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Golgi Apparatus: A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough Endoplasmic reticulum and directing them to secretory vesicles, Lysosomes, or the Cell membrane. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or Golgi apparatus and fuse with the Golgi, lysosomes or cell membrane. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990)

Golgi Apparatus

JoVE 10970

As they leave the Endoplasmic Reticulum (ER), properly folded and assembled proteins are selectively packaged into vesicles. These vesicles are transported by microtubule-based motor proteins and fuse together to form vesicular tubular clusters, subsequently arriving at the Golgi apparatus, a eukaryotic endomembrane organelle that often has a distinctive ribbon-like appearance.

The Golgi apparatus is a major sorting and dispatch station for the products of the ER. Newly arriving vesicles enter the cis face of the Golgi—the side facing the ER—and are transported through a collection of pancake-shaped, membrane-enclosed cisternae. Each cisterna contains unique compositions of enzymes and performs specific protein modifications. As proteins progress through the cis Golgi network, some are phosphorylated and undergo removal of certain carbohydrate modifications that were added in the ER. Proteins then move through the medial cisterna, where they may be glycosylated to form glycoproteins. After modification in the trans cisterna, proteins are given tags that define their cellular destination. Depending on the molecular tags, proteins are packaged into vesicles and trafficked to particular cellular locations, including the lysosome and plasma membrane. Specific markers on the membranes of these vesicles allow them to dock

 Core: Cell Structure and Function

Cell Structure- Concept

JoVE 10587

Background

Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, multicellular organisms like elephants and giant redwood trees. In the mid 19th century, the Cell Theory was proposed to define a cell, which states:



Every living organism is made up of one or more cells.
The cells…

 Lab Bio

Mitosis and Cytokinesis

JoVE 10762

In eukaryotic cells, the cell's cycle—the division cycle—is divided into distinct, coordinated cellular processes that include cell growth, DNA replication/chromosome duplication, chromosome distribution to daughter cells, and finally, cell division. The cell cycle is tightly regulated by its regulatory systems as well as extracellular signals that affect cell proliferation. The processes of the cell cycle occur over approximately 24 hours (in typical human cells) and in two major distinguishable stages. The first stage is DNA replication, during the S phase of interphase. The second stage is the mitotic (M) phase, which involves the separation of the duplicated chromosomes into two new nuclei (mitosis) and cytoplasmic division (cytokinesis). The two phases are separated by intervals (G1 and G2 gaps), during which the cell prepares for replication and division. Mitosis can be divided into five distinct stages—prophase, prometaphase, metaphase, anaphase, and telophase. Cytokinesis, which begins during anaphase or telophase (depending on the cell), is part of the M phase, but not part of mitosis. As the cell enters mitosis, its replicated chromosomes begin to condense and become visible as threadlike structures with the aid of proteins known as condensins. The mitotic spindle apparatus b

 Core: Cell Cycle and Division

Endoplasmic Reticulum

JoVE 10969

The Endoplasmic Reticulum (ER) in eukaryotic cells is a substantial network of interconnected membranes with diverse functions, from calcium storage to biomolecule synthesis. A primary component of the endomembrane system, the ER manufactures phospholipids critical for membrane function throughout the cell. Additionally, the two distinct regions of the ER specialize in the manufacture of specific lipids and proteins. The rough ER is characterized by the presence of microscopically-visible ribosomes on its surface. As a ribosome begins translation of an mRNA in the cytosol, the presence of a signal sequence directs the ribosome to the surface of the rough ER. A receptor in the membrane of the ER recognizes this sequence and facilitates the entry of the growing polypeptide into the ER lumen through a transmembrane protein complex. With the assistance of chaperones, nascent proteins fold and undergo other functional modifications, including glycosylation, disulfide bond formation, and oligomerization. Properly folded and modified proteins are then packaged into vesicles to be shipped to the Golgi apparatus and other locations in the cell. Chaperones identify improperly folded proteins and facilitate degradation in the cytosol by proteasomes. Lacking ribosomes, the smooth ER is the cellular location of lipid and steroid synthesis, cellular detoxification, ca

 Core: Cell Structure and Function

What are Membranes?

JoVE 10971

A key characteristic of life is the ability to separate the external environment from the internal space. To do this, cells have evolved semi-permeable membranes that regulate the passage of biological molecules. Additionally, the cell membrane defines a cell’s shape and interactions with the external environment. Eukaryotic cell membranes also serve to compartmentalize the internal space into organelles, including the endomembrane structures of the nucleus, endoplasmic reticulum and Golgi apparatus. Membranes are primarily composed of phospholipids composed of hydrophilic heads and two hydrophobic tails. These phospholipids self-assemble into bilayers, with tails oriented toward the center of the membrane and heads positioned outward. This arrangement allows polar molecules to interact with the heads of the phospholipids both inside and outside of the membrane but prevents them from moving through the hydrophobic core of the membrane. Proteins and carbohydrates contribute to the unique properties of a cell’s membrane. Integral proteins are embedded in the membrane, while peripheral proteins are attached to either the internal or external surface of the membrane. Transmembrane proteins are integral proteins that span the entire cell membrane. Transmembrane receptor proteins are important for communicating messages from the outside to the insid

 Core: Membranes and Cellular Transport

Gap Junctions

JoVE 10986

Multicellular organisms employ a variety of ways for cells to communicate with each other. Gap junctions are specialized proteins that form pores between neighboring cells in animals, connecting the cytoplasm between the two, and allowing for the exchange of molecules and ions. They are found in a wide range of invertebrate and vertebrate species, mediate numerous functions including cell differentiation and development, and are associated with numerous human diseases, including cardiac and skin disorders. Vertebrate gap junctions are composed of transmembrane proteins called connexins (CX), and six connexins form a hemichannel called a connexon. Humans have at least 21 different forms of connexins that are expressed in almost all cell types. A connexon hemichannel is said to be homomeric when all six connexins are the same, and heteromeric when composed of different types. Most cells express more than one type of connexin. These can form functional connexon hemichannels or a full gap junction channel by pairing up with a counterpart on an adjacent cell. The gap junctions are considered homotypic when each connexon is the same, and heterotypic when they differ. Clusters called gap junction plaques often form where the channels are continually recycled and degraded at the center of the plaques and replaced at the periphery. Gap junctions allow the p

 Core: Cell Structure and Function

Studying Organelle Dynamics in B Cells During Immune Synapse Formation

1Laboratory of Immune Cell Biology, Department of Cellular and Molecular Biology, Pontificia Universidad Católica de Chile, 2Faculty of Medicine, Pontificia Universidad Católica de Chile, 3Centro de Investigaciones en Biología Celular y Biomedicina, Facultad de Ciencia, Universidad San Sebastián

JoVE 59621

 Immunology and Infection

Initial Evaluation of Antibody-conjugates Modified with Viral-derived Peptides for Increasing Cellular Accumulation and Improving Tumor Targeting

1Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, 2Sherbrooke Molecular Imaging Center (CIMS), Université de Sherbrooke, 3Sherbrooke Institute of Pharmacology

JoVE 55440

 Bioengineering

Intracellular Staining and Flow Cytometry to Identify Lymphocyte Subsets within Murine Aorta, Kidney and Lymph Nodes in a Model of Hypertension

1Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, 2Department of Molecular Physiology and Biophysics, Vanderbilt University, 3Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University

JoVE 55266

 Immunology and Infection

Imaging Subcellular Structures in the Living Zebrafish Embryo

1Institute of Neuronal Cell Biology, Technische Universität München, 2Cell Biology, Department of Biology, Faculty of Science, Utrecht University, 3Faculty of Biology, Ludwig-Maximilians-Universität-München, 4Adolf-Butenandt-Institute, Biochemistry, Ludwig-Maximilians-Universität-München, 5German Center for Neurodegenerative Diseases, 6Laboratory of Brain Development and Repair, The Rockefeller University

JoVE 53456

 Developmental Biology

Whole-cell Patch-clamp Recordings of Isolated Primary Epithelial Cells from the Epididymis

1School of Life Science and Technology, ShanghaiTech University, 2Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 3University of Chinese Academy of Sciences, 4Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University

JoVE 55700

 Developmental Biology

Preparation of Mitochondria from Ovarian Cancer Tissues and Control Ovarian Tissues for Quantitative Proteomics Analysis

1Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, 2Hunan Engineering Laboratory for Structural Biology and Drug Design, Xiangya Hospital, Central South University, 3State Local Joint Engineering Laboratory for Anticancer Drugs, Xiangya Hospital, Central South University, 4National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, 5Department of Obstetrics and Gynecology, Xiangya Hospital, Central South University

Video Coming Soon

JoVE 60435

 JoVE In-Press

Analysis of Epididymal Protein Synthesis and Secretion

1Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, 2Hunter Medical Research Institute, 3Department of Physiology, Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, 4School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle

JoVE 58308

 Developmental Biology

In Vitro Growth of Mouse Preantral Follicles Under Simulated Microgravity

1Reproductive Medicine Center, The First Affiliated Hospital of Wenzhou Medical University, 2Department of Orthopaedics, The Second Affiliated Hospital of Wenzhou Medical University, 3Department of Obstetrics, The First Affiliated Hospital of Wenzhou Medical University, 4School of Laboratory Medicine and Life Science, Wenzhou Medical University, 5School of Pharmaceutical Science, Wenzhou Medical University, 6Stem Cells and Genetic Engineering Group, AgriBioscience Research Centre, Department of Economic Development, Jobs, Transport and Resources, 7Department of Histology and Embryology, Wenzhou Medical University

JoVE 55641

 Developmental Biology

Evaluation of T Follicular Helper Cells and Germinal Center Response During Influenza A Virus Infection in Mice

1CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 2School of Life Science, University of Science and Technology of China, 3State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences

Video Coming Soon

JoVE 60523

 JoVE In-Press
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