Cellular Organelles

This page provides a comprehensive overview of cellular organelles, their structures, and functions. It is an essential resource for students studying cell biology as part of their WJEC A level Biology knowledge organisers.

The nucleus is described in detail, highlighting its role in storing genetic material and controlling cellular activities. The page explains the structure of the nuclear membrane, nuclear pores, and the nucleolus.

Definition: The nucleolus is a structure within the nucleus responsible for producing ribosomes.

Mitochondria and chloroplasts are covered extensively, emphasizing their double membrane structure and ability to self-replicate due to the presence of their own DNA and ribosomes.

Highlight: The inner membrane of mitochondria is folded into cristae, which increase the surface area for ATP production during aerobic respiration.

The page also describes other important organelles such as centrioles, endoplasmic reticulum (ER), Golgi body, lysosomes, and ribosomes. Each organelle's structure and function are clearly explained, making this an invaluable resource for WJEC Biology past Papers preparation.

Plant-specific structures like the cell wall and vacuole are also covered, highlighting the differences between plant and animal cells.

Example: The plant cell wall, composed of cellulose microfibrils, provides structural support and allows for the movement of water through the apoplast pathway.

This detailed exploration of cellular organelles is crucial for students aiming to excel in their WJEC Biology A Level exams and coursework.

Prokaryotic and Eukaryotic Cells

This page provides a comparative analysis of prokaryotic and eukaryotic cells, highlighting their key differences and characteristics. It serves as an excellent resource for students studying cell biology as part of their WJEC A level Biology knowledge organisers.

Prokaryotic cells are described as smaller (1-10μm) with no membrane-bound organelles and DNA free in the cytoplasm. They contain 70S ribosomes, which is a distinguishing feature from eukaryotic cells.

Eukaryotic cells, in contrast, are larger (10-100μm) and contain membrane-bound organelles, including a nucleus that houses the DNA. They possess 80S ribosomes and have a more complex internal structure.

Highlight: The presence of a nucleus with nuclear pores in eukaryotic cells allows for the controlled transport of mRNA to the cytoplasm for protein synthesis.

The page details the process of protein synthesis and transport within eukaryotic cells, explaining how proteins are packaged into vesicles, modified in the Golgi body, and distributed throughout the cell.

Example: Proteins synthesized on the rough endoplasmic reticulum are transported to the Golgi body in vesicles for further modification and packaging.

This comprehensive comparison of cell types is crucial for students preparing for WJEC Biology past Papers and exams, providing a solid foundation for understanding more complex biological processes.

The page also briefly mentions viruses, although the information is incomplete in the provided transcript. This topic is likely expanded upon in subsequent pages of the WJEC Biology knowledge organisers Unit 1.