BIOL130 - Ch.1 (Intro to Cells)

Cells
-small membrane-enclosed units filled with a concentrated aqueous solution of chemicals and can create copies of themselves by growing and dividing into two
-Simplest form of life: Solitary cells
-acquire and use energy (“bioenergetics”) and carry out chemical reactions
-Each organism is a community of cells derived by growth and division from a single founder cell
-have many processes that are highly conserved at molecular level (ex: genetic code)
-engage in many mechanical activities (ex: transport of materials, movement)
-respond to environmental signals (ex: move towards stimuli, respond to hormones)
-are capable of homeostasis (self-regulation); evident when systems break down

-Cells vary enormously in appearance and function ex/ bacterial cell is a few micrometers long while a frog’s egg is 2 millimeters long. Both are a single cell ex/ some cells (nerve cells) are enormously extended to send out electrical signals; some cells (cells on surface layers of plants) are squat, immobile prisms with an outer waterproof coating of wax ex/ some cells require oxygen to survive, while oxygen is deadly to others

-In all living cells... -genetic instructions (genes) are stored in DNA molecule, written in the same chemical code and interpreted by essentially the same chemical machinery -Gene expression (Central Dogma) occurs -Transcription: genetic info flows from DNA to RNA -Translation: genetic info flows from RNA to protein 1-synthesis of mRNA occurs in nucleus 2-mRNA moves into cytoplasm via nuclear pore 3-synthesis of protein occurs in cytoplasm
-Protein molecules are built from amino acids. Every living thing uses the same set of 20 amino acids to make its proteins but linked in diff sequences

-Viruses are compact packages of genetic information (in form of DNA or RNA) -not considered ‘living’ -no ability to reproduce themselves by their own efforts -‘chemical zombies’; they are inert and inactive outside host cells

-Evolution: the process by which living species become gradually modified and adapted to their environment in more and more sophisticated ways -All present day cells evolved from the same ancestor. Through mutation, its descendants have gradually diverged
-Genome: cell’s entire genetic make-up
-Before the microscope... Earliest biologists began by looking at tissues and cells, then breaking them open to try to see their contents
-Microscope invented by Robert Hooke (viewed slices of cork, coining the term ‘cell’)
-Anton van worked with glass and improved quality of lenses (to 300x magnification) and became first of observe bacteria from his mouth (“father of microbiology), protists from pond water, blood cells, sperm -Light microscope: microscope that uses visible light to illuminate specimens -Electron microscope -Transmission electron microscope: similar to light microscope but uses beam of electrons to illuminate specimens instead of light -Scanning electron microscope: scatters electrons off the surface of sample (used to look at surface details of cells)

1833: Robert Brown discovered every plant cell contained round structure (nucleus)
1838: Schleiden hypothesized that all plant tissues are composed of cells & that embryonic plants always arose from single cell
1839: Schwann recognizes structural similarities between plants and animals -Schwann signaled “birth” of cell biology by using light microscope to show that cells were the universal building blocks of all living tissues. -Cell theory: all organisms