Cell Structure and Function - Lecture Notes | BIOL 1001, Study notes of Biology

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Chapter 4

Cell Structure & Function

Biol 1001 Fall 2013

Discovery of the Cell

 1665 A.D. - Robert Hooke  (^) Invented primitive microscope  (^) Observed “little boxes” (=cells) in cork  (^) Discovered similar structures in live plants  1670 A.D. - Anton van Leeuwenhoek  (^) Discovered “animalcules” in water samples  (^) Mostly unicellular organisms

The Cell Theory

 Developed in 1855  3 Principals  Every living organism is made up of 1 or more cells  cells=basic unit of life  Smallest living organisms are unicellular  Cells are functional units of multicellular oganisms  cells arise from pre existing cells  (^) cells reproduce!

Cells  Must obtain energy and nutrients  Must eliminate waste  Must synthesize proteins  Must reproduce  Many interact with other cells

Plasma Membrane

 thin, fluid membrane that encloses cell  phospholipid bilayer with embedded proteins  Functions  isolate cells contents from external envirnoment  Regulate flow of materials in and out of cell  Allow cellullar interactions with  other cells  envirnoment

Phospholipid bilayer

 Hydrophilic head (water-loving)  (^) Faces water intracellular and extracellular environments  Hydrophobic tail (water-fearing)  (^) Faces interior of membrane, away from water  Maintains concentrations of materials inside & outside of cell  (^) Allows oxygen, CO 2 & H 2 O to move in and out of cell easily  (^) Barrier to most hydrophilic molecules and ions

Embedded Proteins

 Facilitate communication between cell & its environment  Functions  (^) Allow specific molecules and ions to enter and exit cell  (^) Promote chemical reactions within cell  (^) Join cell to other cells  (^) Receive and respond to signals from molecules  Example: MHC (=glycoprotein)  (^) Major Histocompatibility Complex  (^) Allows body to recognize cell as not being foreign  (^) Prevents immune system from attacking and killing cell

glycoprotein extracellular fluid (outside) cytoplasm (intracellular) membrane protein channel protein Phospholipid bilayer helps to isolate cell's contents Proteins help cell communicate with its environment Fig 4-

DNA & RNA



Deoxyribonucleic acid (DNA)

 genetic material in cells  (^) “blueprints” for  (^) making cell parts  producing new cells  passed on to offspring 

Ribonucleic acid (RNA)

 (^) translates DNA into proteins

Acquisition of Materials & Energy

 Requires plasma membrane, cytoplasm, DNA & RNA  Materials obtained from  (^) Ex: carbon, hydrogen, nitrogen, oxygen, etc.  Must cross cell membrane to enter cell  Used in formation of biological molecules in cytoplasm  Energy needed to perform metabolic activites  acquired from sun or other living organisms

Eukaryotic Cells

mitochondrion flagellum vesicle Ribosomes on rough ER Intermediate filaments Golgi apparatus cytoplasm lysosome nuclear pore nuclear envelope chromatin (DNA) nucleolus nucleus plasma membrane Rough endoplasmic reticulum free ribosome Smooth endoplasmic reticulum microtubules microfilaments General Animal Cell Fig 4-

Cell Wall of Plants

 Cellulose secreted from inside cell cell wall forms  Cell wall joins to adjacent cells via pectin  Pectin = “sticky” polysaccharide  supports and protects cell  (^) Helps plant stand upright & to defy gravity/wind  (^) porpus allows oxygen, CO 2 & H 2 O in & out of cell

Cytoskeleton  anchors organelles & other structures within cell  Network of protein fibers  (^) microfilaments– thinnest of fibers  Intermediate filaments– medium thickness  microtubules– thickest of fibers microfilaments intermediate filaments microtubules microtubules (red) nucleus microfilaments (blue) Fig 4-