Need a report/project with all the stuff asked in the instructions that in the attachment. power points with minimal essential description would be ok. Than you in advance
Scoring Rubric for Oral Presentations
Poor
PRESENTATION SKILLS
1
The main ideas are presented in a clear and organized manner. …………………………….. ,
The presentation fills the allotted time (20 minutes, 5 for questions) ……………………. ,
The presentation slides were well designed ………………………………………………………. ,
The presenters knew the material and did not read off of the slides/notes ……………… ,
The presentation had a theme or take-home message …………………………………………. ,
The presenter clearly and knowledgably addressed audience questions ………………… ,
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3
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Excellent
4 5
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KNOWLEDGE BASE
A proper background was given for the material ………………………………………………… ,
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Appropriate papers were chosen to supplement the “classic” paper ………………………. ,
The presentation provided a clear historical background for the research………………. ,
Irrelevant or filler material was excluded ………………………………………………………….. ,
A citation page with relevant and scholarly citations was provided ……………………… ,
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CRITICAL THINKING
Main issues in the area are clearly identified …………………………………………………….. ,
Both the theoretical positions and empirical evidence were presented ………………….. ,
The strengths and weaknesses of these theories, and the methods used to …………….. ,
gather this evidence were adequately explained
Recommendations were made for further work in this area …………………………………. ,
Information and papers presented were sufficiently related to embryology …………… ,
Competing explanations or theories were considered ………………………………………….. ,
OVERALL IMPRESSION ………………………………………………………………………………………….. _______ / 15
COMMENTS
TOTAL SCORE _______ / 100
© 1961 SCIENTIFIC AMERICAN, INC
Established 1845
SCIENTIFIC
.AME RI CAN”
September 1961
Number 3
Volume 205
The Living Cell
Presenting an lssue on the fundalnental particle of l�fe. Anat01nical
and chendcal views of the cell have now converged to show that it is
not
a
droplet of protoplasln but
by
he living cell is the fundamental
ell1it of which all living organisms
are made. To a reader who finds
this a commonplace, it lllay come as a
surprise that the recognition of the cell
dates back only a little more than 100
years. The botanist Matthias Jakob
Schleiden and the zoologist Theodor
Schwann first propounded thc cell
theon’ in 1839 out of their parallel and
independent studies of the tissues of
plants and animals. Not long after, in
1859, Rudolf Virchow confirmed the
cell’s unique role as the vessel of “living
matter” when he showed that all cells
necessarilv derive from pre-existing
cells: o111nis cellula e cellula. Since cells
are concrete objects and can easily be
observed, the experimental investigation
of cells thereafter displaced philosophi
cal speculations about the problem of
“life” and the uncertain scientific studies
that had pursued such vague concepts
as “protoplaslll.”
In the century that followed investiga-
T
a
highly organized molecular factory
Jean
I3rachet
tors of the cell approached their subject
from two fundamentally different direc
tions. Cell biologists, equipped with in
creaSingly powerful microscopes, pro
ceeded to develop the microscopic and
submicroscopic anatomy of the intact
cell. Beginning with a picture of the cell
as a structure composed of an external
membrane, a jelly-like blob of material
called cytoplasm and a central nucleus,
they have shown that this structure is
richly differentiated into organelles
adapted to carry on the diverse processes
of life. With the aid of the electron
microscope they have begun to discern
the molecular working parts of thc sys
tem. Here, in recent years, their work
has converged with that of the biochem
ists, whose studies begin with the ruth
less disruption of the delicate structure
of the cell. By observing the chemical
activity of materials collected in this way,
biochemists have traced some of the
pathwavs by which the cel! carries out
the biochemical reactions that underlie
NUCLEUS OF THE LIVING CELL is the large round object in the center of the electron
miel’ogl’aph on the opposite page. The Inembrane around the nucleus is interrupted by
pores through which the nucleus possibly communicates with the surrounding cytoplasm.
The smaller round objects in the cytoplasm are mitochondria; the long, thin structures are
the endoplasmic reticulum; the dark dots lining the reticulum are ribosomes. Actually the
micrograph shows not a living cell but a dead cell: the cell has been fixed with a compound
of the heavy metal osmium, immersed in a liquid plastic that is then made to solidify and
finally sliced with a glass knife. The electron beam of the microscope mainly detects the
atoms of osmium, distributed according to the affinity of the fixing compound for various
cell constituents. The micrograph was made by Don W. Fawcett of the Harvard Medical
School. The enlargement is 28,100 diameters. The cell itself is from the pancreas of a baL.
the processes of life, including those re
sponsible for manufacturing the sub
stance of the cell itself.
t is the present intersection of the two
lines of study that provides the occa
sion for this issue of SClEl’>TlFlC AMEHl
CAN, which is devoted to the living cell.
The cell biologist now seeks to explain
in molecular terms what he sees with the
aid of his instruments; he has become a
molecular biologist. The biochemist has
become a biochemical cytologist, in
terested equally in the structure of the
cell and in the biochemical activity in
which it is engaged. As the reader will
see, the mysteries of cell structure and
function cannot be resolved by the exer
cise of either morphological or biochemi
cal techniques alone. If the research is
to be successful, the approach must be
made from both sides at once. But the
understanding of life phenomena that
Bows from investigation of the cell has
already fully ratified the judgment of the
19th-century biologists who perceived
that living matter is divided into cells,
just as molecules are made of atoms.
A description of the functional an
atomy of the living cell must begin with
the statement tbat there is no such thing
as a typical cell. Single-celled organisms
of many different kinds abound, and the
cells of brain and muscle tissue are as
different in morphology as they are in
function. But for all their variety they
are cells, and so they all have a cell mem
brane, a cvtoplasm containing various
I
51
© 1961 SCIENTIFIC AMERICAN, INC
ORA WING OF CELLS in cork was published by Robert Hooke in 1665. Hooke railed them
cells, but the fact that all organisms are made of cells was not recognized until 19th century.
organelles and a central nucleus. In
addition to having a definite structure,
cells have a number of interesting func
tional capacities in common.
They are able, in the first place, to
harness and transform energy, starting
with the primary transformation by
green-plant cells of the energy of sun
light into the energy of the chemical
bond. Various specialized celIs can con
vert chemical-bond energy into electrical
and mechanical energy and even into
visible light again. But the capacity to
transform energy is essential in all cells
for maintaining the constancy of their
internal environment and the integrity
of their sh’ucture [see “How Cells Trans
form Energy,” page 62].
The interior of the cell is distin
guished from the outer world by the
presence of very large and highly com
plex molecules. In fact, whenever such
molecules turn up in the nonliving en
vironment, one can be sure they are the
remnants of dead cells. On the primitive
earth, life must have had its origin in
the spontaneous synthesis of compli
cated macromolecules at the expense of
smaller molecules. Under present-day
conditions, the capacity to synthesize
large molecules from simpler substances
remains one of the supremely distin
guishing capacities of cells.
.Nllong these macromolecules are pro-
PHOTOMICROGRAPH OF CELLS in the blood of a pigeon was made by J. J. Woodward,
a U.S. Ar my surgeon, in 1871. Woodward had made the first cell photomicrograph in 1866.
52
© 1961 SCIENTIFIC AMERICAN, INC
teins. In addition to making up a
major portion of the “solid” substance of
cells, many proteins (enzymes) have
catalytic properties; that is, they are
capable of greatly accelerating the speed
of chemical reactions inside the cell, par
ticularly those involved in the trans
formation of energy. The synthesis of
proteins from the simpler units of the
20-odd amino acids goes forward under
the regulation of deoxyribonucleic acid
(DNA) and ribonucleic acid (RNA) ,
by far the most highly structured of all
the macromolecules in the ceIl [see
“How Cells Make Molecules,” page
74]. In recent years and months in
vestigators have shown that DNA,
localized in the nucleus of the cell,
presides at the synthesis of RNA,
w hich is found in both the nucleus and
the cytoplasm. The RNA in turn ar
ranges the amino acids in proper se
quence for linkage into protein chains.
The DNA and the RNA may be com
pared to the architect and contractor
who collaborate on the construction of a
nice-looking house from a heap of bricks,
stones and tiles.
At one or another stage of life every
ceIl has divided: a mother cell has grown
VARIOUS KINDS OF LIGHT MICROSCOPY are used to photo
microscope at high contrast. The photomicrograph at bottom left
graph the same three paramecia_ The photomi
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