Cell: the smallest unit of life

Discovery of Cells

• 1665- Robert Hooke was the first to identify and name cells.

• 1674- Anton van Leeuwenhoek made better lenses and observed cells in greater detail.

• 1838- Mathias Schleiden noted that plants are made of cells

• 1839- Theodor Schwann concluded that all living things are made of cells

• 1855- Rudolf Virchow proposed that all cells come from other cells

Cell Theory

• All organisms are made of cells

• All existing cells are produced by other living cells.

• The cell is the most basic unit of life.

Prokaryotic cells

• Simple cells

• No nucleus

• Ex: bacteria

Staphylococcus aureus

Prokaryotic Cell

E Coli BacteriaEnterococcus

faecalis Bacteria

Eukaryotic Cells

• More complex

• Have a true nucleus

• Make up all living cells other than bacteria

Eukaryotic Cell

Nerve cellNerve Cell

Hair CellFingernail

White and Red Blood Cells

Similarities and differences between the Prokaryotic and Eukaryotic Cells

Prokaryotic cells Eukaryotic cells

Cell size 1-10 micrometers 10-100 micrometers

Cell membrane? Yes Yes

Membrane-bound organelles?

No Yes

Have nucleus? No Yes

Have cytoplasm? Yes Yes

Have DNA Yes, in cytoplasm Yes, in nucleus

Examples Bacteria Fungi, plants, animals

Cells use three different methods to move themselves or debris

Flagella: long hairlike filaments used by some prokaryotes to move

Flagellum

Cilia: short hairlike projections that some cells use for movement

Pseudopod: false foot

Picture Quiz

• Identify the cells as prokaryotic or eukaryotic.

Eukaryotic- Mushroom Cell

Eukaryotic- Red blood cells

Prokaryotic- Lactobacilli bacteria

Eukaryotic- fish egg cell

Prokaryotic- MRSA

Prokaryotic- Streptococcus pneumoniae bacteria

Eukaryotic- Fern leaf cell

Eukaryotic- taste bud cell

Eukaryotic- Osteocyte (bone cell)

Eukaryotic- cartilage cells

Cell Organelles• Specialized cell parts that carry out many

different processes and functions.

Cell membrane• Barrier around the cell that controls what goes in

and out• Security Guard

Nucleus

• Controls most of the cell’s processes

• Stores DNA

• Control center or ‘brain’

Nuclear Membrane

• Separates the nucleus from the rest of the cell

Nucleolus

• Darker portion inside the nucleus that produces ribosomes

Cytoplasm (cytosol)

• Jelly-like fluid inside the cell where metabolic processes occur

Ribosome

• Small organelles that float in the cytoplasm or on the ER that build proteins

• Cell workers

Endoplasmic Reticulum

• Produces and transports materials such as proteins

• Assembly line

Golgi Apparatus (Golgi body)

• Packages and distributes proteins and lipids

• Shipping and handling department

Lysosome

• Stores enzymes and removes worn-out organelles. Mainly in animal cells.

• Waste disposal unit

Mitochondria

• Provides energy for the cell

• Powerhouse or powerplant

Cytoskeleton• Thin protein fibers that helps keep the

cell’s shape

Centrioles

• Only found in animal cells that are important for cell division

Cell wall

• Found only in plant and fungus cells.

• Provides extra shape, support and protection.

Chloroplast• Found only in plant cell. They contain

chlorophyll used for photosynthesis

Vacuole

• Stores water, salts, and wastes. Plants have larger ones

• Storage unit

Differences Between Plant and Animal Cells

Plant Cells Animal Cells

Have a Cell Membrane, Nucleus, Mitochondria, Ribosomes, Golgi apparatus, and Endoplasmic Reticulum?

YES YES

Have a Cell Wall? YES NO

Have Lysosomes? NO (rarely) YES

Have Vacuoles? YES None or Small

Have Chloroplasts? YES NO

Cellular Differentiation

• 250 different kinds of cells in the human body

• Through cellular differentiation, different types of cells are created to carry out specific tasks or functions.

• In animals the “starter” cells that differentiate are called stem cells

• In plants those cells are called meristematic cells

Cellular Organization

Cells

Tissues

Organs

Organ Systems

Organisms

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stics-of-prokaryotic-cells-312-11445/• http://www.extension.org/pages/28432/staphylococcus-aureus#.Vb5UOkL5NUQ• https://en.wikipedia.org/wiki/Escherichia_coli• https://commons.wikimedia.org/wiki/File:Enterococcus_faecalis_SEM_01.png• https://www.reddit.com/r/RealMicroscopicLife• http://biologos.org/blog/bacterial-flagellum-appearances-can-be-deceiving• http://www.turbosquid.com/Search/Index.cfm?keyword=flagella• http://www.sciencefriday.com/segment/07/22/2011/video-pick-engineering-artificial-cilia.html• http://bio1151.nicerweb.com/Locked/media/ch28/amoeba.html

• http://www.deviantart.com/art/Organelle-Illustrations-260886159• https://www.studyblue.com/notes/note/n/test-2/deck/6315023• http://iws.collin.edu/biopage/faculty/mcculloch/1406/outlines/chapter%207/chap07.htm• http://www2.estrellamountain.edu/faculty/farabee/BIOBK/biobookcell2.html• http://www.enchantedlearning.com/subjects/animals/cell/