BIOL1040 Lecture Notes - Lecture 20: Symbiogenesis, Bacteria, Nucleoid
23 May 2018
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INTRODUCTION TO CELLS
Learning Goals
• Different types of cells, characteristics/ differences
• Microscopes, light, EM
• Cell size
• Endosymbiotic theory
Properties of living organisms - all organisms are made of cells
1. Cells are complicated and highly organised
2. Biological structures serve functional purposes
3. Living systems are actively engaged in energy transformations (ATP and NADPH)
a. Drive unfavourable reactions such as movement
4. Living systems have a capacity for self replication
Two types of cells
• Prokaryotic and eukaryotic
• Now 3 broad classes of life
o Eubacteria
o Archaea
o Eukaryotes
• All arose at a similar time (3.5 billion years ago)
• Eukaryotes have engulfed eubacteria (chloroplasts and mitochondria)
• Manny common metabolic pathways
• Major difference is in
o Eukaryotic cells in DNA is found in the nucleus (bounded by a double membrane)
eukaryotic means true nucleus
o Prokaryotes the DNA is concentrated in a region called the nucleoid
• Both types of cells have cytoplasm
• Eukaryotes have membrane bound organelles
• Organisation in prokaryotes - protein bound
• Eukaryotes generally larger
Prokaryote Cells
• Plasma membrane
• A single chromosome
• Ribosomes, which synthesise proteins
• Stiff cell wall
• DNA
• Most prokaryote species have one supercoiled circular chromosomes found in the nucleoid
region of the cell.(contains a long strand of DNA and a few supportive proteins)
• In addition to the large chromosome, many bacteria contain plasmids
• …
• In addition to the nucleoid chromosome and plasmids, other structures are contained within
they cytoplasm
o All prokaryotic cells contain ribosomes, consisting of RNA molecules and protein, for
protein synthesis
o Many …
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