Topic 2.1: Cell Structure and Function

What are ribosomes composed of?

Ribosomal RNA (rRNA) and protein.

Why are ribosomes found in all forms of life?

They are non-membrane structures that reflect the common ancestry of all known life.

What is the primary function of a ribosome?

To synthesize proteins according to mRNA sequences.

Which organelles make up the endomembrane system?

Endoplasmic reticulum (ER), Golgi complex, lysosomes, vacuoles, transport vesicles, nuclear envelope, and plasma membrane.

What is the collective function of the endomembrane system?

To work together to modify, package, and transport polysaccharides, lipids, and proteins intercellularly.

What are the two primary roles of the Endoplasmic Reticulum (ER)?

Providing mechanical support (maintaining cell shape) and intracellular transport.

What characterizes the Rough ER and what is its function?

It is associated with membrane-bound ribosomes; it functions in compartmentalization and protein synthesis.

What are the two main functions of the Smooth ER?

Detoxification of cells and lipid synthesis.

Describe the structure of the Golgi complex.

A membrane-bound structure consisting of a series of flattened membrane sacs.

What are the two specific functions of the Golgi?

1. Correctly folding and chemically modifying new cellular products.

2. Packaging proteins for trafficking.

How does mitochondrial structure support its function?

It has a double membrane; the inner membrane is highly convoluted (folded), increasing surface area to synthesize ATP more efficiently.

What do lysosomes contain and what are their two roles?

They contain hydrolytic enzymes; they function in digesting materials and programmed cell death (apoptosis).

How do vacuoles differ between plant and animal cells?

Plants: One large specialized vacuole for turgor pressure (water/nutrient storage).

Animals: Multiple smaller vacuoles for storing cellular materials.

What is the structure and function of a chloroplast?

It has a double membrane and serves as the site for photosynthesis in plants and algae.

Function of ribosomal RNA (rRNA)

• Facilities protein synthesis (translation) by binding mRNA and tRNA

• Acts as a ribozyme to catalyze peptide bond formation

• Provides a structural scaffold for ribosome assembly