Structure and Function of the Cell

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Chapter 4

• Structure and Function of the Cell

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4-1 Introduction to the Cell

• Biology The study of life
• Bio life
• Ology study of
• Cell smallest unit of matter that can carry on
  all life functions

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I. Discovery of the cell

• Early 17th century (a.k.a. 1600s) discovery of
  the microscope
• 1665

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ROBERT HOOKE

• The man the discovered cells!
• Looked at a slice of cork
• Plant cells

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• Saw little boxes
• Reminded him of small rooms that monks lived in
  called cells
• So that is how cells got their name!

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Cell Theory

• 150 years later .
• Cell theory 3 parts
• All living things are composed of at least one
  cell
• Cells are the basic unit of structure and
  function in an organism
• Cells come from other cells

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II. Cell diversity
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A. Size

• Most are microscopic few are seen by the naked
  eye
• Size is limited by
• Ratio of surface area to volume
• Nutrients must enter the cell
• If it is too large materials wont enter the
  cell fast enough

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B. Shape

• Shape reflects function
• Examples

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Nerve cell

• Branched and long
• Job Transmit information

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Skin cells

• Flat and layers of dead cells
• Job Protection

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White Blood Cells

• Blob move through small openings and eat
  bacteria
• Job kill bad things

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C. Internal Organization

• Organelles cell component that performs a
  specific function
• Like organs of the body Itty bitty baby organs

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EUKARYOTIC CELL

• Eukaryotic cell has a nuclear membrane and
  membrane- bound organelles
• Just like you and me!!
• All cells that are not bacteria

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PROKARYOTIC CELL

• No membrane bound organelles
• No nuclear membrane
• Example bacteria cells

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4-2 Parts of the eukaryotic cell
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Eukaryotic cells are different

• Three main parts
• Cell membrane
• Organelles
• Nucleus

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I. Cell Membrane

• Holds everything inside the cell
• Semipermeable (selectively permeable) Only
  allows some things through

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Cell Mem. Make-up

• Made of
• Phospholipid bilayer fat with a phosphate group
  attached
• Proteins allows certain things through

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The phospholipid

• Hydrophilic end
• Hydrophobic end
• Latin
• Hydro__________
• Philic__________
• Phobic__________

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The cell membrane Proteins

• Some proteins go all the way through the mem.
• These serve as channels or pores

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Fluid Mosaic Model of cell mem

• What is a mosaic?

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Fluid Mosaic Model of cell mem

• For many years scientists thought that proteins
  were static
• (stuck in 1 place)
• The phospholipid bilayer behaves more like a
  fluid than a solid
• Proteins can move
• Cell membrane is always changing

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II. Organelles of eukaryotic cells

• Organelles Parts that make-up the cell

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1. Cytoplasm

• Area between cell mem. and nucleus
• Also called cytosol

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2. Mitochondria (MIGHTY)

• Powerhouse of the cell (Makes energy)
• Makes ATP (adenosine triphosphate) -molecule that
  gives us energy
• Double membrane with series of folds (Cristae)
• Highly active cells lots of mitochondria
• Has own DNA
• Comes from your mama

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Mitochondria
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3. Ribosome

• Help make proteins
• Most numerous
• NOT membrane bound (in bth eukaryotic and
  prokaryotic cells)
• Some are free others are attached to the
  endoplasmic reticulum

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Ribosome
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4. Endoplasmic Reticulum

• System of tubules and sacs
• Function path for molecules
• Two types
• Rough E.R. has ribosomes
• Smooth E.R.- no ribosomes

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Smooth Endoplasmic Reticulum

• Forms channels within the cell
• Breaks down and make lipids
• Helps detoxify chemicals

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Rough Endoplasmic Reticulum

• Rough b/c of ribosomes on the outside
• Ribosomes help make proteins
• RER connects to the nucleus and helps make
  proteins

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E.R.
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5. Golgi Body (apparatus)

• Processing, packaging, and shipping proteins
• Stacked membranes
• Vesicles (membrane bound bags) carry materials.

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Golgi
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Protein from rough E.R to golgi
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6. Lysosome

• Latin Lys to break or split
• Sac filled with digestive enzymes
• Digests anything bad like the garbage disposal
  of the cell.
• Suicide sac-can kill a cell
• Human hand begins as a solid and lysosome kills
  cells to make spaces btwn fingers

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Lysosome
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7. Cytoskeleton

• Provides support
• Move organelles within the cytoplasm
• Two types
• Microfilaments play a role in cellular movement
• Microtubules form spindle fibers (attach to
  centrioles and chromosome during cellular division

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Microtubules/Spindle fibers
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8. Cilia

• Short hair like extensions that help with
  movement (made of microtubules)
• Single-celled organisms use it to move
• Multi-cellular organisms use it to clean
• Ex Respiratory system

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Paramecium w/ cilia
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9. Flagella

• One up to a few long whip like extensions
• Whip around to move a cell

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Flagellum example

• A SPERM CELL!!!

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Cilia and Flagella
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III. Nucleus

• Filled with Nucleoplasm

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Three main parts

• Surrounded by semi permeable membrane (Nuclear
  membrane/ envelope)
• Double mem. That surrounds the nucleus
• Has pores
• Nucleolus
• Helps make ribosomes
• DNA

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DNA (Deoxyribonucleic acid)

• Two forms of DNA
• Chromosome )( - DNA is condensed around proteins
  ONLY during cellular reproduction
• Chromatin DNA is all spread out like a plate of
  spaghetti

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Nucleus
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The Cell
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IV. Plant Cell
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• Plant cells have all the other organelles three
  others

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1. Cell Wall

• Outside the cell membrane
• Helps support and protect

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2. Vacuole

• Storage for water and food
• Much larger in plant cells
• May not exist in some animal cells

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3. Chloroplasts

• Contain chlorophyll
• Chlorophyll is the pigment that allows plants to
  make food