Cell biology Peng Xi Peking University
Outline • Cell • Structure • Cell process • Tissue • Morphology • Function
Cell • Target that Biomedical optics study: • Cell( Including subcellular organelles) • Tissue (Including organs and body) • Cell • In vivo活体 • Ex vivo死体 • Tissue • In situ原位 • In vivo活体 • Fixed http://www.tokresource.org/tok_classes/biobiobio/biomenu/cell_theory/index.htm
Structure of cell • Plasma membrane • Cell wall • Prokaryotic cell • Eukaryotic plant cell • Cytoplasm • Cytosol胞液 • Organelle • Nucleus 原核细胞 真核细胞
Plasma membrane质膜 • A semipermeable outer boundary of both prokaryotic and eukaryotic cells. This outer membrane, about 4–5nm thick, is a continuous sheet of a double layer (bilayer) of long-chain molecules called phospholipids. • A phospholipid molecule has a long tail of alkyl烷基chain, which is hydrophobic (repels water), and a hydrophilic head (likes water) which carries a charge (and is thus ionic).
Phospholipid molecules spontaneously orient (or self-organize) to form a bilayer in which the hydrophobic tails are pointed inwards (shying away from the outer aqueous environment). • The hydrophilic, ionic head groups are in the exterior and are thus in contact with the surrounding aqueous environment.
Cytoplasm细胞质 • Cytoplasm represents everything enclosed by the plasma membrane, with the exclusion of the nucleus. • It is present in all cells where metabolic reactions occur. • Consists mainly of a viscous粘性ﬂuid medium that includes salts, sugars, lipids, vitamins, nucleotides, amino acids, RNA, and proteins which contain the protein ﬁlaments, actin microﬁlaments, microtubules, and intermediate ﬁlaments. • Many of the functions for cell growth, metabolism, and replication are carried out within the cytoplasm.
Cell skeleton细胞骨架 • Networkof fibers composed of proteins • Three kinds: • Microtubule (25nm) • Intermediate filaments (10nm) • Actin filaments (8nm)
Cell skeleton细胞骨架 • Main functions: • Establish the cell shape • Provide mechanical strength to the cell • Perform muscle contraction • Control changes in cell shape and thus produce locomotion • Provide chromosome separation in mitosis （有丝分裂） and meiosis （减数分裂） • Facilitate intracellular transport of organelles
Nucleus细胞核 • The nucleus is often called the control center of the cell. It is the largest organelle in the cell, usually spherical with a diameter of 4–10 μm, and is separated from the cytoplasm by an envelope consisting of an inner and an outer membrane. All eukaryotic cells have a nucleus. • The nucleus contains DNA distributed among structures called chromosomes染色体, which determine the genetic makeup of the organism. The chromosomal DNA is packaged into chromatin ﬁbers by association with an equal mass of histone proteins组蛋白. • The nucleus contains openings (100nm across) in its envelope called nuclear pores, which allow the nuclear contents to communicate with the cytosol. Ribosome核糖体
Nucleus细胞核 • The inside of the nucleus also contains another organelle called a nucleolus核仁, which is a crescent-shaped 月牙形 structure that produces ribosomes by forming RNA and packaging it with ribosomal protein. The nucleus is the site of replication of DNA and transcription into RNA. In a eukaryotic cell, the nucleus and the ribosomes work together to synthesize proteins. Ribosome核糖体
Mitochondria线粒体 • Cell “power plant” • Shape: fat sausage, 0.5-1.5um wide and 3-10um long. • 20% of the cytoplasmic volume NADH + H+ + 3 ADP + 3 Pi + 1/2 O2 NAD+ + 4 H2O + 3 ATP FADH2 + 3 ADP + 3 Pi + 1/2 O2 FAD + 4 H2O + 3 ATP
Endoplasmic reticulum(ER)内质网 • ER consists of ﬂattened sheets, sacs, and tubes of membranes that extend throughout the cytoplasm of eukaryotic cells and enclose a large intracellular space called lumen. There is a continuum of the lumen between membranes of the nuclear envelope. The rough endoplastic reticulum (rough ER) is close to the nucleus, and is the site of attachment of the ribosomes.
Endoplasmic reticulum(ER)内质网 • Ribosomes核糖体are small and dense structures, 20nm in diameter, that are present in great numbers in the cell, mostly attached to the surface of rough ER, but can ﬂoat free in the cytoplasm. They are manufactured in the nucleolus of the nucleus on a DNA template and are then transported to the cytoplasm. They consist of two subunits of RNA (a large, 50S, and a small, 30S) that are complexed with a set of proteins. • Ribosomes are the sites of protein synthesis. The process of protein synthesis uses a messenger RNA template. • The rough ER transitions into a smooth endoplastic reticulum (smooth ER), which is generally more tubular and lacks attached ribosomes. • The smooth ER is the primary site of synthesis of lipids and sugars and contains degradative enzymes, which detoxify many organic molecules.
Others • Glogi apparatus高尔基体 • Shipping and receiving dept. for protein • Lysosome溶酶体 • Bags of hydrolytic enzymes that are 0.2-0.5um • Peroxisome过氧物酶体 • Membrane bound vesicles containing oxidative enzymes • Chloroplast叶绿体 (only in plant cell) • Site of photosynthesis
Types of cells • Epithelial cell上皮细胞 • Form sheets called epithelia to line the inner and outer surface of the body. Most are squamous cells鳞状细胞. • Blood cell • Nerve cell (neuron) • Sensory cell • Germ cell生殖细胞 • Stem cell
Erythrocytes (Red bloodcell) • 7-9um diameter, no nuclei • Contain hemoglobin which can bind O2 • 1cm cube blood: 5 billion RBC • Leucocyte (White blood cell) • WBC:RBC=1:1000 • Lymphocyte淋巴细胞 • T cell: cell mediate immunity • B cell: produce antibody • Macrophages巨噬细胞and neutrophils中性白细胞 • Thrombocyte (Platelet) • Produce specific substances for blood coagulation http://kids.britannica.com/elementary/art-88528/Blood-is-made-up-of-red-blood-cells-white-blood
Question: What kind of blood cell has to be diagnosed for HIV infection? http://www.thebody.com/content/art2494.html
HIV and T-cell (CD4) • Early in the course of the disease, the body can make more CD4 cells to replace the ones that have been damaged by HIV. Eventually, the body can't keep up and the number of functioning T-cells decreases. As more and more CD4 cells become damaged, the immune system becomes more and more weakened. Eventually, the weakened immune system leaves the body at risk for illness and infection. http://aids.about.com/od/technicalquestions/f/cd4.htm
全能 囊胚 STEM CELLS…. 桑椹胚 ______ Inner cell mass becomes the baby 多能性 内细胞团
The Nobel Prize in Physiology or Medicine 2012 • The Nobel Prize in Physiology or Medicine 2012 was awarded jointly to Sir John B. Gurdon and Shinya Yamanaka "for the discovery that mature cells can be reprogrammed to become pluripotent"
Cellular processes • Replication • Biosynthesis • Energy production • Signaling • Death • Transformation
Replication • Question: How a biological being can survive for evolution? • Driving force in life: replicate for the continuing survival of the species.
Cell Death • Death is a necessary part of life. • Apoptosis细胞凋亡 • Programmed Cell Death (suicide) • Cells infected with a virus • Cells of the immune systems • Cells with DNA damage • Cell killing • Cell death by injury, accidental cell death • Mechanical damage or toxic chemicals • Cell that won’t regularly suicide: cancer cells http://www.fitnesssutra.com/2010/09/13/sun-bath-and-its-importance-to-health/
Cell transformation • Permanent inheritable alteration of cell • Uptake and incorporation of foreign DNA • Virus • Cancer causing agents such as mutagens基因突变 • Oncogenesis肿瘤 properties
Cancer proliferation and screening Squamose cell cancer • Cancer is different with normal cells in: • Cell metabolism; • Cell morphology. • Histology: ex vivo, invasive • Cannot evaluate the progress/cure effectiveness • Trigger the cancer growth from benign to malign http://tissupath.com.au/medical-student-subjects-skin/ http://networks.lww.com/pathology/blog/iow/pages/default.aspx Carcinoma cells Normal skin
Tissues Thispart of ppt is originated from www.lavc.edu/instructor/watson_k/docs/Tissues.ppt
Tissues • Definition: a group of closely associated cells that perform related functions and are similar in structure • Between cells: nonliving extracellular material • Four basic types of tissue…function • Epithelium…covering • Connective tissue…support • Muscle tissue…movement • Nervous tissue…control
Epithelia上皮(plural) • Epithelium: sheet of cells that covers a body surface or lines a body cavity; also form most of the body’s glands • Roles: as interfaces and as boundaries • Functions: Protection Absorption Sensory reception Ion transport Secretion Filtration Formation of slippery surfaces for movement
Special characteristics of epithelia • Cellularity多孔性 • Specialized contacts 触体 • Polarity • Free upper (apical) surface • Lower (basal) surface contributing basal lamina to basement membrane • Support by connective tissue • Avascular无血管but innervated有神经 • Without vessels • With nerve endings • Regeneration再生
Classification of epithelia • According to thickness • “simple” - one cell layer • “stratified” – more than one layer of cells (which are named according to the shape of the cells in the apical layer) • According to shape • “squamous” – wider than tall • “cuboidal” – as tall as wide • “columnar” - taller than wide
where diffusion is important where tissues are involved in secretion and absorption: larger cells because of the machinery of production, packaging, and energy requirements
“ciliated” literally = eyelashes (see next page)
Endothelium内皮 A simple squamous epithelium that lines the interior of the circulatory vessels and heart Mesothelium间皮 Simple squamous epithelium that lines the Peritoneal腹膜, pleural胸膜and pericardial心包cavities and covers the viscera内脏
Glands腺体 • Epithelial cells form them • Production & secretion of needed substances • Are aqueous (water-based) products • The protein product is made in rough ER, packed into secretory granules by Golgi apparatus, released from the cell by exocytosis胞外分泌
Classification of glands • By where they release their product • Exocrine外分泌: external secretion onto body surfaces (skin) or into body cavities • Endocrine内分泌: secrete messenger molecules (hormones) which are carried by blood to target organs; “ductless” glands By whether they are unicellular or multicellular
Exocrine glands外分泌腺unicellular or multicellular Unicellular: goblet cell 杯状细胞scattered within epithelial lining of intestines and respiratory tubes 呼吸道 Product: mucin粘蛋白 mucus黏液 is mucin & water
Multicellular exocrine glands Epithelium-walled duct and a secretory unit
Examples of exocrine gland products • Many types of mucus黏液secreting glands • Sweat glands of skin • Oil glands of skin • Salivary glands of mouth 唾液 • Liver (bile) 胆汁 • Pancreas (digestive enzymes) 胰脏 • Mammary glands (milk) 乳腺