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Chapter 2

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Department
Biology
Course
BIOL 1000
Professor
All Professors
Semester
Fall

Description
Cell – chapter 2.3 pg 31-34 Eukaryotic cells - Four major groups: protists, fungi, animals, plants - Have true nucleus and cytoplasmic organelles enclosed within plasma membrane - Cytosol: energy metabolism and molecular synthesis, special functions to support motility - Plasma membranes: transport proteins into and out of cell o Some act as receptors; bind specific signal molecules in cellular environment and trigger internal environment o Important markers in immune system –if no marker (pathogen) foreign - Cell wall: extracellular structure - PAGE 32 IN txtbk DIAGRAM EUKARYOTIC - Contains much more DNA than prokaryotic o Nucleus is seperated form cytoplasm by nucleus envelope • Which consists of two membranes (lamins-protein filaments- animal cells) • Nuclear pore complex: large, octagonally, cylindrically structure- many types of proteins (nucleoporins) (transports things from nucleus to cytoplasm) -LARGEST o Channel through nulcear pore mem. (large mole.) – proteins and RNA molecule o Within nucleus (semi liquid) –nucleoplasm o Most of the space is filled with chromatin - Chromatin: any collection of eukaryotic DNA molecules with associated proteins - Chromosome: one complete DNA molecule with associated protein - Eukaryotic DNA is much longer than prokaryotic - Nucleoli: singular nucleus genes code for rRNA molecules for with protein form ribosomal subunits o Exit nucleoli to enter nucleus through complexes to cytoplasm to form the mRNA strands - Eukaryotic ribosomes are generally bigger than archaea & bacterial ribosomes o Contain 4 rRNA molecules and more than 80 proteins o Function however is the same between eukaryotic and prokaryotic o Ribosomes that are free in cytosol can join with other organelles: mitochondria chloroplasts o Proteins that enter nucleus become a part of chromatin - Characterized as endomembrane systems (internal membranous sacs that divide cell into structural and functional compartments o Synthesis and modifications of proteins and transport into membranes and organelles/outside of cell, synthesis of lipids and detoxification of toxins o Membranes are connected either physically or indirectly in vesicles  Small membrane bound compartments tat transfer substances between parts of system o Components: nuclear envelope, endoplasmic reticulum, golgi complex, lysosomes, vesicles, and plasma membrane - Endoplasmic reticulum: extensive interconnected network of membranous channels and vesicles (sing. Cristernae) o Formed by a single membrane that surrounds an enclosed space called EL lumen o Two forms rough/smooth ER - Rough E: many ribosomes stud outer surface. The ribosomes enter ER lumen where they fold into final form o Chemical modification occur in ER lumen o They are then pinched off ER an sent to organelles to finish their modificaitons- most go to golgi complex to get packaged – final destination o Nuclear envelope is also studded with ribosomes closely related to in structure and function - Smooth ER: no ribosomes attached o Functions in cytoplasm such as synthesis of lipids (part of cell membrane) o Remove toxins (liver) - Golgi Complex: flat stack of membranous sacs (no ribosomes) cisternae o Not interconnected like ER cristernae only 3-8 or several o Usually loated near concentrated rough ER (between ER and plasma membrane) o When proteins arrive from ER, the vesicles contact CIS face of complex (facing nucleus) release ocntents into cisternal. They are chemically modified (take off amino acid, put on carb or lipid) they are transported with golgi to trans face (facinf plasma membrane) sorted into vesicles and shipped out o Exocytosis: a secretory vesicle fuses with plasma membrane, releasing vesicle contents to cell exterior the vesicle membrane becomes part of plasma membrane – increase surface area o Endocytosis: materials from cell exterior are enclosed in plasma membrane that pockets inwards and pinches off as endocytic vesicle - Lysosomes: small membrane-bound vesicle that contains more than 30 hydrolytic enzymes o Recycles subunits of (nucleic acid, lipids, plysaccharids proteins) o FOUND IN ANIMALS ONLY –(central vacuole plants) o Assume various shapes and sizes o Hydrolytic enzymes synthesize in rough ER, modifies in ER lumen transported in golgi comlex in vesicle then tranposrted to lysosome o Ph=5 acidic o Autophagy: dgest organelles that are not funtioniing properly o Phagocytosis: a process where some types of cells engulf bacteria or other cellular debris (include white blood cells –phagocytes)  Produce a large vesicle that contains engulfed materials until lysosomes fuse with vesicle - Mitochondria: membrane-bound organelles where cellular respiration occurs  Cellular respiration: process of energy-rich molecules (sugars,fats) are broken down to water and CO2 by mitochondrial reactions – release of energy  Energy released captured by ATP (mitochondrion generate most ATP)  Need oxygen o Outer membrane: smotth covers outside o Inner mitochondriol membrane: expanded by folds (critae) innermost compartment –mitochondriol matrix – ATP occur in cristae and matrix - Cytoskeleton: shape o Interconnected system of protein fibres and tubes that extend throughout cytoplasm o Reinforces plasma membrane and functions in movements both within and out o More prominently developed in animal cells because plants also have cell wall and large central vacuole o 3 major types of structural elements: microtubules (largest)-protein, intermediate filaments-protein, and microfilaments (smallest)-actin o Microtubules: microscopic tubes • 13 proteins filaments in wall side by side
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