Download I. A panoramic view of the cell

UNIT II
Chapter 7
Structure and Function of the cell.
I.
A panoramic view of the cell
A. Cell is the basic functional unit of all living things. Prokaryotic & Eukaryotic
cells differ in size and complexity.
a) Prokaryotic: cells without nuclei or other membrane
Enclosed organelles Ex Bacteria Figure 7.4
b) Eukaryotic: cells with membrane enclosed nuclei and other specialized organelles
in their cytoplasm. Ex: All other organism. There are two types of Eukaryotic cells
Figure 7.7and 7.8
B. Internal Membranes compartmentalize the functions of an Eukaryotic cell.
a) Plasma Membrane separates internal metabolic events from the external enviromend
and controls the movement of materials into and out the cell. Figure 7.6
II.
The nucleus and Ribosome. Figure 7.9
a) The nucleus contains an Eukaryotic cell’s genetic library.
b) DNA is organized with proteins into chromosomes, which exist as chromatin in
nondividing cells.
c) Macromolecules pass between nucleus and cytoplasm though pores in the nuclear
envelope.
B. Ribosomes build a cell’s proteins. Figure 7.10
a) Free ribosomes in the cytosol, and boud ribosomes on the outside of the endoplasmic.
III.
The endomembrane system is the collection of membranes inside and around a
Eukaryotic cell, related either through direct physical contact or by the transfer of
membranous vesicles.
A. The endoplasmic reticulum manufactures membranes and performs many other
biosynthetic functions. Figure 7.11
a) Continous with the nuclear envelope, the endoplasmic reticulum (er) is a network
of cisternae.
b) Cristernae: Membrane enclosed compartments
c) Types of endoplasmic reticulum
1. Smooth ER: Lacks ribosomes; synthesizes steroids, metabolizes carbs.
2. Rough ER: has bound ribosomes, produces proteins
B. The Golgi Apparatus finishes, sorts, and ships cell products.
a) Stacks of separate cisternae make up the Golgi
b) Parts of Folgi Apparatus
1. CIS Face: Receives secretory Proteins from the ER in transport vessicles
2. Trans Face: Modifies, sorts and releases proteins in transport vessicles.
C. Lysosomes are digestive compartments.
a) Lysosomes are membranous sacs of hydrolytic enzimes
b) Function: Breakdown cel macromolecules for recycling. Figure 7.13
D. Vacuoles heve diverse funtions in cell maintenance.
a) a plant cell’s central vacuole functions in storage, waste diposal, cell growth, and
protection.
IV
Other membranous organelles.
a) A mitochondria and chloroplasts are the main enrgy tranformers of cells.
b) Mitochondrian: site of cellular respiration in Eukeryotes.
c) Structure: outher membrane and inner membrane folded into cristae.
Chapter 8
I.
Membrane Structure
A. Membrane models have evolved to fit new data: Science as a process. Figure 8.2
a) Current Membrane model: Fluid mosaic model.
B. A membrane is a fluid mosaic of lipids, proteins, and carbohydrates.
a) Integral proteins are embedded in the lipd bilayer.
b) Peripheral proteins are attached to the surface.
c) The incide and Outside membrane Faces differ in composition.
d) Carbohydrates linked to proteins and lipids in the plasma membrane are important
for cell- cell recognition. Figure 8.5
II.
Traffic across membranes
A. A membrane’s molecular organization results in selective permeability
a) A cell must exchange small momecules and ions with its surrounding, a process
controlled by the plasma membrane.
b) Hydrophobic substances are soluble in lipd and pass through membrane rapidly.
c) Small polar molecules such as H2O also pass through the membrane.
d) Larger polar meloculaes and ions require specific transport proteins to help them
across.
B. Passive transport is diffusion across a membrane.
a) Diffusion: The spontaneous movement of a substance down its concentration
gradient.
Figure 8.8
C. Osmosis is the passive transport of water. Figure 8.9
a) Water flows across a membrane from the side where soute is less concentrated
(hypotonic) to the side where solute is more concentrated (hypertonic).
b) If the concentrations are equal (isotonic), no net osmosis occurs.
D. Cell survival depends on balancingwater uptake and loss.
a) Cells lacking cell walls (as in animals) are isotonic with their enviroments or have
adaptations for osmoregulations. Figure 8.10
E. Specific proteins facilitate the passive transport of selected solutes.
a) In facilitated diffusion, a transport protein speeds movement of a solute across a
membrane down its concentrationgradient. Figure 8.12
F. Active transport is the pumping of soutes against their gradients. Figure 8.14
a) Specific membrane proteins use energy, usually in the form of ATP, to do this
work.
G. Some ion pumps generate voltage across membranes. Figure 8.13
a) Ions can have both a concentration (chemical) gradient and an electric gradient
(voltage).
b) These forces combine in the electrochemicla grasient, wich determines the net
direction of ionic diffution.
c) Electrognic pumps, such as sodiupot assium pums and proton pumps, are
transport proteins that contibute to electrochemical gradients.
H. In cotrantsport, a membrane protein couples the transport of one solute to
another. Figure 8.16.
a) One solutes “downhill” diffution drives the others “uphill” transport.
I.
Exocytosis and endocytosis transport large molecules. Figure 8.17.
a) Exocytosis: Transport vesicles migrate to the plasma membrane, fuse with it, and
realeses their contents.
b) Endocytosis: Large molecules enter cells within vesicles pinched inward from the
plasma membrane.
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Phagocytosis
Pinocytosis
Receptor-mediated endocytosis
Chapter 12
The cell cycle overview
I.
The key roles of the cell division.
A. Cell division functions in reproduction, growth, and repair.
a) Uncellular organismreproduce bye the cell division.
b) Multicellular organisms depend on it for development from a fertelized egg, growth and
repair.
B. Cell division distributes identical sets of chromosomes to daughter cells.
a) Eukaryotic cell divition consists of:
-
III.
The mitoic cell cycle. Figure 5.2 of the cliff’s notes.
a)
b)
c)
d)
IV.
Mitosis * (Division of the nucleus)
Cytokinesis * ( Division of the cytoplasm)
The mitoic phase alternates with interphase in the cell cycle: An overview
Mitosis and cytoknesis make up the m (mitotic) phase of the cell cycle.
Between divisions, cells are in interphase: the G1, S, and G2 phases.
The cell grows throughout intrphase, but DNA is replicated only during the S
(synthesis) phase
Process of the Mitosis. Figure 12.6
a) Prophase
In prophase, three activities occur simultaneously. First, the nucleoi disappear and the
chromantin condences into chromosomes. Scond, the nuclear envelope bracksdown.
Third, the mitotic spindle is assembled.
b) Metaphase
Begins when the chromosomes are distribute across the mataphase plate, a plane
lying between the two poles of the spindle. Metaphase ends when the microtubles, still
attached to the kinetochores, pull each chromosomes apart into two chromatids.
b) Anaphase
Begins after the chromosomes are separated into chromatids. During anaphase, the
microtubles connecte to the chromatids (now chromosomes) shorten, effesctively
pulling the chromosomes to opposite poles.
c) Telophase
Concluedes the nuclear division. During this phase, a nuclear enveloped develops
around each pole, forming two nuclei. The chromosomes within each of these nuleic
disperse into chromatin, and the nucleolireppear. Simultaneously, cytokinesis occurs,
dividing the cytoplasm into two cells.
V.
The metotic spindle distributes chromosomes to daughter cells
a) The mitotic spindle is an apparatus of microtubles that controls chromosome
movement during mitosis.
b) The spindle arises from the centrosomes (regions near the nucleous associated with
centrioles in animal cells)
c) Spincle microtubules attachto the metaphase plate.
d) Anaphase: sister chromatidsseparete and move toward opposite poles of the cell.
e) Telophase: Daughter nuclei from at opposite ends of the cell.
VI
Regulation of the cell cycle
a) A molecular control system drives the cell cycle.
 Cyclical change in regulatory proteins work as mitotic clock.
VII
Cancer cells have escaped from cell-cycle controls
a) Cancer Cells: Elude normal regulation and divide out of control, forming tumors.
Malignant Tumors invade surrounding tissues and can metastasize, exporting cance cell to ather
part of the body.