BIO 1140 Chapter Notes - Chapter 1: Cell Membrane, Thermoacidophile, Euryarchaeota
12 Jan 2017
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BIO1140 B Dr. Caroline Petit-Turcotte
Introduction to Cell Biology and its Features 01.19.2017
Two main classes of cells:
Tree of Life – 3 primary branches: bacteria, arcahaea, and eucaryotes
1. prokaryotic (bacteria) – lak a ulei evelope; siple ad saller, less ople geoes ad do’t have
organelles or cytoskeleton;
• live in enormous variety of ecological places and vary in their biochemical capabilities
o organotrophic species use any type of organic molecule as food; sugar, a.as, hydrocarbons,
methane gas
o phototrophic species harvest light energy to generate oxygen as byproduct
o lithotrophic species that feed on inorganic nutrients (carbon from CO2, and H2S)
Two types:
a) archaebacterial live in extreme environments
• thermoacidophiles live in hot sulfur springs; temp of 80°C and pH of 2
• halophiles need high concentrations of salt to survive
• methanogens live in oxygen-free milieus and make methane
• has RNA, membrane and phospholipids; more similar to eukarya at molecular level
o similar in machinery for handling genetic info (replication, transcription, and translation)
• i.e euryarchaeota, crenarachaeota, korarcheoata
b) eubacteria are common and live in a wide range of environments (soil, water, and other organisms)
• most are spherical, rod-shaped, or spiral with a diameter of 1-10µm
• their DNA range from 0.6 to 6 million base pairs (sufficient to encode ~5000 different proteins)
• largest and most complex prokaryote is cyanobacteria (photosynthesis is involved)
• structure of typical prokaryote is Escherichia coli (E. coli), a common inhabitant of human intestinal tract
o rod shaped, diameter of 1 µm, ~2 µm long, surrounded by rigid cell wall made of polysaccharides
and peptides; plasma membrane of phospholipids and proteins; DNA is single circular molecule
in the nucleoid
• i.e protebacteria, green bacteria, cyanobacteria. Gram-positive bacteria, spirochetes, chhalmydias
2. eukaryotic cells that have a nucleus (~5 µm) where genetic material is separated from cytoplasm; 10-100 µm
• surrounded by plasma membrane with ribosomes; contains nucleus, many organelles, and a cytoskeleton
• in the nucleus DNA is organized in linear molecules and replicates, RNA is synthesized; translation of RNA
into proteins happens in ribosomes in the cytoplasm
• i.e plants, fungi, and animals
Evolving Genes – some evolve rapidly, others are highly conserved
• when storing & copying genetic info random accidents occur altering the nucleotide seqnce – mutations
o change may be for the better (rarely); altered cells has increased likelihood of reproducing itself
o ost ofte it auses o sigifiat differee i the ell’s prospets seletivel eutral; attle
for which has a better chance of succeeding when resources are limited
o in many cases it will cause serious damage (i.e disrupting coding for a key protein); cell suffers
and dies
• through continual mutation and natural selection organisms evolve
• DNA that does’t ode for protei ad has o sigifiat regularotr role hages freel; gee that odes
for essential protei or RNA oleule a’t e haged easil high oserved
Architecture of Cells
Plasma Membrane – each cell is bounded by a plasma membrane that is a selective barrier that gathers nutrients
from its environment to use for synthesis of products and excrete its waste products; also stores energy
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