Cell Structure

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Cell Structure Function
http//koning.ecsu.ctstateu.edu/cell/cell.html
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Cell Theory

• All living things are made up of cells.
• Cells are the smallest working units of all
  living things.
• All cells come from preexisting cells through
  cell division.
• Proposed by three German biologists, Matthias
  Schleiden, Theodor Schwann, and Rudolf Virchow

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Definition of Cell

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

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

• Prokaryotic
• Eukaryotic

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Prokaryotic

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

http//library.thinkquest.org/C004535/prokaryotic_
cells.html
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Figure 6.6 A, B
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Eukaryotic

• Contain organelles surrounded by membranes
• Most living organisms

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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• A animal cell

Figure 6.9
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Typical Plant Cell
http//waynesword.palomar.edu/images/plant3.gif
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• A plant cell

CYTOSKELETON
In plant cells but not animal cells Chloroplasts
Central vacuole and tonoplast Cell
wall Plasmodesmata
Figure 6.9
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Cell Parts

• Organelles

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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

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

• Most commonly found in plant cells bacteria
• Supports protects cells

http//library.thinkquest.org/12413/structures.htm
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Inside the Cell
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Nucleus

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

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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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• The nuclear envelope
• Encloses the nucleus, separating its contents
  from the cytoplasm

Figure 6.10
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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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Nucleolus

• Inside nucleus
• Contains RNA to build proteins

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

• Gel-like mixture
• Surrounded by cell membrane
• Contains hereditary material

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Prokaryotic

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

http//library.thinkquest.org/C004535/prokaryotic_
cells.html
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Eukaryotic

• Contain organelles surrounded by membranes
• Most living organisms

Plant
Animal
http//library.thinkquest.org/C004535/eukaryotic_c
ells.html
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Endoplasmic Reticulum

• 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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• The ER membrane
• Is continuous with the nuclear envelope

Figure 6.12
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Ribosomes

• Each cell contains thousands
• Make proteins
• Found on ribosomes floating throughout the cell

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

• Produces energy through chemical reactions
  breaking down fats carbohydrates
• Controls level of water and other materials in
  cell
• Recycles and decomposes proteins, fats, and
  carbohydrates

http//library.thinkquest.org/12413/structures.htm
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• Mitochondria are enclosed by two membranes
• A smooth outer membrane
• An inner membrane folded into cristae

Figure 6.17
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Golgi Bodies

• Protein 'packaging plant'
• Move materials within the cell
• Move materials out of the cell

http//library.thinkquest.org/12413/structures.htm
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Golgi apparatus

• Functions of the Golgi apparatus

Figure 6.13
TEM of Golgi apparatus
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Lysosome

• Digestive 'plant' for proteins, fats, and
  carbohydrates
• Transports undigested material to cell membrane
  for removal
• Cell breaks down if lysosome explodes

http//library.thinkquest.org/12413/structures.htm
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• Lysosomes carry out intracellular digestion by
• Phagocytosis

Figure 6.14 A
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Vacuoles

• Membrane-bound sacs for storage, digestion, and
  waste removal
• Contains water solution
• Help plants maintain shape

http//library.thinkquest.org/12413/structures.htm
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• Central vacuoles
• Are found in plant cells
• Hold reserves of important organic compounds and
  water

Figure 6.15
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Chloroplast

• Usually found in plant cells
• Contains green chlorophyll
• Where photosynthesis takes place

http//library.thinkquest.org/12413/structures.htm
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• Chloroplasts
• Are found in leaves and other green organs of
  plants and in algae

Figure 6.18
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• Cell structure is correlated to cellular function

Figure 6.1
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• The cytoskeleton
• Is a network of fibers extending throughout the
  cytoplasm

Figure 6.20
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• Contains a pair of centrioles

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• Flagella beating pattern

Figure 6.23 A
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• Ciliary motion

15 µm
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In Summary
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There are two major types of cells

• Prokaryotic
• Found in Domains Bacteria and Archaea
• Kingdoms Eubacteria and Archaebacteria
• Eukaryotic
• Found in Domain Eukarya
• Kingdoms
• Protista
• Plantae
• Animalia
• Fungi

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Major Characteristics

• Prokaryotes
• Small
• Simple cells
• Have cell membrane, cytoplasm, ribosomes, DNA in
  form of nucleoid
• Sometimes have cell wall, capsule, other
  projections from wall (bacterial cilia, pili)
• DO NOT HAVE internal organelles or nucleus

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Major Characteristics

• Eukaryotes
• Larger
• Complex cells
• Have cell membrane, cytoplasm, ribosomes, DNA in
  form of chromosomes
• Sometimes have cell wall (plants and fungi) and
  structures for movement (cilia and flagella)
• HAVE internal organelles and nucleus