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RAD 114 RADIATION
PROTECTION
OVERVIEW OF CELL
BIOLOGY
PROTOPLASM
z PROTEINS
z CARBOHYDRATES
z LIPIDS
z NUCLEIC
ACIDS
z INORGANIC SALTS
z WATER
PROTEINS
Formed by combining amino
acids (from among 22 known)
and serve STRUCTURAL or
ENZYMATIC functions.
Proteins can also exist as
hormones (regulatory functions)
and antibodies (immune
response).
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CARBOHYDRATES
Are simple sugars
(saccharides). Serve the
short-term energy needs of
cells. They also comprise
parts of cell walls and
intercellular (inter=between)
materials.
LIPIDS
Loosely called “fats,” are substances
made up of fatty acids, the
constituents of amino acids. They do
not dissolve in water, and form long
chains of molecules
(macromolecules). Lipids provide
long-term storage of energy and
comprise portions of cell
membranes.
NUCLEIC ACIDS
Complex macromolecules
consisting of linked molecules
called nucleotides. Nucleotides
consist of a nitrogen-containing
organic base, a five-carbon sugar
molecule and a phosphate
molecule.
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NUCLEIC ACIDS
z DEOXYRIBONUCLEIC
ACID
(DNA)
z RIBONUCLEIC ACID (RNA)
DNA
Responsible for control of cell
functions. Also contains
genetic information
representing the cell.
Reproductive cells contain
DNA for the whole organism.
DNA
DNA is contained in the
nucleus of each cell.
Cellular activities cannot be
carried out directly by DNA,
but is mediated by the
creation of messenger RNA.
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RNA
Ribonucleic acid is a partial copy
of DNA. Each copy is
representative of the type of
protein to be made from amino
acids. The instruction code
contained in mRNA is
transferred to another kind of
RNA called transfer RNA.
RNA
The tRNA obtains the correct
amino acid in the correct
order and links them together
with the help of the
RIBOSOMES. The linked
amino acids become proteins.
PROTEIN SYNTHESIS
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ANATOMY OF DNA
DNA is structured like a spiral
staircase, with the rails
consisting of alternating bands
of sugar and phosphate
molecules (sugar-phosphatesugar-phosphate). The rungs
consist of nitrogenous bases
arranged in specific order...
DNA
DNA MACROMOLECULE
P
S
P
C
S
PURINE
ADENINE (A)
GUANINE (G)
P
P
S
WITH
S
P
G
T
G
P
S
A
C
P
S
P
PYRIMIDINE
THYMINE (T)
CYTOSINE (C)
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OTHER CELL COMPONENTS
ENDOPLASMIC RETICULUM
LYSOSOMES
z GOLGI APPARATUS
z MITOCHONDRIA
z CENTROSOME (CENTRIOLES)
z NUCLEUS
z NUCLEOLUS
z RIBOSOMES
z
z
ENDOPLASMIC
RETICULUM
The transportation network of
the cell. Certain reticula are
speckled with ribosomes and
are called ROUGH
ENDOPLASMIC RETICULA.
These are essential to protein
synthesis.
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LYSOSOMES
Serve the digestive or
debris removal function of
the cell. Lysosomes are
sac-like structures which
contain enzymes to digest
cellular fragments.
GOLGI APPARATUS
Serves the packaging and export
needs of the cell. A network of
tubes and tiny sacs extend from
the nucleus to the cell membrane.
Hormones and enzymes are
transported to the extracellular
environment via the golgi
apparatus.
MITOCHONDRIA
Large bean-shaped structures
responsible for energy
production. Nutrients are
broken down to produce
adenosine triphosphate (ATP).
Mitochondria are responsible for
active transport within the cell.
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ACTIVE TRANSPORT
A biochemical process that causes the
movement of solutes across a
membrane from lower concentration to
higher concentration. This is not the
same as osmosis, which causes the
solvent (water) to move across a
membrane from lower concentration to
higher concentration.
CENTROSOMES
Located in the center of the cell
near the nucleus. They
contain the CENTRIOLES
which are believed to form
spindle fibers during cellular
division.
NUCLEUS
The “heart” of the cell, contains
genetic material in its molecular
structure. Controls all aspects of
cell function including replication.
Within the nucleus is the
NUCLEOLUS which contains
large amounts of RNA.
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RIBOSOMES
Small spherical structures
which are attached to certain
endoplasmic reticula. These
are responsible for protein
synthesis. Ribosomes consist
of RNA (2/3) and protein (1/3).
CELL MEMBRANE
Semi-permeable barrier
between the cell and its
environment. Serves to
protect the cell and acts to
control the passage of water
and other materials into and
out of the cell.
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TYPES OF CELL DIVISION
z MITOSIS
z MEIOSIS
MITOSIS
Cell reproduction involving
“somatic” cells. This process
results in the formation of two
daughter cells containing roughly
equal amounts of cellular
material. Each human somatic
cell contains 46 chromosomes.
MEIOSIS
Cell division involving
reproductive cells (sperm or
egg cells). Each MATURE
daughter cell contains half the
number of chromosomes
contained in somatic cells
(23).
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CELL DIVISION CYCLE
z INTERPHASE
z PROPHASE
z METAPHASE
z ANAPHASE
z TELOPHASE
INTERPHASE
A preparatory period for the cell prior to
cell division. The period is divided
into three phases: G1, S and G2. G1
involves the production of RNA
helpful to DNA replication. S is the
actual DNA replication phase. G2
involves the production of RNA and
proteins needed for mitosis (M).
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PROPHASE
Is characterized by the loss of
the nuclear membrane and
the genetic material coiling
up to take shape as
chromosomes. Centrioles
manufacture spindle fibers.
METAPHASE
Spindle fibers attach to organelles
called centromeres (connect 2
pairs of chromatids).
Chromosomes align at the cell’s
middle. During this phase, cell
division can be stopped and the
chromosomes examined under a
microscope.
ANAPHASE
The centromeres split
and the chromatids
migrate to opposite
sides of the cell, drawn
by the spindle fibers.
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TELOPHASE
Genetic material uncoils, becoming
indistinct. Two nuclear membranes
appear. The cytoplasm divides,
surrounding each nucleus. Finally,
they separate to become two
daughter cells.
2ND (MEIOTIC) DIVISION
Sperm and egg cells must divide
one additional time in order to
halve the number of
chromosomes. Therefore 2
daughter cell become 4
“granddaughter” cells, each
containing 23 chromosomes.
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