Cell Structure and Function (2) PDF

Introduction to Cells  https://newbiescience.files.wordpress.com/2013/11/70261_420x315-cb1375994886.jpg Session Learning Outcomes (SLOs) SLO# 1: Explain the cell theory and the basic cell structure SLO# 2: Compare the structure of a prokaryotic cell with...

Introduction to Cells  https://newbiescience.files.wordpress.com/2013/11/70261_420x315-cb1375994886.jpg Session Learning Outcomes (SLOs) SLO# 1: Explain the cell theory and the basic cell structure SLO# 2: Compare the structure of a prokaryotic cell with the structure of a eukaryotic cell SLO# 3: Explain how cell fractionation is used to isolate the cell components. SLO# 1: Recognize organelles found in eukaryotic cells. SLO# 2: Identify the function and organization of the various organelles in eukaryotic cells. SLO# 3: Explain how the diseases are associated with specific cell-organelles.  Cell Theory 1- Cells are the smallest structural and functional unit of organisms 2- All organisms are composed of cells 3- All cells come only from preexisting cells (Cell division)  Characteristics of a Cell  Store information in the DNA  Make and Use energy wife  Capable of movement  Sense environmental changes By receptors  Can duplicate (growth, repair, reproduction & development) division maintainenestable state in our bodies  Capable of self-regulation (homeostasis)  Build molecules (proteins, carbohydrates, fats, nthesis nucleic acids) Types of cells Prokaryote Cells with nucleus in Eukaryotes Bacteria cells Animal cells Plant cells  Prokaryotes vs. Eukaryotes Prokaryotic Eukaryotic Cells Cells < 10 µm Size 10-100 µm Does not have a true Nucleus Has a true membrane nucleus. Only a nucleoid bound nucleus www.shsmsmm Has no membrane bound Membrane Has membrane bound organs are surroundedby organelles bound Organelles organelles org mes One circular piece of DNA DNA Many linear pieces of with no proteins with nonostone DNA with proteins no one Small ribosomes Ribosomes Large ribosomes All Prokaryotes are Number of cells Eukaryotes are either unicellular unicellular oryeast multicellular image Asexual only through Reproduction Sexual and asexual sin binary fission ibis through mitosis & prostistsFungi p Eubacteria and Kingdom of life meiosist.joj andanimal  h b Three important Cell Regions 1- Cell membrane: 2- Nucleus This is the outermost The control center of boundary on the cell. the cell that contains the DNA (deoxyribonucleic acid) which directs the functioning of the cell. 3- Cytoplasm: The part between the cell membrane and the nucleus It contains a liquid called cytosol. Within the cytosol are organelles which are special structures that carry out different cell functions.  Three important Cell Regions As well, two other important terms are: 1- Intracellular which refers to the area inside of the cell. 2- Extracellular which refers to the area outside of the cell.  Why study cells?  Cells Tissues Organs Bodies Bodies are made up of cells. Cells do all the work of life.  How study cells? We study cells using biochemistry techniques. Is Cell fractionation cell components It - Isolating organelles - Homogenization im - Ultracentrifugation I www.ws  Cell Fractionation separate APPLICATION: Fractionate cell components based on size and density. different speed different TECHNIQUE: duration Cells are homogenized in a blender. The resulting homogenate is centrifuged. iii A Differential centrifugation results in a series of pellets, each containing different cell components RESULTS: Using microscopy to identify the organelles in each pellet Using biochemical methods to determine the metabolic functions of the organelles. o  Organelles in eukaryotic cells The Cell Membrane Structure The cell membrane is also known as the plasma membrane. xowm.im It is composed of two layers of phospholopids. Irwin It is called the phospholipids bilayer because it is made of these two layers A phospholipid is a type of fat interact with extracellular composed of: β Aqueous environment Phosphate head 1- A hydrophilic “water-loving” phosphate head that faces the aqueous Fatty acid tails environment. interactwith 2- Two hydrophobic water-fearing” eachother Aqueous environment fatty acid tails which face other fatty acid tails  The Cell Membrane Structure Besides the phospholipid bilayer, the cell membrane also contains: proteins, sterols and sugars within the bilayer which help it perform specific functions. jwimnmrc.im This model of the membrane is called the fluid mosaic because it allowsmolecules model. I cohrainsdifferent topass through  The Cell Membrane Function The cell membrane has several important functions: 1- It forms a physical barrier to protect the inside of the cell from outside environment. ii i sina.im sin w ii 2- It controls the transport of substances into and out of the cell. This is possible because the membrane is selective semi-permeable. ik.sn Yesenia to flecules pass wmse.am and  d a oh The Cell Membrane 3- It plays a role in cell-to-cell communication. lymphocytes interaction T and B between the cells between the cell and the wall extracellular matrix g 4- It is an attachment surface for cell walls, other cells and the intracellular cytoskeleton. swima  Organelles of the Cell  Organelles do the work of cells  The basic set of organelles found in most animal cells. http://image.tutorvista.com/content/feed/tvcs/Cell20organelle.jpg biggest organell - Nucleus it i side - Endoplasmic reticulum - Golgi apparatus prison - lysosomes - Mitochondria - Peroxisomes animism - Ribosomes Model Animal Cell  Cell organelles are of 2 types Membranous Organelles 1. Endoplasmic Non-Membranous O reticulum. Organelles 2. Mitochondria. O 1. Ribosomes O 3. Golgi. O 2. O Cytoskeletal fibers 4. Lysosomes. O structures  Organelles of the Cell  Many cell organelles are connected through the endomembrane system Miskimpose  Many of these organelles work together in: -Synthesis FIforming protiens -Storage, and -Export molecules.  The Nucleus: Information Central Structure  The nucleus is the largest cellular organelle in animals.  The nucleus is composed of: nuclearenvelope β nuclearpore 1- Nuclear Membrane 2- Nucleoplasm like cytoplasm 3- Nucleolus 4- Chromatin and Chromosomes DNA Protien chromatin  in Structure The Nucleus 1-Nuclear Membrane  It surrounds and protects the contents of the nucleus  It consists of double layer of membrane and it contains nuclear pores. KikeTransporter  It contains nuclear pores which permit exchange between nucleoplasm & cytoplasm. selective The Nucleus Structure 2- Nucleoplasm  The liquid within the nucleus.  It is similar to the cytosol within the cytoplasm have nomembrane 3- Nucleolus  is a "sub organelle" of the cell nucleus.  Made up of a combination of rRNA and proteins. nucleolus  Site of ribosomes synthesis.  The nucleolus loses its identity during cell division. Tppear dis  The Nucleus Structure Chromatin The nucleus is composed of: nucleosome DNA histone 4- Chromatin and chromosomes  Strands of DNA wrapped around proteins called histones create chromatin.  There are two types of chromatin: not true cromatine orlooselypacked 1- Euchromatin, is the less compact DNA doesn't expressd form, and contains genes that are fogfrequently expressed by the cell. Active http://2.bp.blogspot.com/_HtLvymcBlKo/TJJ18_Eq-bI/AAAAAAAAAA8/l6AyC3lzG2Y/s1600/2.png telomere protectsthe endofchromosome  The Nucleus Structure ñ  Chromatin forms chromosomes when it condenses into easily visible strands during cell division  Chromosome Structure Structure a. Nuclesosomes – Core of DNA wrapped around 8 histone proteins plus linker DNA 4types of histone each 2 me j b. Solenoid – coiling of nucleosomes like phone cord c. Chromatin fiber – series of nucleosomes a Ist shared d. Metaphase chromosomes  http://ccftp.scu.edu.cn:8090/Downl Each human cell contains 46 chromosomes (except sperm or egg cells)  I am in Anucleated and polynucleated cells 1- Anucleated cells contain no nucleus and are therefore incapable of dividing to produce daughter cells. Red blood cells 2- Polynucleated cells contain multiple nuclei.  In humans, skeletal muscle cells, called myocytes, become polynucleated during development imf  Multinucleated cells can also be abnormal in humans. 2.681 JIN Cells arising from the fusion of monocytes and em macrophages, known as giant multinucleated cells, sometimes accompany inflammation and are also implicated in tumor 49 formation. Giant-cell tumor of the bone (GCTOB) is a relatively uncommon tumor of the bone. It is characterized by the presence of multinucleated giant cells (osteoclast-like i.mn cells). Malignancy in giant-cell tumor is uncommon and occurs in about 2% of all cases. cause can cancer Multinucleated giant cells due to an infection. Biomedical importance Functions The nucleus of a eukaryotic cell stores DNA and directs the cell's activities.  Nucleus contains the biochemical processes involved in the Replication of DNA before mitosis. polymerases Enzyme DNA  Involved in the DNA repair.  Transcription of DNA – RNA synthesis. polymerases RNA The nucleus contains a variety of proteins: 2m 1- Enzymes mediate transcription. j.d  RNA polymerases that synthesize the growing RNA molecule. js sj.fi  Topoisomerases that change the amount of supercoiling in DNA. the compact of DNA 2- Enzymes involved in regulating the transcription.  Transcription factors that regulate expression. Activated according to the signs that sent Nuclear transport  Small molecules can enter the nucleus without regulation withneedforenergy molecules  Macromolecules: RNA and Proteins are actively transported across the nuclear membrane with regulation by the nuclear pore complexes Allow some molecules to pass Assembly and disassembly of the nucleus  During its lifetime a nucleus may be broken down: o The process of cell division. o As a consequence of apoptosis 201 4801in  Disorders of nucleus u  Defective nucleoli (singular = nucleolus) have been implicated in several rare hereditary diseases, mostly maim neurodegenerative disorders such as Alzheimer’s and Huntington’s disease. ess swinesong  Parkinson’s disease may be caused by oxidative stress within cells due to defective nucleoli.  Antibodies to certain types of chromatin organization, particularly nucleosomes, have been associated with a www.sos.mn number of autoimmune diseases, such as systemic lupus erythematosus, and multiple sclerosis These are known as anti-nuclear antibodies (ANA). missingw.ie Nucleus Summary  Cytoplasm:  It is jelly-like substance containing water and miniral salts.  Acts as a medium where biochemical reactions and most living processes occur within the cell. w̅ Enzymes (glycolytic pathway) All the machinery for protein synthesis (mRNA, transfer RNA, enzymes, and other factors) traibosom Oxygen, CO2, electrolytic ions, low molecular weight substrates, metabolites, waste products, etc  Contains organelles with different cell functions.  The Endoplasmic Reticulum: Biosynthetic Factory  Endoplasmic reticulum (ER) is a network of membranes throughout the cytoplasm of the cell.  There are two kinds of endoplasmic reticulum: Smooth and rough. Rough ER is embedded with ribosomes on cytoplasmic side. Smooth ER Rough ER membrane Is lacks attached ribosomes continuous with the nuclear envelope surrounding the nucleus  Although physically interconnected, smooth and rough ER differ in structure and function. Biomedical importance Smooth Endoplasmic Reticulum mm many metabolic processes (synthesis & hydrolysis) I m Im 1- Lipids biosynthesis: synthesizes lipids, phospholipids as in plasma membranes, and steroids som qui is 2- Detoxification: the detoxification of alcohol, and other potentially harmful substances. drugs storage 3- Sequestration of Ca++: Some smooth ER helps store and release calcium ions. Fencelneedit Rough ER  The ER system serves as a location for the proteins- synthesizing ribosomes.  Directs molecules towards single places. it o Intracellular storage (eg, in lysosomes and specific granules of leukocytes), w̅ 's o Provisional intracellular storage of proteins before exocytosis w o Integral membrane proteins.  Sends proteins to the Golgi apparatus. Er golgi apparatus  Synthesis of other organelles (lysosomes & Peroxisomes). produce redblood cells no Ev synthesis oesn't protein too mulh Er very active in in Pencrias synthesisproteins  signal sequences direct proteins to the correct organelle. each protein specific has sequences gnal inter in Er an if Nao  proteins destined for the ER possess an N-terminal signal sequence that directs them to that organelle, j  whereas those destined to remain in the cytosol lack this sequence. 65014  recombinant DNA techniques can be used to change the location of the two proteins Golgi Apparatus: finishes, sorts, and ships cell products  3 main structures can be observed under EM :  Flattened vesicles.  secretory vesicles.  Microvesicles. keyfeatureof Golgiapparatus  The main structural unit of Golgi apparatus is a flattened membrane vesicle described as GOLGI farfromE SACCULE. ME 5  Each stack of saccules in Golgi complex possess 1. Forming face(Cis–face) 2. Maturing face(Trans-face)  Biomedical importance fine offas a molecular warehouse and finishing  Serves in factory for products manufactured by the ER. - Products travel in transport vesicles from the ER to the Golgi apparatus. cis face a - One side of the Golgi apparatus functions as a receiving dock for the product and the other as a shipping dock. trainsface Biomedical importance - Products are modified as they go from one side to the Golgi apparatus to the other side - Prepares for “shipment” in vesicles from trans face to other sites em ratus  cisternal maturation tothelessmature Golgi cisterna 1- Vesicles for transport (the secretion of proteins from the cells(hormones, plasma proteins, and digestive enzymes). 2- Vacuoles for storage. 3- lysosomes for find out later https://youtu.be/iA8hFSHS6Ho no  for 3 destinations  Shipping and sorting done by the Golgi complex is a very important step in protein synthesis.  If the Golgi complex makes a mistake in shipping the proteins to the right address, certain functions in the cell may stop.  Defects in various aspects of Golgi function leads to to 1. Congenital glycosylation disorders. mom 2. Muscular dystrophy. 3. Diabetes. 4. Cancer. if'm 5. Cystic fibrosis.  Lysosomes: Digestive Compartments kinda  Membrane-bound vesicles responsible for the intracellular digestion of both intra and extracellular substances. damage recycling organelles of pray  Enzymes & membrane of lysosomes are synthesized by rough ER & transferred to the Golgi apparatus for processing.  The membrane serves to safely isolate these potent enzymes from the rest of the cell.  Biomedical importance  The enzyme content varies in different tissues according to the requirement of tissues or the metabolic activity of the tissue.  Lysosomal membrane is impermeable and specific translocators are required. me ini acid  Contain lytic enzymes (Low pH) ‰ Digestion of large molecules ‰ Recycling of cellular resources ‰ Apoptosis The metabolites that result are transported either by vesicles or directly across the membrane.  Cellular digestion  Lysosomes carry out intracellular digestion by Phagocytosis  Lysosomes help digest food particles engulfed by a cell. 1. A food vacuole binds with a lysosome. 2. The enzymes in the lysosome digest the food. 3. The nutrients are then released into the cell. Cellular digestion Digestive enzymes Lysosome Digestion Food vacuole Plasma membrane  Cellular digestion www.w Products of lysosomal digestion are released and reutilized. ÑÉ  Indigestible material accumulates in the vesicles called residual bodies and their material is removed by exocytosis. insta extraceaictrients  Some residual bodies in non dividing cells contain a high amount of a inso pigmented substance called Lipofuscin.  Also called age pigment or wear –tear a pigment.  Recycler  Lysosomes also help remove or recycle damaged parts of a cell by autophagy. 1. The damaged organelle is first enclosed in a membrane vesicle. 2. Then a lysosome ‰ Fuses with the vesicle, Ñ ‰ Dismantles its contents, and ‰ Breaks down the damaged organelle.  Autophagy is enhanced in secretory cells that have accumulated excess secretory granules. Digested products from autophagosomes are reutilized in the cytoplasm.  Dismantleit content Breakdown damaged organelle Lysosome Vesicle containing damaged mitochondrion Digestion retuilized cytoplasm in the  Apoptosis = cell death photic cell - Critical role in programmed destruction of cells in multicellular organisms add soil  Auto-destruct mechanism “cell suicide”  Some cells have to die in an organized fashion, especially During development ex: development of space between your fingers is.si During embryonic development ex: if cell grows improperly this b self-destruct mechanism is triggered to remove damaged cell cancer over-rides this to enable tumor growth  Disorders of Lysosomes Tay-Sachs disease Lysosomes play an important role in the metabolism of several substances in the human body, and consequently many diseases have been ascribed to deficiencies of lysosomal enzymes  Individual lysosomal enzymes are missing or inactive and this lead to the accumulation of that particular substance.  lysosomes gets enlarged and they interfere the normal function of the cell.  Diseases called lysosomal storage diseases which are usually fatal Most important is Tay-Sachs disease lipids build up in brain cells child dies before age 5. Endomembrane System: Relationships among the major organelles of the endomembrane system lysosome  Ribosomes: Protein Factories haveno membrane Ribosomes are the structures where proteins are made.  They are produced in the nucleolus  Composed of rRNA and ribosomal proteins known as a Ribonucleoprotein l l  Consists of a large subunit and a small subunit 1. In Prokaryotes: only free ribosomes; 70S ribosomes large: 50S subunit 1. Eukaryotes: free and Small: 30s subunit bound ribosomes; 80S ribosomes Large: 60S subunit. Small: 40S  Some ribosomes are free ribosomes; others are bound. 1- Free ribosomes: in Suspended in the cytoplasm (singly or in groups called polyribosomes) Involved in making proteins that function within the cytoplasm cell. attached a 2- Bound ribosomes: Attached On the endoplasmic reticulum associated with nuclear envelope Associated with proteins packed in certain organelles or exported from the cell. Ribosomes make proteins for use in the cell and export in plantcells Nucleus, Ribosomes, & ER Disorders of ribosomes Defects in the function of ribosomes may cause: 1. Anemia (5 infants in 1 million are affected) a 2. Cartilage hair hypoplasia www.oiz.si NI 3. Shwachman diamond syndrome.(1 child in every s 100,000 is born with ribosomal disorder) mini in a 4. Dyskeratosis congenita (1 child in 1 million is affected)  Mitochondria: factories of energy  Consists of flattened membranous sacs called cisternae.  Every type of cell has a different amount of mitochondria. Figure 1-18 Essential Cell Biology (© Garland Science 2010)   The singular for mitochondria is mitochondrion.  A mitochondrion is composed of: 1- Outer membrane (smooth) 2- Inner membrane (folded) 3- Matrix: (liquid within smooth inner membrane) DNA 4- Christae (folds of the folded inner membrane) 5- Intermembrane space (liquide between membranes) 6- Each one also has singular circular chromosomes as well as its own ribosomes which allow it to self replicate.  Biomedical importance The main function of mitochondria is to produce energy for the cell in a chemical process called cell respiration. Chemical formula for cellular respiration: C6H12O6 +O2 Co2 + H2o + ENERGY (ATP)  Both the membranes have different appearance and biochemical functions: Outer membrane: Inner membrane:  It is permeable to most ions  It surrounds the matrix. and molecules which can  It contains components of move from the cytosol to electron transport system. intermembranous space.  It is impermeable to most ions including H, Na, ATP, GTP, CTP and to large Matrix: molecules.  It is enclosed by the inner  special carriers are present mitochondrial membrane. (ATP –ADP transport).  Contains enzymes of citric acid cycle. Week  mitochondria Mitochondria plays a key role in aging (apoptosis) Mitochondria have a role in their own replication- they contain copies of circular DNA. Mitochondrial DNA has information for some mitochondrial proteins and some RNAs. from the o site Jst o III is mother This DNA is inherited maternally. Mitochondrial matrix contains some rRNA and some tRNA used in the translation of mRNA. i mDNA encodes some enzymes, involved in oxidative phosphorylation awTower Most mitochondrial proteins are derived from genes in nuclear DNA.  Disorders of mitochondria system norepair mitochondria to inthe p  Mutation rate in mt DNA is 10 times more.  The mutations of mtDNA are more likely to cause muscular dysfunctions. si.IS'M  The most mitochondrial deficiency diseases are characterized by muscular dysfunction.  Because of their high-energy metabolism, skeletal muscle fibers are very sensitive to mitochondrial defects. Wife I  These diseases typically begin with drooping of the upper eyelid and progress to difficulties in swallowing and limb weakness.  Generally, in these diseases the mitochondria show morphological changes.  Peroxisomes  Called Peroxisomes because of their ability to produce or utilize H2O2. 5963  They are small, oval or s spherical in shape. I I II win for  They have a fine network of tubules in their matrix.  Peroxisomes  About 50 enzymes have been identified.  Enzymes synthesized by free ribosomes i in cytoplasm. differ  The number of enzymes fluctuates according to the function of the cells. Kitification river active  Peroxisomes are relatively large in hepatocytes and kidney cells but very small in intestine cells so called microperoxisomes Biomedical importance  Some peroxisomes use oxygen to break fatty acids down into smaller molecules that are transported to mitochondria and used as fuel for cellular respiration.  Peroxisomes in the liver detoxify alcohol and other harmful compounds by transferring hydrogen from the poisons to oxygen and produce H2O2. pt I have somemolecules to prevent  The H2O2 formed by peroxisomes is itself toxic, but the organelle also contains an enzyme (catalase) that converts H2O2 to water.  Disorders of Peroxisomes  A large number of disorders arise from defective peroxisomal proteins, because this organelle is involved in several metabolic pathways.  The most common peroxisomal disorder is X-chromosome- linked adrenoleukodystrophy, 1 I caused by a defective integral membrane protein that participates in transporting very long- chain fatty acids into the peroxisome for oxidation.  Accumulation of these fatty acids in body fluids destroys the myelin sheaths in nerve tissue, causing severe neurologic symptoms. Is  Deficiency in peroxisomal enzymes causes the fatal Zellweger i syndrome, with severe muscular impairment, liver and kidney lesions, and disorganization of the central and peripheral IN nervous systems.  Summary mitochondria make ATP energy lysosome 195 from sugar + O2 intracellular degradation Peroxisome cytoplasm oxidation of toxic contains many molecules metabolic pathways protein synthesis Golgi apparatus nucleus modification, sorting, protects DNA and packaging of controls cell proteins and lipids vesicles transport inside cells Endoplasmic Reticulum storage synthesis of most lipids cell membrane ribosomes synthesis of proteins for cell boundary builds proteins distribution to many controls movement organelles and plasma of materials in & out membrane recognizes signals