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The Nucleus. Robin Bauman Advanced Bio Mr. Daly. The Nucleus. Highly specialized organelle that serves as the information processing and administrative center of the cell. Two major functions Stores the cell’s hereditary material (DNA) Coordinates cell’s activities

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the nucleus

The Nucleus

Robin Bauman

Advanced Bio

Mr. Daly

the nucleus1
The Nucleus
  • Highly specialized organelle that serves as the information processing and administrative center of the cell.
  • Two major functions
    • Stores the cell’s hereditary material (DNA)
    • Coordinates cell’s activities
      • Include growth, intermediary metabolism, protein synthesis, and reproduction (cell division).
  • Only Eukaryotes have nucleus.
the nucleolus
The Nucleolus
  • Membrane-less organelle within the nucleus that manufactures ribosome's.
  • Large dark spot within the nucleus.
  • During cell division, the nucleolus disappears.
  • After cell divides, a nucleolus is formed when chromosomes are brought together
the nuclear membrane envelope
The Nuclear Membrane (Envelope)
  • A double-layered membrane that encloses the contents of the nucleus
  • Envelope is perforated with tiny holes called nuclear pores
    • .
  • During cell division (mitosis), the nuclear envelope disintegrates, but reforms as the two cells complete their formation.
nuclear pores
Nuclear Pores
  • Nuclear pores

regulate the

passage of


between the

nucleus and the


works cited
Works Cited
  • Molecular Expressions.
  • Google Images.

Ribosome is a particle composed of protein and RNA that serves as the site of protein synthesis

Found in cytoplasm of prokaryotic and eukaryotic cells

Has a large and small subunit that act as one to read the genetic sequence from the mRNA to make proteins

“Using the mRNA as a template, the ribosome traverses each codon, pairing it with the appropriate amino acid. This is done through interacting with transfer RNA (tRNA) containing a complementary anticodon on one end and the appropriate amino acid on the other.”

  • Ribosomes in translation
Large Subunit- mostly RNA, “Proteins are distributed mainly on the surface. Some proteins have long tails that extend into the interior of the complex. These tails, which are highly basic, interact with the negatively charged RNA.

The active site domain for peptide bond formation is essentially devoid of protein. The peptidyl transferase function is attributed to the 23S rRNA, making this RNA a ‘ribozyme’.“

Small Subunit- a cleft in the small subunit is the binding site for tRNA. Small subunit is also really flexible and can assume different conformations.

In eukaryotes, ribosomes are made up of 4 strands of RNA & are often attached to the membranes of endoplasmic reticulum to form Rough ER

In prokaryotes, ribosomes are made of 3 strands of RNA & occur free in cytoplasm

Ribosomes in translation 40% protein and 60% ribosomal RNA (rRNA)

  • In the last 50 years, ribosome research has made two significant discoveries: the discovery of mRNA as a molecule in the transmission of genetic information and the “optimization of an in vitro protein synthesis system”
  • Recent studies have also shown that the secondary structure of the RNA molecules has been “strongly conserved throughout evolution”.


Marissa Martinez

what are r ibosomes
What are Ribosomes?
  • Complexes(small brown dots) that make up proteins
  • There are ribosomes that are in bacteria and eukaryotes. These have different structures but the same functions.
  • There are free and bound ribosomes

- Free: are found in cytosol

- Bound: are bound to rough ER or in the nuclear envelope.

history of ribosomes
History of Ribosomes

First observed in mid-1950’s by Romanian cell biologist George Palade using an electron microscope.

George Palade won the Nobel Prize for his discovery.

Scientist Richard B. Roberts in 1958 proposed the name “ribosome”.

structure of ribosomes
Structure of Ribosomes

Made up of two subunits, called large and small subunits.

These subunits consist of proteins and RNA molecules named ribosomal RNA’s (rRNA’s).

About two-thirds of the mass of a ribosome consist of rRNA, either three molecules in prokaryotes or four in eukaryote.

structure of eukaryote and prokaryote ribosomes
Structure of Eukaryote and Prokaryote Ribosomes

These subunits are made in the nucleolus

The main difference between these two ribosomes is that Eukaryote ribosomes are slightly bigger and slightly differ in their molecular structure.

Ribosomes found in chloroplasts and mitochondria of eukaryotes also consist of large and small subunits bound together with proteins.

Descendents of bacteria and this is why their ribosomes are similar to bacteria.


They are the “workhorses” of protein biosynthesis which is the process of translating mRNA into proteins.

Build proteins from the genetic instructions held with the messenger RNA.

Translate messenger RNA to build polypeptide chains using amino acids delivered by transfer RNA.

building sites
Building sites
  • Ribosomes have three building sites for tRNA.

1. P-site (peptidyl-tRNA): hold the tRNA carring the growing polypeptide chain

2. A-site (aminoacyl-tRNA): holds the tRNA carrying the next amino acid to be added to the chain.

3. E-site: the exit site where the tRNA leaves the ribosome.

work cited
Work Cited
  • Biology Book: by Reece Campbell
facts about rough er
Facts about rough ER
  • Endoplasmic means “within the cytoplasm” and reticulum is Latin for “little net”
  • It is a eukaryotic organelle
  • The rough ER is attached to the nuclear envelope which also has ribosomes.
more facts about rough er
More Facts about Rough ER
  • Rough ER is part of the endomembrane system
  • Its membrane allows for water soluble proteins to pass through into the lumens
  • The rough ER has ribosomes on the outside of it which read mRNA and make proteins .
function of the rough er
Function of the Rough ER
  • Many cells emit proteins made by ribosomes. (also called secretory proteins)
  • It folds proteins into their “native” shape
  • Adds proteins to cell membrane making them integral proteins.
smooth er

Smooth ER

Maja Whitaker

September 24, 2009

  • Smooth ER found in the Endoplasmic Reticulum
    • Membranous network in eukaryotic cells
  • Differs from rough ER
    • Tubular structure, rather than disc-like
    • Surface lacks ribosomes
form and function
Form and Function
  • Metabolic processes
    • Synthesis of lipids
      • Fatty acids, phospholipids, lipid-based hormones
    • Cholesterol/Calcium metabolism
    • Calcium storage
  • Detoxification of drugs/poisons
  • Transport of materials in/out of cell
    • Controls movement of newly synthesized proteins to proper location in cell or membrane before being sent out of cell
  • Provides surface area and space for the action of enzymes
form fitting function
Form Fitting Function
  • Sarcoplasmic Reticulum of muscle cells
    • Smooth ER stores calcium
    • Calcium is released during muscle contraction
    • Movement of a muscle is triggered
evolutionary origin of smooth er
Evolutionary Origin of Smooth ER
  • Endomembrane Hypothesis
    • Eukaryotic Cell
      • Endoplasmic Reticulum: one of the organelles that composes the endomembrane system
      • Continuous with the nuclear envelope
        • Directly connected to nucleus
        • Indirectly connected to other organelles through transport vesicles

works cited1
Works Cited
  • The Endoplasmic Reticulum.
  • Rough and Smooth Endoplasmic Reticulum.

  • The Endoplasmic Reticulum Organelle: Function and Appearance of Rough and Smooth ER

structure of the smooth er
Structure of the Smooth ER
  • Connected to the nuclear envelope
  • The SER consists of a network of tubules and vesicles
    • The folded network of tubules and vesicles allow for a greater surface to volume ratio
  • Found in a variety of both plant and animal cells
functions of the smooth er
The SER has functions in several metabolic processes

Synthesizes lipids and steroids

Synthesizes the metabolism of carbohydrates

Regulates calcium concentration

Functions of the Smooth ER
sarcoplasmic reticulum
Sarcoplasmic Reticulum
  • A special type of SER found in smooth and striated muscle
  • The main difference between the SER and the SR is that the SER synthesizes molecules while the SR stores and pumps calcium ions
works cited2
Works Cited
the golgi apparatus

The Golgi Apparatus

By: Nikki Chase

general information
General Information
  • The Golgi Apparatus is a membrane-bound organelle that has a single membrane and is made up of a stack of membrane-bound vesicles that take part in the packaging of macromolecules that are to be sent out to other parts of the cell.
  • It has a cis-face that is able to receive transport vesicles from the Endoplasmic Reticulum
  • In this cis-face, protein products and lipid bilayers are made into vesicles and distributed to parts of the cell.
  • The Golgi Apparatus also has a trans-face which is the part of the organelle that sends the vesicles out to the other parts of the cell.


fotograf as de golgi apparatus
Fotografías de Golgi Apparatus

the golgi apparatus1

The Golgi Apparatus

By: Nikki Chase

transport vesicles
Transport Vesicles

Transport Vesicles are tiny membranous sac in a cell, that are involved in shuttling cargo from the interior of the cell, to the cell surface, and from the surface of the cell to the interior the cell. They also provide movement of materials in and around the cell.

Most common example of a Transport vesicle movement, is the transfer of proteins from the rough (ER) to the Golgi Apparatus.

transport vesicles1
Transport Vesicles

Transport vesicle

Transport vesicle

Transport Vesicles are protected from the cytosol by a least one phospholipid bilayer.

Transport vesicles can fuse their phospholipid bilayer with the cell membrane to release waste or other materials outside of the cell. Or can also fuse with other organelles within the cell.

Transport Vesicles are from through the Endomembrane Hypothesis. The vesicles are made though the folding of membranes.

transportation vesicles
Transportation Vesicles

Vesicle trafficking- vesicles that travel over a large distance to get to their target.

Vesicle tethering- is the liking of a vesicle to its target form a further distance. Vesicle fusion may not always occur.

Vesicle docking- docking refers to the holding of two membranes together, and needs to occur for bilayer fusion.

Vesicle fusion- the transportation vesicle phospholipidbilayer, attaches to cell membrane or surface of other organelles. The substance inside the vesicles is then released out of the cell or into other organelles of the cell. This fusion process also adds phospholipids to the cell membrane due to the fact that vesicle is completely absorbed to the entire cell membrane.

form and function1
Form and Function~

Transport Vesicles,

form and function2
Form and Function~
  • Transport vesicles transport molecules between different membrane-enclosed compartments inside the cell.
    • For example, they transport proteins from the rough endoplasmic reticulum to the Golgi apparatus.
  • This vesicular transportation therefore maintains the functional organization of the cell.
  • The membrane-bound and secreted proteins which are made on ribosomes, found in the rough endoplasmic reticulum, exist inside of the cell, which in turn exists inside of the transport vesicles.


The Mechanism of Vesicular Transport,

form and function3
Form and Function~
  • Budding from membrane  Formation of vesicle  cytoplasm surfaces of transport vesicles coated with proteins  vesicle budding/transport based off of assembly of protein coats 
  • -clathrin-coated vesicles~ take up extra cellular molecules from plasma membrane by endocytosis and transport molecules from trans Golgi to lysosomes (in this vesicle coating process the cell is very selective)
  • -nonclathrin-coated vesicles~ one class buds from ER and carries cargo along secretory pathway, to Golgi apparatus, the other buds from ER-Golgi intermediate compartment or the Golgi apparatus and in the retrieval pathways they retain proteins in the Golgi and ER.

The Mechanism of Vesicular Transport,

  • The transport vesicle evolution is based off of the endomembrane hypothesis
  • The endomembrane system of Eukaryotic cells consists of the cell membrane, nuclear envelope, ER system, Golgi apparatus, lysosomes, vacuoles, and vesicles
  • Within the cytoplasm of the cell inside the endomembrane system exist transport vesicles

Endomembrane System,

electron micrographs
Electron Micrographs~

Transport Vesicles,


Transport Vesicles,

l ysosomes



Joel Begay

what is a lysosome
What is a Lysosome?
  • They are small machines that float around in the cytoplasm, until needed, and when they are needed, they digest (break down) complex molecules, such as cellular waste products, macromolecules and even old organelles.
  • They are single-membrane organelles
how a lysosome is made
How a Lysosome is Made
  • The Rough Endoplasmic Reticulum (RER) creates enzyme proteins that go directly to the Golgi Apparatus.
  • The Golgi Apparatus then creates digestive enzymes and pinches off a tiny vesicle, now called a lysosome, that has a very specific job.
evolution of a lysosome
Evolution of a Lysosome
  • The Endomembrane Hypothesis:
    • The in-folding of the (lysosomal) membrane to increase the surface area to volume ratio
    • Due to the increase in surface area to volume ratio, more reactions can occur.
a lysosome s work
A Lysosome’s Work
  • When a cell consumes food, the lysosomes quickly attach themselves to the molecules of food and let loose hydrolytic enzymes that will break down the molecule into simple compounds. This process is known as Endocytosis.
  • If a cell has no food to process, the lysosomes will burst and consume old cell organelles to produce nutrients so that the cell can continue living. This is known as Autophagy which only happens when a signal is given. For this reason, they are also known as “Suicide Bags”.
a lysosome s work cont d
A Lysosome’s Work(cont’d)
  • Click on the following link to view an animation of a Lysosome's duty.
  • It will ask “Would you like to open file?”
  • Click “OK”
form fits function
Form fits function
  • The hydrolytic enzymes found in lysosomes need a low pH environment to operate correctly because when the pH becomes more acidic, the enzymes are activated. Thus the interior of a lysosome is more acidic than the cytoplasm of the cell.
  • The lysosome membrane creates a compartment which indicates specialization. The specialization in this case is the breaking down of old organelles, food, or waste.
resources used
Resources used
  • Biology 4 Kids:
  • McGraw Hill:
  • Molecular Expressions:
  • Lysosome Electron micrograph:
  • Lysosome Diagram:
  • Lysosomes and Peroxisomes:
  • The purpose of the lysosome is to digest the nutrients that the cell wall has allowed inside. They have enzymes capable of breaking down the four base macromolecules for their nutritional value. The enzymes are also capable of destroying any material within the cell that is not needed, in excess or is harmful to the cell such as bacteria.
  • Lysosomes are bound by a single membrane which allows them to properly function at a different acidity than the cytosol that surrounds them. This membrane also protects the interior of the cell from the destructive hydrolase enzymes within the lysosome.
  • The shape and size of the Lysosome varies due to the various functions they are needed to perform.
evolution of the lysosome
Evolution of the Lysosome
  • The lysosome evolved into the digestive system of the cell. They probably evolved from a vesicle coming from the golgi apparatus, explaining why it has its own membrane. Because it was given its own membrane, it was then able to perform a specialized function, allowing it to evolve into a lysosome. This follows the endomembrane evolution theory.
  • Vacuoles are the storage containers of the cell world
    • In all cells they can carry nutrients or waists
    • Plants can also store water in them
form and function4
Form and Function
  • They have to be membrane bound with room in the middle so that they can store materials within themselves. If they were not open in the middle they would not be effective.
  • In plants they help support the cell wall. When they are filled with water the cell wall is supported and when they are not the cell wall is much more malleable. This is why plants droop when they do not have enough water.
  • A vacuole is a membrane bound organelle that follows the Endo-membrane Hypothesis.
    • This hypothesis states that a cell originally started in a ball (or as close to a ball as a cell can be) and then began to fold.
    • It eventually folded into a circle around the middle, leaving a storage area in the middle
    • All of this folding eventually turned into the complex system that we know as a vacuole today.
works cited3
Works Cited


“specialized lysosomes”

By Isaac Rubin

  • Replicate by division
  • Surrounded by a membrane
  • Created in a process where proteins are translated and then transported into the membrane
  • Has a lipid bilayer and a crystalline core
what do they do
What do they do?
  • provide compartments for oxidation reactions
  • perform oxidation reactions that lead to hydrogen peroxide creation then use catalase to convert it to water and oxygen or to oxidize other organic compounds
  • contain enzymes that are involved with the synthesis of plasmalogens (phospholipids)
what else do they do
What else do they do?
  • synthesize cholesterol and dolichol in animal cells
  • synthesize bile acids when in the liver
  • in plants they convert fatty acids to carbohydrates, if a peroxisome does this function it is called a glyoxysome because the reaction is called the glyoxylate cycle
purpose function in cell
Purpose/Function in cell
  • Supplies a cell with the energy it needs to function
    • Produces ATP, cell’s main energy source
  • Component for synthesis of RNA and DNA
  • Size of bacteria, take different shapes according to cell type
  • Have a double membrane
    • Outer membrane is smooth
    • Inner membrane has intricate folds called cristae
      • creates high surface area
      • where ATP is created (through combination of sugar and oxygen)
  • Has its own DNA
  • Synthesizes its own protein
  • Reproduces (fission)
  • Endosymbiotic Hypothesis / “Pac Man Hypothesis”
    • Explains origin of mitochondria and chloroplast
    • symbiosis= “living together” (mutualistic relationship)
    • Started w/mitochondria entering the chloroplast, the larger cell
    • Chloroplast benefits b/c the mitochondria takes in/produces energy that chloroplast can use
    • Mitochondria benefits b/c is protected, can get food from large cell which can get it easily
    • Now, neither can survive without the other
form function
  • Because of its small size, it can exist inside chloroplast and provide it with ATP.
  • A chloroplast’s job is to create food for the cell.
  • So, it makes sense that the mitochondria should take form inside the chloroplast, since it is necessary to help the chloroplast perform its job.
works cited4
Works Cited
  • “Eukaryotic Cells,”
  • “Electron Micrograph Showing Single Nucleus and Many Mitochondria,”
  • “Mitochondria,”
  • “The Mitochondria,”
  • “Chloroplasts- Show me the Green,”


The Power Center of the Cell

form and function5
Form and Function

Mitochondria can have different shapes, but all serve the same function.

Dual Membrane structure

Inner membrane and Outer membrane

The Space in between the membranes is the intermembrane space.

Inner membrane is folded (SA/V ratio), and the folds are called CRISTAE.

The Cristae are where oxygen and sugar are combined to create ATP-the main source of energy for the cell.

The Area inside the folded inner membrane is called the matrix.

Intermembrane Space

form and function cont d
Form and Function Cont’d…
  • Responsible for Cellular Respiration
    • The digestion of nutrients which are used to create ATP.
  • The number of mitochondria depends on the work the cell needs to do
    • For example- a muscle cell will have more mitochondria than a nerve cell.

evolution hypothesis
Evolution Hypothesis

Mitochondria have their own DNA

DNA similar to that of bacteria

Endosymbiosis- small species of bacteria survived ingestion by a Prokaryote and was incorporated into the cytoplasm- where it then evolved into the organelle it is today.

Evolution- cells capable of the creation of energy would have a serious advantage over other cells- natural selection


endosymbiotic hypothesis
Endosymbiotic Hypothesis!
  • Cytomembranes and the Nuclear Envelope developed in a simple cell from the Plasma Membrane by Endocytosis.
  • Purplebacteria were “eaten” by the cell throughEndosymbiosisand became early-stage Mitochondria.
  • Cyanobacteria were “eaten” by the cell throughEndosymbiosisand became Chloroplasts! (At this time the Mitochondria appear to be fully formed.)
form and function6
Form and Function!
  • Chloroplasts are in photosynthetic cells which are usually in the middle (mesophyll) of plant leaves, because they can receive the most energy from the sun that way.
  • Inside of the Chloroplast is a double membrane that forms a fluid compartment (stroma) between the layers. Between these layers are Thylakoids which are very important, small, disc-like sub-organelles that hold all the machinery for photosynthesis. Stacks of Thylakoids are called grana.
  • There are Chlorophyll molecules in the membrane that catch the light energy and convert it into chemical energy that the plant can use.
  • The double membrane and the Thylakoids in there are very helpful because they increase the surface area of the cell and can hold lots of enzymes and other stuff that’s good for the cell!
  • Origin: Endosymbiotic
  • Electron Micrograph of Plant Cell

  • Energy Production: Chloroplasts and Mitochondria



By Emily Schwab

  • Definition: “A thin, helical, single-stranded filament of the cytoskeleton found in the cytoplasm of eukaryotic cells, composed of actin subunits, and functions primarily in maintaining the structural integrity of a cell and cell movements.”
  • Microfilaments are polar because the actin subunits they are made of are polar
  • The ends of a microfilament are often called “pointed” or “barbed” because they look like arrowheads when they have fragments of myosin II


Structural role is to bear tension from forces pulling in different directions

Makes a three-dimensional support system just inside the plasma membrane to support the cell’s shape

Bunches of microfilaments also make up the core of microvilli, which increase a cell’s surface area


  • Primary function is maintaining the structure of a cell
    • Forms a band under the cell membrane
  • Allows cell to move
    • Play a role in the contraction of muscle
    • Important for amoeboid movement
  • Gives the outer layer of a cell a semisolid consistency
  • Anchors centrosomes on opposite sides of a cell during mitosis
  • Attaches transmembrane proteins to cytoplasmic proteins
  • Part of some cell junctions

Electron Micrograph Images


works cited5
Works Cited
  • “Microfilament”
  • “Microfilament”
  • Biology Eighth Edition by Campbell and Reece
  • Image 1
  • Image 2
  • Image 3
  • Image 4
intermediate filaments
Intermediate Filaments
  • Fibrous Proteins
  • Found in almost all eukaryotes except fungi
  • Larger than Actin smaller than Microtubules
  • No motor proteins
  • One of three types of cytoskeleton elements
    • Works to enhance cell structure, shape and integrity
    • Most common in cells that withstand mechanical stress
    • Most insoluble part of the cell
five different types
Five Different Types
  • I
    • Acidic Keratin-Epithelial cells
  • II
    • Basic Keratin-Epithelial Cells
  • III
    • “Intermediate filaments are distributed in a number of cell types, including:Vimentin in fibroblasts, endothelial cells and leukocytes; desmin in muscle; glial fibrillary acidic factor in astrocytes and other types of glia, and peripherin in peripheral nerve fibers.”
  • IV
    • Neurofilament H (heavy), M (medium), L (low).
  • V
    • Lamins that have nuclear signal sequence. Important for the re-formation of nuclear envelope after cell division
form and function7
Form and Function
  • Polymers
  • Constructed like a multistrand rope
  • Spontaneously self-assembles
    • Easily adaptable to help support the cell in changing structural conditions


Hannah Braun

  • One of the main components of the cytoskeleton
  • Polymers
  • They are polar
  • Organized by centrioles and basal bodies
  • Are able to grow and shrink their size in order to generate energy
  • Formed in the aster which is near the nucleus
  • The half lives tend to be very short for microtubules
  • Hollow cylinders
  • The building blocks of microtubules
  • Two types of tubulin
    • Alpha
    • Beta
    • Sometimes found as individual proteins
  • Involved in mitosis, cytokinesis, and vesicular transport
  • Cell transport and cell division in eukaryotes
  • Cilia and flagella movement in eykaryotes
works cited6
Works Cited
  • Are found only in animal cells.
  • Composed of grouping of microtubules, then organize the assembly of microtubules during cell division.
  • They can handle dramatic pertrubutions while still maintaining their basic functions.
electron micrograph of centrioles
Electron Micrograph of Centrioles
  • A form of 9 triplets of a microtubule make one centriole.
  • Arranged in a 9+3 pattern.
  • Have a nine fold symmetric structure.
  • Have a very basic core structure, which means it only need a few amount of genes in its structure.
evolution function
“Forms Spindle Fibers to separate chromosomes during cell division.”

Form Cilia and Flagella.

Replicate in interphase stage of mitosis.

Evolution Function
  • Many do not know how Centrioles evolved because of their capability of apparent self-reproduction.
cilia and flagella
Flexible extensions of cell.

Cilia are the many short extensions of the cell, and flagella are the one or two long extensions.

The evolution of cilia and flagella have not yet been determined.

Cilia and Flagella
cilia and flagella1
Flagella cross section

Their function is to create the main source of movement for the cell and bring food particles into the cell.

They not only allow the cell itself to move, but they also allow liquids and particles to move across their surface.

Ex) moving the egg from the ovary through the fallopian tube

They have 9 sets of 2 microtubules inside. Collected, they are called “axoneme”.

Cilia and Flagella
cilia and flagella2
Movement is caused when ATP is present, causing a bending motion of the microtubules inside the cilia and flagella.

The bending motion of the microtubules is caused by a protein called “dynein”. Dynein is located in between the sets of microtubules. It pulls one set down and then releases it, causing the other to bend and then bounce back up.

Cilia and Flagella
the cell wall

The Cell Wall

By: Nikki Vinyard

the organelle
The Organelle
  • Helps distinguish between the animal cell and the plant cell
  • Contains molecules that monitor the growth of plants but also protect from disease
  • Cellulose (complex carbohydrate) found in cell wall
  • Polysaccharides present (pectins & cross-linking glycans)
    • The main polysaccharides: hemicellulose and pectin
  • Some proteins discovered in cell wall
  • Enzymes exist here as well
  • Secondary wall will sometimes develop inside first cell wall after the cell cedes growth
  • Protects plant cells
  • Maintains shape of cell
  • Prevents too much intake of H2O
  • Structural support
  • Resistance of internal pressure
  • Growth rate
  • Material regulation
  • Carb storage
  • Cell -> Cell reactions
  • Enzymes:
    • Start reactions, remodel, breakdown
  • The evolution of the cell wall is unclear
  • (picture)
  • (picture)
  • Plant Cell Wall:
  • Plant Cell Walls: