Podcast
Questions and Answers
What is the primary difference between a prokaryotic cell and a eukaryotic cell?
What is the primary difference between a prokaryotic cell and a eukaryotic cell?
What is the term for a single-celled organism that is capable of living an independent existence?
What is the term for a single-celled organism that is capable of living an independent existence?
What is the term for the membrane-enclosed nucleus found only in eukaryotes?
What is the term for the membrane-enclosed nucleus found only in eukaryotes?
What was used to determine the evolutionary relationships between living organisms in a 1977 study?
What was used to determine the evolutionary relationships between living organisms in a 1977 study?
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How many distinct phylogenetic lineages were identified using rRNA sequence data?
How many distinct phylogenetic lineages were identified using rRNA sequence data?
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What are the three domains of life?
What are the three domains of life?
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What is the primary reason why Archaea and Bacteria were traditionally grouped together as prokaryotes?
What is the primary reason why Archaea and Bacteria were traditionally grouped together as prokaryotes?
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What is the term for the study of the relationships between organisms?
What is the term for the study of the relationships between organisms?
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What is the main function of the prokaryotic cell wall?
What is the main function of the prokaryotic cell wall?
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Which type of bacteria has a cell wall with up to 25 layers of peptidoglycan?
Which type of bacteria has a cell wall with up to 25 layers of peptidoglycan?
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What is the term for the outer layer of the Gram negative cell wall?
What is the term for the outer layer of the Gram negative cell wall?
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What is the result of removing the cell wall from a prokaryotic cell?
What is the result of removing the cell wall from a prokaryotic cell?
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What is the purpose of the Gram stain?
What is the purpose of the Gram stain?
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What is the characteristic of bacterial cells that divide in only one plane?
What is the characteristic of bacterial cells that divide in only one plane?
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What is the term for the fever-inducing component of the lipopolysaccharide layer?
What is the term for the fever-inducing component of the lipopolysaccharide layer?
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What is the characteristic of eukaryotic cells?
What is the characteristic of eukaryotic cells?
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What is the purpose of the cytoplasmic membrane?
What is the purpose of the cytoplasmic membrane?
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What is the characteristic of the prokaryotic chromosome?
What is the characteristic of the prokaryotic chromosome?
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Study Notes
Domains of Life
- The three domains of life are: Bacteria, Archaea, and Eukarya
- These domains differ significantly and are categorized based on their characteristics
Cell Structure
- Prokaryotes (Bacteria and Archaea):
- Usually small in size
- Have a cell wall that provides strength and is semi-permeable
- Have a cytoplasmic membrane that allows nutrients to enter and wastes to leave
- Have cytoplasm that contains proteins, nucleic acids, organic molecules, and ribosomes
- Have a single, usually circular chromosome that may contain extra-chromosomal DNA known as plasmids
- Eukaryotes:
- Are usually larger in size
- Typically do not have a cell wall (except for some exceptions)
- Have membrane-enclosed organelles such as a nucleus, mitochondria, and chloroplasts
Prokaryotic Cell Wall
- The main function of the cell wall is to provide integrity, rigidity, and shape to the cell
- If the cell wall is removed, the cell will lyse or burst
- The Gram stain is used to divide bacteria into two groups: Gram positive and Gram negative based on the composition of their cell walls
Gram Positive and Gram Negative Bacteria
- Gram Positive:
- Have a thick layer of peptidoglycan (PTG) in their cell wall
- PTG is arranged in parallel rows linked through glycan side chains and bridges of amino acids
- Gram Negative:
- Have a thin layer of PTG and an additional outer layer of lipopolysaccharide (LPS)
- LPS is composed of lipids and polysaccharides and is released from dead cells
- Lipid A, a component of LPS, is a pyrogen that induces fever in humans and animals
The Gram Stain
- Is a differential stain that differentiates between bacterial cell types based on their cell wall composition
- Stains Gram positive bacteria purple and Gram negative bacteria pink
- Provides information on cellular morphology and arrangement
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Description
This session introduces bacteria, emphasizing the prokaryotic cell and its differences from eukaryotic cells. Understand the characteristics of single-celled prokaryotes and their independent existence. Compare them to eukaryotic cells in multicellular organisms.
