TOPIC 1: The Cell

What are the 3 Domains of life?

Bacteria, Archaea, and Eukarya.

What feature differentiates Domain Bacteria from Archaea and Eukarya?

Most bacteria have a cell wall made from peptidoglycan.

What is the historical classification system established by Carolus Linnaeus?

The 5-Kingdom taxonomic hierarchy.

What initiated the shift from the 5-Kingdom system to the 3-Domain system?

Molecular Biology, particularly comparing ribosomal RNA sequences.

What genetic material do all life forms store?

DNA molecules.

How are ribosomes essential for life?

They translate genetic information into proteins.

What defines a prokaryotic organism?

Lack of a nucleus and generally smaller size.

What is the fundamental distinction between prokaryotic and eukaryotic cells?

The presence of a nucleus in eukaryotic cells.

What is endosymbiosis?

The theory that eukaryotic organelles originated from independent prokaryotic cells.

What are two examples of organelles that originated from endosymbiotic events?

Mitochondria and chloroplasts.

Why are eukaryotic cells generally larger than prokaryotic cells?

Eukaryotic cells have an endomembrane system that allows for compartmentalization.

What does the Endosymbiotic Theory explain about eukaryotic cells?

It explains their origin as hybrids of Bacteria and Archaea.

What type of cell wall do most bacteria have?

A cell wall made from peptidoglycan.

What is the significance of surface area to volume ratios (SA:V) in cells?

It affects the efficiency of nutrient exchange and growth limits.

What happens to the SA:V ratio when a cell doubles in size?

The ratio decreases by half.

What supports the internal volume of a cell?

The cell membrane, which is the site of nutrient exchange.

What types of cells are defined as prokaryotic?

Bacteria and Archaea.

What are the three main components of the cytoskeleton?

Microtubules, intermediate filaments, and microfilaments.

Which cytoskeletal structure is the largest?

Microtubules.

What is the structural role of microfilaments?

They support the cell structure and are involved in cell movement.

How do plant cells differ from animal cells?

Plant cells contain chloroplasts and have a rigid cell wall.

What is the primary function of chloroplasts?

To conduct photosynthesis.

What are photoautotrophs?

Organisms that use light for energy and inorganic carbon for growth.

What are chemolithotrophs?

Organisms that obtain energy from inorganic molecules.

What do chemoorganoautotrophs use for energy and carbon?

Organic molecules for energy and inorganic molecules for carbon.

What distinguishes eukaryotic cells from prokaryotic cells?

The presence of internal membrane-bound organelles.

What is included in the endomembrane system of a eukaryotic cell?

Rough ER, Smooth ER, and Golgi apparatus.

What evidence supports the Endosymbiotic Theory?

Mitochondria and chloroplasts have ribosomes and DNA similar to modern prokaryotes.

Define hybrid organisms in the context of eukaryotic cells.

Eukaryotic cells are considered hybrids of Bacteria and Archaea.

How does diffusion relate to cell size?

Larger cells have decreased SA:V ratios, limiting nutrient exchange.

What is a unique feature of mitochondria?

They originated from aerobic bacteria.

What is the significance of endosymbiotic relationships in cellular evolution?

They led to the development of complex eukaryotic cells.

How do chloroplasts function in plants?

They convert light energy into chemical energy via photosynthesis.

What is the role of the cytoskeleton in cells?

To provide structural support and facilitate movement.

What are the nutritional classifications based on energy sources?

Chemical and light.

What is the carbon source classification for organisms?

Organic and inorganic.

What does the term 'Last Universal Common Ancestor' or LUCA refer to?

The most recent common ancestor from which all current life forms descended.

Why are some prokaryotes significant for the study of molecular biology?

They provide insights into the basic mechanisms of life due to their simplicity.