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The Cell

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by

Meg Hernandez

on 1 October 2013

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Transcript of The Cell

The Cell
Nucleus
Basic Types of Cell
1. Eukaryotic Cell
- are organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton.
- The most characteristic membrane bound structure is the nucleus.T his feature gives them their name, which comes from the Greek ευ,
eu
meaning good/true, and κάρυον,
karyo
meaning nucleus,
Animals, plants, fungi, and protists are eukaryotes.
2. Prokaryotic Cell
- Prokaryotes do not have a nucleus, mitochondria, or any other membrane-bound organelles. Most are unicellular, but some prokaryotes are multicellular.
Prokaryotes include two major classification domains: the bacteria and the archaea.
- from Old Greek
pro
meaning before and
karyon
meaning nucleus.
3 Basic Cell Division
is the basic structural, functional and biological unit of all known living organisms. Cells are the smallest unit of life that is classified as a living thing, and are often called the "building blocks of life".
nucleus
plasma/cell membrane or plasmalemma
cytoplasm
Parts of the Cell
Nucleolus
- is usually visible as a dark spot in the nucleus.
- responsible for making ribosomes.
- houses the DNA and genes
- The control center for all cellular activity.

- most obvious part of the cell
- contains information to run cell
The circles on the surface of the nucleus are the nuclear pores. These are where ribosomes, and other materials move in and out of the cell.
Nuclear membrane
Ribosomes
- Organelles that help in the synthesis of proteins.
- are where RNA is translated into protein, this process is called protein synthesis.
Ribosomes are made up of two parts, called subunits.
> small
> large
Populations of ribosomes:
1.
Free ribosomes
- make protein that remain inside the cell; for domestic use.
2.
Attached ribosomes
- manufacture proteins to be exported from the cell.
When the two units are docked together with a special information unit called
messenger RNA
, they make proteins.
Endoplasmic reticulum
- is the transport system for molecules needed for certain changes and specific destinations, instead of molecules that float freely in the cytoplasm.
- made up of flattened channels called "
cisterns
"
Two Types of Endoplasmic reticulum
1.
Smooth Endoplasmic Reticulum
- synthesizes lipids in the cell.
- also helps in the detoxification of harmful substances in the cell.
-there are no ribosomes
attached
2.
Rough

Endoplasmic Reticulum
- is where most protein synthesis occurs in the cell.
= ribosomes are attached
Golgi Complex
- It is the organelle in the cell that is responsible for sorting and correctly shipping the proteins produced in the ER.
- changes molecules and divides them into small membrane contained sacs called
vesicles
.
- made up of flattened sacs with bulging ends called
cisternae
.
These sacs can be sent to various locations in the cell. Just like our postal packages which should have a correct shipping address, the proteins produced in the ER, should be correctly sent to their respective address.
In the cell,
shipping
and
sorting
is done by the Golgi complex. It is a very important step in protein synthesis. If the Golgi complex makes a mistake in shipping the proteins to the right address, certain functions in the cell may stop.
This organelle was named after an Italian physician-Camillo Golgi. He was the first person to describe this organelle in the cell. It is also the only organelle that is capitalized.
Peroxisomes
- are small, membrane-enclosed organelles that contain enzymes involved in a variety of metabolic reactions, including several aspects of energy metabolism. They collect and safely break down chemicals that are toxic to the cell.
Vacuoles
- are membrane-bound sacs found in the cytoplasm. They provide storage, structural support, transport substances and aid in waste disposal.

- isolates substances that might be harmful to the cell and maintains an acidic internal pH. It also helps maintain turgor pressure within the cell as well as exports unwanted substances from a cell.
Plant cells have a
central vacuole
which is used for storage and help to maintain hydrostatic pressure.
Cytoskeleton
- this structure acts as both muscle and skeleton, for movement and stability.
- maintains the shape of the cell.
3 types of the Cytoskeleton
Microtubules
- 25 nanometers
- 9 + 2 arrangement
Microtubules are responsible for a variety of
cell movements
, including the
intracellular transport
and
positioning of membrane vesicles and organelles
, the
separation of chromosomes
at mitosis, and the
beating of cilia and flagella
.
Conveyor belts
- responsible for the ditribution of organelles or particles
Centrosomes
- form the spindle during cell division
- is an organelle that serves as the main microtubule organizing center of the animal cell as well as a regulator of cell-cycle progression.
Centrioles
- the part of a cell that helps to organize microtubules, and it is involved in mitosis.
Intermediate filaments
- 8 to 12 nanometers
Intermediate filaments
are responsible for providing structural reinforcements. They appear to play basically a structural role by providing mechanical strength to cells and tissues.
Microfilaments
- ≤≤≤≤less than or equal to 8 nanometers
Microfilaments
are highly versatile, functioning in cytokinesis, amoeboid movement, and changes in cell shape. They also play a key role in the motility of the cell.
Mitochondrion
- is an organelle that carries out cellular respiration producing ATP molecules
- often called the
power-houses of the cell.
Two Kinds of Membranes
Inner Membrane
-permeable only to oxygen, carbon dioxide and water.

-contains the complexes of the
electron transport chain
and the
ATP synthetase complex.

-highly convoluted intro
cristae
that project into the
matrix.
Cristae

Cristae
are inner foldings that increase the surface area for the complexes and proteins that aid in the production of ATP, the energy rich molecules.
Matrix
Matrix
is a complex mixture
of enzymes that are important
for the synthesis of ATP molecules, special mitochondrial ribosomes, tRNA's and the mitochondrial DNA.
Outer Membrane
-permeable to nutrient molecules, ions, ATP and ADP molecules.

-separates the i
ntermembrane space
from the
cytosol.
Intermembrane Space
A proton gradient is built inside of the intermembrane space. The election transport chain uses this proton gradient to help drive the production of ATP by ATP synthase.
Cytosol
Cytosol
is the internal fluid of the cell, and where a portion of cell metabolism occurs.
Lysosome
- are specialized vesicles that contain digestive enzymes. These enzymes break down foreign material which may enter the cell.

-are membrane bounded vesicles produced by the Golgi apparatus

-are needed in order to accomplish the digestion of food particles.

-product of the golgi complex
Lysosomes also participate in
apoptosis
or programmed cell death, which is a normal part of development.
Cell Membrane
-a selective barrier that allows sufficient passage of oxygen, nutrients, and wastes to allow the cell to function.

-it protects the interior of the cell by allowing certain substances into the cell, while keeping other substances out.

-it also serves as a base of attachment for the cytoskeleton in some organisms.

-helps support the cell and help maintain its shape.
Components of the Cell Membrane
Phospholipids
-A phospholipid has a backbone derived from a three-carbon molecule called gylcerol, and attatched to the molecule are fatty acids.

-Each phosholipid has two fatty acids attached to its backbone, fatty acid chains are non-polar

- At the end it has two strongly non-polar fatty acids tails and the head is strongly polar

-The tails are
hydrophobic (non polar)
and the heads are
hydrophilic (polar)

The tails of the nonpolar are
directed inward
and the head of the polar are
directed outward
which forms a
phospholipid bilayer.
-when two layers form with the tails facing each other, no tail ever comes into contact with water (lipid bilayer)
-non-polar tails create a barrier to the passage of water soluble substances (sugars, polar amino acids and proteins)
Lipid Bilayer is Fluid

A lipid bilayer is fluid because hydrogen bonding of water holds a membrane together.
The greater the degree of alignment, the less fluid the membrane.
Fluid-Mosaic Model
S. Singer and G. Nicolson
introduced the
fluid-mosaic model
, which proposes that the membrane is a fluid phospholipic bilayer in which protein molecules are either partially or wholly embedded.
Membrane Proteins
The plasma membranes of various cells and the membranes of various organelles each have their own unique collections of proteins.
Channel Protein
-allows a particular molecule the plasma or ion to cross the plasma membrane freely

-without this movement of hydrogen ions, ATP would never be produced.
Carrier Protein
-Carrier proteins
are involved in the passage of molecules through the membrane.

-also transports sodium and potassium ions across a nerve cell membrane.

-without this carrier protein, nerve conduction would be impossible.
Receptor Proteins
Receptor proteins
have a shape that allows a specific molecule to bind it. The binding of this molecule causes the protein to change its shape and thereby bring about a cellular response.
Cell Recognition Protein
Cell recognition proteins
are glycoproteins. These proteins help the body recognize when it is being invaded by the pathogens so that an immune reaction can occur. Without this recognition, pathogens would be able to freely invade the body.
Enzymatic Protein
Enzymatic protein
catalyzes a specific reaction, without this presence of enzymes a cell would never be able to perform the metabolic reactions necessary to its proper function.
Chloroplast
Chloroplast
are a type of plastid, plant algal organelles that are bounded by a double membrane and contain a series of internal membranes and/or vesicles.

-use solar energy to synthesize carbohydrates, and carboyhydrate-derives products are broken down in
mitochondria.

-
Chloroplasts
contain chlorophyll and carry on photosynthesis, while the other types of plastids have a storage function.

-
Photosynthesis
which usually occurs in chloroplasts, is the process by which solar energy is converted to chemical energy within carbohydrates.


Other Types of Plastids
Chromoplasts
Chromoplasts
contain pigments that result in a yelllow, orange, or red color. They are responsible for the color of autumn leaves, fruits, carrots, and some flowers.
Leucoplasts
Leucoplasts
are generally colorless plastids that synthesize and store starches and oils.
Parts of the Chloroplast
The double membrane encloses a large space called the
stroma,


Stroma contains
thylakoids
which are disklike sacs formed from a third chloroplast membrane.

A stack of thylakoids is a
granum.
presented by Meg Hernandez and Ariel Lee
Full transcript