Cells

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Cells

• Chapter 3
• Bio 156
• Fall 2006

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What is the Cell Theory?

• All organisms are made of cells.
• The cell is the smallest unit of life.
• New cells come from pre-existing cells.

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What are microscopes? tools used to view cells

• Compound light microscope light rays focused by
  lenses, viewed by the eye, magnifies up to 1000X

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Dissecting microscope

• For observing surface details of objects,
  magnifies up to 30X

Penny
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Electron microscopes

• For viewing details, magnifies 1,000,000X

TEM
Surface of a cell, cilia
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How are cells classified? according to their
internal organization?

• What structures do all cells have?
• Cell or plasma membranes living phospholipid
  bilayer and associated proteins

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Internal organization of cells cont..

• Plant cells also have a rigid cell wall made
  of cellulose
• Cytoplasm a semifluid gel inside the cell that
  contain cell contents

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What are Eukaryotic Cells? Have a true
nucleus, plant and animal cells

• What are organelles? "little organ", cellular
  structures that perform specific functions
• What does the nucleus do? control center of the
  cell

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What are prokaryotic cells? before" the
nucleus (bacteria)
Bacillus polymyxa

• DNA single circular DNA in a nuceloid region
• Ribosomes enzymes that synthesize proteins
• Cell membrane regulates transport in/out of the
  cell
• Cell wall for strength, may have a capsule or
  slime layer

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How does cell structure reflect cell function?

• Simple cuboidal epithelium (400x) is made up of
  one layer of cube-shaped cells.  These cells
  frequently make up the tubes of your body.

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How does cell structure reflect cell function..

• Blood Cells
• Why do you think Red Blood Cells dont have a
  nucleus and White Blood Cells do?
• (hint think about their functions)

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How does cell structure reflect cell function

• Skeletal muscle (400x) is striated
• What is the function of these cells?
• Why do you think these are long cells?

http//www.mhhe.com/biosci/ap/histology_mh/skmuscl
s.jpg
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How does cell structure reflectcell function

• Plant Cell Anacharis (Elodea) leaf cells
  (1000x). 
• What do you think is the function of these
  cells? 
• How is the function dependent on the structure?

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How does cell structure reflect cell function

• Potato cells with stained leucoplasts (100x). 
• The leucoplasts (starch storage units) have been
  stained with gram iodine (stains for starch)

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What limits cell size?

• Surface area-to-volume ratio needs to be greater
  for an exchange of materials

Microvilli some cells increase surface area by
micro-extensions called microvilli
http//distance.stcc.edu/AandP/AP/imagesAP2/digest
ion/microvilli.jpg
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What is a plasma membrane made of? (how is a
cell membrane like a house?)

• Phospholipids a. polar heads (hydrophilic or
  water soluble) b. nonpolar tails (hydrophobic
  or not water soluble)
• Cholesterol gives strength to the cell
  membrane
• Proteins transport, communication

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What is the fluid-mosaic model of the cell
membrane?

• How is it fluid? (flows, pliable) phospholipid
  bilayer
• How is it a mosaic? proteins partially or wholly
  embedded

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What are channel proteins? Space where a
substance moves across the membrane

• What are carrier proteins?
• Combine with a substance and
• help it move across the membrane

http//www.aber.ac.uk/gwydd-cym/graffeg/biolgell/c
ludiant/sianel.gif
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What are receptors? Specific shape that allows a
molecule to bind to it, ex) hormone

• What are glycoproteins? For cell to cell
  identification

http//www.emc.maricopa.edu/faculty/farabee/BIOBK/
5_11.jpg
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How are membranes selectively permeable? Allows
some molecules to pass through and not others

• What is passive transport?
• Doesn't need energy to happen, goes with
  concentration gradient
• What is diffusion? Movement of molecules from
  high to low concentration

http//www.biology.arizona.edu/cell_bio/problem_se
ts/membranes/graphics/CHANNEL.GIF
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What is osmosis? Diffusion of water into and
out of cells

• What is a solute? usually a solid
• What is a solvent? usually a liquid
• Define tonicity based on concentrations of
  solutes

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• What are isotonic solutions?
• Same concentration of solutes on either side of
  the membrane

http//www.cat.cc.md.us/courses/bio141/lecguide/un
it4/metabolism/growth/images/isotonicanim.gif
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What are hypotonic solutions?

• Low solutes in solution, water enters the cell,
  hemolysis

http//images.google.com/imgres?imgurlhttp//www.
cat.cc.md.us/courses/bio141/lecguide/unit4/metabol
ism/growth/images/hypotonicanim.gifimgrefurlhttp
//www.cat.cc.md.us/courses/bio141/lecguide/unit4/
metabolism/growth/hypotonicanim.htmlh290w362s
z357tbnidlOPoZ-_M4ysJtbnh93tbnw117hlens
tart2prev/images3Fq3Dosmosis2Banimation26sv
num3D1026hl3Den26lr3D
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What are hypertonic solutions?

• High solutes in solution, causes water to leave
  the cell (water follows salt), crenation

http//www.cat.cc.md.us/courses/bio141/lecguide/un
it4/metabolism/growth/images/hypertonicanim.gif
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What is turgor pressure? Plant cells swell in
response to a hypotonic solution
Put some wilted celery in a glass of cool water.
If it has not wilted too much, it will become
stiff again. This is because of turgor pressure
when the plant cell vacuoles become filled with
water, push against the cell walls and become
firm.
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What is facilitated transport? Carrier proteins
assist movement of specific molecules
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What is active transport? Requires ATP to move
molecules against their concentration gradient

• What is the Na-K pump?
• Concentrates more Na outside, K inside cell
  membranes

http//www.biologie.uni-hamburg.de/b-online/librar
y/biology107/bi107vc/fa99/terry/images/ATPpumA.gif
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What is Exocytosis or Endocytosis? Move
materials outside or inside the cell
http//www.stanford.edu/group/Urchin/GIFS/exocyt.g
if
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What is Phagocytosis? Cell eating, white blood
cells
http//faculty.uca.edu/johnc/leukocyto.gif
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What is Pinocytosis? Cell drinking, root
cells get water
http//images.google.com/imgres?imgurlhttp//www.
cat.cc.md.us/gkaiser/biotutorials/eustruct/images
/pinocyt.gifimgrefurlhttp//www.cat.cc.md.us/gk
aiser/biotutorials/eustruct/pinocyt.htmlh362w3
63sz55tbnid0qGkaPabQ3MJtbnh116tbnw117hl
enstart1prev/images3Fq3Dpinocytosis2Banimat
ion26svnum3D1026hl3Den26lr3D26sa3DG
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What is receptor-mediated endocytosis? Coated
proteins attract specific molecules to the cell
surface
http//srs.dl.ac.uk/VUV/home-page/hot-topics/graph
ics/uffig1.gif
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Construction of the Cell Membrane

• This is an interactive activity
• Construction of the Cell Membrane
• In this activity you will learn about the cell
  membrane structure by assembling it. Interactive
  exercise from Wisc-Online.

http//www.wisc-online.com/lrnobj/ap1/AP1101/index
.html
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How do internal structures carry out specific
functions?

• What are the structures of the nucleus?
• Nuclear membrane has nuclear pore spaces
• Nucleolus forms RNA and ribosomes
• Chromatin all of the DNA molecules

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What do ribosomes do? Assemble proteins
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What does endoplasmic reticulum (ER) do?

• Makes and transports large molecules
• Smooth ER enzymes make lipids, steroids
• Rough ER with ribosomes (RNA) have ribosomes for
  making protein

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What does the Golgi apparatus look like? Stacks
of sacules (like pancakes)

• What is its function?
• Stores and distributes products from ER
• Processes, packages and secretes
• Breaks off pieces as vesicles (small sac)

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What are Vacuoles? Large membranous sacs for
transport and storage

• What do lysosomes do?
• Digestive enzymes in vesicles
• What are Peroxisomes?
• Vesicles with enzymes that destroy toxins

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What are mitochondria? Site for aerobic
respiration, "burns food"

• Produces ATP cell's powerhouse
• Cristae inner membrane increases surface
  area for metabolism
• Matrix inner fluid-filled space

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What are chloroplasts? Organelles only found in
plant cells

• Photosynthesis use solar energy to make
  carbohydrates
• Thylakoids interconnected flattened sacs
• Grana stacks of thylakoids (granny's
  pancakes)
• Stroma syrupy fluid filled space (syrup)

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What provides cells with structure for support
and movement?

• Cytoskeleton? interconnected microtubules and
  microfilaments
• Cilia small whips, move cell, or fluids across a
  surface
• Flagella larger whip, moves cell like an oar on
  a boat

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Centrioles in animal cells for spindle fibers
during mitosis, pull chromosomes apart
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How do cells use and transform matter and energy?

• What are metabolic pathways? When one chemical
  reaction leads to another ex) A B -gt C D

• What are reactants? participate in a reaction,
  ex) A B -gt (enzyme)
• What are products? result from a reaction, ex) C
  D

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What is Anabolism?

• Building up of larger molecules, takes energy
  (endergonic)

What is Catabolism?
Breaking down into smaller molecules, gives
up energy (exergonic)
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What is ATP? A universal packet of energy used
in cells

• ATP adenosine triphosphate (Adenine-ribose-P-P-
  P)
• Exergonic the energy currency of the cell
• ATP -gt ADP P energy
• Endergonic
• ADP P energy -gt ATP

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What is cellular respiration? Chemical
reactions that produce ATP in cells

• What is glycolysis? breaks down glucose (C6) -gt 2
  pyruvate (C3) 2 ATP
• Where does it take place? in the cytoplasm, in
  all cells, no O2 needed
• How does it get started? it needs 2 P from 2 ATP
  activate glucose

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What is aerobic respiration? Respiration with
oxygen

• Where does it take place? Inside the
  mitochondria yields 36-38 ATP
• What does the Krebs cycle do? 1) pyruvate is
  broken down to O2 acetyl group (C2) -gt 2
  CO2 2 ATP 2) NAD and FAD H2 -gt NADH and
  FADH2 -gt electron transport system

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What does the electron transport system do?

• Coenzyme carriers move electrons to make 32-34 ATP

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What is fermentation? Alternative pathway of
energy when no oxygen is present

• Glycolysis first
• Alcoholic fermentation
• Glucose is broken down to pyruvate, then to
  Alcohol CO2 2 ATP
• Used for brewing, baking

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What is lactic acid fermentation?

• Glucose -gt pyruvate gt lactate 2 ATP
• Used in making yogurt,
• sour cream, cheese,
• sauerkraut
• In O2 starved muscles,
• oxygen debt
• O2 lactic acid to
• pyruvate

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Need more help?

• For extra learning practice see links on Bb under
  CH 3
• Read your test clues each night before you go to
  bed to help remember them
• For extra credit fill out review sheet (1 pt) and
  write 15 multiple choice questions and answer
  them (1 pt)