Transcript Cell Structures and Their Functions

Cell Structures and Their
Functions
Cell Structure
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Highly Organized
. Specialized structures called organelles in
a jelly like substance called
cytoplasm
Amount and type of organelles is related to
function
Functions of the Cell
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Basic Unit of Life -smallest part that still retains
characteristics of life
Protection And Support – cells secrete substances that
provide
Movement- occurs because of molecules that are located
in specific cells e.g. muscle cells
Communication-cells receive information that allow them
to communicate with each other eg nerves cell tells
muscle cells to contract
Cell metabolism and energy release- all the chemical
reactions that occur within the cell
Inheritance – each cell contains a copy of the genetic
information of the individual
The Organelles
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The Nucleus
Nucleoli and Ribosomes
Rough and Smooth Endoplasmic Reticulum
The Golgi Apparatus
Secretory Vesicles
Lysosomes and Peroxiisomes
Mitochondria
Cytoskeleton
Centrioles
Cilia, Flagella and Microvilli
The Cell Membrane
Cell Membrane
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Phospholipid Bilayer
Protection and Transport
Types of Transport
Active ( requires ATP)
Passive
Nucleus
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Contains the genetic material of cell
(DNA)
Located near the center of the cell
Some cells lose their nucleus as they mature,
some have more than one nucleus bone cells
Nuclear envelop (outer and inner membranes
and nuclear pores)
Contains loosely coiled fibers called chromatin
consisting of DNA When a cell divides the
chromatin becomes more tightly coiled to form
the 23 pairs of chromosomes
Nucleoli and Ribosomes
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Nucleoli- are rounded dense well defined
nuclear bodies with no surrounding
membranes
Ribosome's- are the organelles where
proteins are produced
-may be free
-attached to the endoplasmic reticulum
-made in the nucleus
Smooth and Rough
Endoplasmic Reticulum
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The ER is a series of membranes forming
sacs and tubules that extends from the
outer nuclear membrane into the
cytoplasm
Rough ER – has ribosomes attached
indicting that it is synthesizing large
amounts of protein for export from the cell
Protein Synthesis
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Transcription
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Translation
RNA
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mRNA
t RNA
r RNA
The Golgi Apparatus
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Golgi Apparatus- closely packed stacks of curved
membrane –bound sacs.
Its function is to collect modify , package and
distribute proteins and lipids manufactured by
the Endoplasmic Reticulum
May also chemically modify the proteins by
attaching carbohydrates or lipids to them
Found in great number in cells tat make a great
deal of protein e.g. pancreas
Secretory Vesicles
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a vesicle is a small membrane bound sac that
transports or stores materials within cells
Secretory vesicles – pinch off from the
golgi apparatus and move to the surface of
the cell . Their membranes fuse with the
cell membrane and release contents to the
exterior of the cell
Lysosomes and Peroximes
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Lysosomes are membrane bound vesicles
formed from the golgi apparatus . They
contain a variety of enzymes that
functions as intracellular digestive systems
Peroxisomes small membrane bound
vesicles containing enzymes that break
down fatty acids , amino acids and
hydrogen peroxide.
Mitochondria
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Mitochondria- small bean shaped, long
threadlike organelles that has inner and outer
membranes separated by a space. The outer
membranes have a smooth corebut the inner
membrane has numerous folds called cristae
Site of ATP production within the cells and carry
out aerobic respiration
muscle cells
Cytoskeleton
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Cytoskeleton- consists of proteins that
support the cell , hold organelles in place
and enable the cell to change shape.
Microtubules, Microfilaments and
Intermediate filaments
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Microtubules
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Microfilaments
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Intermediate filaments
Centrioles
Centosome- a specialized zone of cytoplasm
close to the nucleus that is the center of
microtubule formation.
 It contains the centrioles normally oriented
perpendicular to each other
 Shaped like a cylinder and has nine triplets
, each consisting of three parallel
microtubules joined together.
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Protein Synthesis
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DNA in nucleolus is Transcribed to MRNA
MRNA is translated at the level of the
ribosomal subunits where the codons are
read and translated into amino acids
The amino acids form peptide bonds to
create one larger protein
DNA and RNA
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DNA has 4 nitrogenous bases : adenine,
guanine, cytosine and thiamine plus the sugar
deoxyribose
RNA has 4 nitrogenous bases : adenine,
guanine, cytosine and uracil plus the sugar
ribose.
Remember there are 64 sets of codons (a codon
is 3 base pairs) that encode for only 20 amino
acids
Fate of the Cell
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Divides ( Mitosis and Meiosis)
Differentiates
Apoptosis
Tumor ( Benign or Malignant)
Ages
Death
* The Cloning of Cells
Cell Division
Mitosis all cells except sex cell(meiosis)
Interphase
 Prophase
 Metaphase
 Anaphase
 Telophase
 Cytokinesis
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Differentiation
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We learned that through mitosis all cells in
an individuals body contain the same
amount and type of DNA
So, even though the genetic material is the
same , why is it that cells do not look and
function the same way, example of diverse
cells in text
The process by which a cell develop
special structure and functions is called
DIFFERENTIATION.
What happens during
differentiation?
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DNA is either active or inactive pending in
the cell type via the selective activation of
certain portions of the DNA
As they mature and differentiate the
rate eventually slows and stops
Apoptosis
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Programmed cell death is a normal
process by which cell numbers within
various tissues are adjusted and controlled
. During development any extra tissue s
removed, such as the webs between the
toes and the fingers.
Cellular Aging
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Cellular Clock after a certain time or number of
cell divisions cell death occurs in a given line
Death genes turn on causing cells to deteriorate
DNA damage over years
Free Radicals (unpaired electrons) cause direct
damage via mutations
Mitochondrial damage causes a loss of energy
needed to maintain cell life
Cellular Tumor Transformation
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Tumor- any swelling that occurs within the
body
malignant- spreads rapidly, can get
large
benign- can get large
Cancer
Cancers are malignant spreading tumors
Can spread via the lymphatic, hematologic, or local expansion routes
Growth becomes out of control and the cancer breaks away from normal
control
Occur as a result of viruses, toxins
Treatment in the form of
Chemotherapy
Immunotherapy
Radiotherapy ‘
Starvation to cancer
Cloning
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A nucleus removed from a differentiated
cell can be transferred to an oocyte with
the nucleus removed and a complete frog
can be formed