Lecture 1 Intro to Cells & Nucleic Acids
Tree of Life – share similar things (DNA, RNA, proteins)
- Composed of 3 major kingdoms:
Procaryotes o Bacteria (Eubacteria) – true/normal bacteria
Composed of o Archaea (archaebacteria) – characteristics of eubacteria & eucaryotes, grow
unicellular in diverse places (thermal places, sewage pits, salt marshes, high acid, low
o Eucaryotes – multicellular (vertebrates, invertebrates, plants, humans) or
2 main types of cells:
1) Procaryotic cells
- No nuclei
- Single-celled (mostly exist as independent individuals, known to form colonies/communities)
- Bacteria & archaea
2) Eucaryotic cells
- Nuclei (nucleic acids are separated by nuclear membrane)
- Multicellular (not always)
- Plants, fungi, animals, humans
- Very simple cell, not many specialized compartments
- Plasma membrane – serves as filter to separate inside from
outside & mediate what diffuses in/out
- Nucleiod – nucleic acids that are not enclosed by any sort of
- Cell wall – protects bacteria from outside
- Ribosomes – sites of protein synthesis & free-floating in cytosol.
- Much more complex & divided into many different types
of specialized compartments.
- Larger (though not always)
- Much greater degree of complexity requires structural
elements called cytoskeleton which mediate division of cell
into specialized compartments, mediate shape cell can
have, movements of cell towards things.
- Microtubule – help move different organs & proteins
up/down these structures.
- DNA – contained w/in nuclear envelope.
- Ribosomes – tend to be organized into structure called
endoplasmic reticulum although some occur in cytosol.
- Energy-producing units are contained in mitochondria
which produce ATP – site where O is used to oxidize food
to produce ATP which is energy currency of cell.
Origins of Mitochondria
- How does such complex cellular structure evolve?
- When O became present, bacterium was able to synthesize O.
Mitochondria – use O to make ATP – symbiotic relationship
with ancestral eucaryotic cell.
- 1 theory of origin of eucaryotic cell: may have come from
ancient symbiotic event that would have occurred 1.5 billion years ago when O became plentiful. In beginning, there may
have been eucaryotic ancestor that was anaerobic – made its
living off of eating free-living aerobic bacteria that were able