* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Cell Boundaries
Biochemical switches in the cell cycle wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell encapsulation wikipedia , lookup
Signal transduction wikipedia , lookup
Cell nucleus wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Cell growth wikipedia , lookup
Cell membrane wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell Membrane •Double layer of phosholipids •Controls movement of materials in and out of cells • Selectively permeable because it only allows certain materials into and out of the cell. • This membrane is composed of two main groups of organic molecules: lipids and proteins. Lipids: • The lipid bilayer -the phosphate “head”; is polar is attracted to water (hydrophilic) - the two “tails”; the hydrocarbon chains are nonpolar and repelled by water (hydrophobic) Proteins: • Embedded in the plasma membrane are cell surface proteins that allow larger materials to pass into and out of the cell. • These proteins are called channels. Cells All cells can be divided into two groups • Prokaryotes • Cells that DO NOT contain a nucleus • Eukaryotes • Cell that DO contain a nucleus and many specialized “organelles” Size of a bacterium Compared to a eukaryotic cell ALL cells have these 3 things: 1 - Cell Membrane 2 – Cytoplasm 3 – DNA Organelles -Specialized structures inside a eukaryotic cell that perform important cell functions http://www.studiodaily.c om/2006/07/cellularvisions-the-inner-life-of-acell/ Nucleus • Membrane enclosed structure • Contains the cells genetic material (DNA) • The nucleus directs the cells activities • Nuclear envelope: membrane composed of thousands of pores that surrounds the nucleus • • • • Nucleolus – dense region within the nucleus where ribosomes are produced. Cytoplasm • Cytoplasm is everything INSIDE of the cell membrane but OUTSIDE of the nucleus. • It is the area inside the cell where all the organelles lie Cytoskeleton – Network of protein filaments that help a cell maintain shape • Mitochondrion converts chemical energy stored in food into the energy molecule Adeosine Triphosphate (ATP). Endoplasmic Reticulum (smooth) membrane where lipid components of the cell membrane are assembled Ribosome – Protein factories of the cell. Found free-floating or attached to the ER ◊ Rough Endoplasmic Reticulum – Membrane with ribosomes for making proteins. • Golgi Apparatus – Modifies/packages molecule for export out of cell • Note- It is near the cell membrane Organelles only found in Animal Cells Lysosome – contains enzymes for digesting or recycling molecules Centrioles – two tiny structures in cytoplasm near nuclear envelope used in cell division. Organelles only found in Plant Cells • Central VacuolesStorage units of cells. Very large in plants for holding water. • Chloroplast – uses energy from the sun to convert CO2 molecules into carbohydrates ub the process called photosynthesis. • Cell walls • Are stiff fibers of cellulose (a carbohydrate) OUTSIDE the cell membrane • Cell walls support and protect the plant • Keeps cell from rupturing when osmotic pressure is too great VIRUSES Chapter 19-2 19-2 What is a Virus? • Core of DNA or RNA; genetic material surrounded by a protein coat (Capsid). • Can reproduce only by infecting living cells – once inside the cell, they use the machinery of the cell to produce more viruses • Very small – need an electron microscope to see • Capsid – virus’s protein coat • Unique shape of capsid proteins and spikes enable virus to attach to a cell • DNA rests inside capsid until injected into host cell • Cell transcribes and translates the viral genetic information into viral capsid proteins; • host cell often destroyed • Viruses are very and highly specific to the cells they infect http://www.npr.org/blogs/ krulwich/2011/06/01/11407 5029/flu-attack-how-avirus-invades-your-body Cell vs Virus • Viruses are not enclosed by a cell membrane. • Viruses do not have any organelles. • Viruses do have either DNA or RNA (either can be single or double stranded) as their genetic information. • Viruses cannot metabolize. • Viruses cannot replicate themselves. Are Viruses Alive? • They are on the borderline between living and nonliving • Like living things – they reproduce, regulate gene expression, and evolve. • But they are not made of cells and cannot live independently. There is no metabolism, no homeostasis, etc. • No. Viruses are not considered living. Types of Transport B. Passive Transport • • • • • – DIFFUSION (simple) The movement of materials into and out of cells depends on the process of diffusion. Occurs when there is a difference in concentration within the solution. This difference in concentration is called a concentration gradient. Particles of a solute and solvent are constantly moving from areas of high concentration to areas of low concentration. These particles continue to move until the concentrations are equal or reach… equilibrium. http://highered.mcgrawhill.com/sites/0072495855/student_view 0/chapter2/animation__how_diffusion_w orks.html -OSMOSIS (simple) •Diffusion of water molecules from an area of high concentration to an area of low concentration. •This process is called osmosis. •The increased pressure that results from an increase of water is called osmotic pressure. C. The Effects of Osmosis on Cells The mixture of solutes and solvents are called solutions. NOTE: The following terms are based on the concentration of solute which will then determine the movement of water. Hypertonic- “high” levels of solute/Low H20 Hypotonic-”low” levels of solute/high H2O Isotonic-“equal” levels on both sides of membrane –”tonic” This is the shrinking of the cell due to water leaving the cell… plasmolysis. 93% water 7% solute 95% water 5% solute This is the bursting of the cell due to water entering the cell… cytolysis. 93% water 7% solute 95% water 5% solute 1. This cell solution is _______________ Hypotonic . There is a higher concentration of solute in the environment than that in the cell. Thus, the environment solution is said to be Hypertonic _________________. Water will move _______ out of the cell. This is the shrinking of the cell due to water leaving the cell… plasmolysis. 2. This cell solution is _______________ Hypertonic . There is a lower concentration of solute in the environment than that in the cell. Hypotonic Thus, the environment solution is said to be _________________. Water will move _______ into the cell. This is the bursting of the cell due to water entering the cell… cytolysis. isotonic 3. A cell is _______________ when the concentration of solutes in the environment and in the cell are the same. into and Equal amounts of water will move _________ out of the cell. ___________ • Facilitated diffusion is diffusion through the channel proteins in the membrane. http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_facilitated_diffu sion_works.html Diffusion Osmosis Facilitated Diffusion These are all forms of passive transport because no energy is required by the cell. D. Active Transport • Cells must have a way to maintain concentrations of important food molecules at a level different from the concentration level outside the cell. • Active transport uses energy to transport particles through membrane against the concentration gradient. An example of an active transport channel is the sodiumpotassium pump. http://highered.mcgrawhill.com/sites/0072495855/student_vie w0/chapter2/animation__how_the_sodi um_potassium_pump_works.html D. Active Transport Bulk Transport • Energy is required. • Two kinds: 1. Endocytosis is the taking in (engulfing) of particles into a cell. – Two types: • Pinocytosis is the taking in of liquid or dissolved materials. • Phagocytosis is the taking in of large solid materials. 2. Exocytosis is the removal of wastes out of a cell.