Introduction to Early Cells and Prokaryotic Cells

These flashcards cover key concepts related to early cells, prokaryotic cell structure, the cell theory, differences between prokaryotic and eukaryotic cells, and the functions of various cellular components.

What is the cell theory?

1. All organisms are composed of one or more cells. 2. The cell is the basic structural and functional unit of all living organisms. 3. Cells arise only from the division of pre-existing cells.

What is the structure that contains chromosomal DNA in prokaryotic cells?

The nucleoid.

Which features are unique to prokaryotic cells?

A. A cell wall made of peptidoglycan. B. Pili. C. A capsule. D. A single circular chromosome in the nucleoid region. E. All of the above.

What role do pili play in prokaryotic cells?

Pili aid in adhesion, biofilm formation, mobility, and horizontal gene transfer.

What defines the Last Universal Common Ancestor (LUCA)?

LUCA was a prokaryotic single-celled organism that lived around 4.2 billion years ago.

What metabolic process is LUCA likely associated with?

LUCA was likely a chemoautotroph that oxidized inorganic substances.

What is the main difference between bacteria and archaea in terms of cell wall composition?

Bacteria have a cell wall made of peptidoglycan, while archaea do not have peptidoglycan.

How do archaea and bacteria differ in their ribosomal RNA (rRNA)?

The sequence of archaea's rRNA is more similar to eukaryotes than to bacteria.

What is the role of the cell wall in prokaryotic cells?

The cell wall provides structural support, protects from osmotic lysis, and can be toxic to other organisms.

What technique is used to differentiate between gram-positive and gram-negative bacteria?

Gram staining.

What is the difference in the structure of the cell membrane of bacteria and archaea?

Bacteria have ester-linked phospholipids, while archaea may have ether-linked phospholipids.

What characterizes the cytoskeleton of eukaryotic cells compared to prokaryotic cells?

Eukaryotic cells have a highly complex cytoskeleton with true microfilaments, microtubules, and intermediate filaments.

What is a plasmid?

A plasmid is a small, extrachromosomal DNA molecule that can replicate independently of the main chromosome.

How do prokaryotic cells and eukaryotic cells differ in terms of chromosome structure?

Prokaryotic cells typically have a single circular chromosome; eukaryotic cells have several linear chromosomes.

Where is the DNA located in prokaryotic cells?

The DNA is localized in the nucleoid region.

What is the function of ribosomes in cells?

Ribosomes produce proteins by translating messenger RNA (mRNA) into a chain of amino acids.

What are the two types of ribosomes based on size?

Eukaryotic ribosomes are larger (80S) than prokaryotic ribosomes (70S).

What is one function of the capsule in prokaryotic cells?

The capsule provides protection from the host’s immune system and helps prevent desiccation.

What is the primary function of ribosomes?

To produce proteins by translating mRNA into amino acid chains.

What distinguishes the cytoplasm of prokaryotic cells from that of eukaryotic cells?

Prokaryotic cells do not contain organelles within their cytoplasm.

Which gene transfer mechanism allows prokaryotes to obtain genes from their environment or other prokaryotes?

Horizontal gene transfer.