studying bio grade 7a final

Bacteria and Archaea: Branching Diagrams

• Bacteria and archaea are prokaryotic organisms, meaning their cells lack a nucleus and other membrane-bound organelles.
• They're fundamentally different from eukaryotes, which have these components.
• Branching diagrams illustrate the evolutionary relationships between these groups.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic cells: Smaller, simpler cells lacking membrane-bound organelles like a nucleus. DNA is circular. Often single-celled.
• Eukaryotic cells: Larger, more complex cells with membrane-bound organelles, including a nucleus. DNA is linear, packaged into chromosomes. May be single-celled or multicellular.

Differences Between Prokaryotes and Eukaryotes

• Prokaryotic cells lack membrane-bound organelles, while eukaryotic cells have them.
• Prokaryotic DNA is circular and not enclosed in a nucleus, while eukaryotic DNA is linear and contained within a nucleus.
• Prokaryotes are typically smaller than eukaryotes.

Binary Fission

• Binary fission is the primary method of asexual reproduction for prokaryotes.
• It involves the replication of the single circular chromosome and its segregation into two daughter cells.

Genetic Transfer Mechanisms in Bacteria

• Transformation: Uptake of foreign DNA from the environment
• Transduction: Transfer of DNA via a bacteriophage (virus). A virus injects the DNA of a bacteria into another.
• Conjugation: Transfer of DNA between bacteria through direct contact. A form of sexual reproduction for bacteria.

Characteristics of Viruses

• Viruses are not considered living organisms because they can't reproduce independently. They need a host cell to reproduce.
• Viruses are much smaller than bacteria
• Viruses have a protein coat surrounding a nucleic acid (DNA or RNA).