Basic Structure of a Cell

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Basic Structure of a Cell
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Introduction to Cells

• Cells are the basic units of organisms
• Cells can only be observed under microscope
• Basic types of cells

Bacterial Cell
Animal Cell
Plant Cell
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Number of Cells

• Organisms may be
• Unicellular composed of one cell
• Multicellular- composed of many cells that may
  organize

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Cells May be Prokaryotic or Eukaryotic

• Prokaryotes include bacteria lack a nucleus or
  membrane-bound structures called organelles
• Eukaryotes include most other cells have a
  nucleus and membrane-bound organelles (plants,
  fungi, animals)

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Prokaryotes

• Nucleoid region contains the DNA
• Cell membrane cell wall
• Contain ribosomes (no membrane) to make proteins
  in their cytoplasm

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Eukaryotic Cell

• Contain 3 basic cell structures
• Nucleus
• Cell Membrane
• Cytoplasm with organelles

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Two Main Types of Eukaryotic Cells
Animal Cell
Plant Cell
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Organelles

• Very small size
• Can only be observed under a microscope
• Have specific functions
• Found throughout cytoplasm

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CELL WALL
Cell wall
Protect and support the enclosed substances
(protoplasm) Resist entry of excess water into
the cell Give shape to the cell
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CELL WALL

• Made of cellulose which forms very thin fibers
• Strong and rigid
• Found in plant cells

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Cell or Plasma Membrane
Cell membrane
Living layer Controls the movement of materials
into and out of the cell Selectively permeable
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Surrounding the Cell
Lies immediately against the cell wall in plant
cells Made of protein and phospholipids Selectivel
y permeable
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Cytoplasm of a Cell
Jelly-like substance enclosed by cell
membrane Provides a medium for chemical reactions
to take place
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More on Cytoplasm
Cytoplasm
Contains organelles to carry out specific
jobs Examples chloroplast mitochondrion
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NUCLEUS
Controls the normal
activities of the cell Bounded by a

nuclear membrane Contains chromosomes
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More on the Nucleus
Nucleus
Each cell has fixed
number of chromosomes that
carry genes Genes control cell characteristics
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Nucleolus

• Cell may have 1 to 3 nucleoli
• Inside nucleus
• Disappears when cell divides
• Makes ribosomes that make proteins

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Smooth Rough Endoplasmic Reticulum
Smooth ER lacks ribosomes makes proteins USED
In the cell Rough ER has ribosomes on its surface
makes proteins to EXPORT
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RIBOSOMES

• Small specks made of RNA.
• Found in cytoplasm or on the endoplasmic
  reticulum
• Makes proteins

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Cell Powerhouse
Rod shape Site of Cellular respiration
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In Animal Cells
Mitochondria
Active cells like muscles have more
mitochondria Burn sugars to produce energy ATP
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Plant Cell Organelles
Have a large central vacuole Surrounded by
tonoplast Contains cell sap Sugars, proteins,
minerals, wastes, pigments
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Plant Cell Organelles
Contain the green pigment chlorophyll Traps
sunlight to make sugars (food) Process called
photosynthesis
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Golgi Bodies

• Stacks of flattened sacs
• Have a shipping side a receiving side
• Receive modify proteins made by ER
• Transport vesicles with modified proteins pinch
  off the ends

Transport vesicle
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Lysosome

• Contain digestive enzymes
• Break down food and worn out cell parts for cells
  
• Programmed for cell death (lyse release enzymes
  to break down recycle cell parts)

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LYSOSOME

• Small cylindrical
• Used during mitosis

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Different kinds of plant cells
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Animal cell
cytoplasm
vacuole
No cell wall or chloroplast Stores glycogen in
the cytoplasm for food energy
nucleus
mitochondrion
cell membrane
glycogen granule
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Animal Cell Organelles

• Near the nucleus
• Paired structures
• Help cell divide

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Different kinds of animal cells
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Similarities between plant cells and animal cells

• Both have a cell membrane surrounding the
  cytoplasm

Both have a nucleus
Both contain mitochondria
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Differences between plant cells and animal cells
Animal cells
Plant cells
Relatively smaller in size
Relatively larger in size
Irregular shape
Regular shape
No cell wall
Cell wall present
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Differences between Plant Cells and Animal Cells
Animal cells
Plant cells
Vacuole small or absent
Large central vacuole
Glycogen as food storage
Starch as food storage
Nucleus at the center
Nucleus near cell wall
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STRUCTURE FUNCTION OF CELL MEMBRANE(pp. 59-60)
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Structure function of cell membranes

• Lipids form foundation of membranes
• Separates inside of cell from outside
• Selectively permeable how phospholipids
• interact with H2O

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CELL MEMBRANE AS BARRIER

• Phospholipids Phosphate group 2 fatty acids
• Polar head phosphate group attracted to water
• (hydrophilic)
• 2 Non-polar tails fatty acids repelled by
  water interior of membrane
• (hydrophobic)

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• Lipid bilayer double layer
• Non-polar tails interior repels ions, polar
  molecules (sugars, proteins)

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PROTEINS EMBEDDED IN LIPID BILAYER

• What keeps proteins within lipid bilayer?
• Some amino acids (remember, amino acids make up
  proteins) are polar / non polar
• Non polar part attracted to the interior of
  lipid bilayer, but repelled by H2O on either side
• Polar part attracted to H2O on either side of
  lipid bilayer
• DUAL ATTRACTION holds protein in lipid bilayer

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Cell Membranes Contain Different Types of Proteins

1. MARKER proteins attached to carbohydrate on
   cells surface (help other cells recognize their
   cell type (heart, liver)
2. RECEPTOR proteins recognize and bind to
   specific substances
3. ENZYMES involved in important biochemical
   reactions
4. TRANSPORT proteins aid in the movement of
   substances into and out of the cell