University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2022
Views:

279

Pages:

16
Author:

Donavan Williams

Section 2.3: Structure of Eukaryotic Cells Structurally complexity – more sophisticated regulation •Larger - increase surface area for chemical reactions •Membrane-bound organelles •Contain biomolecules specialized to specific functions •Endomembrane system – interconnecting internal membranes that divide cell into functional compartments •Vesicles – transports molecules •Compartments devoid of membranes •Ribosomes – protein synthesizing machines •Cytoskeleton – complex of filaments giving shape, structural support Figure 2.10 Animal Cell Section 2.3: Structure of Eukaryotic Cells §Plasma membrane §Endoplasmic reticulum §Golgi apparatus §Nucleus §Lysosomes §Mitochondria §Ribosomes, §Cytoskeleton §Chloroplasts Figure 2.11 Plant Cell §Plant only Figure 2.10 Animal Cell From McKee and McKee, , Section 2.3: Structure of Eukaryotic Cells §Plasma Membrane §Isolates the cell and is selectively permeable §Composed of lipid bilayer with associated integral & peripheral proteins §Extracellular face contains glycocalyx – proteins & lipids that contain covalently attached carbohydrate §Extracellular matrix protects exterior §Membrane skeleton – 3-D meshwork of proteins attached to peripheral proteins Section 2.3: Structure of Eukaryotic Cells Endoplasmic Reticulum §Series of membranous tubules, vesicles, and flattened sacks §ER lumen -internal space enclosed in ER membrane §Rough ER – due to ribosomes on surface §Ribosomes – consist of 2 subunits (40S/60S); protein synthesis; chaperones facilitate folding process; glycosylation reactions §Smooth ER – no ribosomes; continuous with RER §Key functions: lipid biosynthesis; Ca2+ storage Figure 2.14 Endoplasmic Reticulum Section 2.3: Structure of Eukaryotic Cells Rough ER §ER stress – accumulation of misfolded molecules §ER-associated protein degradation – mechanism of degradation Smooth ER §Hepatocytes - biotransformation & synthesis of lipid components of very-low-density lipoproteins §Biotransformation reactions – convert water insoluble metabolites & xenobiotics into soluble products for excretion Figure 2.14 Endoplasmic Reticulum Section 2.3: Structure of Eukaryotic Cells §Golgi Apparatus §Golgi apparatus - large, flattened, sac-like membranous vesicles §Processes, packages, and distributes cell products §Two faces: cis (cisternae) and a trans face Figure 2.16 The Golgi Apparatus Section 2.3: Structure of Eukaryotic Cells §Cisternal maturation model vesicles are recycled back to the cis Golgi from the trans Golgi §Secretory products concentrated at the trans Golgi into secretory vesicles §Involved in exocytosis ü Movement of membrane-bound vesicles from Golgi apparatus to plasma membrane Figure 2.15 Exocytosis Section 2.3: Structure of Eukaryotic Cells §Vesicular Organelles §Eukaryotic cell has vesicles §Vesicles originate in the ER, Golgi and/or via endocytosis Figure 2.17 Receptor-Mediated Endocytosis Section 2.3: Structure of Eukaryotic Cells §Lysosomes are vesicles that contain digestive enzymes §Enzymes are acid hydrolases §Degrade encapsulated materials §Autophagy degradation of debris in cells Lysosomes Section 2.3: Structure of Eukaryotic Cells Nucleus §Contains the hereditary information §Site of transcription §Nuclear components: §Nucleoplasm – surrounded by membrane, contains chromatin fibers & DNA §Chromatin (genome) §Nuclear envelope – barrier; outer/ inner nuclear membrane §Nucleolus – transcription of rRNA genes §Nuclear matrix – scaffold of proteins on which chromatin organized Figure 2.19 Eukaryotic Nucleus Section 2.3: Structure of Eukaryotic Cells §Nuclear envelope surrounds the nucleoplasm §Nuclear pores (nuclear pore complexes) §Molecules enter and leave the nucleus Figure 2.20 The Nuclear Pore Complex Section 2.3: Structure of Eukaryotic Cells §Mitochondria Figure 2.24 The Mitochondrion §Site of aerobic metabolism §Principle source of cellular energy §Outer membrane surrounds matrix §Smooth, porous <10,000 Daltons §Inner membrane projects inward into folds, cristae §Premeable to O2, CO2, H2O; not ions Section 2.3: Structure of Eukaryotic Cells §Peroxisomes §Small organelle containing oxidative enzymes §Detoxifies peroxides (e.g., H2O2) Section 2.3: Structure of Eukaryotic Cells §Cytoskeleton §Intricate supportive network of fibers, filaments, and associated proteins §Three main components: §Microtubules §Microfilaments §Intermediate filaments §Main functions §Cell shape and structure §Large- and small-scale cell movement §Cell movement; organelle movement §Solid-state biochemistry §Enzymes assemble on solid surface, improves efficiency and control §Signal transduction §Filaments facilitate & support signal transduction processes Section 2.3: Structure of Eukaryotic Cells Figure 2.27 The Cytoskeleton Section 2.3: Structure of Eukaryotic Cells §Cytoskeleton §Cilia and flagella, whip-like appendages encased in plasma membrane, are highly specialized for their roles in propulsion §Undulating motion occurs via ATP-driven structural changes in dynein molecules (arms)