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Introductory Questions #11) What is the basic unit of measurement used by biologists
to measure cells? What about internal organelles?2) What are the approximate sizes for:
-human egg cell -mitochondria-virus -protein
3) What are the magnification limits of the human eye, a light microscope, and an electron microscope
4) How does a TEM differ from an SEM? What is the main limitation with using electron microscopes?
5) Briefly explain what the cell fractionation process does and how differential centrifugation can be helpful in the study of Cytology.
6) How do cells keep their internal contents separate from the outside environment?
7) Why is the surface to volume ratio an important factor with regard to cell size limits?
Introductory Question #21) Name three structures found in prokaryotic cells, eukaryotic
plant cells, and eukaryotic animal cells. 2) Name the three layers that surround and protect a
prokaryotic cell. Why are prokaryotes considered to be “simple” cells and eukaryotic are called “complex” cells?
Matching Ex.Cellular respiration A. NucleolusDigests waste, worn out organelles B. Endoplasmic Ret.Produces rRNA and ribosomes C. Ribosomes
Produces H2O2 D. Golgi ComplexForms Mitotic spindle in Mitosis E. LysosmesSite for protein synthesis F. PeroxisomesSite for the synthesis of lipids G. MitochondriaModifies, packages and ships protein H. Centrioles
IQ #3
What purpose do vesicles serve in the cell? Name all of the organelles that are a part
of the endomembrane system.4) Explain how the rough ER is different
from the smooth ER,5) How is a lysosome different from a
peroxisome?6) What do the chaperone proteins in the
ER do?
Introductory Questions # 41) Name the people that helped to develop the cell
theory. What contribution did each person make (what did they discover)?
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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
History & Discovery of Cells
• Anton Van Leeuwenhoek (pond water 1600’s)
• 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
• 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: 1m – 1mm
EM: 1nm – 1mm
Chicken Egg (largest cell)
Mitochondria (1m)
Ribosomes (20-30 nm)
Viruses (80-100 nm)
• The light microscope enables us to see the overall shape and structure of a cell
Microscopes provide windows to the world of the cell
Figure 4.1A
Image seen by viewer
Eyepiece
Ocularlens
Objective lens
Specimen
Condenser lens
Light source
• Scanning electron microscope (SEM)
Figure 4.1B
• Scanning electron micrograph of cilia
• Transmission electron microscope (TEM)
Figure 4.1C
• Transmission electron micrograph of cilia
Cytology: science/study of cells• Light microscopy• resolving 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-Pg 97Cell Fractionation-Pg 97
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 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)
• A small cell has a greater ratio of surface area to volume than a large cell of the same shape
30 µm 10 µm
Surface areaof one large cube= 5,400 µm2
Total surface areaof 27 small cubes= 16,200 µm2Figure 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
• 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
Natural laws limit cell size
The Prokaryotic Cell-(See Fig. pg 98)(Also See Pages 534-547 in Ch. 27)
• Characteristics include:– No true distinct nucleus – Have a “Nucleoid” region = DNA & Plasmids– No complex, membranous organelles (Ribosomes only)– Most have rigid cell walls – Flagella (rotary type structure & not composed
w/microtubules)– Some have pigments (autotrophic)– Classified according to their metabolic needs– Eubacteria & Archeabacteria– Some have sticky capsules, pili, peptidoglycan,
Endospores– Asexually Reproduce: Binary Fission, Budding,
Fragmentation– Genetic Material Can be exchanged by 3 mechanisms:
– Transformation, Transduction, and Conjugation
A Prokaryotic Cell
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
Figure 4.5B
Nucleus
Golgiapparatus
Not inanimal
cells
Centralvacuole
Chloroplast
Cell wall
Mitochondrion
Peroxisome
Plasma membrane
Roughendoplasmicreticulum
Ribosomes
Smoothendoplasmicreticulum
Cytoskeleton
Microtubule
Intermediatefilament
Microfilament
• An animal cell
Plasma membrane
Figure 4.5A
Golgiapparatus
Ribosomes
NucleusSmooth endoplasmicreticulum
Roughendoplasmicreticulum
Mitochondrion
Not in most plant cells
Cytoskeleton
Flagellum(exception is some plants)
Lysosome
Centriole
Peroxisome
Microtubule
Intermediatefilament
Microfilament
Endomembrane Functionhttp://users.uma.maine.edu/SusanBaker/nucleus_endo.html
Nucleus, Ribosomes, Rough & Smooth ER,
Flow of Genetic information and protein Synthesis
Nucleus (Pg. 103)Control Center of the CellGenetic material:
•chromatin
•chromosomesNucleolus: ribosome
synthesisDouble membrane
envelope with pores1st part of Protein
synthesis:Transcription (DNAmRNA)
Nuclear pores
Figure 4.6
Chromatin
Nucleolus
Pore
NUCLEUS
Two membranesof nuclearenvelope
ROUGHENDOPLASMICRETICULUM
Ribosomes
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
envelopeSmooth ER •no ribosomes; •synthesis of lipids•metabolism of carbohydrates• detoxification of drugs and
poisonsRough ER
•with ribosomes•synthesis of secretory proteins (glycoproteins), membrane production
**Found extensively in Pancreas
• The rough ER manufactures membranes• Ribosomes on its surface produce proteins
Rough Endoplasmic Reticulum makes membrane and proteins
1 2
3
4Transport vesiclebuds off
Ribosome
Sugarchain
Glycoprotein
Secretory(glyco-) proteininside transportvesicle
ROUGH ER
PolypeptideFigure 4.8
SMOOTH ER
ROUGHER
Nuclearenvelope
Ribosomes
SMOOTH ER ROUGH ER
Figure 4.9
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 consists of stacks of membranous sacs – These receive and modify ER products, then
send them on to other organelles or to the cell membrane
The Golgi apparatus finishes, sorts, and ships cell products
• The Golgi apparatus
Golgiapparatus
“Receiving” side ofGolgi apparatus
Transportvesiclefrom ER
Newvesicleforming
Transport vesiclefrom the Golgi
Golgi apparatus
“Shipping”side of Golgiapparatus Figure 4.10
• Lysosomes are sacs of digestive enzymes budded off the Golgi
Lysosomes digest the cell’s food and wastes (Pg.107)
LYSOSOME
Nucleus
Figure 4.11A
Lysosomes
Lysosomes:
– Contain lysosomal enzymes (hydrolytic enzymes)
– digests food molecules (macromolecules)– destroys bacteria– recycles damaged organelles– function in embryonic development in animals
– undergoes phagocytosis & engulfs material
– Recycle cell’s own organic material
**Found extensively in Macrophages (WBC’s)
Figure 4.11B
Rough ER
Transport vesicle(containing inactivehydrolytic enzymes)
Golgiapparatus
Plasmamembrane
LYSOSOMES
“Food”
Engulfmentof particle
Foodvacuole
Digestion
Lysosomeengulfingdamagedorganelle
• Lysosomal Storage Diseases are hereditary that interfere with other cellular functions
*Examples:
Pompe’s disease (build up of glycogen)
Tay-Sachs disease (lipid build up)
(Pgs. 93, 331)
Lysosomes can cause Fatal Diseases
Vacuoles-Membrane-bound sacs
(larger than vesicles)
-Food (phagocytosis)
-Contractile
(pump excess water)
-Central
(storage in plants)
-Tonoplast membrane
• Plant cells contain a large central vacuole– The vacuole
has lysosomal and storage functions
Vacuoles function in the general maintenance of the cell
Centralvacuole
Nucleus
Figure 4.13A
Peroxisomes (Pg. 111)• Single membrane• Oxidative organelle ***strips e-’s (H’s) 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)
• 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
Mitochondria harvest chemical Energy from food
Figure 4.16
Outermembrane
MITOCHONDRION
Intermembranespace
Innermembrane
Cristae
Matrix
• Chloroplasts are found in plants and some protists
• Chloroplasts convert solar energy to chemical energy in sugars
Chloroplasts convert solar energy to chemical energy
Chloroplast Stroma
Inner and outer membranes
Granum
IntermembranespaceFigure 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
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
• A network of protein fibers makes up the cytoskeleton
The cell’s internal skeleton helps organize its structure and activities
Figure 4.17A
Comparing Cytoskeletal Filaments
• Scan image
MICROFILAMENT
Figure 4.17B
INTERMEDIATEFILAMENT
MICROTUBULE
Actin subunit Fibrous subunitsTubulinsubunit
7 nm 10 nm25 nm
The Cytoskeleton
• 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 (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)
• 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
Cilia and flagella move when microtubules bend
Figure 4.18A
FLAGELLUM
Outer microtubule doublet
Plasmamembrane
Centralmicrotubules
Outer microtubule doublet
Plasmamembrane
Electron micrograph of sections:
Flagellum
Basal body
Basal body(structurally identical to centriole)
Dynein Arm Function (pg. 116)
• Clusters of microtubules drive the whipping action of these organelles
Figure 4.18B
Microtubule doublet
Dynein arm Slidingforce
ECM Composition
• Extracellular matrix (ECM) composed of:-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
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)
Figure 4.19A
Vacuole
Layers of one plant cell wall
Walls of two adjacent plant cells
PLASMODESMATA
Cytoplasm
Plasma membrane
• Tight junctions can bind cells together into leakproof sheets
• Anchoring junctions link animal cells
• Communicating junctions allow substances to flow from cell to cell
TIGHTJUNCTION
ANCHORING JUNCTION
COMMUNICATINGJUNCTION
Plasma membranes ofadjacent cells
ExtracellularmatrixFigure 4.19B
Movin’ on to Chapter 7
Science and Art
• Artists are often inspired by biology and biology depends on art
• The paintings of Wassily Kandinsky (1866-1944) show the influence of cellular forms
The Art of Looking at Cells
• Illustration is an important way to represent what scientists see through microscopes
• The anatomist Santiago Ramón y Cajal (1852-1934) was trained as an artist– He drew these retina
nerve cells
Eukaryotic organelles comprise FOUR functional categories
Table 4.20
Table 4.20 (continued)
Summary of Organelles & their Function
• The various organelles of the endomembrane system are interconnected structurally and functionally
A review of the endomembrane system
Transport vesiclefrom ER
Rough ER
Transport vesiclefrom Golgi
Plasmamembrane
Vacuole
LysosomeGolgiapparatusNuclear
envelope
Smooth ER
Nucleus
Figure 4.14
• 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
Extraterrestrial life-forms may share features with life on Earth
Figure 4.21
Samples of Various Types of Cells
• Protists may have contractile vacuoles
Figure 4.13B
Nucleus
Contractilevacuoles
– These pump out excess water
• Cell, stained for mitochondria, actin, and nucleus
Figure 4.1x
• 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
• Prokaryotic and eukaryotic cells compared
Figure 4.4x5
• 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
