Cancer Cells, The Cell Membrane
Cancer Cells, The Cell Membrane BIOL 121N
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This 9 page Class Notes was uploaded by Dominick Ramos on Sunday October 4, 2015. The Class Notes belongs to BIOL 121N at Old Dominion University taught by DOUGLAS J MILLS in Fall 2015. Since its upload, it has received 46 views. For similar materials see GENERAL BIOLOGY I in Biological Sciences at Old Dominion University.
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Date Created: 10/04/15
BiollZlNCancer Cells Cancers Present quotA Difficult Set of Problems Cancer cells in a single tumor have different genotypes and thus respond differently to a single treatment Eg the cancer cells in a glioblastoma brain tumors show variation in 0 Go signal recognition 0 The rate of mitotic cell division 0 The response to the immune system including the complement system 0 Hypoxia oxygen deficiency in the body s tissues and the response to hypoxia The Defining Characteristics of Cancer Cells 0 the cell cycle is unregulated 0 one or more cell cycle checkpoints are ignored 0 they can divide indefinitely 0 their lifespan is increased due to abnormal aging due to telomere replacement 0 telomerase is abnormally expressed in 90 of aggressive cancers 0 some cannot selfdestruct by apoptosis cell death 0 some show abnormal binding to other cells and abnormal binding to the extracellular matrix 0 these characteristics promote metastasis malignant growth away from the primary cancer site Benign Tumors and Malignant Tumors Benign tumors contain cells that cannot metastasize 0 cells cannot invade new location Malignant tumors contain cells that can metastasize o the cells can invade new locations 0 some early stage cancer cells can metastasize IN Lympht 7 l vessel Tumor Blood w Lg vessel Glandular quot Sgllilcer tissue 39 Metastatic r quot tumor 0 A tumor grows 8 Cancer cells 9 Cancer cells spread 0 Cancer cells may from a single invade neigh to other parts of survive and cancer cell boring tissue the body establish a new tumor in another part of the body Dominick Ramos BiollZlNCancer Cells 2 Colchicine Taxol and the Vinca Alkaloids These plant derived compounds 0 bind to spindle microtubules and disrupt spindle function 0 cause M phase spindle checkpoint activation 0 induce apoptosis Methotrexate and Hvdroxvurea These anticancer drugs inhibit nucleotide synthesis and thus inhibit DNA replication 0 methotrexate prevents thymine dTTP synthesis 0 it inhibits the enzyme dihydrofolate reductase by blocking the action of folic acid vitamin 39 o it also inhibits purine synthesis to inhibit both DNA and RNA synthesis 0 hydroxyurea inhibits the enzyme ribonucleotide reductaste to reduce the supply of nucleotides available for DNA replication AntiHormone Therapy It deprives some breast endometrial and prostate cancer cells of their quotgosignals o the lack of a gosignal activates the G1 checkpoint resulting in apoptosis in some of these cancerceHs o antiestrogens amp antiprogestins treat breast and endometrial cancers 0 antiandrogens treat prostate cancer The Inhibition of Angiogenesis Blood Vessel Formation o a tumor must recruit new blood vessels as it grows o tumor cells secrete growth factors that stimulate angiogenesis o angiogenesis inhibitors reduce blood flow to tumors that deprives the cancer cells of nutrients and 02 o the drug angiostatin is a potential treatment for some metastatic cancers Radiation Therapy Radiation therapy induces numerous mutations in the genome of cancer cells 0 these mutations activate the 62 DNA damage checkpoint o the mutations cannot be repaired o the cancer cells selfdestruct due to apoptosis Dominick Ramos BiollZlNCancer Cells Two Vaccines Prevent Cervical Cancer But Do Not Cure It The vaccines train the acquired immune system to recognize and eliminate human papilloma virus HPA before it infects cervical cells inactivates the cell cycle checkpoints to stimulate cell division and causes cervical cancer Gardasil immunizes against some HPV surface proteins produced by HPV strains 611 16 and 18 Cervarix immunizes against HPV strains 16 and 18 The Potential of Nanoparticle Therapy In order to be safe and effective nanoparticles must Be soluble in blood lymph fluid and tissue fluid Identify all cancer cells in body Deliver drugs to cancer cells and never to healthy cells Avoid detection by the immune system Avoid immediate elimination from the body by the liver and kidneys Dominick Ramos BiollZlNCancer Cells 4 TODAY S STUDY GUIDE QUESTIONS CANCER CELLS DIFFER FROM NONCANCEROUS CELLS WHAT ARE THE DEFINING CHARACTERISTICS OF CANCER CELLS DO CANCER CELLS IGNORE ONE OR MORE CELL CYCLE CHECKPOINTS WHY IS IT OFTEN DIFFICULT TO A TREAT SINGLE TUMOR EFFECTIVELY WHY IS A MALIGNANT TUMOR A MORE SIGNIFICANT HEALTH CONCERN THAN A BENIGN TUMOR HOW CAN A BENIGN TUMOR POSE A SIGNIFICANT THREAT TO HEALTH WHAT ARE SOME SIDEEFFECTS OF CANCER CHEMOTHERAPY WHAT ARE SOME SIDEEFFECTS OF ANTIHORMONE THERAPY IN WOMEN IS THE DIVISION OF ADULT STEM CELLS IN THE BODY INHIBITED BY ANTICANCER DRUGS WHICH METABOLIC PROCESSES ARE TARGETED BY THE ANTICANCER DRUGS WE DISCUSSED WHICH CANCER TREATMENTS ARE INTENDED TO INDUCE APOPTOSIS IN CANCER CELLS WHY IS ANGIOGENESIS A TARGET OF CANCER CHEMOTHERAPY WHICH TYPE OF CANCER CAN BE PREVENTED THROUGH VACCINATION WHY ARE MEN AND WOMEN IMMUNIZED WITH THESE TWO VACCINES Dominick Ramos Biol121NThe Cell Membrane The cell membrane has many functions 0 Regulates the import and export of substances 0 Forms the boundary between the living world and nonliving world 0 Cell to cell binding and cell to cell identification 0 Maintains a voltage difference in electrical charge 0 The voltage is like a battery for our cells The synthesis of cell membranes The endoplasmic reticulum ER and the Golgi apparatus are the two organelles that interact to 0 Make phospholipids and steroids 0 Deliver the vesicles containing new membrane materials to the existing cell membrane 0 Vesicles are small membranebound sacks that transport materials within the cell and also the cell membrane 0 The vesicle fuses with the existing cell membrane during exocytosis to increase sell size The transport of small hydrophobic substances Small hydrophobic nonpolar substances directly diffuse across the cell membrane and organelle membranes from areas of higher concentration to areas of lower concentration The transport of small hydrophilic substances Passive transport Facilitated diffusion THESE HYDROPHILIC 4 3914 q SUBSTANCES MOVE FROM TRANSPORT occ HIGIllElR CONCENTRATION To v 39A V V LOWER CONCENTRATION or EACH CHAN lEI PROTEIN Channel protein THERE ARE SPECIFI BHAlNNEL PROTEINS FOR CA CI Nanii li39Eig Himi AN ION IS A CHARGE PARTICLE AN ELEMENT IS A PU lE CHEMICAL SUBSTANCE CONSIS ING OF ONE Elements with an electrical charge and water molecules can diffuse across the cell membrane through specific channel proteins This is called 0 uses the energy of diffusion to drive transport Biol121NThe Cell Membrane 2 Our cells will use channel proteins to transport these substances Carrier proteins can transport small hydrophilic molecules like glucose or lactose across cell membranes l5 l 39 l395 vii 9133 m HESE GLUCOSE f 26 11 1 merwnlig 39quot g 7 MOLECULES Q MOVE lF RlJWI Glucose Q HIGHER carrier protein GONGElNTRATIGN T0 LOWER CONCENTRATION Plasma membrane I quotif SCMNCF of WHO Scumquot airman gun 5 1 A Chillv quotvolm flclllmol Munoquot VIII 1 m a H mm u V 4 AV mm WWW v w r 11er C T lquotquotfquot c r ril flrlc 39rf39i39 an The active transport of substances across the cell membrane 0 active transport proteins transport hydrophilic substances from the side of the membrane where they are present at lower concentration to the side of the membrane where they are present at higher concentration 0 ATP provides the energy required for active transport to occur Multidrug resistance proteins These active transport proteins export 0 Foreign compounds from our normal healthy cells 0 Anti cancer drugs from cancer cells Antibiotics from pathogenic bacteria Our cells must import larger substances Endocytosis is the process that enables cells to import relatively large particles and entire cells 0 Phagocytosis cellular eating is a type of endocytosis that imports food particles and foreign invaders like bacteria or viruses Biol121NThe Cell Membrane 3 o The cell membrane engulfs the particle or cell to be imported PHAGOCYTOSIS garvxaamwia CYTOPLASM 1 m f quotl l l Pseudopodium 4 of amoeba Bacterium Food VaCUOle Food vacuole An amoeba engulfing a bacterium via phagocytosis TEM Our cells must import extracellular fluid Pinocytosis cellular drinking enables cells to import large bulk quantities of substances that are dissolved in the surrounding extracellular fluid PINOCYTOSIS Plasma membrane Pinocytosis vesicles forming arrows in a cell lining a small blood vessel TEM Vesicle Cooyngm 2008 Pearson Educatlcn inc publish 39ng as Pearson Benia39nm Cummings o Dissolved food molecules 0 Other types of dissolved solutes 0 Water molecules RECEPTORM EDIATED ENDOCYTOSIS Our cells must import some specific large molecules MIMI39Coat protein quot Coated veslole Receptormediated endocytosis imports specific larger molecules in a regulated manner o It imports specific substances such as the low density lipoproteins the transferrins that contain iron and some protein hormones o It imports ligands bound to receptors to participate in signal transduction 3 Acoated pit 39 andacoated l vesicle formed durlng I receptor mediated quot539 endocytosis quot TEMs 9 A 39r 5A membra 39 39 I Lm LL Jl sltewrarku39 Dnuuu39aul lvE39uHILu u gt Biol121NThe Cell Membrane Cells must export a range of hydrophilic molecules EXTERNAL ENVIRONMENT 9 39 I V 44quot Cell membrane Vesiltle Exocytosis enables cells to export hydrophilic proteins and other substances like neurotransmitters o A vesicle containing multiple copies of a soluble protein or other hydrophilic molecule fuses with the cell membrane to release its contents into the extracellular space BiollZlNThe Cell Membrane TODAY S STUDY GUIDE QUESTIONS HOW DO SMALL HYDROPHOBIC MOLECULES CROSS THE CELL MEMBRANE WHICH SOURCE OF ENERGY DRIVES THE FACILITATED DIFFUSION OF SMALL HYDROPHILIC POLAR SUBSTANCES ACROSS THE CELL MEMBRANE DOES THE FACILITATED DIFFUSION OF LACTOSE REQUIRE A CHANNEL PROTEIN OR A CARRIER PROTEIN DOES THE FACILITATED DIFFUSION OF POTASSIUM K IONS REQUIRE A CHANNEL PROTEIN OR A CARRIER PROTEIN IS EACH CHANNEL PROTEIN AND CARRIER PROTEIN SPECIALIZED TO TRANSPORT A SPECIFIC HYDROPHILIC SUBSTANCE ACROSS THE CELL MEMBRANE VIA FACILITATED DIFFUSION WHY DO ACTIVE TRANSPORT PROTEINS REQUIRE AN ENERGY SOURCE LIKE ATP IS ENDOCYTOSIS SPECIALIZED TO IMPORT LARGER SUBSTANCES INTO OUR CELLS 39 WHICH TYPE OF ENDOCYTOSIS IMPORTS FOOD MOLECULES DISSOLVED IN EXTRACELLULAR FLUID INTO OUR CELLS 39 WHAT IS THE FUNCTION OF RECEPTORMEDIATED ENDOCYTOSIS 39 WHICH TYPE OF ENDOCYTOSIS DO OUR MACROPHAGES USE TO IMPORT BACTERIA AND VIRUSES FOR DESTRUCTION HOW DO THE BETA CELLS OF THE PANCREAS THAT MAKE INSULIN EXPORT MULTIPLE COPIES OF THIS PROTEIN HORMONE SIMULTANEOUSLY 39 HOW DO CANCER CELLS EXPORT MULTIPLE COPIES OF PROTEINS THAT STIMULATE ANGIOGENESIS NEW BLOOD VESSEL FORMATION