Transcript BIO 156 CH 3 Cells

Cells
Chapter 3
Bio 156
Fall 2006
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.
What are microscopes?
tools used to view cells
•
Compound light
microscope: light rays
focused by lenses, viewed by
the eye, magnifies up to
1000X
Dissecting microscope:

For observing
surface details of
objects, magnifies
up to 30X
Penny
Electron microscopes

For viewing
details, magnifies
1,000,000X
Surface of a cell, cilia
TEM
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
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
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
What are prokaryotic cells?
“before" the nucleus (bacteria)
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
Bacillus polymyxa
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.
How does cell structure reflect cell function…..



Blood Cells
Why do you think Red Blood Cells don’t
have a nucleus and White Blood Cells do?
(hint: think about their functions)
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/skmuscls.jpg
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?
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)
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 microextensions called
microvilli
http://distance.stcc.edu/AandP/AP/imagesAP2/digestion/microvilli.jpg
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
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
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/cludiant/sianel.gif
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
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_sets/membranes/graphics/CHANNEL.GIF
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
What are isotonic solutions?
Same concentration of solutes on either side of the
membrane
http://www.cat.cc.md.us/courses/bio141/lecguide/unit4/metabolism/growth/images/isotonicanim.gif
What are hypotonic solutions?

Low solutes in solution, water enters the cell,
hemolysis
http://images.google.com/imgres?imgurl=http://www.cat.cc.md.us/courses/bio141/lecguide/unit4/metabolism/growth/images/hypotonicanim.gif&imgrefurl=http://www.cat.cc.md.us/course
s/bio141/lecguide/unit4/metabolism/growth/hypotonicanim.html&h=290&w=362&sz=357&tbnid=lOPoZ_M4ysJ:&tbnh=93&tbnw=117&hl=en&start=2&prev=/images%3Fq%3Dosmosis%2Banimation%26svnum%3D10%26hl%3Den%26lr%3D
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/unit4/metabolism/growth/images/hypertonicanim.gif
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.
What is facilitated transport?
Carrier proteins assist movement of specific
molecules
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/library/biology107/bi107vc/fa99/terry/images/ATPpumA.gif
What is Exocytosis or Endocytosis?
Move materials outside or inside the cell
http://www.stanford.edu/group/Urchin/GIFS/exocyt.gif
What is Phagocytosis?
“Cell eating”, white blood cells
http://faculty.uca.edu/~johnc/leukocyto.gif
What is Pinocytosis?
“Cell drinking”, root cells get water
http://images.google.com/imgres?imgurl=http://www.cat.cc.md.us/~gkaiser/biotutorials/eustruct/images/pinocyt.gif&imgrefurl=http://www.cat.cc.md.us/~gkaiser/biotutorials/eustruct/pi
nocyt.html&h=362&w=363&sz=55&tbnid=0qGkaPabQ3MJ:&tbnh=116&tbnw=117&hl=en&start=1&prev=/images%3Fq%3Dpinocytosis%2Banimation%26svnum%3D10%26hl%3Den%26lr%3D%2
6sa%3DG
What is receptor-mediated endocytosis?
Coated proteins attract specific molecules to the cell
surface
http://srs.dl.ac.uk/VUV/home-page/hot-topics/graphics/uffig1.gif
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
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
What do ribosomes do?
Assemble proteins
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
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)
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
What are mitochondria?
Site for aerobic respiration, "burns food"



Produces ATP
“cell's powerhouse”
Cristae: inner
membrane increases
surface area for
metabolism
Matrix: inner fluidfilled space
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)
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

Centrioles in animal cells for spindle fibers
during mitosis, pull chromosomes apart
How do cells use and transform matter and
energy?
•What are metabolic pathways?
When one chemical reaction leads to another
ex) A + B -> C + D
•
What are reactants?
participate in a reaction,
ex) A + B -> (enzyme)
•
What are products?
result from a reaction,
ex) C + D
What is Anabolism?
Building up of larger molecules,
takes energy (endergonic)
What is Catabolism?
Breaking down into smaller
molecules, gives up energy
(exergonic)
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 -> ADP + P + energy
Endergonic:

ADP + P + energy -> ATP
What is cellular respiration?
Chemical reactions that produce ATP in cells
•
What is glycolysis? breaks
down glucose (C6) -> 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
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) ->
2 CO2 + 2 ATP
2) NAD+ and FAD + H2 ->
NADH and FADH2 ->
electron transport system
What does the electron transport system do?

Coenzyme carriers
move electrons to
make 32-34 ATP
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
What is lactic acid fermentation?

•
•
Glucose -> pyruvate –> lactate + 2 ATP
Used in making yogurt,
sour cream, cheese,
sauerkraut
In O2 starved muscles,
oxygen debt:
O2 + lactic acid to
pyruvate
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)