Week 4 Notes
Week 4 Notes EXSC 223
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This 11 page Class Notes was uploaded by Madison Waterman on Sunday September 18, 2016. The Class Notes belongs to EXSC 223 at University of South Carolina taught by Dr. Raymond Thompson in Fall 2016. Since its upload, it has received 17 views. For similar materials see Anatomy and Physiology I in Science at University of South Carolina.
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Date Created: 09/18/16
EXSC 223: Week of 9/12/16 Notes from the textbook Ch. 3.10 3.10 The cell cycle consists of interphase and a mitotic phase • Cell cycle: changes a cell goes through from when it is formed to when it reproduces • Two major periods for the cell o Interphase: cell grows and carries out normal activities § G1 (gap 1 subphase) • Metabolically active • Synthesizing proteins • Growing rapidly • Most variable in length, can last minutes to years • Cells that permanently stop dividing are in the G0 phase § S phase • DNA is replicated to ensure the two future cells will have identical copies of genetic material • New histones made and assembled into chromatin § G2 (gap 2 subphase) • Enzymes and other proteins needed for division are synthesized and moved to their proper sites • By the end, centriole replication is complete o Nuclear division (mitosis): nucleus divides into two nuclei § Prophase: nuclear envelope dissolves, chromatin condenses into chromosomes § Metaphase: chromosomes line up at metaphase plate § Anaphase: sister chromatids are pulled apart § Telophase: cleavage furrow forms, nuclear envelope reforms § CELL division: Cytokinesis Lecture Notes 9/12 Chromosomes • They come in pairs in humans o diploid o Two copies of each gene (1 from mom, 1 from dad) • Chromatin vs chromosomes o Just different states of DNA o Two sides of the same coin Chromatin Chromosome Uncondensed Condensed Not visible under a light microscope Visible under a light microscope Loosely wound Tightly wound DNA is in this state majority of the time DNA is only in this state during mitosis and meiosis • Centromere: point at which two strands of DNA attach o It is marked by a DNA sequence o Present in chromatin and chromosomes • Sister chromatids: 2 strands of DNA connected by a centromere o In mitosis, microtubules attach to kinetochores which are attached to centromeres o Sister chromatids are separated in anaphase • Telomere: DNA sequences found at the end of chromatin o End caps o Don’t code for any genes o DNA polymerase can’t read end sequence so DNA wouldget shorter and shorter, the telomeres prevent this degradation o Telomerase: enzyme that rebuilds end caps o Present on both ends of the DNA strand Cell cycle • 2 phases interphase and mitotic phase • cells spend most of their time in interphase • interphase subphases o G1: growth § Checkpoint: make sure everything is in its proper place to advance in the cell cycle o S: DNA replication and growth o G2: growth and final prep for division § Enzymes and regulatory proteins for the mitotic phase are produced § Checkpoint: make sure cell is ready for division o G0: cell stops in the cell cycle, never enters S phase § Sometimes called “post-mitotic” or “amitotic” § Most cells are always in G0 • DNA replication in S phase o Helicase unwinds the DNA and separates the 2 strands o DNA polymerase: enzymes that work together to read the template and bring in complementary nucleotides for the existing strand (template) § There is a DNA polymerase on both strands (leading and lagging strands) • Leading: DNA polymerase works continuously • Lagging: DNA polymerase makes complementary pieces in fragments (Okizaki fragments) o Ligase comes and connects the Okizaki fragments • Mitotic Phase o Mitosis: a subphase of the mitotic phase § MITOSIS IS THE DIVISION OF THE NUCLEUS NOT THE CELL o Cytokinesis=cell division § Can begin before mitosis is finished o Early vs late prophase § Early prophase: spindles have not yet moved to opposite sides of the cell § Early prophase: there is still a nucleus • Late prophase: the nuclear envelope dissolves § Chromosomes condense in early prophase § Late prophase • Nuclear envelope degenerates • Spindles are on opposite sides of the cell • Microtubules start pushing chromosomes to the center o Metaphase § Very brief § All chromosomes lined up at the center (metaphase plate, equator) § Chromosomes are still attached at the centromere o Anaphase § Sister chromatids are pulled apart § Microtubule structures attach to kinetochore proteins o Telophase § Nuclear envelope reforms § Contractile ring at the cleavage furrow forms § Cells start to separateàdivide all contents equally • Cell cycle regulated by cyclin and cdk o Both are proteins o Work together to produce MPF (mitotic producing factors) o Cdk will always be present regardless if cell will go through mitosis or not o Cyclins vary: sometimes they are prevalent, sometimes not o Regulate progression of the cell by regulating the amount of cyclin present § Cyclin=cytosolic protein § Produced in standard protein synthesis § Eliminated by ubiquitin proteasome pathway Notes from textbook 4.3 4.3 Connective tissue is the most abundant and widely distributed tissue in the body • Common characteristics o Same origin: all connective tissue comes from mesenchyme o Degrees of vascularity: some avascular, some highly vascularized o Extracellular matrix: connective tissue largely composed of non-living extracellular matrix in addition to cells § Allows connective tissue to bear weight, withstand high tension, endure abuses and abrasion • Structural elements o Ground substance § Unstructured material that fills space in between cells and fibers § Composed of interstitial fluid, cell adhesion proteins, and proteoglycans o Fibers § Proteins that provide support § 3 main types • Collagen • Elastic • Reticular o Cells § Exist in immature (-blast) and mature (-cyte) forms § Primary cell types for different types of connective tissues • Connective tissue proper: fibroblast • Cartilage: chondroblast • Bone: osteoblast • Blood: hematopoietic stem cell • Types of connective tissue o Connective tissue proper § Loose connective tissues • Areolar • Adipose • Reticular § Dense connective tissue • Dense regular • Dense irregular • Elastic o Cartilage § Hyaline cartilage § Elastic cartilage § Fibrocartilage o Bone § Osseous o blood Lecture notes 9/14 4 types of tissue 1. Nervous 2. Muscle 3. Epithelial 4. Connective • Epithelial and connective are the most likely to go through mitosis • Epithelial tissue: most likely to develop cancer Connective tissue • Found everywhere in the body • Most widely distributed and abundant of primary tissues • Major functions o Binding and support § Ex: each muscle is surrounded by connective tissue to bind and support them o Protection § Ex: adipose surrounds kidneys to protect them o Insulation § Ex: adipose helps retain heat o Transportation of substances or heat within the body § Ex: blood, red blood cells transport oxygen • Common properties o Common origin: Mesenchyme § Stem-like cell that arises during embryonic division o Extracellular matrix § Majority is non-cellular § Proteins, water, etc. o Degrees of vascularity (lacks uniformity) § Some have a large blood supply, others not so much Structural elements • 3 main components o Ground substances (extracellular matrix) o Fibers (extracellular matrix) o Cells (produce extracellular matrix) • The amount of each structural element varies, some connective tissue has a lot of ground substances and fibers and few cells and others have lots of cells and few fibers and ground substances • Ground substance: proteoglycan structure o Unstructured material filling the space between cells o Cell adhesion proteins § Connects tissue cells to matrix elements § Ex: laminin, fibronectin § Connect fibers to integral proteins § Directly connects extracellular matrix to the cells o Proteoglycans § Have a protein core that glycoaminoglycans (GAGs) attach § Intertwine and trap water § Regulate ground substance viscosity o Interstitial fluid § Water § Bathes cells § Fluid that comes and goes • Fibers o Collagen fibers § Most abundant protein in the body § Fibrous collagen proteins § Secreted into extracellular space and spontaneously assemble into cross- linked fibers § High tensile strength § Rigid, limited flexibility o Elastic fibers (elastin) § Elastin protein (with some collagen) § Stretches and recoils § Found where elasticity is needed • Skin • Lungs • Blood vessels o Reticular fibers § Short, fine proteins § Delicate networks § Fine collagenous fibers § Abundant in lymph nodes § Support soft tissue around organs • Cells o Development of connective tissue from mesenchyme § First tissue formed from mesoderm layer • Composed of mesenchymal cells, fluid and ground substances § Differentiates into all other connective tissue § Some mesenchymal cells remain (undifferentiated) o MESENCHYME § Cellular descendants: • Fibroblast-fibrocyte o Class of connective tissues: connective tissue proper o Subclasses § Loose connective tissue • Areolar • Adipose • Reticular § Dense connective tissue • Regular • Irregular • Elastic • Chondroblast-chondrocyte o Class of connective tissue: cartilage o Subclasses § Hyaline cartilage § Fibrocartilage § Elastic cartilage • Osteoblast-osteocyte o Class of connective tissue: osseous (bone) o Subclasses: § Compact bone § Spongy bone • Hematopoietic stem cells o Class of connective tissue: blood cells o Subclasses § Blood Loose areolar • Description: gel-like matrix with all 3 fiber types; cells: fibroblasts, macrophages, mast cells, some white blood cells • Function: wraps and cushions organs • Location: under epithelia of body, forms lamina propria, surrounds organs Adipose • Description: not much matrix, closely packed adipocytes, fat droplet takes up most of the cell so the nucleus is pushed to the side • Function: stores energy, insulates, protects organs • Location: subcutaneous tissue, around kidneys and eyeballs, abdomen, breasts Loose (reticular) • Description: loose network of reticular fibers in gel-like ground substance, reticular cells lie on the network • Function: fibers form a soft internal skeleton that supports other cell types • Location: lymph nodes, bone marrow, spleen Dense regular • Description: parallel collagen fibers, few elastic fibers, fibroblasts • Function: attaches muscles to bones or to muscles, attaches bones to bones, withstands tensile stress • Location: tendons, ligaments, aponeuroses Dense irregular • Description: irregularly arranged collagen fibers, some elastic fibers, fibroblasts • Function: structural strength, withstand tension • Location: dermis, submucosa of digestive tract Elastic • Description: dense regular connective tissue, lots of elastic fibers • Function: allows tissue to recoil after stretching • Location: walls of large arteries, bronchial tubes, ligaments in the vertebral column Cartilage • Properties are intermediate qualities to bone and dense connective tissue and include o Avascular o Lacks nerve fibers o Ground substance § Rich in glycoaminoglycans: chondroitin sulfate, hyaluronic acid, collagen, and elastic fibers § Up to 80% water o Can withstand tension and compression forces • Primary cell type: chondroblast which secretes matrix • Types: hyaline, elastic, fibrocartilage Notes from the textbook Ch. 4.2 4.2 Epithelial tissue covers body surfaces, lines cavities, and forms glands • Epithelial tissue: sheet of cells that covers a body surface or lines a body cavity • Two forms exist in the body o Covering and lining epithelium § Forms outer layer of skin § Lines open cavities of urogenital, digestive, and respiratory systems § Covers walls and organs of closed ventral body cavity o Glandular epithelium § Fashions the glands of the body • Epithelia form boundaries between different environments • Functions o Protection o Absorption o Filtration o Excretion o Secretion o Sensory reception • Characteristics of epithelia o Polarity: all epithelia have an apical surface (upper, free surface exposed to body exterior or cavity of internal organ) and a basal surface (lower, attached) § Apical-basal polarity o Specialized contacts § Fit close together and form continuous sheets § Tight junctions and desmosomes bind adjacent cells together § Tight junctions keep proteins in the apical region from going to the basal region o Supported by connective tissue § Epithelial sheets supported by connective tissue o Avascular but innervated § Avascular: no blood vessels § Innervated: supplied by nerve fibers § Cells nourished by substance diffusing from blood vessels o Regeneration § High regenerative capacity • Classification of epithelial tissue o Number of cells present § Simple: single cell layer • Absorption, secretion, filtration § Stratified: 2 or more cell layers stacked • High abrasion areas, protection needed o Shapes of cells § Squamous: flattened, scale-like § Cuboidal: boxlike, approximately as tall as it is wide § Columnar: tall, column shaped • Types o Simple squamous § Single layer, flat cells § Allows diffusion and filtration § Ex: blood vessels o Simple cuboidal § Single layer, cube-like cells § Secretion and absorption § Ex: kidney tubules o Simple columnar § Single layer of tall cells § Absorption, secretion of mucus § Ex: digestive tract o Pseudostratified columnar § Single layer, differing heights, nuclei seen at different levels § Secrete things, especially mucus § Ex: trachea o Stratified squamous § Several layers, basal cells are cuboidal, surface are squamous § Protects underlying tissues from abrasion § Ex: esophagus, mouth, vagina, skin (keratinized version) o Transitional epithelium § Resembles stratified squamous and stratified cuboidal § Basal cells are cuboidal or columnar, surface cells are dome shaped/squamous-like § Stretches readily § Ex: ureter, bladder, urethra • Glandular epithelia o Gland: one or more cells that make and secrete a particular product (secretion) § Exocrine: externally secreting • Secrete products onto the skin or into body cavities • Ex: salivary glands § Endocrine: internally secreting • Ductless • Produce hormones Lecture notes 9/16 Hyaline • Description: firm matrix, collagen fibers, chondroblasts produce the matrix and mature into chondrocytes and lie in lacunae, no blood supply to cells • Function: supports and reinforces, resists compressive stress • Location: covers the ends of long bones in joint cavities, ribs, nose, trachea, larynx Elastic • Description: similar to hyaline but more elastic fibers in matrix • Function: maintains shape of a structure while allowing great flexibility • Location: external ear (pinna), epiglottis Fibrocartilage • Description: matrix similar to hyaline but less firm, lots of collagen fibers, much denser than other cartilage • Function: absorb compressive shock • Location: intervertebral discs, discs of knee joint Bone, osseous • Description: hard, calcified matrix with many collagen fibers, very well vascularized, osteocytes lie in lacunae • Function: supports and protects, stores calcium, marrow inside is site of blood cell formation • Location: bones Blood • Description: red and white blood cells in a fluid matrix (plasma) • Function: transport respiratory gases, nutrients, wastes, etc • Location: in blood vessels • Classification as a connective tissue o Develops from mesenchyme o Surrounded by a fluid matrix (plasma) o Has fibers (blood fibers)-visible during clotting Epithelial Tissue • Epithelium: sheet of cells lining a body surface or cavity • 2 types: covering/lining epithelium and glandular epithelium • functions as an interface tissue o protection: skin protects body from the environment o absorption: small intestine absorbs nutrients o filtration: kidneys filter blood o excretion (of waste products): kidneys excrete what isn’t wanted (ex: urine) o secretion: sweat is secreted from glands § secretion: release of products produced by that cell. NOT waste o sensory reception: tactile receptors in skin • special characteristics o polarity § apical (exposed surface) § basal (surface you can’t see, adjacent to connective tissue) o specialized contacts § different junctions (covered in chapter 3) o supported by connective tissue (basal surface) § epithelial cells rest on basal membrane § basement membrane=basal lamina + reticular lamina § thin layer of connective tissue next to the basal surface o innervated but avascular § has nerves § no blood vessels • does still have a nutrient supply • mitotically capable o regeneration • classifications o shape: squamous (scale-like), cuboidal (cube-like), columnar (column shaped) o layering (strata): simple (one layer), stratified (more than one layer) • Simple squamous o Description: single layer of flattened cells o Function: allows materials to easily diffuse, site of filtration secretes lubricating substances in serosae o Location: kidney glomeruli, lining of heart, blood vessels, lungs o Also called mesothelium and endothelium • Simple cuboidal o Description: single layer of cube-like cells, large central nuclei o Function: secretion and absorption o Location: kidney tubules, ducts and secretory portions of small glands
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