cellular structures & functions. cytoplasm (between nucleus and cell membrane) includes...
TRANSCRIPT
Cellular Structures & Functions
CYTOPLASM (Between nucleus and cell membrane)
Includes
ORGANELLES-small structures with a specific function
CYTOSOL-semi-fluid “goo”
Image from: http://vilenski.org/science/safari/cellstructure/cytoplasm.html
Image from: http://faculty.stcc.cc.tn.us/jiwilliams/labprojectsmenu.htm
NUCLEUS• Surrounded by DOUBLE membrane (Nuclear envelope)
•Nuclear pores- allow molecules in & out
•Contains DNA
•Control center Replication (DNA → DNA) Transcription (DNA → RNA)
Image from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCELL2.html
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
NUCLEAR ENVELOPE
Figure 6.10
Nucleus
NucleusNucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Rough ER
Porecomplex
Surface of nuclear envelope.
Pore complexes (TEM). Nuclear lamina (TEM).
Close-up of nuclearenvelope
Ribosome
1 µm
1 µm
0.25 µm
NUCLEOLUS
• Dark spot in nucleus• Produces ribosomal RNA• Assembles ribosomes (RNA & proteins)
Image from: http://lifesci.rutgers.edu/~babiarz/histo/cell/nuc3L.jpg http://universe-review.ca/I09-08-RNA.gif
DNA
CHROMATIN- spread out in NON-dividing cells to access info
CHROMOSOMES- condensed in dividing cells for easier transport
Cytoskeleton
Network of protein fibers supporting cell shape and anchoring organelles
– Microtubules– Microfilaments
RIBOSOMES
Composed of two subunits that join and attach to messenger RNA
Made of r-RNA & proteins
Site of protein synthesis
(~translation of genetic instructions to yield specific polypeptides)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
ENDOMEMBRANE SYSTEMRegulates protein traffic and performs
metabolic functions in the cell
Includes:Plasma membraneNuclear membraneEndoplasmic reticulumGolgi apparatusVacuolesLysosomes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
CELL MEMBRANE(also called plasma membrane)
PHOSPHOLIPID BILAYER with PROTEINSHydrophobic tails face inHydrophilic heads face out
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
Membrane Image from: © Pearson Education Inc, Publishing as Pearson Prentice Hall; All rights reservedPhospholipid image from: http://bioweb.wku.edu/courses/BIOL115/Wyatt/Biochem/Lipid/P_lipid2.htm
SEE HOW MEMBRANES FORM
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
FLUID MOSAIC MODEL
Molecules in cell membranes are constantly moving and changing
Click here to See Fluidity
Animation from: http://www.sp.uconn.edu/~terry/images/anim/fluidmem.gif
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
CELL MEMBRANES
• act as boundary
• selectively permeable~ gases & hydrophobic molecules can pass through~ large, ionic, OR polar molecules need help (facilitated diffusion, ion channels,
Na+-K+ pump, endocytosis & exocytosis)
http://vilenski.org/science/safari/cellstructure/cellmembrane.html
http://www.d.umn.edu/~sdowning/Membranes/membraneImages/jpegimages/diffusionmedium.jpg
ENDOPLASMIC RETICULUM (ER)Lipid bilayer continuous with nuclear envelope
Smooth ER • no ribosomes • synthesis of lipids
Rough ER• with ribosomes• synthesis of secretory proteins (glycoproteins)• membrane production • compartmentalizes: serves as mechanical
support, site specific protein synthesis with membrane bound ribosomes, and intracellular transport
Image from: http://www.agen.ufl.edu/~chyn/age2062/lect/lect_06/5_10B.GIF
Golgi apparatus (collection of Golgi bodies)
•Consists of a series of flattened membrane sacs called cisternae
“UPS” of cellModify, sort, & package molecules from ER for storage OR transport out of cell via vesicles
Produces lysosomes
http://vilenski.org/science/safari/cellstructure/golgi.h
Image from: http://vilenski.org/science/safari/cellstructure/golgi.h
Image from: http://www.rsbs.anu.edu
Animation from: http://www.franklincollege.edu/bioweb/A&Pfiles/week04.html
See a Golgi movie
EVERYTHING’S CONNNECTED!
18
LYSOSOMES (common in animal cells but rare in plant cells)
Contain hydrolytic enzymes for intracellular digestion
• Food (Phagocytosis)• Damaged organelles
AUTOPHAGY ~ “eating self”
• BacteriaRecycles cell’s organic materialsHelps in APOPTOSIS
See movie
http://www.mgm.ufl.edu/images/bharfe/image3.jpghttp://research.yale.edu/ysm/images/78.3/articles-apoptosis-cells.jpg
“PROGRAMMED CELL DEATH” APOPTOSIS
Embryo developmentCell maintenance
Signal to self destructlost in cancer cells
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LYSOSOMES: Uncontrolled release of lysosome contents into the cytoplasm can also cause cell death (necrosis)
• APOPTOSIS (self-destruct mechanism)“cell suicide”
Embryonic development
Removes damaged cells
Immune response
Cancer cells and AIDS virus override self-destruct signals
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
WHITE BLOOD CELLS USE LYSOSOMES TODIGEST ENGULFED BACTERIA(Phagocytosis)
http://fig.cox.miami.edu/~cmallery/255/255ion/fig14x28.jpg
CENTRIOLESMade of microtubulesAppear during cell division in animal cells to pull chromosomes apart
CENTRIOLES/MITOTIC SPINDLE
Made of MICROTUBULES (Tubulin)
Image from: http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm
MITOCHONDRIA• DOUBLE MEMBRANE
•Creates compartmentalization within mitochondria•Outer membrane is smooth•inner membrane highly convoluted to (increase surface area) forming cristae that contain enzymes that make ATP
Images from:
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
MITOCHONDRIA• Has own DNA
• Powerplant of cell ~ site of cellular respiration
– ~ burn glucose
– ~ store energy as ATP
• Specializes in energy capture and transformation
CHLOROPLASTS• DOUBLE MEMBRANE
•Compartmentalize structures
• Contains thylakoid sacs with chlorophyll (key light trapping molecules in photosynthesis and reason why plants are green) for photosynthesis= energy capturing reactions in thylakoids produce ATP and NADPH which fuel C fixing reactions in Calvin Cycle. C fixation occurs in the stroma where molecules of CO2 are converted to carbohydrates.
•Has own DNA•
http://www.seorf.ohiou.edu/~tstork/compass.rose/photosynthesis/chloro_sun_bathing.gif
http://stallion.abac.peachnet.edu/sm/kmccrae/BIOL2050/Ch1-13/JpegArt1-13/04jpeg/04-28_chloroplasts_1.jpghttp://media.pearsoncmg.com/bc/bc_campbell_essentials_2/cipl/04/HTML/source/04-17-chloroplast-nl.htm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Who else has a circular chromosome notfound within a nucleus?
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Endosymbiotic Theory
• Originally proposed in early 1900’s
• Idea reintroduced in 1963 by Lynn Margulis
• Suggests that engulfed prokaryotes sharedsymbiotic relationship with host cell
• Advantages for both:~ one supplies energy~ other raw materials & protection
http://en.wikipedia.org/wiki/Lynn_Margulis
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
ENDOSYMBIOTIC THEORY
http://www.mun.ca/biology/scarr/Endosymbiosis_theory.gif
See a movie about ENDOSYMBIOTIC THEORY
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Evidence for Endosymbiotic theory
1. Mitochondria and chloroplasts have circular DNA like bacteria.
2. Mitochondria and chloroplasts have ribosomes whose size and structure resemble bacterial ribosomes.
3. Mitochondria and chloroplasts replicate independently of cell division using binary fission like bacteria.
4. Inner membranes of mitochondria and chloroplasts have a composition similar to bacterial membranes.
http://www.stchs.org/science/courses/sbioa/metenergy/flagella.jpghttp://www.geocities.com/CollegePark/Lab/4551/fig12b.jpg
Move substances past cells
Help move cells
http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htmhttp://www.sk.lung.ca/content.cfm?edit_realword=hwbreathe
FLAGELLA & CILIAMade of microtubules
CILIA • Many• short
FLAGELLA•Few•Long
WHAT’S THE DIFFERENCE?
Animation from: http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm
WHAT’S SPECIAL ABOUT PLANT CELLS?
• Cell wall
• HUGE vacuoles
• Chloroplasts
• No centrioles
CELL WALL
Outside cell membrane
Supports and protects cell
Plants- Cellulose makes it “sturdy”
Bacteria- have peptidoglycan instead
http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm
http://www.windows.ucar.edu/kids_space/images/brick_wall.jpg
VACUOLES
• Huge in plants
• Storage space for water, food, enzymes, waste
•Helps with intracellular digestion with release of cellular waste productsImage from: http://www.biologycorner.com/resources/plant_cell.gif
Freshwater organisms have contractile vacuoles to control excess water in cells (HOMEOSTASIS)
http://www.microscopy-uk.org.uk/mag/imgjun99/vidjun1.gif
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PLANT VACUOLES (Central Vacuole)
Surrounded by membrane = Selectively permeable – controls what goes in & out
STORAGE• Water• Stockpile proteins/inorganic ions• Deposit metabolic byproducts• Store pigments• Store defensive compounds against herbivores
WHAT’S DIFFERENT ABOUT BACTERIAL CELLS?
• Cell wall
• NO NUCLEAR MEMBRANE
• DNA is circular
• No membrane bound organelleshttp://www.eurekascience.com/ICanDoThat/bacteria_cells.htm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
WHICH IS BIGGER?
_________ > _____________ > ___________Plant cell Animal cell bacteria