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HOMEWORK! • READ & TAKE NOTES ON Chapter 3.1-3.3 • Turn in your macromolecules lab – Fill out a yellow sheet if you don’t have it! We are beginning Ch.3 • Watch the “Introducing the Cell” video segment (19:13) • Cells are too small to be seen w/ the naked eye. So how can you see a cell? _______________________________ Who was the 1st to ID cells? • mid 1600s scientists begin to use microscopes • 1665 Robert Hooke used early version cmpd microscope to view a thin slice of cork. – He called what he saw “cells,” b/c it reminded him of the monastery’s tiny rooms, which they called cells. there are several types of microscope: • cmpd light microscope- allows light to pass thru a specimen & 2 lenses form an image -used to view dead orgs, tiny live orgs, live cells; -dyes can be used to make images better • electron microscope- used to view objects much smaller than size of cell (for ex: cell organelles), it uses beams of e-’s to view images 2 types of e- microscope: TEM shine beam of e-’s thru specimen reveal lots of detail inside cell SEM scan narrow beam of e-’s back & forth across specimen surface produce realistic often 3-D images of specimen surface *cannot see live specimens w/either type b/c they must be preserved & dehydrated before they can be viewed using either microscope New Class of Microscope! • 1990s scanning probe microscopes were perfected -a fine probe traces the surfaces of samples -the probe is similar to the needle on turntable that plays records -the force of the probe is so slight it usually causes no damage to the specimen The Cell Theory • several basic ideas from diff scientists were combined to create the cell theory: – All living things are composed of cells. – Cells are the basic units of structure & function for all living things. – New cells are produced from existing cells. Prokaryotes vs. Eukaryotes • Prokaryotes • DNA not contained in a nucleus • Generally less complicated • Single-celled • Eukaryotes • DNA contained in a nucleus • Nucleus separated from other organelles • Great variety of organisms • Can be single or multicellular • inside of each eukaryotic cell, there are little compartments called organelles (literally “little organs”) that have a special job to do • talk about the cell in terms of nucleus, & everything outside of the nucleus • cytoplasm - the space outside the nucleus where all the other organelles are housed nucleus (control center of the cell) -contains the DNA which has the coded instructions for how to make proteins & other molecs -several parts: -nuclear envelope - dotted w/ lots of pores so that material can move in & out -chromatin – DNA spread out & attached to proteins; when cell divides it will condense to form chromosomes -nucleolus – where assembly of ribosomes begins Ribosomes • • • • • Proteins are assembled on the ribosomes They get their instructions from… ____________________ Made of RNA & protein Found throughout the cytoplasm or attached to the ER Where are ribosomes assembled? ____________________ Endoplasmic Reticulum (ER) • An internal membrane system • rough endoplasmic reticulum (RER) • Ribosomes are attached (rough) • Where proteins are made by the ribosomes, then chemically modified • smooth endoplasmic reticulum (SER) • enzymes perform special tasks • Making lipid parts of cell membrane • Detoxifying drugs Golgi Apparatus (Golgi Body) • looks like a purse/sack • modifies, sorts, & packages proteins & other materials from ER • then stores them or secretes them into cell or out of cell wherever needed Lysosomes • small, round organelles filled w/ enzymes • job is to digest / breakdown lips, carbs, proteins, organelles that are no longer useful into smaller molecules that can be reused by the rest of the cell • if not for the membrane, the contents of the lysosome would destroy the cell! • several serious human diseases linked to malfunctioning lysosomes Peroxisomes • small memb-enclosed organelles that contain enzymes to break down a variety of things via oxidative rxns – for ex: it breaks down H2O2 which is toxic to the cell via catalase; – it also breaks down uric acid, amino acids, & fatty acids Vacuoles • looks like irregular circle • stores things like H2O, salts, proteins, carbs • in plant cells, it is large enough to help support heavy structures like leaves & flowers mitochondria -inner membrane folded inside an outer membrane -convert chemical E from food into compounds cells can use -contains its own small DNA molecules -interesting human fact: most of mitochondria are inherited from the cytoplasm of the ovum/egg cell chloroplasts -look a lot like mitos -capture sunlight & create chemical E via process called ____________________ -contain green pigment chlorophyll, which gives plants color -only available in whom? ____________________ -also contains its own small DNA molecs plastids - occur only in plant cells or cells capable of photosynthesis - leucoplasts (a.k.a amyloplasts) = store starch, as well as sometimes protein or oils -chromoplasts = store pigments assoc’d w/ the bright colors of flowers and/or fruits. cytoskeleton (structure & transportation system) -network of prot filaments that help cell maintain its shape, also involved in movement of material throughout cell microfilament = threadlike, made of prot called actin; tough, flexible frame for support & help cells move microtubules = hollow, made of prot called tubulin; -help cell maintain shape; -also impt in cell ÷ion b/c form spindle which separates the c’somes; -also in animal cells forms centrioles which organize cell ÷ion -help form cilia & flagella which are projections enable cell to “swim” thru fluids Who am I? What do I do? Who am I? What do I do? Who am I? What do I do? I haven’t looked like this to you before….but this is what I really look like Did you know that lysosomes come from the golgi body? Who am I? What do I do? a few more things about chloroplasts -filled w/ chlorophyll -stacks of membranes called thylakoids -thylakoids submerged w/in fluid called stroma Credits……. previous pictures from various websites….& good bit of info & some pictures from: http://www.emc.maricopa.edu/faculty/farabee/B IOBK/BioBookCELL2.html Homework • Read and answer the questions on pg. 80 – Put your answers and any notes you take in the warm-up section of your notebook Can you tell the diff btwn an animal & plant cell? Picture below from: http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm The cell wall is composed of cellulose, which gives us fiber! Vacuole Smooth endoplasmic reticulum Ribosome (free) Chloroplast Cell Membrane Ribosome (attached) Nuclear envelope Cell wall Nucleolus Golgi apparatus Mitochondrion Nucleus Rough endoplasmic reticulum On to Section 3 •The cell membrane is a phospholipid bilayer. What does that mean? picture below from http://library.thinkquest.org/C004535/cell_membranes.html Picture below from: http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%2010 1%20Lectures/Membranes/membrane.htm GREAT SITE! So what does the bilayer act like? • …kind of like a fluid (i.e. film of oil on H2O) – The cell membrane is flexible – The phospholipids can move around and go past one another in a layer • But only side to side, no somersaults for the embedded proteins • We call this the “fluid mosaic model” Selective Permeability • A property of the cell membrane • Allows some materials to cross • Aka: semipermeable and selectively permeable • Helps maintain homeostasis – Why is that important? Molecule Movement • Some methods require energy, some don’t • Small, nonpolar: go through the membrane easily • Small, polar: transported via proteins • Large: moved in vesicles Chemical signals are transmitted across the cell membrane • Receptor: a protein that detects a signal molecule and performs an action as a response – Recognizes and binds to only certain molecules – The molecule that attaches to it = ligand – When they bind, they change shape Intracellular Receptor • Intra=inside/within • Molecule must first be able to cross the membrane, like………… – Small, nonpolar – Ex. Many hormones • An effect is only seen if there is a specific receptor Ex. of Intracell. Recpt. • Aldosterone enters a kidney cell – Binds to an intracell. Recpt. • Receptor-ligand complex enters the nucleus – Interacts w/ the DNA – Turns on certain genes • Result: specific proteins are made that help the kidneys absorb sodium ions and retain water Membrane Receptor • If molec cannot cross membrane, it can bind to a receptor in the membrane • The entire recptor changes shape – Molecs inside the cell respond Diffusion • diffusion = • 2 maj types of diffusion: – passive diffusion does not require E – active diffusion requires E • Conc. Gradient: the diff in the conc of a substance from one place to another – High -> low Diffusion & Osmosis if diffusion = movement from area of high conc to an area of low conc • osmosis = movement of H20 from area of hi to lo conc Types of Osmosis (refer to Fig 3.23): isotonic soln equal conc hypotonic soln filled w/ H2O (about to burst). Soln has less solutes hypertonic soln losing H2O (shriveled) Facilitated Diffusion facilitated diffusion = when a prot helps a molec, like gluc, move across a memb It does not require E! Still moving down the conc gradient. Transport Proteins • Some are simple channels, or tunnels • Others act like enzymes – When bound, the prot changes shape • Molec travels the rest of the way Facilitated Diffusion Glucose molecules High Concentration Cell Membrane Low Concentration Protein channel Figure 7-15 Osmosis Section 7-3 Active Transport active transport = movement across a memb that requires E b/c it is going against the normal movement of particles Proteins use E 2 types: endocytosis phagocytosis (“cell eating”) pkg it w/in a food vacuole & engulf it pinocytosis tiny pkgs filled w/ liquid exocytosis Active Transport Section 7-3 Molecule to be carried Energy Molecule being carried Review Parts of the Cell • Is it true that prokaryotes don’t have DNA? • Which organelle incorporates the lipids into the membrane? • Which organelle breaks down peroxide? • What is the path that proteins take? • What part of the cytoskeleton is involved in mitosis and makes up cilia and flagella? • Which organelle stores pigment? • Which organelle converts chemical energy to ATP? Review the Cell Membrane • What phrases should be used to describe the cell membrane? • What are the parts of the membrane? -What are the functions of each part? Review the Types of Diffusion • What are the 2 major types of diffusion? -What is the difference between the 2 major types? • What are the types of passive diffusion? • What are the types of active diffusion? •What are the types of osmosis? What do diff cells look like? Adipocytes = fat cells Erythrocytes as seem with the SEM. The bottom image is human red blood cells, platelets and T-lymphocyte (erythrocytes = red; platelets = yellow; T-lymphocyte = light green) (SEM x 9,900). This image is copyright Dennis Kunkel at www.DennisKunkel.com, used with permission. Levels of Organization So you see why the levels of biological organization work? Section 7-4 Muscle cell Smooth muscle tissue Stomach Digestive system HOMEWORK! Review your notes! Finish any unfinished note-taking from last class.