Are All Cells Alike

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Are All Cells Alike?

• All living things are made up of cells. Some
  organisms are composed of only one cell. Other
  organisms are made up of many cells.
• 1. What are the advantages of a one-celled
  organism?
• 2. What are the advantages of an organism that is
  made up of many cells?

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Cells

• vary in size
• possess distinctive shapes
• measured in micrometers

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Cells
Prokaryotes
Eukaryotes
Nucleus Endoplasmic reticulum Golgi
apparatus Lysosomes Vacuoles Mitochondria Cytoskel
eton
Cell membrane Ribosomes Cell wall
Animal Cells
Plant Cells
Cell membrane Ribosomes Nucleus Endoplasmic
reticulum Golgi apparatus Vacuoles Mitochondria Cy
toskeleton
Lysosomes
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Plant Cell
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Animal Cell
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A Composite Cell

• major parts
• nucleus
• cytoplasm
• cell membrane

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Cell Membrane

• outer limit of cell

• controls what moves in and out of cell

• selectively permeable

• phospholipid bilayer
• water-soluble heads form surfaces
• water-insoluble tails form interior
• permeable to lipid-soluble substances

• cholesterol stabilizes the membrane

• proteins
• receptors
• pores, channels, carriers

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Outside of cell
Inside of cell (cytoplasm)
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Cell Nucleus

• control center of cell

• nuclear envelope
• porous double membrane
• separates nucleoplasm from cytoplasm

• nucleolus
• dense collection of RNA and proteins
• site of ribosome production

• chromatin
• fibers of DNA and proteins
• stores information for synthesis of proteins

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Cytoplasm

• area between plasma membrane and nuclear membrane
• cytosol--semi-flluid, jellylike medium in which
  organelles are suspended
• cytoskeleton--network of fibers helps with cell
  support locomotion

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Cytoplasmic structures and Organelles

• Endoplasmic Reticulum
• Ribosomes
• Golgi apparatus
• Mitochondria
• Chloroplasts (Plant cells only)
• Vesicles
• Lysosomes (Animal cells only)
• Peroxisomes
• Centrosomes (centrioles)
• Cilia
• Flagellum
• Microfilaments Microtubules

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Endoplasmic Reticulum

• connected, membrane-bound sacs, canals, and
  vesicles
• transport system
• rough ER
• studded with ribosomes
• protein synthesis
• smooth ER
• lipid synthesis
• added to proteins arriving from rough ER
• break down of drugs

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Ribosomes

• Site of protein synthesis
• manufacture proteins using information provided
  by DNA
• 2 types of ribosomes
• free ribosomes-single or in strands
• fixed (bound) ribosomes-attached to rough
  endoplasmic reticulum

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Golgi apparatus

• 1898 Camillo Golgi (Italian Scientist) stack of
  flattened, membranous sacs (cisternae)
• modifies, packages and delivers proteins (Ex.
  hormones or enzymes for release through
  exocytosis)
• Packaging of special enzymes within vesicles for
  use in the cytosol

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Mitochondria

• membranous sacs with double membrane
• Outer surrounds organelles
• Innerfolds called cristae increase S.A.
• generate energy (ATP)
• in cell depends on cell energy demands

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Mitochondria
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Vesicles

• membranous sacs
• store substances

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Lysosomes

• enzyme-containing sacs
• digest worn out cell parts or unwanted substances
• vesicles filled with digestive enzymes
• produced at Golgi Apparatus
• function in defense against disease

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Peroxisomes

• enzyme-containing sacs
• break down organic molecules
• smaller than lysosomes
• carry different group of enzymes
• originate in RER
• absorb neutralize toxins. Ex. alcohol
• most abundant in liver cells

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Centrosomes

• Centrosome
• two rod-like centrioles
• used to produce cilia and flagella
• distributes chromosomes during cell division

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Cilia Flagellum

• Cilia
• short hair-like projections
• propel substances on cell surface

• Flagellum
• long tail-like projection
• provides motility

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Microfilaments and Microtubules

• thin rods and tubules
• support cytoplasm
• allows for movement of organelles

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Chloroplast

• Found in plants and algae only
• Plant plastids
• Chloroplast (green plastids)-store chlorophyll
• Leucoplast (white plastid)- store starch
• Chromoplast (colored plastid)-named for
  pigments besides chlorophyll i.e. carotene
  (orange) etc.