when looking over look at lecture 4 slides not sufficient info. Proteins - Wide variety of functions including structural, enzymatic, and mechanical. - Also known as polypeptides, proteins are polymers of amino acids, held together by covalent bonds. -- Peptide Bond; amine group bonded to a carboxyl group. - All human proteins are made from up to 20 different types of amino acids. Amino Acids - Each amino acid has one amine group and one carboxyl group and one of 20 R side chains. - Different R group give different characteristics of size, polarity, and ph. Peptide Bond - Put together using dehydration synthesis and broken apart by hydrolysis. Primary Protein Structure - Linear sequence/ order of amino acid sequence in a polypeptide chain - String of letters no spaces or punctuation. Secondary Structure - Refers to shapes of alpha helices or beta pleated sheets, that form when amino acids form the primary structure interact with each other through hydrogen bonding. Tertiary structure - Three-dimensional shape of a polypeptide chain. - Shape arises from how the chain folds based on regions of amino acids that are hydrophilic and regions that are hydrophobic attracting and repelling water. Quaternary Bonding - Two or more polypeptide chains join to make one functional multimer. - Not all proteins have quaternary structure. - Strand like, insoluble molecules that provide mechanical support and tensile strength to tissues. - Job is to not break. Globular Proteins - Compact, spherical, water-soluble, and chemically active molecules that oversee most cellular functions. Protein Denaturation - Loss of specific three-dimensional structure of a globular protein, leading to possible loss in function. Enzymes - Globular proteins that act as biological catalysts to regulate and increased the speed of chemical reactions without being used in the process. - Lower the activation energy, leading to increased rate of reaction without requiring temperatures. - Active sites; lock and key systems Nucleic Acids - Made of monomers and polymers of nucleotides. - DNA and RNA Deoxyribonucleic Acid - DNA encodes the genetic recipe for the synthesis of all proteins. - Controls development and functionality. - Double Helix - Complimentary Base Pairing A-T C-G Ribonucleic Acid - RNA is used to take nucleotide sequence information from DNA and use it to make proteins. - Complimentary Base Pairing A-C G-U - mRNA- messenger, tRNA- transfer, rRNA- ribosomal ATP Synthesis - energy from many sources' carbs, fats, proteins. If you use all these sources to make ATP, you can use the ATP to power any enzymes. Lecture \#5 Metabolism - sum of all biochemical reactions inside a cell involving nutrients. Nutrient Processing - food is digested in the gastrointestinal tract and absorbed nutrients enter through the blood to reach cells. - Within cells, nutrients can either be used in anabolic pathways to build molecules or broken down through catabolic pathways to produce energy. (ATP) Oxidation-Reduction Reactions - Oxidation - reaction involves the gain of oxygen or loss of hydrogen atoms. - Oxidation-reduction (REDOX) - Involve oxidized substances losing electrons and reduced substances gaining electrons. LEO GER, OIL RIG Capturing Energy from Food - Glucose is an energy rich, highly reduced molecule (many hydrogen atoms). Which can be oxidized into lower-energy, highly oxidized compounds. (Many oxygen atoms or double bonds) to release energy. - Metabolizing glucose with oxygen - C6H12O6 is oxidized into CO2. - O2 is reduced to H2O. - Released energy is then used to make ATP. Redox Enzymes and Coenzymes - Redox are catalyzed by enzymes that usually require a B vitamin or coenzyme. - Two important coenzymes act as hydrogen/electron acceptors in oxidative pathways. - NAD+ id derived from Vitamin B3 and can be reduced into NADH + H+ - FAD id derived from Vitamin B2 and can be reduced into FADH2. Adenosine Triphosphate - ATP powers all known forms of life. - ATP briefly holds chemical energy. - ATP transfers that chemical energy into an enzyme to power chemical reaction. By releasing that energy ATP turns into ADP - ADP then gets recharged into ATP and used again. ATP Synthesis - Two mechanisms are used to make ATP. - Chemical binds are broken and energy from reactants is used to phosphorylate ADP into ATP. Doesn't require oxygen. Glycolysis when done with glucose. - Energy from food creates a proton gradient (electron transport chain) that is used to attach phosphates to ADP. Requires oxygen as the final electron acceptor. Glycogenesis - Process that forms glycogen from glucose. ATP cannot be stored for periods of time so we make the storage product of glycogen which can later be broken down into energy. Glycogenolysis - Process that breaks down glycogen when blood glucose levels drop cells can respond by breaking glycogen into glucose. Lecture \#6 Cell Theory - Al cell is a basic structural unit of all forms of life. - Cells are evidence of common ancestry. Extracellular Materials - Material found outside the cell. - Include, interstitial fluid, blood, plasma, and cerebrospinal fluid. - Cellular secretions including signalling chemicals like hormones enzymes and other things that aid digestion and lubrication. - Extracellular matrix is jellylike, full of proteins and polysaccharides that help hold cells together like glue. Plasma Membrane - Active barrier separating inter and extracellular fluids. - Controls what enters and exits the cell (semi permeable) - Structure - Integral proteins: reach through the membrane - Peripheral proteins: are attached to the inside or the outside of the cell. - Glycocalyx: fuzzy, sticky, carb-rich are at cell surface that acts as a biological marker allowing identification of cells among each other. Lipid Bilayer - 75% phospholipid. Tails are hydrophobic (nonpolar), heads are hydrophilic (polar). - 20% cholesterol, which increases membrane stability. - 5% glycolipids, lipids with sugar groups on outer membrane surface. \\\\ Membrane Proteins - Integral proteins - reach across the membrane. - Involved with transports as channels. - Ion channel, transporter, receptor, enzyme, linker, - Peripheral proteins - are attached to the inside or the outside of the cell. - Function as enzymes or in mechanical functions. - enzyme, linker. Membrane Receptors - Chemical signaling involves the binding of a ligand to a membrane receptor, resulting in initiation of cellular processes. - When ligand binds, receptor changes shape and becomes activated. G protein-like Receptors - Type of chemical signaling - Indirectly cause cellular changes by activating G proteins, which can activate other enzymes, or cause the release of internal second messenger chemicals. Glycocalyx - Coat of sugars on the cell surface, some attached to lipids, and some attached to proteins. - Every cell type has different patterns, functions as biological marker for cell-to-cell recognition. - Glycocalyx in cancer cells can change so rapidly that immune system cannot recognize cells as being damaged, avoiding apoptosis. Cell Junctions - Tight Junctions - Integral proteins that join adjacent cells to prevent molecules from passing through the extracellular space between cells. - Desmosomes - Scattered attachment of adjoining cells that reduce the chance of cells tearing apart when tissue is stressed. - Gap Junctions - Hollow cylinders of proteins between cells that allow some small molecules to pass between adjacent cells. Electrical signals, think proteins. Lecture \#7 Membrane Transport - Passive - Does NOT require energy. - High to low concentration - Active - Requires energy. - Against concentration gradient, solute could be too large for channels, solute is not lipid or soluble. - Primary Active Transport - Requires energy directly from ATP, shape change causes solute to bind to protein to then be pumped across membrane. (Ion pump) - Secondary Active Transport - Requires energy made indirectly from ionic gradients created by primary active transport. Energy from ion gradient diffusion is used to drive transport of other solutes. - Antiporters - Use secondary active transport to move one substance into the cell while transporting a different substance out of the cell. - Symporters - Transport two different substances in the same direction in OR out. - Vesicular Active Transport - Uses membranous vesicles to transport large particles and fluids across the plasma membrane or within the cell process requires ATP. - Endocytosis - Vesicular transport into the cell. - Exocytosis - Vesicular transport out of the cell. - Transcytosis - Vesicular transport into, across, and then out of the cell. - Vesicular Trafficking - Vesicular transport from one area or organelle in the cell to another. - Diffusion - Movement of molecules down the concentration gradient - Rate of diffusion depends on mass, temperature of the molecules and the steepness of diffusion gradient, surface area and distance of diffusion. - Bigger, heavier molecules take longer to diffuse in comparison to lighter smaller molecules. - Simple diffusion - Through the plasma membrane - Only done with lipids or small uncharged molecules. - Facilitated diffusion. - Sugars, amino acids, or ions are moved through plasma membranes with the aid of transport protein carriers or by moving through channels. - Osmosis - Movement of water through a selectively permeable membrane. Tonicity - Ability that a solution to change shape or tone of cells by changing the volume of water in said cell. - Hypertonic solution (higher solute concentration), result in water leaving the cell causing cell to shrivel and crenate. - Hypotonic solution (lower solute concentration) result in net movement of water into the cell, which may cause cell to burst of lyse. Phagocytosis - ''cell eating.'' - Type of endocytosis where large solid materials are brought into the cell. - Performed by cells called phagocytes, specialized immune cells that dispose of debris and pathogens by phagocytosing the particles and digesting them. Pinocytosis - ''cell drinking.'' - Form of endocytosis that takes in a small volume of extracellular fluids with dissolves solutes into the cell. Often used to sample exterior environment. - No receptor is used, process is non-specific. Receptor-mediated Endocytosis - Large molecules - Main mechanism for the specific endocytosis or transcytosis of large molecules. - Receptors only bind specific ligands, allowing cells to collect and concentrate on rare molecules found in extracellular fluid. Lecture \#8 Cytoplasm - Cellular material located between plasma membrane and nucleolus. - Cytosol - Gel like solution made up of water and soluble molecules like proteins sugars etc. - Inclusions - Insoluble molecules that vary with cell type (glycogen, granules, pigments, lipid droplets, vacuoles, and crystals) - Organelles - Metabolic machinery structures of the cell, with specialized functions. Cytoplasmic Organelles - Membranous (allows for compartmentalization, essential to cell function) - Mitochondria - ER - Golgi Apparatus - Peroxisomes - Lysosomes - Non-Membranous - Ribosomes - Cytoskeleton - Centrioles Cytoskeleton - Series of flexible protein rods in the cytosol, supporting cellular structures and aiding in cell movement. - Microvilli - Finger like extensions of plasma membrane that increase surface area. Core actin microfilaments that are used to stiffen the projections. Increase surface area. - Microfilaments - Made of actin, attach to inside of cell membrane to strengthen cell surface, help resist compression and aid motility. - Intermediate Filaments - Help cells resist by pulling forces. - Microtubules (the tube referred to the NYC subway, cell transport) - Hollow tubes made from tubulin. - Give cell shape and distribute organelles. - Structures are moved around by motor proteins on microtubule tracks. Centrosome - Region near nucleolus that organizes microtubules and mitotic spindle during cell division. Centriole - Small barrel shaped organelles that form the bases of cilia and flagella. Cilia - Motile extensions on surfaces of certain cells that work together to sweep substances like mucus across cell surface. Flagella - Longer extensions that propel an entire cell (sperm tails) Ribosomes - Small non-membranous organelles consisting of protein and ribosomal RNA. - Site of protein synthesis - Free Ribosomes - Free floating within cytoplasm - Synthesize protein for use inside cell. - Membrane-Bound Ribosomes - Attached to rough ER. - Synthesize proteins for export from the cell. Endomembrane System - Consists of rough and smooth ER, Golgi apparatus, secretory vesicles, and lysosomes, as well as the nuclear and plasma membranes. - Work together to: produce, degrade, store and export biological molecules. Endoplasmic Reticulum - Rough - Studded with ribosomes to manufacture proteins. - Smooth - Contains catalytic enzymes for lipid and glycogen metabolism and detoxification. Golgi Apparatus - Stacked flattened sacs associated with groups of membranous vesicles. - Main function is to concentrate and package proteins and lipids made in ER. - Packed into 3 groups. - Secretory -- export out of the cell - Membrane -- to be fused to membranes. - Transport -- for delivery inside the cell. Lysosomes - Membranous organelles that contain enzymes to digest particles taken in by endocytosis, degrade worm out organelles or non-used tissue and perform glycogenesis, (stomach or a cell) Peroxisomes - Membranous organelles containing enzymes, oxidases, and catalases, used to oxidize and detoxify reactive substances such as alcohol, formaldehyde, and free radicals. (Neutralize harmful bacteria) Ubiquitin - Protein tag that can be added onto molecules to signal they should be destroyed. Proteasomes - Barrel shapes structures that destroy unneeded, damaged, or faulty proteins by cutting long proteins into peptides. Mitochondria - Membranous organelles that produce most of a cell's ATP by breaking down food molecules and transferring the energy into phosphate bonds. Lecture \#9 Nucleus - Largest organelle. Contains the genetic catalog for synthesis of nearly all cellular proteins. - Responds to internal and external signals and decide what kinds and amounts of proteins need to be synthesized to respond to signals. - Nuclear Envelope - Double membrane barrier surrounding nucleolus, enclosing fluid, and solutes of the nucleolus. Outer membrane is continuous with the rough ER, while inner is lined with shape maintaining network of proteins called nuclear laminae. - Nuclear Pores - Penetrate areas where the membranes of nuclear envelope fuse and regulate passage of large particles in and out of the nucleus. Nucleoli - Dark-staining nuclear bodies within the nucleus that are sites of assembly of the two ribosomal subunits. - Associated with nucleolar organizer regions that contain the DNA that codes for ribosomal RNA. - Typically, one or two per cell. Chromatin - Made of nucleosomes, clusters of eight histones proteins connected by DNA. - When a cell is preparing to divide, chromatin condenses into rod-like chromosomes. This helps protect chromatin during cell division. Non-Coding RNA - 98% of your genome does not encode for proteins, AKA junk DNA. - Much of DNA transcribes noncoding RNAs which play many essential roles in regulating DNA and RNA. - Research is slowly discovering more and more functions and may be more important than DNA in health and disease perspective. - Though every cell in your body contains identical DNA, not every cell is the same due to transcription factors that affect how often and when genes are expressed. - Activator Proteins - Bind to DNA regions called enhancers to encourage the transcription of specific genes, these affected genes are unregulated. - Repressor and Silencers - Discourage the expression specific genes. Protein Synthesis - Each gene is a segment of DNA that carries instructions for a polypeptide chain. - There are 4 nucleotide bases A, G, T, and C, that compose DNA. Each set of three nucleotides bases is called codon, DNA codons also known as triplets. - Each DNA codon specifies a particular amino acid in that can be assembled into a protein. The Genetic Code - Gene expression is uses gene's DNA sequence to build a protein with specific amino acids. Transcription - DNA to RNA: The process of transferring information from a gene's DNA base sequence to a complementary mRNA molecule. - To create an mRNA complement, a transcription factor coordinates the binding of RNA polymerase, the enzyme that synthesizes the mRNA strand. - The DNA strand used to create the complementary mRNA strand is called the template strand. - The coding strand of DNA has the same sequence as the mRNA transcript, except that thymine (T) is replaced by uracil (U) in RNA. - Both DNA strands can contain genes. - RNA to amino acids - Each DNA codon corresponds to a complementary RNA codon. There are 64 codons, each specifying one of the 20 amino acids or a stop codon. - tRNA picks up specific amino acid from cytoplasm, by binding to mRNA, transfers it to the ribosomes to be attached to the growing protein strand. RNA - RNA is the go between molecule that takes your genetic sequence from DNA and translates it into proteins. - Three types of RNA are constructed on the DNA in the nucleolus, then released to migrate to the cytoplasm while DNA recoils to its original form. - mRNA - messenger - copies the sequence of DNA. mRNA codon is a three-base sequence that lines up with a DNA codon. - tRNA - transfer - three-base sequences of RNA on one end (anti codons) and corresponding amino acids on the other end, to translate the nucleic acid sequence into amino acids. - rRNA - ribosomal - temporarily binds to mRNA in ribosome, catalyzing the reaction to bind the amino acid onto the polypeptide chain. Splicing - before mRNA leaves nucleolus noncoding introns are cut out and exons are reconnected. Alternative Splicing - regulated process that removes some exons along with introns, allowing one gene to make different proteins. Lecture \#10 Cognitive Behavioral Skills Lecture \#11 Cell Cycle - series of changes that a cell undergoes from time of formation until it reproduces. There are two major periods: - Interphase - Cell grows and carries on usual activities. This is the period from cell formation till cell division and has three subphases. During Interphase, nuclear material is in uncondensed chromatin state. - G1 (gap 1) cell is synthesizing proteins and actively growing. - S (synthesis) DNA is replicated - G2 (gap 2) enzymes and other proteins are synthesized and distributed throughout the cell. DNA Replication - Takes place when the helix uncoils and the hydrogen bonds between its base pairs are broken. Each nucleotide strand of the DNA acts as a template for construction of a complementary nucleotide strand. - Two identical daughter DNA molecules are formed from the original. This process is called semiconservative replication because each new double stranded DNA molecule is composed of one old strand and one new strand. DNA Polymerase - Attaches to one strand of DNA and joins nucleotides into a new complimentary strand. - The leading strand of DNA is synthesized continuously in 5' to 3' direction., moving towards replication fork where DNA is "unzipping". - The lagging strand is backwards; 5'is towards the fork, so nucleotides can only be added in the opposite direction of unzipping. It is synthesized discontinuously in short segments, that DNA ligase joins Ozaki Fragments of lagging strand. Mutations - DNA is copied every time a cell divides. - With high efficiency DNA replicates with 99.99999999% accuracy. Because the human genome is 3.2 billion bases long. There are approximately 100 mutations for every replication. - While many things can increase risk of mutation, these mutations are non-heritable because those cells are not inherited by the next generation. Confusing Vocabulary Centrosome - Organelle in cytoplasm that organizes microtubules. It is composed of two centrioles and a mass of protein to use as microtubule building supplies. Centriole - Tubulin cylinder that is part of the centrosome and form the base of cilia or flagella. Centromere - Region of a chromosome that links sister chromatids together. Also, the site of assembly of the kinetochore, the structure that allows microtubules to connect to each chromatid to polar centrosomes for mitosis to complete. Chromatids - Sister chromatids are each of two copies of a replicated chromosomes. - Daughter chromosomes are single chromosomes that were previously sister chromides but have now been pulled apart. Cell Division - Mitosis - Process of nuclear division. - Cytokinesis - Dividing cytoplasm. Mitosis - Division of nucleolus and its duplicated DNA to new daughter cells. DNA must be replicated in S phase prior to mitosis. - Prophase (early) - Chromatin condenses, forming visible chromosomes. - Each chromosome and its duplicate are held together by a centromere. - The centrosome and its duplicate begin synthesizing microtubules that push each centrosome to opposing sides of the cell. This set of microtubules is called the mitotic spindle. Other microtubules called asters and astral strays extend from centrosome to stabilize it. - Prophase (late) - Nuclear envelope breaks - Special microtubules attach to Kinetochore and pull the chromosomes to equator of the cell. - The remaining non-kinetochore microtubules of mitotic spindle push against each other, causing poles of cell to move further apart. - Metaphase - Centromeres of chromosomes are aligned at cells equator by spindle fibers. - Anaphase - Centromeres of chromosomes split each sister chromatid is now a separate chromosome. - Chromosomes pulled toward their respective poles by motor proteins on kinetochores. One chromosome from each pair goes to opposing poles. - Telophase and Cytokinesis - Begins when chromosome movement stops. - Each set of chromosomes (at opposite sides of cell) uncoils to form chromatin mass. - Nuclei reappear and spindle disappears. - Cytokinesis begins during late anaphase. A ring of actin microfilaments contracts to form cleavage furrow until 2 daughter cells are pinched apart. Lecture \#12 Chromosomes - You have 23 pairs, one set from each parent. - Most of your cells are diploid meaning, they each contain 2n (46) chromosomes. DNA inherited from parents; your genes are the total of what each parent gave you. - Gametes are haploid meaning they contain one version of each chromosome with a 50% chance of each chromosome coming from either parent. Miosis and Meiosis - Mitosis and meiosis differ, meiosis involves 2 consecutive cell divisions (meiosis I and meiosis II) but only one round of DNA replication, producing 4 daughter cells. - Functions of meiosis - To reduce number of chromosomes in half (2n to n OR 46 to 23) - To introduce genetic diversity, as daughter cells are genetically different from the original. Meiosis I - Prophase I - Synapsis: when homologous replicated chromosomes pair up forming tetrads consisting of 4 chromatids. - Crossover: the exchange of genetic material between homologous chromatids, resulting in unique chromosomes that are mixtures of maternal and paternal chromosomes. - Metaphase I - Tetrads lineup randomly at the metaphase plate. 50% chance of each chromosome being pulled in either direction, each chromosome is independent in this behaviour. - Anaphase I - Each tetra is pulled apart into 2 replicated chromosomes. Still 2 sister chromatids. - Telophase I - Nuclear envelope may reform. - No DNA replication - Brief period of interkinesis (in humans) At the end of meiosis, I - Each cell will contain 2 copies of one member of each homologous pair. - Each cell will contain the haploid chromosomal number (n rather than 2n) because still-untied sister chromatids are one chromosome if they are connected by centromere. (Twice the amount of DNA) Meiosis II - Each of the two daughter cells are new haploid. - All 23 chromosomes in haploid cell are replicated chromosomes, each made up by two sister chromatids. - Meiosis II is just like mitosis except cells are haploid, starting as replicated chromosomes and finishing as single chromosomes. - Sister chromatids from meiosis I are spirited and pulled toward opposite poles, resulting in each cell getting one of the daughter chromosomes. - During meiosis I, crossing over between maternal and paternal chromosomes result in an exchange of genetic material between members of tetrad. - Also, in meiosis I each tetrad randomly lines up at metaphase plate, resulting in independent assortment of single maternal and paternal homologues into the two daughter cells. - Meiosis II resembles mitosis except cells are haploid. Mitosis VS Meiosis - Mitosis has one round of division; meiosis has two. - Synapsis and crossing over occur in meiosis. - Mitosis produced haploid (2n) daughter cells identical to mother cell. Meiosis produces four haploid (n) daughter cells that all differ. - Mitosis produces somatic cells; meiosis produces gametes. Autophagy - Self-eating - Process of disposing non-functional organelles and cytoplasmic bits by forming autophagosome, which can then be degraded by lysosomes. - Unneeded proteins marked by ubiquitin's, small protein tags to indicate that the protein is ready to be destroyed. - Proteasomes disassemble ubiquitin tagged proteins, recycling the amino acids and ubiquitin. Apoptosis - Programed cell death - Causes certain cells to neatly self-destruct. - Process begins when mitochondrial membranes leak chemicals that activate enzymes called caspases. These enzymes degrade the cell's DNA and cytoskeleton which leads to cell death. - The dead cell shrinks and is phagocytized out of the cell. Aging - Wear and tear theory; lifetime of chemical damage and free radicals cumulated effects. - Mitochondrial theory - ; free radicals in mitochondria diminish energy production un each cell. - Immune system disorders; autoimmune responses, as well as progressive wakening of the immune response, lead to a loss of homeostasis. - Genetic theory: the cessation of mitosis and cell aging are programmed into genes. - Telomeres are strings of nucleotides that protect the ends of chromosomes. - Every time a cell divides, the telomere shortens, so telomeres may act like hourglass on how many times a cell can divide. - Telomerase is an enzyme that lengthen telomeres. It is found in germ cells of embryos but absent in adult cells, except cancer cells. 87 Lecture \#13