Transcript File

Cellular Structures & Functions
CYTOPLASM
Image from: http://faculty.stcc.cc.tn.us/jiwilliams/labprojectsmenu.htm
(Between nucleus and cell membrane)
Includes
ORGANELLESsmall structures with
a specific function
CYTOSOL-semi-fluid “goo”
Image from: http://vilenski.org/science/safari/cellstructure/cytoplasm.html
NUCLEUS
Image from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCELL2.html
• Surrounded by DOUBLE membrane
(Nuclear envelope)
•Nuclear pores-
allow molecules in & out
•Contains DNA
•Control center
Replication
(DNA → DNA)
Transcription
(DNA → RNA)
NUCLEAR ENVELOPE
Nucleus
Nucleus
1 µm
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Pore
complex
Rough ER
Surface of nuclear
envelope.
1 µm
Ribosome
0.25 µm
Close-up of
nuclear
envelope
Figure 6.10
Pore complexes (TEM).
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Nuclear lamina (TEM).
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
CHROMATINspread out in NON-dividing cells to access info
CHROMOSOMEScondensed 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)
ENDOMEMBRANE SYSTEM
Regulates protein traffic and performs
metabolic functions in the cell
Includes:
Plasma membrane
Nuclear membrane
Endoplasmic reticulum
Golgi apparatus
Vacuoles
Lysosomes
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CELL MEMBRANE
(also called plasma membrane)
SEE HOW
MEMBRANES FORM
PHOSPHOLIPID BILAYER with PROTEINS
Hydrophobic tails face in
Hydrophilic heads face out
Outside
of cell
Carbohydrate
chains
Proteins
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Membrane Image from: © Pearson Education Inc, Publishing as Pearson Prentice Hall; All rights reserved
Phospholipid
image
from:
http://bioweb.wku.edu/courses/BIOL115/Wyatt/Biochem/Lipid/P_lipid2.htm
Copyright © 2005
Pearson
Education,
Inc. publishing as Benjamin Cummings
FLUID MOSAIC MODEL
Click here to
See Fluidity
Molecules in cell membranes are
constantly moving and changing
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Animation from: http://www.sp.uconn.edu/~terry/images/anim/fluidmem.gif
CELL MEMBRANES
http://vilenski.org/science/safari/cellstructure/cellmembrane.html
• 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)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
http://vilenski.org/science/safari/cellstructure/golgi.h
called cisternae
“UPS” of cell
Modify, sort, & package molecules from ER
for storage OR transport out of cell via
vesicles
Image from: http://www.rsbs.anu.edu
Produces lysosomes
Image from: http://vilenski.org/science/safari/cellstructure/golgi.h
Animation from: http://www.franklincollege.edu/bioweb/A&Pfiles/week04.html
See a Golgi movie
EVERYTHING’S CONNNECTED!
LYSOSOMES
(common in animal cells but rare in plant cells)
Contain hydrolytic enzymes for intracellular
digestion
•
Food (Phagocytosis)
•
Damaged organelles
AUTOPHAGY
movie self”
~See
“eating
•
Bacteria
Recycles cell’s organic materials
Helps in APOPTOSIS
18
“PROGRAMMED CELL DEATH”
APOPTOSIS
Embryo development
Cell maintenance
Signal to self destruct
lost in cancer cells
http://www.mgm.ufl.edu/images/bharfe/image3.jpg
http://research.yale.edu/ysm/images/78.3/articles-apoptosis-cells.jpg
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
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WHITE BLOOD CELLS USE LYSOSOMES TO
DIGEST ENGULFED BACTERIA
(Phagocytosis)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
http://fig.cox.miami.edu/~cmallery/255/255ion/fig14x28.jpg
CENTRIOLES
Made of microtubules
Appear 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:
MITOCHONDRIA
• Has own DNA
• Powerplant of cell
~ site of cellular respiration
– ~ burn glucose
– ~ store energy as ATP
• Specializes in energy capture and
transformation
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
http://www.seorf.ohiou.edu/~tstork/compass.rose/photosynthesis/chloro_sun_bathing.gif
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://stallion.abac.peachnet.edu/sm/kmccrae/BIOL2050/Ch1-13/JpegArt1-13/04jpeg/04-28_chloroplasts_1.jpg
http://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
Who else has a circular chromosome not
found within a nucleus?
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Endosymbiotic Theory
http://en.wikipedia.org/wiki/Lynn_Margulis
• Originally proposed in early 1900’s
• Idea reintroduced in 1963 by Lynn Margulis
• Suggests that engulfed prokaryotes shared
symbiotic relationship with host cell
• Advantages for both:
~ one supplies energy
~ other raw materials & protection
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
ENDOSYMBIOTIC THEORY
See a movie about
ENDOSYMBIOTIC THEORY
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
http://www.mun.ca/biology/scarr/Endosymbiosis_theory.gif
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.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
http://www.stchs.org/science/courses/sbioa/metenergy/flagella.jpg
http://www.geocities.com/CollegePark/Lab/4551/fig12b.jpg
FLAGELLA & CILIA
Made of microtubules
Move substances past cells
Help move cells
http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm
http://www.sk.lung.ca/content.cfm?edit_realword=hwbreathe
WHAT’S THE DIFFERENCE?
CILIA
•
•
Many
short
Animation from: http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm
FLAGELLA
•Few
•Long
WHAT’S SPECIAL ABOUT PLANT CELLS?
• Cell wall
• HUGE vacuoles
• Chloroplasts
• No centrioles
http://www.windows.ucar.edu/kids_space/images/brick_wall.jpg
CELL WALL
Outside cell membrane
Supports and protects cell
PlantsCellulose makes it
“sturdy”
Bacteria- have
peptidoglycan instead
http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm
VACUOLES
• Huge in plants
• Storage space for water, food, enzymes, waste
•Helps with intracellular digestion with release of
cellular waste products
Image 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
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
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
WHAT’S DIFFERENT ABOUT
BACTERIAL CELLS?
• Cell wall
• NO NUCLEAR
MEMBRANE
• DNA is circular
http://www.eurekascience.com/ICanDoThat/bacteria_cells.htm
• No membrane
bound organelles
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
_________ > _____________ > ___________