Cell Structure

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Cell Structure Function
http//koning.ecsu.ctstateu.edu/cell/cell.html
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Cytology-Study of Cell Biology
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Definition of Cell

• A cell is the smallest unit that is capable of
  performing life functions.

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The Cell

• A cell is the smallest unit of living matter.
• Dont confuse this with atom, element, proton,
  etc.

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Cell Structure

• Relies on 4 critical properties
• Matter
• Energy
• Organization
• Information

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Matter

• Matter found in living matter is composed of
  elements, molecules, and macromolecules
• Life (cells) depend on organic molecules
• Cells are composed of the same macromoleculescarb
  ohydrates, lipids, proteins, nucleic acids.
• These compounds are composed of 6 main elements.
  C H O N P S

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Energy

• Needed to carryout life processes
• Build molecules and macromolecules(synthesis)
• Break down macromolecules and molecules
• To carryout cell functions
• To overcome disorder , to maintain organization
• Energy molecule the cell uses is
• ATP adenosine triphosphate

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Organization

• Cells are not a haphazard bag of components
• Molecules and macromolecules that make up cells
  have specific sites where they are found.

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Information-Cell organization requires
instructions

• Genetic materials that carries the instructions
• Genome- the entire complement of its genetic
  material
• Every living cell has a copy of its genome
• Genome contains the genes that carry the
  information to create cells with particular
  structures and functions.

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Cell Theory

• Theory is not a casual term in science.
• Tested innumerable times with consistent results.
• Universally accepted
• One of the most basic, fundamental concepts in
  the foundation of biology.

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Cell Theory 1800s

• 1. Matthias Schleiden- GermanBotanist
• Studied plant material
• Saw compartments with dark areas
• Cells are living entities and plants are
  aggregates of cells
• 2. Theodor Schwann-German physiologist
• friend of Schleiden
• He saw similar compartments and large
  numbers nuclei in animal tissues.
• Schwann extended Schleidens hypothesis to
  animals.
• 3.Rudolf Virchow-German Biologist
• Research diseased cells-discovered that every
  cell originate from another cell

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Cell Theory

• All organism are made of cells.
• Cells are the smallest structural and functional
  units of organisms
• All cells come from pre-existing cells
• Cells are capable of self-reproduction by cell
  division.

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Cell Size-Cells are small
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Types of Organisms based on number of cells

• Unicellular organisms
• Bacteria, Protists, etc.
• Multicellular organisms
• Protist
• Fungi
• Plants
• Animals
• Muscles, skin, nerves, liver, digestive, bones,
  blood, immune system, lungs, etc.

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Two Types of Organism based on Cell Structures

• Prokaryotes- organisms that have prokaryotic
  cells- cells that do not have a nucleus or
  organelles
• Eukaryotes-organism that have eukaryotic
  cells-cells that have a nucleus and structures
  called organelles that carryout specific
  functions.

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All Cells have the following

• Plasma membrane-Maintains Homeostasis
• Structure--Made of 2 layers (bilayer) of
  phospholipids and embedded proteins, can give
  some cells their shape
• Insoluble in water
• Main Function-Maintain Homeostasis by
• Forms a barrier between the cells internal
  environment and the external environment
• Semipermeable-controls movement of material into
  and out of cell
• Communicates with other cell membranes and
  molecules in the external environment

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2. Cytoplasm

• Region of the cell that is contained within the
  plasma membrane
• Fluid within the cell that contains water and
  molecules

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3. Ribosomes

• Made of RNA molecules Ribonucleic Acid
• Function- place where polypeptides and protein
  are synthesize (produced)
• Free Ribosomes are found in cytoplasm of both
  prokaryotic and eukaryotic cells
• Bound Ribosomes are found on rough Endoplasmic
  reticulum in eukaryotic cells

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4.Genetic Material-DNA

• Prokaryotic Cells-DNA is found in the central
  part of cytoplasm called the nucleoid region
• Eukaryotic Cells-DNA is found inside the Nucleus
• DNA in the two cell types is precisely the same
  kind of DNA, and the genetic code is exactly the
  same

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Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
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Prokaryotic Cell

• Do not organelles-- structures surrounded by
  membranes
• Few internal structures
• One-celled organisms,
• Bacteria

http//library.thinkquest.org/C004535/prokaryotic_
cells.html
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Prokaryotic Cells

• Small, less complexity
• all materials within the cell are relatively
  close together
• Prokaryotic cells have no nucleus.
• DNA is circular (it has no ends) and is found in
  nucleoid region is essentially an imaginary
  "structure." There is no physical boundary
  enclosing the nucleoid.

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Prokaryotic Cells

• Prokaryotic ribosomes are small and composed of
  only three kinds of rRNA and about fifty kinds of
  protein.
• contains no membrane-bound organelles.

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Basic Prokaryotic Cell
Capsule or Slime layer Some bacteria Surrounds
the cell wall and plasma membrane Made up of
polysaccharides . Function Traps water to keep
the bacterium from drying out and to protect it
from phagocytosis (engulfing) by larger
microorganisms.
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More Structures

• Cell Wall-
• rigid structure outside the plasma membrane.
• Functions
• It supports and protects the plasma membrane.
• It is permeable and will allow material to reach
  the plasma membrane.

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More Structures

• Pili - Many species of bacteria have pili
  (singular, pilus), small hairlike projections
  emerging from the outside cell surface.
• These outgrowths assist the bacteria in attaching
  to other cells and surfaces, such as teeth,
  intestines, and rocks. Without pili, many
  disease-causing bacteria lose their ability to
  infect because they're unable to attach to host
  tissue.
• Flagella - Flagella (singular, flagellum) are
  hairlike structures that provide a means of
  locomotion for those bacteria that have them.
  They can be found at either or both ends of a
  bacterium or all over its surface. The flagella
  beat in a propeller-like motion to help the
  bacterium move toward nutrients away from toxic
  chemicals or, in the case of the photosynthetic
  cyanobacteria toward the light.

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Eukaryotic

• Contain organelles small structures surrounded
  by membranes that perform specific functions
• All other organisms except Bacteria

Plant
Animal
http//library.thinkquest.org/C004535/eukaryotic_c
ells.html
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Typical Animal Cell
http//web.jjay.cuny.edu/acarpi/NSC/images/cell.g
if
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Typical Plant Cell
http//waynesword.palomar.edu/images/plant3.gif
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Surrounding the Cell
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Cell Membrane

• Outer membrane of cell that controls movement in
  and out of the cell
• Double layer of phospholipids (bilayer)
• Animal (Blue 1)
• Plant (Blue 4)

http//library.thinkquest.org/12413/structures.htm
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Cell Wall

• Most commonly found in plant cells bacteria
• Made of carbohydrates-cellulose in plants
• Not found in animal cells
• Supports protects cells
• Plant Cell (Red 2.3)

http//library.thinkquest.org/12413/structures.htm
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Cells walls are in plant cells not animal cells
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Inside the Cell
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Eukaryotic Cell

• Part I. Cytosol
• Occupies about 50 of volume
• Site of many chemical reactions-Metabolism
• 1. Main Structure is Cytoskeleton
• 1.Microfilaments
• 2. Microtubules
• 3. Cilia
• 4. Flagellum

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Part II Nucleus
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Nucleus

• Directs cell activities
• Separated from cytoplasm by nuclear membrane
• Contains genetic material - DNA

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Nucleus DNA stored here.The Control Center
Nuclear envelope membrane surrounding the
nucleus Nuclear pores open portals of
communication between the nucleus
cytoplasm Chromatin condensed DNA Chromosome
very tightly packed DNA Nucleolus dense region
of chromatin
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Nucleolus

• Inside nucleus
• Contains RNA to build proteins

http//library.thinkquest.org/12413/structures.htm
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Nuclear Membrane

• Surrounds nucleus
• Made of two layers
• Openings allow material to enter and leave
  nucleus

http//library.thinkquest.org/12413/structures.htm
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Chromosomes

• In nucleus
• Made of DNA
• Contain instructions for traits characteristics
  

http//library.thinkquest.org/12413/structures.htm
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Part III Endomembrane System

• Network of membranes and organelles where
  molecules are produced and modified and
  transported in and out of cell

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Endoplasmic Reticulum

• Interconnected highway within the cell
• Moves materials around in cell
• Smooth type lacks ribosomes
• Rough type (pictured) ribosomes embedded in
  surface

http//library.thinkquest.org/12413/structures.htm
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Ribosomes protein factories Rough ER make
proteins (studded with ribosomes) Smooth ER
make lipids, modify proteins made in RER
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Golgi Bodies

• Protein processing, modifications and repackaging
  organelle
• Called Golgi complex or apparatus also

http//library.thinkquest.org/12413/structures.htm
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1-receives proteins lipids in membrane-bound
vesicles from ER.2-modifies those proteins
lipids.3-sorts and ships the proteins lipids
away in membrane-bound vesicles.
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Lysosome

• Digest cell parts and waste
• Contains many digestive enzymes
• Break down proteins, fats, and carbohydrates and
  waste products
• Transports undigested material to cell membrane
  for removal
• Cell breaks down and is digested if lysosome
  membrane is broken
• Animal development

http//library.thinkquest.org/12413/structures.htm
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Vacuoles

• Membrane-bound sacs for storage,
• Stores water, waste, toxins,
• Stores enzymes for digestion, and waste removal
• Contains fluid (water and molecules
• Help plants maintain shape (central vacuole)

http//library.thinkquest.org/12413/structures.htm
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Central Vacuole-takes up much of plant cell
volume
Tonoplast is the membrane around the central
vacuole Central vacuole stores water, salts,
organic compounds etc. for the plant cell The
pressure inside the vacuole builds up and
enables plant cells to support omplex structure
such as leaves and flowers
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        Vacuoles and vesicles are storage
organelles in cells. Vacuoles are larger than
vesicles. Either structure may store water, waste
products, food, and other cellular materials. In
plant cells, the vacuole may take up most of the
cell's volume.
The membrane surrounding the plant cell vacuole
is called the tonoplast.
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Video of Paramecium contractile vacuole
http//www.youtube.com/watch?v4z98WIeNtjM
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Part IV Semiautonomous Organelles

• These organelles can grow and divide to
  reproduce themselves
• But still depend on other parts of the cell

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Mitochondria

• Small, can be few hundred to thousands.
• Cell needing a lot of energy will have thousands
• Cellular Respiration changes chemical energy (
  fats carbohydrates) into a energy
  molecule(ATP)
• ATP is what cell used to do work
• Controls level of water and other materials in
  cell
• Recycles and decomposes proteins, fats, and
  carbohydrates

Contains Maternal DNA
http//library.thinkquest.org/12413/structures.htm
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Chloroplast-site of Photosynthesis

• Only found in plant cells and other
  photosynthetic cells
• Never found in animal cells

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Chloroplast

• Contain there own DNA
• Contains green chlorophyll pigment
• Where photosynthesis takes place
• Converting Inorganic compounds into sugar using
  suns energy

Not found in animal cells
http//library.thinkquest.org/12413/structures.htm
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Peroxisomes

• Catalyze certain chemical reactions
• Breaks down molecules by removing hydrogen or
  adding oxygen
• Liver cells have many peroxisomes
• Toxins in the liver cells are broken down and
  release hydrogen peroxide- a lethal toxin to
  cells.
• Catalase enzyme breaks hydrogen peroxide into
  water and oxygen gas