Bacterial and Fungal Cell Structures

This page delves deeper into the structures of bacterial and fungal cells, providing detailed diagrams and explanations of their unique features.

Bacterial cells are described as having a circular chromosome, plasmids, and a cell wall with a different chemical structure compared to plant and fungal cells. The absence of a nucleus and mitochondria in bacterial cells is noted as a key difference from other cell types.

Highlight: Bacterial cells lack a true nucleus and instead have a circular chromosome and plasmids containing their genetic material.

Fungal cells are shown to have similarities to both plant and animal cells, possessing a cell wall like plant cells but also containing mitochondria like animal cells. The irregular shape of fungal cells is highlighted as a distinguishing feature.

Example: Fungal cells have a cell wall like plant cells, but they also contain mitochondria similar to animal cells, making them unique among eukaryotic cells.

The page emphasizes that all cell types contain ribosomes, cell membranes, and cytoplasm, reinforcing the fundamental similarities across different cell types despite their structural differences.

Cell Structure Comparison

This page provides a comprehensive comparison of plant, animal, fungal and bacterial cell structures. It highlights the key differences and similarities between these cell types.

Plant cells are characterized by the presence of a cell wall, large vacuole, and chloroplasts, which are absent in animal cells. The page includes detailed diagrams of plant and animal cells, labeling important organelles and structures.

Highlight: Plant cells have unique features like a cell wall, large vacuole, and chloroplasts that are not found in animal cells.

Vocabulary: Chloroplasts are organelles found in plant cells that are responsible for photosynthesis.

The page also introduces bacterial and fungal cell structures, noting their unique features such as plasmids in bacterial cells and the different chemical composition of cell walls in plant, fungal, and bacterial cells.

Definition: Plasmids are small, circular pieces of DNA found in bacterial cells that can replicate independently of the main chromosome.

Common structures found in all cell types, including ribosomes, cell membrane, and cytoplasm, are also highlighted, emphasizing the fundamental similarities across different cell types.

Transport Across Cell Membranes

This page focuses on the mechanisms of transport across cell membranes, explaining key concepts such as diffusion, active transport, and osmosis.

Diffusion is described as the passive movement of molecules from areas of high concentration to low concentration, requiring no energy. Active transport, in contrast, is explained as the movement of molecules against the concentration gradient, requiring energy and involving proteins in the cell membrane.

Definition: Osmosis is the diffusion of water molecules across a selectively permeable membrane from an area of high water concentration to an area of low water concentration.

The page details the molecules that can enter and exit cells through the membrane, such as oxygen and glucose entering, and carbon dioxide and urea exiting. It also explains that larger molecules like starch and proteins are too big to pass through membrane pores.

Example: Oxygen and glucose can enter cells through the membrane, while carbon dioxide and urea can exit. However, larger molecules like starch and proteins cannot pass through due to their size.

The effects of osmosis on plant and animal cells are described, introducing the concepts of turgid and plasmolysed cells. The page explains how plant cells can withstand water gain due to their cell walls, while animal cells may burst when they gain too much water.

Vocabulary: Turgid refers to a plant cell that has gained water and is swollen, while plasmolysed describes a plant cell that has lost water and has a shrunken cytoplasm.