Cells

Chapter 7

• Cell consists of nucleus and cytoplasm.

• In cytoplasm - organelles (“little organs”)

• Cell membrane – boundary of cell.

• Membrane thin but selectively permeable (allows certain materials to pass through but not others).

http://www.geosciences.unl.edu/~dbennett/images/Cell_membrane.gif

• Membrane has receptors that help receive messages (i.e. hormones)

• Called phospholipid bilayer (composed of phospholipids); also various proteins in membrane.

http://en.wikipedia.org/wiki/Cell_membrane

• 1Endoplasmic Reticulum – increased surface area for reactions to take place.

• ARough ER – Makes proteins (holds ribosomes)

• BSmooth ER – Makes lipids.

http://micro.magnet.fsu.edu/cells/endoplasmicreticulum/images/endoplasmicreticulumfigure1.jpg

• 2Ribosomes – some attached to rough ER (bound); some scattered throughout cytoplasm (free).

• Function - protein synthesis.

http://www.brown.edu/Courses/BI0105_Miller/read/ribosomes/ribosomes.jpg

• 3Golgi apparatus – proteins modified and packaged, then sent into cytoplasm.

http://web.mit.edu/esgbio/www/cb/org/golgi.gif

Modified protein

• 4Mitochondria – cellular respiration.

• Transform glucose into form of energy cell can use.

http://micro.magnet.fsu.edu/cells/mitochondria/images/mitochondriafigure1.jpg

• 5Lysosomes – contain enzymes that break down molecules of foreign particles (“garbage cans” of cell)

http://micro.magnet.fsu.edu/cells/lysosomes/images/lysosomesfigure1.jpg

• 6Centrosome – consists of 2 hollow cylinders (centrioles) - function in reproduction by separating chromosomes to new cells.

http://www.nicerweb.com/doc/class/bio1151/Locked/media/ch06/06_22CentrosomeStructur.jpg

• 7Cilia and 8flagella – extensions of cells; used for cell movement.

• Flagella - longer and fewer.• Cilia - smaller and more

numerous.

http://pediatrics.med.unc.edu/div/infectdi/pcd/images/cilia.jpg

Respiratory cilia

http://discover.edventures.com/images/termlib/f/flagella/support.gif

• 9Vacuoles – vesicles found in cell that have various functions.

• AFood vacuole – breakdown of food.

• BCentral vacuole – storage of waste.

• CContractile vacuole – removal of water (osmoregulation).

http://micro.magnet.fsu.edu/cells/plants/images/plantvacuolesfigure1.jpg

• 10Microfilaments and microtubules – responsible for movement within cell (also responsible for structure)

http://www.puc.edu/Faculty/Gilbert_Muth/art0053.jpg

• 11Nucleus – center of cell.• Covered by nuclear envelope

with pores to allow substances to pass through.

• Contains 12nucleolus (ribosome production) and chromatin (loose DNA).

http://micro.magnet.fsu.edu/cells/nucleus/images/nucleusfigure1.jpg

Movement through cells

• Passive does not require energy.• 4 passive movements (diffusion,

facilitated diffusion, osmosis, filtration).

• 1Diffusion – molecules or ions spread randomly from area of high concentration to area of low.

http://epswww.unm.edu/coursinf/eps462/graphics/diffusion.gif

• Particles will move until equilibrium reached (both sides equal).

• Happens in lungs; O2, CO2 move by diffusion to be exchanged with air.

• 2Facilitated diffusion - substance too large to cross cell membrane.

• Special protein carrier allows substance to pass through membrane.

http://w3.uokhsc.edu/human_physiology/presentation/facildiffani.gif

• 3Osmosis - movement of water only from area of high to low.

• If substance has higher [ ] of solute - hypertonic.

• If lower [ ] - hypotonic.• Isotonic means they are even.

http://www.biologycorner.com/resources/hypertonic.gif

http://www.biologycorner.com/resources/hypotonic.gif

http://www.biologycorner.com/resources/isotonic.gif

• Filtration –molecules forced through membranes (result of blood pressure)

• Active movement – requires energy.

• Active transport – movement from area of low [ ] to high [ ].

• Requires pumps (a.k.a carrier molecules) to cross membrane.

http://www.sp.uconn.edu/~terry/images/anim/antiport.gif

• 2 processes – no crossing membrane.

• 1Endocytosis – substances fuse with membrane, brought into cell.

• 2Exocytosis – substances move out of cell (2 types).

• APinocytosis – cell lets out small droplets of liquid.

• BPhagocytosis – cell lets out solids.

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/endocytosis.gif

http://www.biologie.uni-hamburg.de/b-online/library/biology107/bi107vc/fa99/terry/images/PhagoAnA.gif

http://www.sirinet.net/~jgjohnso/endocytosissmall.jpg

Cell Cycle

• Life cycle of cell - cell cycle.• Interphase is the first part of the

cell cycle.• It is the period of preparing for

cell division.• Mitosis is the division of the

nucleus and is divided into four phases.

http://www.bioteach.ubc.ca/CellBiology/TheCellCycle/cellcycle.gif

• Prophase - The chromosomes appear in nucleus from chromatin. Centrioles move to opposite sides of the nucleus.

• Metaphase - The newly formed chromosomes line up midway between the centrioles and attach spindle fibers to the centrioles.

Prophase

http://sst.nsu.edu/bio110/exams/Prophase_Quiz.jpg

http://everyschool.org/u/logan/cellreproductionx/jonesc/pictures/metaphase.jpg

• Anaphase - The chromosomes begin to separate into chromatids.

• Telophase - The chromatids are now separate in their new cells.

http://www.biologycorner.com/resources/anaphase.jpg

Anaphase

http://iws.ccccd.edu/jbeck/CellDivision%20web/Telophase.JPG

Telophase

• After the nucleus has divided, cytokinesis (division of the cytoplasm) occurs.

• This is the last phase of the cell cycle.

• The two cells are now completely separated.

This will breakand the cellswill be separated.

http://img.sparknotes.com/figures/D/d756b5b73abe2974f3521a828791899f/cytokinesis.gif

• Cell differentiation occurs to allow cells to become specialized.