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Transcript of TEORIA CELULAR
Blga. Silvia Carrasco Dioses
In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork, a plant material.
Cork looked like thousands of tiny, empty chambers.
Hooke called these chambers “cells.”
Cells are the basic units of life.
At the same time, Anton van Leeuwenhoek used a single-lens microscope to observe pond water and other things.
The microscope revealed a world of tiny living organisms.
In 1838, Matthias Schleiden concluded that all plants were made of cells.
In 1839, Theodor Schwann stated that all animals were made of cells.
In 1855, Rudolph Virchow concluded that new cells were created only from division of existing cells.
These discoveries led to the cell theory.
The cell theory states:
All living things are composed of cells.
Cells are the basic units of structure and function in living things.
New cells are produced from existing cells.
Cells come in a variety of shapes and sizes.
are surrounded by a barrier called a cell membrane.
at some point contain DNA.
Eukaryotes are cells that contain nuclei.
Prokaryotes are cells that do not contain nuclei.
Prokaryotic cells have genetic material that is not contained in a nucleus.
Prokaryotes do not have membrane-bound organelles.
Prokaryotic cells are generally smaller and simpler than eukaryotic cells.
Bacteria are prokaryotes.
Eukaryotic cells contain a nucleus in which their genetic material is separated from the rest of the cell.
Eukaryotic cells are generally larger and more complex than prokaryotic cells.
Eukaryotic cells generally contain dozens of structures and internal membranes.
Many eukaryotic cells are highly specialized.
Plants, animals, fungi, and protists are eukaryotes.
skeletal muscle (striated)
Cell membranes protect and organize cells.
All cells have an o
uter plasma membrane
that regulates not only what enters the cell, but also how much of any given substance comes in.
Unlike prokaryotes, eukaryotic cells also possess
that encase their organelles and control the exchange of essential cell components.
With few exceptions, cellular membranes — including
plasma membranes and internal membranes
— are made of
, molecules composed of
a phosphate group, and
two fatty acid chains.
Glycerol is a three-carbon molecule that functions as the backbone of these membrane lipids.
Within an individual glycerophospholipid, fatty acids are attached to the first and second carbons, and the
is attached to the third carbon of the glycerol backbone.
Variable head groups are attached to the phosphate.
What Are Cellular Membranes Made Of?
to be continue....
is the control center of the cell.
The nucleus contains nearly all the cell's
and with it the coded instructions for making proteins and other important molecules.
The DNA combines with protein to form
which is found throughout the nucleus.
The nucleus is surrounded by a nuclear envelope composed of
The envelope is dotted with
, which allow material to move in and out of the nucleus.
The granular material in the nucleus is called
Chromatin consists of
bound to protein.
When a cell divides, chromatin condenses to form
Chromosomes contain the genetic information that is passed from one generation of cells to the next.
Most nuclei also contain a
The nucleolus is where the assembly of ribosomes begins.
The small, dense region in the nucleus is the nucleolus.
Lysosomes are simple
tiny spherical sac
-like structures evenly distributed in the cytoplasm.
Each lysosome is a
surrounded by a
single membrane and contains powerful enzymes.
These enzymes are capable of
digesting or breaking down all organic materials.
Cellular functions are highly diverse and complex.
In some cases, each cell performs a function completely different from that of the others.
Organisms have "specialist"
that enable them to perform such cellular functions efficiently and uniformly while preserving their diversity.
structure found in both animal and plant cells.
It is a
It has the
The membranes are made up of
phospholipids and proteins.
Ribosomes are small particles, present in large numbers in all the living cells.
They are sites of
The ribosome word is derived - 'ribo' from ribonucleic acid and 'somes' from the Greek word 'soma' which means 'body'.
Similar to the cytoplasm of a cell, the nucleus contains
(nucleus sap) or
Functions of mitochondria depends on the cell type in which they are present:
The most important function is to produce energy. The simpler molecules of nutrition are sent to the mitochondria to be processed and to produce charged molecules. These charged molecules combine with oxygen and produce
This process is known as
Mitochondria help the cells to maintain proper
concentration of calcium
ions within the compartments of the cell.
The mitochondria also help in
building certain parts of blood and hormones
like testosterone and estrogen.
The liver cells mitochondria have enzymes that
The mitochondria also play important role in the process of
apoptosis or programmed cell death.
Abnormal death of cells due to the dysfunction of mitochondria can affect the function of organ.
The ribosomes are made up of two subunits - a
small and a large subunit.
Types of Lysosomes:
There are basically four types of lysosomes present: which co-relates with what is the the lysosome's function
/ digestive vacuole
/cytolysosome/ autophagic vacuole
/ telolysosome/ Dense bodies
) : Inside the cell there exists membranous network enclosing a fluid-filled lumen rich almost fills up the intra cellular cavity. It is called
On the one end ER is connected to the outer membrane of the nucleus and on the other end to the plasma membrane.
The plant cells contain many freely distributed subunits of Golgi apparatus called
The main function of Golgi apparatus is
It acts as a way station or assembly area for the
of various cellular secretions.
These are fluid filled and membrane bounded spaces.
In animal cells, the vacuoles if present are small and temporary. They store water, glycogen and proteins.
The function of this plant cell organelle is to help maintain the osmotic pressure in a cell.
These occur in most plant cells and are absent in animal cells.
The plastids are of two types:
are colourless and occur in the cell not exposed to sunlight. the
are coloures and occur in the cel exposed to sunlight.
The chromoplasts having green pigment,
are known as the
Chloroplasts are most common types of plastids.
Chloroplasts trap solar energy and utilise it to manufacture food for the plant.
The chloroplasts have a system of three membranes: the outer membrane, the inner membrane and the thylakoid system. The outer and the inner membrane of the chloroplast enclose a semi-gel-like fluid known as the stroma. This stroma makes up much of the volume of the chloroplast, the thylakoids system floats in the stroma.
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