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Key Concepts:
- Cells are the Basic Unit of Life
Cell Theory, Surface to Volume
- 2 Cell Types
Prokaryotic, Eukaryotic
- Cell Membrane
Membrane Structure
- Cell Organelles
Fertilization of a
human _____ cell
Endomembrane system, *Chloroplasts, *Mitochondria *Learn these from text/connect1 Microinjection of stem cells into mouse fertilized egg.
(Chronicle photo by Chris Stewart, 2002)
1!
Microscopes Reveal the World of Cells
 The
Cell theory
– All
living things are made of
cells
– All
cells come from ‘parent’
cells
 Why
are cells so small?
– Most
cells are bt. 1-100 um
(micrometers)
The size range of cells
and related objects
2!
Small Cell Size => Efficient Exchange
 Small
cell has more
surface area relative
to volume
Which shape has more!
Surface area to Volume?!
 High
surface to
volume ratio
increases rates of
exchange
— substances
moving
across the cell
membrane
3!
Clicker Question #1!
Which cell shape has the highest ratio of
surface area to volume?!
A.!
B.!
C.!
D.!
!
© 1996 PhotoDisc, Inc./Getty Images/RF
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.!
4!
The 3 Domains of Life Have 2 Cell Types
What are the names of the 2 cell types?
5!
Prokaryotic cells
6!
Eukaryotic cells
 All
cells have a plasma membrane, 1 or more
chromosomes, cytoplasm, and ribosomes
 Prokaryotes
do not have a ___________, instead
they have a nucleoid
 Eukaryotic
cells have a membrane-bound
nucleus, and other organelles
7!
The Anatomy of an Animal Cell
8!
The Anatomy of a Plant Cell
Plant cells are
also eukaryotic,
but note the cell
wall and
chloroplasts.
9!
3.2 Mastering Concepts
In what two ways do
prokaryotic cells differ
from eukaryotic cells?
10!
A Membrane Surrounds Each Cell
 Composed
of
A phospholipid bilayer,
– Have embedded and attached proteins
– Commonly described as a fluid mosaic
– The plasma membrane of an animal cell
11!
 Cell
membranes are
composed of
molecules called
phospholipids !
 A phospholipid
has
two regions:!
- Hydrophilic head:
(polar bonds)
attracted to water!
- Hydrophobic tails:
(nonpolar bonds)
repel water!
12!
Because of their chemical structure, phospholipids
spontaneously form bilayers in water.
13!
Membrane video: <http://www.youtube.com/watch?
v=Rl5EmUQdkuI&feature=related>
14!
Clicker Question #3!
Cholesterol is a molecule in animal cell
membranes. Since cholesterol is
hydrophobic, where is it most likely to
occur?!
A. region X!
B. region Y!
15!
3.3 Mastering Concepts!
How does the chemical
structure of phospholipids
enable them to form a
bilayer in water? !
16!
Eukaryotic Organelles Divide Labor
 Membranes
– w/in eukaryotic cells form compartments
Each compartment maintains conditions that favor particular
metabolic processes
 Organelles
(& other cell structures) perform 4 basic
functions
– Genetic control of cell (Which organelle does this?)
– Manufacture, distribution and breakdown of molecules
– Energy processing
– Structural support, movement, and communication bt. cells
17!
The Endomembrane System
 Endomembrane
system = a collection
of internal membranes
– work
together in
synthesis, storage, &
export of molecules
 Some
are physically connected, some are
functionally connected by tiny vesicles
What is meant by “functionally connected”?!
18!
Endoplasmic Reticulum – A Molecular Factory
 2
kinds of ER
– Smooth
ER
– Rough ER
Nuclear!
envelope!
Ribosomes!
Smooth ER!
Rough ER!
19!
 Smooth
ER – no attached ribosomes. Involved in
a variety of metabolic processes
– synthesis of lipids, oils, phospholipids, and steroids
– In liver cells, enzymes from smooth ER break down
alcohol and drugs
 Rough
ER – attached _____________, makes
membrane for itself and proteins destined for
secretion
– Once proteins are made, transported in tiny
___________ to other parts of the endomembrane
system
20!
Transport vesicle!
buds off!
4!
Ribosome!
Secretory!
protein!
inside trans-!
port vesicle!
3!
Sugar!
chain!
1!
2! Glycoprotein!
Polypeptide!
Rough ER!
21!
Golgi Apparatus Finishes & Ships Products
 The
Golgi apparatus functions in conjunction
with the ER by modifying products of the ER
– Products
travel in transport vesicles from ER
to Golgi
– One
side of Golgi functions as a receiving dock
and the other as a ___________ dock
– Products are modified as they go from one side to
the other
– Products “shipped” in vesicles to other sites
22!
“Receiving” side of!
Golgi apparatus!
Golgi !
apparatus!
Golgi apparatus!
Transport!
vesicle!
from ER!
New vesicle!
forming!
“Shipping” side!
of Golgi apparatus!
Transport!
vesicle from!
the Golgi!
23!
Lysosomes = Garbage Disposal of Cells
 Lysosomes
= sacs of
digestive enzymes
budded off of the Golgi
Rough ER
1
Plasma
membrane
 They
digest food
particles engulfed by cell
– The enzymes & membrane
are produced by ______ ___
and transferred to Golgi for
processing
Transport vesicle
(containing inactive
hydrolytic enzymes)
Golgi
apparatus
Engulfment
of particle
Food”
Lysosome
engulfing
damaged
organelle
2
Lysosomes
3
5
Food
vacuole
4
Digestion
Lysosomes in a white blood cell
24!
Review of Endomembrane System
 The
organelles of the endomembrane system are
interconnected structurally and _____________
Transport vesicle
Rough ER from ER to Golgi
Transport vesicle from
Golgi to plasma membrane
Plasma
membrane
Nucleus
Vacuole
Lysosome
Smooth ER
Nuclear envelope Golgi apparatus
Connections among the organelles of the endomembrane system
25!
Mitochondria – Power House of Cells
 Cellular
respiration occurs
inside mitochondria
– Mitochondrion
Cellular respiration =
converts energy in food to ATP
(adenosine triphosphate) energy Intermembrane
space
Outer
membrane
✶ Double
Inner
membrane
membrane
Cristae
— Inner
membrane highly folded
TEM 44,880×
C6H12O6 + 6O2 – 6CO2 + 6H2O
Matrix
Figure 4.15
What does the increased folding do to surface area?!
26!
Chloroplasts Convert Sunlight to Sugar
 Chloroplasts
– organelles of plant cells, contain a
green colored pigment = _______________
– Photosynthesis = the conversion of _______ energy to
chemical energy (produces sugar molecules)
 Double
 Inside
membrane
are stacks of membranes = granum
Chloroplast
Stroma
Inner and outer
membranes
Granum
Figure 4.14 The chloroplast
Intermembrane
space
27!
Endosymbiosis – The Origin of
Mitochondria & Chloroplasts
 Endosymbiont
theory = mitochondria & chloroplasts
evolved from small prokaryotes that began living w/in
larger host cells
– Symbiosis benefited both symbiont and host cells
 Evidence
that supports theory
– Mitos & chloros have their own unique DNA and ribosomes
– DNA and ribosomes very similar to prokaryotic cells
– Mitos & chloros replicate like prokaryotic cells
How is a theory different from a hypothesis?!
28!
Mitochondrion!
Engulfing of!
photosynthetic!
prokaryote!
Some!
cells!
Engulfing !
of aerobic!
prokaryote!
Chloroplast!
Host cell!
Mitochondrion!
Host cell!
29!
 Membranes
are selectively permeable
– Not all molecules can cross the cell membrane
– Small non-polar molecules (carbon dioxide and oxygen)
diffuse freely
– Polar molecules (water, glucose and other sugars), ions,
and large molecules can not diffuse through membrane
 Transport
proteins allow molecules that can not
diffuse to enter and leave a cell
30!
Ribosomes Build Cell Proteins
 Ribosomes
- involved in protein synthesis
– Cells
that synthesize lg. amounts of protein
have a lg. # of ribosomes
 Some
ribosomes are free; others are bound
– Free ribosomes are suspended in the cytoplasm
– Bound ribosomes are attached to the endoplasmic
reticulum (ER)
What cells in your body might produce lots of protein?!
31!
Ribosomes!
ER!
Cytoplasm!
Endoplasmic reticulum (ER)!
Free ribosomes!
Bound ribosomes!
Large!
subunit!
TEM showing ER!
and ribosomes!
Small!
subunit!
Diagram of !
a ribosome!
32!