18 Questions
What is the primary difference between a prokaryotic cell and a eukaryotic cell?
The presence of a true nucleus
What is the term for a single-celled organism that is capable of living an independent existence?
Prokaryote
What is the term for the membrane-enclosed nucleus found only in eukaryotes?
Karya
What was used to determine the evolutionary relationships between living organisms in a 1977 study?
Ribosomal RNA sequence data
How many distinct phylogenetic lineages were identified using rRNA sequence data?
Three
What are the three domains of life?
Eukarya, Bacteria, and Archaea
What is the primary reason why Archaea and Bacteria were traditionally grouped together as prokaryotes?
They share similar characteristics
What is the term for the study of the relationships between organisms?
Phylogenetics
What is the main function of the prokaryotic cell wall?
To confer integrity, rigidity and shape
Which type of bacteria has a cell wall with up to 25 layers of peptidoglycan?
Gram positive
What is the term for the outer layer of the Gram negative cell wall?
Lipopolysaccharide
What is the result of removing the cell wall from a prokaryotic cell?
The cell will lyse or burst
What is the purpose of the Gram stain?
To differentiate between Gram positive and Gram negative bacteria
What is the characteristic of bacterial cells that divide in only one plane?
They form chains
What is the term for the fever-inducing component of the lipopolysaccharide layer?
Endotoxin
What is the characteristic of eukaryotic cells?
They have membrane-enclosed organelles
What is the purpose of the cytoplasmic membrane?
To allow nutrients to enter and wastes to leave
What is the characteristic of the prokaryotic chromosome?
It is circular and has a single chromosome
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
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.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
