Cellular Structures & Functions. CYTOPLASM (Between nucleus and cell membrane) Includes ORGANELLES- small structures with a specific function CYTOSOL-semi-fluid

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)


ENDOMEMBRANE SYSTEMRegulates protein traffic and performs

metabolic functions in the cell

Includes:Plasma membraneNuclear membraneEndoplasmic reticulumGolgi apparatusVacuolesLysosomes


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


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


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


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


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:


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



Who else has a circular chromosome notfound within a nucleus?


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


ENDOSYMBIOTIC THEORY

http://www.mun.ca/biology/scarr/Endosymbiosis_theory.gif

See a movie about ENDOSYMBIOTIC THEORY


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


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



WHICH IS BIGGER?

_________ > _____________ > ___________Plant cell Animal cell bacteria

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Cellular Structures & Functions. CYTOPLASM (Between nucleus and cell membrane) Includes ORGANELLES- small structures with a specific function CYTOSOL-semi-fluid