Cell Organelles, Cell Types, and Prokaryote vs. Eukaryote Differences

What is the role of the plasma membrane?

It is selectively permeable, defining what enters and exits the cell.

What is the composition of the plasma membrane?

It is a single membrane composed of two molecules thick, made of lipids that are amphipathic.

What is the function of the cell wall in plant cells and bacteria?

It provides rigid structural support and limits the passage of molecules in and out of the cell.

What are peptidoglycans?

They are components that make up the cell wall in bacteria.

What is the difference between Gram-positive and Gram-negative bacteria?

Gram-positive bacteria have a thick peptidoglycan layer that retains the stain, while Gram-negative bacteria have a thin layer that allows the stain to wash out.

What is an organelle?

A tiny cellular structure that performs specific functions within a cell.

What is the function of the nucleus?

It contains DNA, the cell's blueprint for proteins, and is involved in cell division.

What is the nucleolus responsible for?

It is the site of ribosomal synthesis and contains ribosomal genes.

What is the nuclear membrane?

A double membrane (nuclear envelope) that surrounds the nucleus and contains nuclear pores for controlled movement.

What are centrioles?

Specialized microtubules found adjacent to the nucleus in animal cells, organizing the mitotic spindle.

What is the role of mitochondria?

They generate ATP through aerobic catabolism and oxidative phosphorylation.

Why are the inner membranes of mitochondria highly folded?

To increase surface area for ATP synthesis.

What is the endosymbiotic theory related to mitochondria?

It suggests that mitochondria have a prokaryotic origin and contain their own DNA.

What is the function of ribosomes?

They are responsible for protein synthesis.

What is the role of the endoplasmic reticulum?

It synthesizes proteins and lipids and is involved in the transport of materials within the cell.

What does the Golgi apparatus do?

It modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

What are secretory vesicles?

Vesicles that transport materials to be secreted from the cell.

What is apoptosis?

Programmed cell death mediated by mitochondria.

What is the significance of calcium storage in mitochondria?

It plays a role in various cellular processes, including signaling and muscle contraction.

What is the cytoplasm?

The aqueous environment within the cell that contains organelles and is the site of metabolic processes.

What is the cytoskeleton?

A structural support system within the cell that helps maintain its shape and aids in movement.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both.

What is the fluid mosaic model?

A model that describes the structure of the plasma membrane as a mosaic of various proteins embedded in a fluid lipid bilayer.

What is the role of amphipathic lipids in the plasma membrane?

They allow the membrane to be selectively permeable, with hydrophilic and hydrophobic regions.

What is the role of ribosomes in protein synthesis?

Ribosomes translate mRNA code into an amino acid sequence (peptide/protein).

What are the two subunits of ribosomes composed of?

Each ribosomal subunit is a complex of rRNA and proteins.

What are polysomes?

Polysomes are clusters of many ribosomes translating the same mRNA template.

What is the structure of the Endoplasmic Reticulum (ER)?

The ER is a continuous, highly convoluted membrane system extending from the nucleus to the plasma membrane.

What is the main difference between Smooth and Rough Endoplasmic Reticulum?

The Rough ER has ribosomes on its surface, while the Smooth ER does not.

What functions does the Rough Endoplasmic Reticulum serve?

The Rough ER is involved in protein synthesis, transport, sorting, and glycosylation of proteins.

What is the primary function of the Smooth Endoplasmic Reticulum?

The Smooth ER is primarily involved in lipid synthesis and detoxification.

What is the Golgi Apparatus?

The Golgi Apparatus is a series of stacked membranes (cisternae) that processes and sorts proteins and lipids from the ER.

How do molecules enter and exit the Golgi Apparatus?

Molecules enter on the cis face from the ER and exit from the trans face via vesicular trafficking.

What is vesicular trafficking?

Vesicular trafficking involves vesicles budding off from one membrane and fusing with another membrane, transporting both luminal and membrane content.

What are the three types of endosomes?

The three types of endosomes are early endosomes, recycling endosomes, and late endosomes.

What is the function of lysosomes?

Lysosomes contain digestive enzymes that break down excess or worn-out cell parts, bacteria, and viruses.

What is the role of peroxisomes in the cell?

Peroxisomes are involved in the catabolism of fatty acids, amino acids, and polyamines, generating hydrogen peroxide which is then broken down by catalase.

How do cells differ in size and shape?

Cells differ in size, shape, and function; for example, oocytes are large, while erythrocytes are small and flattened.

Why do mammalian erythrocytes lack nuclei?

Mammalian erythrocytes lack nuclei to facilitate the transport of respiratory gases and to allow them to enter small blood capillaries.

What is the significance of the number of mitochondria in cells?

Different cell types have varying numbers of mitochondria; for example, liver cells have many, while mature lens fiber cells have none.

What distinguishes eukaryotic cells from prokaryotic cells?

Eukaryotic cells have a nucleus and membrane-bound organelles, while prokaryotic cells do not.

What is the main structural difference between eukaryotes and prokaryotes?

Eukaryotes have helical DNA associated with histones, while prokaryotes have circular naked DNA without histones.

What types of organisms are classified as eukaryotes?

Eukaryotes include mainly single-celled organisms and some multicellular organisms, though multicellularity is rare.

What are the learning outcomes related to sub-cellular organelles?

Students should be able to describe the roles of named sub-cellular organelles and understand differences between cell types related to function.

What does 'karyon' mean?

It means 'nut' or 'kernel'.

What is the defining feature of Prokaryotes?

They do not have a nucleus; 'before the nucleus'.

What is the defining feature of Eukaryotes?

They have a nucleus surrounded by a double membrane (nuclear envelope).

What are the two main classifications of organisms based on cellular structure?

Prokaryota and Eukaryota.

Name three examples of multicellular Eukaryotes.

Animals, Plants, Fungi.

Name two examples of unicellular Eukaryotes.

Yeast and Amoeba.

What are the two main groups of Bacteria?

Gram positive and Gram negative.

What are the two main groups of Archaea?

Euryarchaeota and Crenarchaeota.

What is a common organelle found in Prokaryotes?

Ribosome.

What is the structure of Prokaryotic DNA?

A single circular molecule of 'naked' DNA (no histones).

Where does metabolism occur in Prokaryotes?

In the cytosol, as they lack mitochondria.

How is ATP produced in Prokaryotes?

Across the cell's surface (plasma membrane) rather than the inner membrane of mitochondria.

What are the four morphologies of Prokaryotes?

Cocci (spherical), Bacillus (rod-like), Spirochetes (spiral), Vibrio (curved rods).

Are all Prokaryotes unicellular?

No, some bacteria can form multicellular stages or colonies (e.g., cyanobacteria).

What is a unique characteristic of Archaea?

Archaea are always unicellular.

What is the difference in cellular structure between Prokaryotes and Eukaryotes?

Prokaryotes lack membrane-bound organelles, while Eukaryotes have them.

What is the significance of the nuclear envelope in Eukaryotes?

It surrounds the nucleus, protecting the genetic material.

What is the role of named sub-cellular organelles?

They perform specific functions within the cell.

What should you be able to explain after studying Prokaryotes and Eukaryotes?

The differences between cell types related to function.