Cell Introduction
4.1
History
 Robert Hooke, in mid-1600’s, coined the phrase ‘cell’ after
looking at cork b/c it looked like a monk’s room.
 Anton van Leeuwenhoek saw inside the cell.
cell theory:
 All living things are made of cells
 Cells are the basic unit of structure & function of
organisms
 Cells come from other cells
SIZE
 average plant/animal is 10 to 50 µm (micrometer =
0.0000001 or 10-6)
 all nutrients enter the cell thru its surface
 Greater surface area allows in more nutrients (potato demo)
 As cell grows, its volume inc more rapidly than surface so,
eventually it doesn’t get enough nutrients quickly enough to
meet it’s needs
SHAPE
 is related to function
e.g. Blood cell changes shape: allows it to move thru narrow
openings to isolate, engulf & destroy bacteria
Cell membrane
 surrounds the cell
 Regulates movement in/out of cell
http://sun.menloschool.org/~cweaver/cells/c/cell_membrane/
Note:
 Extracellular fluid – outside of
cell
 Cytoplasm –
inside of cell
Both are
watery
(aqueous)
environments
(review)
 Organelles – cell parts that perform a specific function
 Nucleus – lg, near ctr, has genetic info & directs activities
 Eukaryotes – (eu = true; kary = nucleus) contains membrane bound
nucleus & organelles
e.g. animals & plants
 Prokaryotes – (pro = before; kary = nucleus) no membrane around
nucleus or organelles
e.g. bacterium
Prokaryote
Eukaryote
Found only in bacteria &
archaebacteria: unicellular
Found in the Kingdoms:
protista, fungi, plantae, &
animalia
No true nucleus; lacks
nuclear envelope
True nucleus; bound by
nuclear envelope
Genetic material in nucleoid Genetic material w/in
region
nucleus
No membrane-bound
organelles
Contains cytoplasm with
cytosol and membranebound organelles
Prokaryote
Eukaryote
Parts of the Eukaryotic Cell
4.2
 Membrane – regulates movement in/out of cell -
Selectively permeable or semi-permeable
Made of lipids & proteins
Lipid bilayer
 (bi means 2) Arrangement in membrane facing
outside/inside of cell

(remember - Phospholipid – head is polar/tail is
nonpolar -- See fig. 4-5 on pg.74)
 phospholipid – heads outward facing water environment
so water can come in hydrating the cell while tails
inward, keeping water inside
 steroids – between phospholipids – cholesterol in animal
cells
 (see picture of bi-layer)
Peripheral proteins – located on the edge of bilayer membrane
Integral proteins – embedded in bilayer
Both used for transporting molecules thru layer
Fluid mosaic model
 membrane is dynamic
 acts like fluid
 lipids & proteins move laterally
 view short animations on membrane:
http://telstar.ote.cmu.edu/Hughes/tutorial/cellmembrane
s/
ORGANELLES
 Animal & Plant model -
http://www.cellsalive.com/cells/cell_model.htm
 Cytoplasm – area between membrane & nucleus
 Cytosol – gelatin, aqueous fluid within cytoplasm
Mitochondria
 (mitos = thread; chondrion = grain) “POWERHOUSE”
 large organelle where chemical reactions that transfer
energy from organic compounds to produce ATP (molecule
used by cells as main energy source)
 Number in cell varies – related to function of cell e.g. liver
needs more b/c needs more energy
 Moves within cell
 Cellular respiration occurs here
 Contains enzymes to catalyze chemical reactions
 mtDNA (mitochondrial DNA)– grow & divide to produce
new mitochondria
 Smooth outer membrane – lipid bilayer – permeable to
small solutes; blocks macromolecules
 Cristae – inner membrane w/folds to enlarge surface area for
chemical reactions to take place (cell respiration)
New Theory
 – mitochondria developed because as a prokaryote it gained
protection by living inside the eukaryote and in turn
produced energy for the eukaryote (symbiotic relationship)
Ribosomes
 site for protein synthesis –
“PROTEIN FACTORY”
 constructed in nucleolus
 assemblage of protein & RNA (ribonucleic acid)
 most numerous
 not surrounded by membrane (found in prokaryotic cells too)
 free/loose in cytosol or attached to endoplasmic reticulum
(ER)
Ribosomes manufacture proteins based on messenger RNA
(mRNA) instructions. Each ribosome reads mRNA, recruits
transfer RNA (tRNA) molecules to fetch amino acids, and
assembles the amino acids in the proper order.
endoplasmic reticulum(ER)
 “INTRACELLULAR HIGHWAY” – path along which
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molecules move w/in the cell
rough ER – has ribosomes
smooth ER – no ribosomes
synthesis of steroids
regulate calcium level in muscle cells
breakdown toxic substance by liver cells
Golgi apparatus – “Post Office” – processing, packaging &
secreting organelle
- Modifies proteins for export
Lysosomes
 “THE CUSTODIAN”
 sm hydrolytic enzymes w/in membranes
 Acidic enviro
 digest proteins, carbohydrates, lipids, DNA, & RNA, even
bacteria
 Rare in plant cells
Remeber that hydrolysis breaks down the water molecule and separates a
polymer into monomers, thus hydrolytic means to make eliminate water, then it
becomes acidic
Cytoskeleton
 network of lonG protein strands in cytosol to maintain shape
 Microfilaments – small strands
Actin – protein molecules linked to form polymer chain
 Microtubules – lg tubes
 Spindle fibers – assist in the movement of chromosomes during cell
division
 Cilia – many short hairlike extensions fr surface assist in
movement
- Line respiratory tract to trap particles in air
e.g. nose hair
 Flagella – few or single long extension
- e.g. sperm
 Nuclear matrix – gives nucleus its shape
 Nuclear envelope – double membrane surrounds nucleus
 Chromatin – combination of DNA & protein
 Chromosomes – formed when chromatins pack together
before cellular division
 Nuclear pores – sm holes in nuclear envelope that allow RNA
to travel to cytosol for protein synthesis
 Nucleolus – ribosomes are synthesized
PLANT CELLS
 Cell wall – rigid, support & protect plant
Cellulose fiber embedded
 Vacuoles – fluid-filled; store enzymes & metabolic wastes
 Plastids – contain DNA surrounded by 2 membranes
 Store starch/fats
 Absorb visible light – pigments
 Chloroplast – site where photosynthesis takes place
 Thylakoids – membranous sacs contains chlorophyll
Difference btw animal & plant cells
 Plants have & we don’t:
 cell wall
 Vacuoles
 Plastids (where photosynthesis takes place)
Activities
 cell biology -
http://www.cellsalive.com/cells/cell_model.htm
 cell biology worksheet needed
 cell biology quiz http://www.biologycorner.com/bio1/cellquiz.html
Multicellular Organization
4.3
Organization
 Tissues – organized groups of cells that carry out specific
functions
E.g. skin, muscle
 Organ – several types of tissues that interatct to perform a
specific function
E.g. stomach, liver, heart
 Organ system – group of organs that work together to
perform a set of related tasks
e.g. digestive system, respiratory system
 Colonial organisms – collection of genetically identical cells
that live close together
E.g. volvox
Organization review from
least to greatest:
 Cell > tissue > organ > organ system
References
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http://micro.magnet.fsu.edu/cells/animals/images/animalcell.jpg
http://www.cartage.org.lb/en/themes/sciences/zoology/AnimalPhysiology/Anatomy/AnimalCellStru
cture/Mitochondria/mitochondria.jpg
http://images.google.com/imgres?imgurl=http://publications.nigms.nih.gov/insidethecell/images/ch2
_ribosome_proteinbig.jpg&imgrefurl=http://publications.nigms.nih.gov/insidethecell/chapter2.html&h
=274&w=284&sz=35&hl=en&start=10&um=1&tbnid=pGsv2UDZt4F_6M:&tbnh=110&tbnw=114&
prev=/images%3Fq%3Dribosome%26svnum%3D10%26um%3D1%26hl%3Den%26rlz%3D1T4GGIC
_enUS233US233%26sa%3DN
http://images.google.com/imgres?imgurl=http://computer.act.ac.th/webproject5_2548/st/m53/divi
sion/Endoplasmic%2520reticulum.jpg&imgrefurl=http://computer.act.ac.th/webproject5_2548/st/m
53/division/menu.html&h=286&w=402&sz=44&tbnid=nCYKX9rqWjAVoM:&tbnh=88&tbnw=124&
prev=/images%3Fq%3Dendoplasmic%2Breticulum%26um%3D1&start=1&sa=X&oi=images&ct=imag
e&cd=1
http://library.thinkquest.org/C004535/endoplasmic_reticulum.html
http://library.thinkquest.org/C004535/golgi_apparatus.html
http://microscopy.fsu.edu/cells/lysosomes/images/lysosomesfigure1.jpg