Unit #1-Cells and Energy
Chapter 6:Tour of the Cell Chapter 7:Cell Membrane Chapter 8:Metabolism, Enzymes & ATP Chapter 9:Cellular Respiration A Tour of the Cell Chapter 6 (Pgs 94-123) History & discoveries
Microscopy Limits to Cell Size (Surface area to volume ratio) Cell Fractionation (Structure & Function of Organelles) Prokaryotic vs.Eukaryotic Plant cells vs. Animal Endomembrane System Cytoskeleton Intercellular junctions Video #1-Secrets of the Cell
What part of the football players body does the first segment focus on to show how cells work together? What is Dr. Heath focusing on in plants? Name three differences between prokaryotic and Eukaryotic cells mentioned in segment #3 of the video; **Write the title for each segment and FIVE key statements. Below is a list of the most common units of length biologists use (metric)
Table 4.2 Biological Size and Cell Diversity (Pg. 95)
Human Eye: 1mm - meter+ LM: m 1mm EM: nm 1mm Chicken Egg (lgst cell) Mitochondria (1m) Ribosomes(20-30 nm) Viruses ( nm) History & Discovery of Cells
Anton Van Leeuwenhoek (1600s) Robert Hooke (Cork Cells, 1665) Robert Brown (Nucleus, 1833) Matthias Schleiden (Plant Cells, 1838) Theodor Schwann(Animal Cells, 1839) Rudolf Virchow(All Cells arise from other cells) Cell Theory: 3 aspects Microscopes provide windows to the world of the cell
The light microscope enables us to see the overall shape and structure of a cell Image seen by viewer Eyepiece Ocular lens Objective lens Specimen Condenser lens Light source Figure 4.1A Scanning electron microscope (SEM)
SEM of cilia View SEM Images: Figure 4.1B Transmission electron microscope (TEM)
Transmission electron micrograph of cilia Figure 4.1C Cytology: science/study of cells
Light microscopyresolving power~ measure of clarity Electron microscopy (2 types) TEM~ electron beam to study cell ultrastructure SEM~ electron beam to study cell surfaces Cell fractionation~ cell separation; organelle study Ultracentrifuges~ cell fractionation; 130,000 rpm Cell Fractionation Physically separates and purifies cell parts
Spun in a centrifuge (up to 500,000 rpm) Two fractions: supernatant & pellet Differential: successively at higher speeds Density gradient: forms bands in tube according to density differences of organelles Cell Fractionation-Pg 97 Cell Size Is it more advantageous to be a single cell that is large or to be broken down into several small cells ? (Explain your answer) Natural laws limit cell size
At minimum, a cell must be large enough to house the parts it needs to survive and reproduce The maximum size of a cell is limited by the amount of surface needed to obtain nutrients from the environment and dispose of wastes A small cell has a greater ratio of surface area to volume than a large cell of the same shape
Surface area of one large cube = 5,400 m2 Total surface area of 27 small cubes = 16,200 m2 Figure 4.3 Cell size - (surface area:volume)
As cell size increases, the surface area to volume ratio decreases(sa/vol) Rates of chemical exchange may then be inadequate for cell size Cell size, therefore, remains small AProkaryotic Cell A prokaryotic cell is enclosed by a plasma membrane and is usually encased in a rigid cell wall
The cell wall may be covered by a sticky capsule Prokaryotic flagella Ribosomes Capsule Cell wall Inside the cell are its DNA and other parts Plasma membrane Nucleoid region (DNA) Pili Figure 4.4 Prokaryotic cells, Bacillus polymyxa
Figure 4.4x1 Prokaryotic cell, E. coli
Figure 4.4x2 Pili on a prokaryotic cell
Figure 4.4x3 Prokaryotic flagella Figure 4.4x4 The Prokaryotic Cell-(See Fig. pg 98) (Also See Pages 534-547 in Ch
Characteristics include: No true distinct nucleus Have a Nucleoid region = DNA & Plasmids No complex, membranous organelles (Ribosomes only) Most have cell walls Flagella (rotary type structure & not composed w/microtubules) Some have pigments (autotrophic) Classified according to their metabolic needs Eubacteria & Archeabacteria Some have Capsules, pili, peptidoglycan, Endospores Asexually Reproduce: Binary Fission, Budding, Fragmentation Genetic Material Can be exchanged by 3 mechanisms: Transformation, Transduction, and Conjugation Prokaryotic and eukaryotic cells compared
Figure 4.4x5 The Eukaryotic Cell Eu = true Karyo = kernal (nucleus)
Protists, Plants, Fungi, and Animals Internal Membrane System Has many membranous organelles (Table 4.1) that include: -Nucleus-Lysosomes -Golgi complex-Endoplasmic reticulum (R & S) -Mitochondria-Chloroplast (plastids) -Peroxisomes (glyoxysomes)-Vesicles -Vacuole (food, contractile)-Ribosomes Cytoskeleton: microtubules, microfilaments, and int. filaments Centrioles (nine triplets of microtubules) Cilia & Flagella (9+2 microtubule arrangement) Extracellular matrix (ECM)-proteins & carbodydrate -glycoproteins-glycolipids-integrins -fibronectins-collagen Rough endoplasmic reticulum
Nucleus Ribosomes Smooth endoplasmic reticulum Golgi apparatus Microtubule Central vacuole Not in animal cells Intermediate filament Cytoskeleton Chloroplast Microfilament Cell wall Mitochondrion Peroxisome Plasma membrane Figure 4.5B Plant Cell Cell wall Chloroplasts Water Vacuole Mitochondria An animal cell Smooth endoplasmic reticulum Nucleus
Rough endoplasmic reticulum Flagellum Not in most plant cells Lysosome Centriole Ribosomes Peroxisome Golgi apparatus Microtubule Plasma membrane Cytoskeleton Intermediate filament Microfilament Mitochondrion Figure 4.5A Animal Cell Centrioles Mitochondria Plasma Membrane Nucleus, Ribosomes, Rough & Smooth ER,
Flow of Genetic information and protein Synthesis Nucleus (Pg. 103) Control Center of the Cell Genetic material:
chromatin chromosomes Nucleolus: ribosome synthesis Double membrane envelope with pores 1st part of Protein synthesis: Transcription (DNAmRNA) Nuclear pores Two membranes of nuclear envelope
NUCLEUS Chromatin Two membranes of nuclear envelope Nucleolus Pore ROUGH ENDOPLASMIC RETICULUM Ribosomes Figure 4.6 Ribosomes Manufactures Protein
Free cytosol; protein function in cell Bound endoplasmic reticulum; membranes, organelles, and export Endoplasmic Reticulum (pg. 105)
Endoplasmic reticulum (ER) Continuous with nuclear envelope Smooth ER no ribosomes synthesis of lipids, hormones, and steroids ***Abundant in testes, ovary, and adrenal glands Metabolism of carbohydrates Detoxification of drugs and poisons(Liver) Stores calcium ions (muscle cells---sarcoplasmic reticulum) Rough ER with ribosomes synthesis of secretory proteins (glycoproteins), membrane production **Found extensively in Pancreas & nerve cells SMOOTH ER ROUGH ER Nuclear envelope Ribosomes SMOOTH ER ROUGH ER
Figure 4.9 Rough Endoplasmic Reticulum makes membrane and proteins
The rough ER manufactures membranes Ribosomes on its surface produce proteins 1 2 3 4 Transport vesicle buds off Ribosome Sugar chain Glycoprotein Secretory (glyco-) protein inside transport vesicle ROUGH ER Polypeptide Figure 4.8 Golgi Apparatus (complex) Golgi Complex (pg. 106) Golgi apparatus
ER products are modified, stored, and then shipped Cisternae: flattened membranous sacs trans face (shipping) & cis face (receiving) Transport vesicles The Golgi apparatus finishes, sorts, and ships cell products
The Golgi apparatus consists of stacks of membranous sacs These receive and modify ER products, then send them on to other organelles or to the cell membrane Specialized for secretion (salivary glands & pancreas) Removes and changes the sugars attached to the protein Many polysaccharides are secreted by the Golgi The Golgi apparatus Golgi apparatus Golgi apparatus
Receiving side of Golgi apparatus Transport vesicle from ER New vesicle forming Shipping side of Golgi apparatus Transport vesicle from the Golgi Figure 4.10 Lysosomes & Vacuoles Lysosomes digest the cells food and wastes (Pg.107)
Lysosomes are sacs of digestive enzymes budded off the Golgi LYSOSOME Nucleus Figure 4.11A Lysosomes Lysosomes: undergoes phagocytosis & engulfs material
Contain lysosomal enzymes (hydrolytic enzymes) digests food molecules (macromolecules) destroysbacteria recycles damaged organelles function in embryonic development in animals undergoes phagocytosis & engulfs material Recycle cells own organic material **Found extensively in Macrophages (WBCs) Transport vesicle (containing inactive hydrolytic enzymes)
Rough ER Transport vesicle (containing inactive hydrolytic enzymes) Plasma membrane Golgi apparatus Engulfment of particle Lysosome engulfing damaged organelle Food LYSOSOMES Digestion Food vacuole Figure 4.11B Lysosomes can cause Fatal Diseases
Lysosomal Storage Diseases are hereditary that interfere with other cellular functions *Examples: Pompes disease Tay-Sachs disease (Pgs. 93, 331) Endomembrane Function (pg. 109) Vacuoles -Membrane-bound sacs (larger than vesicles)
-Food (phagocytosis) -Contractile (pump excess water) -Central (storage in plants) -Tonoplast membrane Vacuoles function in the general maintenance of the cell
Plant cells contain a large central vacuole The vacuole has lysosomal and storage functions Central vacuole Nucleus Figure 4.13A Peroxisomes (Pg. 111) Single membrane Oxidative organelle
***strips e-s (Hs) from substances Produce hydrogen peroxide (H2O2) in cells Metabolism of fatty acids; detoxification of alcohol (liver) Hydrogen peroxide then converted to water Mitochondria & Chloroplasts
-Energy Harvesting Organelles Mitochondria -Site of Cellular Respiration(Pg. 110) See page 111 Mitochondria harvest chemical Energy from food
Site for Cellular Respiration---Prod. of ATP Uses O2 to extract energy from sugar, fats, and other molecules Found in cells that are motile and contractible Has a double membrane Has Convoluted inner membranes: Cristae Two spaces: Matrix & intermembrane space Not part of the endomembrane system Has its own DNA and rbosomes (able to regenerate & divide)---Semiautonomous MITOCHONDRION Outer membrane Intermembrane space Inner membrane
Cristae Matrix Figure 4.16 Chloroplasts convert solar energy to chemical energy
Chloroplasts are found in plants and some protists Chloroplasts convert solar energy to chemical energy in sugars Chloroplast Stroma Inner and outermembranes Granum Intermembrane space Figure 4.15 The Chloroplast (pg. 111) Site for Photosysnthesis: combines CO2 & H2O
Converts solar energy into chemical energy (sugar molecules) A Type of Plastid Three types: (Amyloplastid, chromoplast, and chloroplast) Double membrane w/ thylakoids (flattened disks) Grana (stacked thylakoids) Three compartments -Stroma -Intermembrane space -Within the thylakoid membranes Has its own DNA Cytoskeleton The Cytoskeleton (pg. 112-113)
-Fibrous proteins (actin & tubulin) -Support, cell motility, biochemical regulation, organelle movement -Microtubules: thickest (nm) tubulin protein; shape, support, transport, chromosome separation -Microfilaments: thinnest ( nm) actin protein filaments; motility, cell division, shape -Intermediate filaments: middle diameter; keratin; shape, nucleus anchorage The cells internal skeleton helps organize its structure and activities
A network of protein fibers makes up the cytoskeleton Figure 4.17A Comparing Cytoskeletal Filaments
Scan image INTERMEDIATE FILAMENT
The Cytoskeleton Tubulin subunit Actin subunit Fibrous subunits 25 nm 7 nm 10 nm MICROFILAMENT INTERMEDIATE FILAMENT MICROTUBULE Figure 4.17B Microfilaments of actin enable cells to change shape and move
Intermediate filaments reinforce the cell and anchor certain organelles Microtubules give the cell rigidity provide anchors for organelles act as tracks for organelle movement Cytoskeletal Movement (Polymerization & De-polymerization) Centrosomes/Centrioles (pg. 114)
Centrosome:region near nucleus Centrioles:9 sets of triplet microtubules in a ring; (used in cell replication; only in animal cells) Cilia & Flagella-Eukaryotes
Internal Structure & Function Cilia/Flagella (pg. 115-116) -Locomotive appendages
-Ultrastructure:9+2 (9 doublets of microtubules in a ring) (2 single microtubules in center) -Connected by radial spoke -Anchored by basal body (nine triplets of microtubules) -Dynein arm proteins (red) Cilia and flagella move when microtubules bend
Eukaryotic cilia and flagella are locomotor appendages that protrude from certain cells A cilia or flagellum is composed of a core of microtubules wrapped in an extension of the plasma membrane Electron micrograph of sections:
FLAGELLUM Electron micrograph of sections: Outer microtubule doublet Plasma membrane Flagellum Central microtubules Outer microtubule doublet Plasma membrane Basal body Basal body (structurally identical to centriole) Figure 4.18A Dynein Arm Function (pg. 116) Clusters of microtubules drive the whipping action of these organelles
Microtubule doublet Sliding force Dynein arm Figure 4.18B ECM: Extracellular Matrix ECM Composition Extracellular matrix (ECM) composed of: -Specifically:
-Proteins & Carbodydrate -Specifically: -glycoproteins -glycolipids -integrins -fibronectins -collagen (50% of all protein in the body) Extracellular Matrix (ECM) - Pg. 118-120
Glycoproteins: proteins covalently bonded to carbohydrate Collagen (50% of protein in human body embedded in proteoglycan (another glycoprotein-95% carbohydrate) Fibronectins bind to receptor proteins in plasma membrane called integrins (cell communication?) Animal cells are embedded in an extracellular matrix
It is a sticky layer of glycoproteins It binds cells together in tissues It can also have protective and supportive functions Eukaryotic organelles comprise FOUR functional categories
Table 4.20 Summary of Organelles & their Function
Table 4.20 (continued) Intercellular Junctions Intracellular Junctions (pg. 121)
PLANTS: Plasmodesmata: cell wall perforations; water and solute passage in plants ANIMALS: Tight junctions~ fusion of neighboring cells; prevents leakage between cells Desmosomes~ riveted, anchoring junction; strong sheets of cells Gap junctions~ cytoplasmic channels; allows passage of materials or current between cells Cell surfaces & Junctions
-Cell wall: not in animal cells protection, shape, regulation -Plant cell: primary cell wall produced first middle lamella of pectin (polysaccharide) -Holds cells together some plants have a secondary cell wall; strong durable matrix; wood (between plasma membrane and primary wall) Walls of two adjacent plant cells
Vacuole PLASMODESMATA Layers of one plant cell wall Cytoplasm Plasma membrane Figure 4.19A Tight junctions can bind cells together into leakproof sheets
Anchoring junctions link animal cells Communicating junctions allow substances to flow from cellto cell TIGHT JUNCTION ANCHORING JUNCTION COMMUNICATING JUNCTION Plasmamembranes of adjacent cells Extracellular matrix Figure 4.19B The End of Chapter 6 Science and Art The Art of Looking at Cells
Artists are often inspired by biology and biology depends on art The paintings of Wassily Kandinsky ( ) show the influence of cellular forms Illustration is an important way to represent what scientists see through microscopes
The anatomist Santiago Ramn y Cajal ( ) was trained as an artist He drew these retina nerve cells A review of the endomembrane system
The various organelles of the endomembrane system are interconnected structurally and functionally Transport vesicle from Golgi Transport vesicle from ER Rough ER Plasma membrane Vacuole Nucleus Lysosome Golgi apparatus Smooth ER Nuclear envelope Figure 4.14 Extraterrestrial life-forms may share features with life on Earth
It is almost certain that Earth is the only life-bearing planet in our solar system But it is conceivable that conditions on some of the moons of the outer planets or on planets in other solar systems have allowed the evolution of life Figure 4.21 Samples of Various Types of Cells Protists may have contractile vacuoles
These pump out excess water Nucleus Contractile vacuoles Figure 4.13B Cell, stained for mitochondria, actin, and nucleus
Figure 4.1x Paramecium, an animal cell
Figure 4.5Ax Plant cells Figure 4.5Bx1 Chloroplasts in plant cells
Figure 4.5Bx2 Nuclei (yellow) and actin (red)
Figure 4.6x