Cell Structures and Functions
Nov 16, 2014
Cell Structures and Functions
The Cellthe smallest unit of life that can carry out all the functions of a living thing.
fundamental building blocks of organisms.
Brief History of the Cell
Antonie van Leeuwenhoek (1632-1723)
Robert Hooke (1635-1703)
Cork Cell
The word cell comes from the Latin cella, a small room.
The Cell Theory Robert Brown (1831)
Described the nucleus of the cell Matthias Schleiden (1838)
All plants are composed of cells. Theodor Schwann (1838)
All animals are composed of cells Rudolph Virchow (1850s)
Cells reproduce
The Cell Theory
All organisms are composed of cells.
Cells are the basic units of structure and function in organisms.
Cells come only from pre-existing cells because cells are self-reproducing.
Microscopy Today
Electron Microscopes are scientific instruments that use a beam of highly energetic electrons to examine objects on a very fine scale.
10
Sizes of Living Things10 m1 m0.1 m1 cm1 mm100 nm10 nm1 nm0.1 nm
mousefrog egg
human eggmost bacteria
virus
protein
atomant
electron microscope
light microscope
human eye
humanblue whale
chloroplastrose
1 km100 m100 m10 m1 m
plant and animal
cellsaminoacid
ostrichegg
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Microscopy Today
Topography: shows the surface features of an object or "how it looks", its texture; and materials properties (hardness, reflectivity...etc.)
Morphology: shows shape and size of the particles making up the object; and materials properties (ductility, strength, reactivity...etc.)
12
Animal Cell Anatomy
*not in plant cells
Plasma membrane:outer surface thatregulates entrance andexit of molecules
phospholipid
protein
Cytoskeleton: maintainscell shape and assists movementof cell parts:
Actin filaments: proteinfibers that play a role inchange of shape
Cytoplasm: semifluidmatrix outside nucleusthat contains organelles
Intermediate filaments:protein fibers that providestability of shape
Microtubules: proteincylinders that moveorganelles
Vesicle: small membrane-bounded sac that storesand transports substances
Centrioles*: shortcylinders of microtubulesof unknown function
Centrosome: microtubuleorganizing center thatcontains a pair of centrioles
Lysosome*: vesicle thatdigests macromoleculesand even cell parts
Nucleus: command center of cell
Rough ER: studded withribosomes that synthesizeproteins
Ribosomes:particles that carryout protein synthesis
Golgi apparatus: processes, packages,and secretes modified proteins
Peroxisome: vesiclethat is involved infatty acid metabolism
Smooth ER: lacksribosomes, synthesizeslipid molecules
Endoplasmic reticulum:protein and lipid metabolism
Mitochondrion: organellethat carries out cellular respiration, producing ATP molecules
Polyribosome: string ofribosomes simultaneouslysynthesizing same protein
Nucleolus: region that producessubunits of ribosomes
Chromatin: diffuse threadscontaining DNA and protein
Nuclear envelope: doublemembrane with nuclear poresthat encloses nucleus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
13
Microscopy and Cheek Cells
Bright-field. Lightpassing through thespecimen is broughtdirectly into focus. Usually,the low level of contrastwithin the specimeninterferes with viewing allbut its largest components.
Bright-field (stained).Dyes are used to stainthe specimen. Certaincomponents take upthe dye more than othercomponents, and thereforecontrast is enhanced.
Differential interferencecontrast. Optical methodsare used to enhancedensity differences withinthe specimen so thatcertain regions appearbrighter than others. Thistechnique is used to viewliving cells, chromosomes,and organelle masses.
Phase contrast. Densitydifferences in thespecimen cause light raysto come out of “phase.”The microscope enhancesthese phase differences sothat some regions of thespecimen appear brighteror darker than others. Thetechnique is widely usedto observe living cells andorganelles.
Dark-field. Light is passedthrough the specimen atan oblique angle so thatthe objective lens receivesonly light diffracted andscattered by the object.This technique is used toview organelles, whichappear quite bright againsta dark field.
25 m 25 m 25 m30 m 30 m
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Bright field): © Ed Reschke; (Bright field stained): © Biophoto Associates/Photo Researchers, Inc.;(Differential, Phase contrast, Dark field): © David M. Phillips/Visuals Unlimited
Prokaryotic
Eukaryotic
Two Basic Types of Cell Structure
Prokaryotic “pro” = before, “kary”= nut
(nucleus) NO nucleus or NO organelles Genetic material (DNA) is naked in
the cytoplasm Cell division is called binary fission
Two Basic Types of Cell Structure
Prokaryotic
Two Basic Types of Cell Structure
Believed to be the first cells to evolve.
Ribosomes are the only organelle.
Binary Fission: Prokaryotes Cell Division
Two Basic Types of Cell Structure
Prokaryotic• Kingdom Monera
• Kingdom Archaea
Prokaryotic
Eukaryotic
Two Basic Types of Cell Structure
Eukaryotic Nucleus containing DNA “Eu” - true Organelles (membrane bound) with specialized functions
Cell division: mitosis and meiosis
Two Basic Types of Cell Structure
Two Basic Types of Cell Structure
Eukaryotic• Kingdom Protista• Kingdom Fungi• Kingdom Plantae• Kingdom Animalia
Differences between Prokaryotic & Eukaryotic cellsBacterial cells also contain flagellum, plasmid and capsule.
Feature Prokaryote Eukaryote
Size Small about 0.5 micrometers
Up to 40 micrometers
Genetic material
Circular DNA (in cytoplasm)
DNA in form of linear chromosomes ( in nucleus)
Organelles Few present, none membrane bound
Many organelles:•Double membranes e.g.: nucleus, mitochondria & chloroplasts•Single membrane e.g.: GA, ER & lysosomes
Cell wallsRigid formed from glycoproteins (mainly murein)
•Fungi: rigid, formed from polysaccharide, chitin. •Plant: rigid, formed from polysaccharides. E.g.: cellulose. •Animals no cell wall
Ribosome’s 70s 80s
VIDEO
Section 7-2
Figure 7-5 Plant and Animal Cells
Go to Section:
Animal Cell
NucleusNucleolus
Cell Membrane
Cytoplasm
Eukaryotic Cell Organelles and Function
1. Nucleus Nickname: “The Control
Center” Function: holds the DNA Parts:
1. Nucleolus: dark spot in the middle of the nucleus that helps make ribosomes
Eukaryotic Cell Organelles and Function
Section 7-2
Figure 7-5 Plant and Animal Cells
Go to Section:
Animal Cell
Nucleus
Nucleolus RibosomesCell Membrane
Cytoplasm
Eukaryotic Cell Organelles and Function
2. Ribosomes Function: makes
proteins Found in all cells,
prokaryotic and eukaryotic
Eukaryotic Cell Organelles and Function
3. Endoplasmic Reticulum (ER)
Nickname: “Roads” Function: The internal
delivery system of the cell
Section 7-2
Figure 7-5 Plant and Animal Cells
Go to Section:
Animal Cell
Nucleus
Nucleolus
Rough Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Cell Membrane
Cytoplasm
Ribosomes
Endoplasmic Reticulum
Rough ER: Rough appearance because of ribosomes
Function: helps make proteins, that’s why it has ribosomes
Smooth ER:• similar in appearance with RER but NO ribosomes•Function: functions depending on the specific cell type including lipid and steroid hormone synthesis, breakdown of lipid-soluble toxins in liver cells, and control of calcium release in muscle cell contraction.
Endoplasmic Reticulum
Section 7-2
Figure 7-5 Plant and Animal Cells
Go to Section:
Animal Cell
Nucleus
Nucleolus
Rough Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Ribosomes
Golgi Complex
Cell Membrane
Cytoplasm
Eukaryotic Cell Organelles and Function
4. Golgi Complex Nickname: The shippers Function: packages, modifies,
and transports materials to different location inside/outside of the cell
Appearance: stack of pancakes
Eukaryotic Cell Organelles and Function
Golgi Complex Modifies
proteins and lipids made by the ER and prepares them for export from the cell
Section 7-2
Figure 7-5 Plant and Animal Cells
Go to Section:
Animal Cell
Nucleus
Nucleolus
Rough Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Ribosomes
Golgi Bodies
Cell Membrane
Cytoplasm
Eukaryotic Cell Organelles and Function
5. Lysosomes: circular, but bigger than ribosomes
Nickname: “Clean-up Crews” Function: to break down
food into particles the rest of the cell can use and to destroy old cells
Single membrane bound structure.
Contains digestive enzymes that break down cellular waste and debris and nutrients for use by the cell.
Http://micro.magnet.fsu.edu/cells/animals/lysosome/html
Eukaryotic Cell Organelles and Function
Animation
Section 7-2
Figure 7-5 Plant and Animal CellsAnimal Cell
Nucleus
Nucleolus
Rough Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Ribosomes
Golgi Bodies
MitochondriaCell Membrane
Cytoplasm
Eukaryotic Cell Organelles and Function
6. Mitochondria Nickname: “The Powerhouse” Function: Energy formation
Breaks down food to make ATP ATP: is the major fuel for all
cell activities that require energy
Animal Cell
Nucleus
Nucleolus
Rough Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Ribosomes
Golgi Bodies
Mitochondria
Cell Membrane
Cytoplasm
Eukaryotic Cell Organelles and Function
7. Plasma Membrane
• Another name: Cell Membrane; “traffic enforcer”
• Function: hold the cell together. It keeps all of the pieces, like the organelles and the CYTOPLASM inside; regulates the entrance and exit of materials in and out the cell.
Plasma Membrane
Fluid Mosaic Model of Plasma Membrane
Lipid bilayera. Phospholipids: polar head and nonpolar tailb. Cholesterol: makes membrane a bit more rigidc. Proteins: provide means of transportation through membrane and receptor proteinsd. Carbohydrates: recognition patterns for cells and organisms (“self” markers to avoid immune system attack)
Fluid Mosaic Model of the Plasma MembraneThe membrane is seen as a bilayer of phospholipids in which protein molecules are embedded.
8. Cytoskeleton-composed of filaments and microtubules that maintain the cell shape and assist movement of its part
Eukaryotic Cell Organelles and Function
9. Cilia and flagella External
appendages from the cell membrane that aid in locomotion of the cell.
Cilia also help to move substance past the membrane.
• The most common examples of ciliated cells are those that line the trachea, or wind pipe of animals. • The cilia move mucus containing dirt and other inhaled particles up the windpipe and into the esophagus where they can be coughed up or swallowed.
Cilia and Flagella
Cilia and Flagella
Paramecium sp.
This unicellular organism sweeps food into its mouth by using cilia.
Cilia and Flagella
Sperm cell has a tail or "flagellum" which executes the lashing movements to propel the sperm.
Eukaryotic Cell Organelles and Function
10. Centrioles Found only in animal cells.
Self-replicating Made of bundles
of microtubules. Help in organizing
cell division.
11. Cytosol/Cytoplasm• The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism
occurs.* Though mostly water, the cytosol
is full of proteins that control cell
metabolism including signal transduction
pathways, glycolysis, and transcription
factors.
Structures only found in PLANT Cells
Section 7-2
Figure 7-5 Plant and Animal Cells
Go to Section:
Plant Cell
Cell Membrane
Vacuole
Eukaryotic Cell Organelles and Function
11. Huge vacuoles Function: store water, waste
products, food, and other cellular materials.
It may take up most of the cell's volume.
When there is no water, the plant wilts
Eukaryotic Cell Organelles and Function
Section 7-2
Figure 7-5 Plant and Animal Cells
Go to Section:
Plant Cell
Cell Membrane
Vacuole
Chloroplasts
Eukaryotic Cell Organelles and Function
12. Chloroplasts Function: traps energy from
the sun to produce food for the plant cell
Green in color because of chlorophyll
Chloroplasts
Section 7-2
Figure 7-5 Plant and Animal Cells
Go to Section:
Plant Cell
Cell Membrane
Vacuole
Chloroplasts
Cell Wall
Eukaryotic Cell Organelles and Function
9. Cell Wall Function: provides support
and protection to the cell membrane; gives rigidity to the cell structure.
Found outside the cell membrane in plant cells.
Eukaryotic Cell Organelles and Function
Plant Cell
Cell Membrane
Vacuole
Chloroplasts
Cell Wall
Nucleolus
Nucleus
Rough ER
Smooth ER
Golgi Bodies
Mitochondria
Ribosomes
Cytoplasm
Muscle cells: contain numerous mitochondria providing energy needed for muscle contraction (action).
Cell Structure Reflects Cell Function
Cell Structure Reflects Cell Function
Cells of renal tubule lining are cube-shaped (helps with their function of absorption/secretion)
Cell Structure Reflects Cell Function
Nerve cells: are long and thin to carry impulses over distance.
Cell Structure Reflects Cell Function
Columnar epithelium with cilia on the free surface lines of the respiratory tract, fallopian tubes and uterus. The cilia beat rhythmically to transport particles.
Cell Structure Reflects Cell Function
Sperm cell has a tail or "flagellum" which executes the lashing movements to propel the sperm.
Red blood cells contain hemoglobin which permits them to transport oxygen (and carbon dioxide).
Cell Structure Reflects Cell Function
Animal Cell vs. Plant Cell
Comparing Plant and Animal CellsPlant Animal