Cell Biology: Cilia, Flagella & Microtubules

Cell Shape and Movement: Cilia, Flagella & Mitosis

• Microtubule Structure and Function is the focus.
• Cilia are hair-like structures that move materials across cell surfaces.
• Flagella are tail-like structures that propel cells through liquid.
• Sperm and Chlamydomonas are examples of cells with flagella.
• Ciliated epithelium is tissue with cilia.
• Microtubules are protein structures found in cilia and flagella.
• The image shows a cross-section of a cilium.
• Shows the arrangement of the microtubules (doublets and triplets).
• Diagrams depict the 9+2 arrangement of microtubules in cilia and flagella.
• Images show the structure of a cilia and flagella.
• Basal bodies are structures at the base of cilia and flagella.
• Dynein arms are proteins that create movements in cilia and flagella.
• Radial spokes are structures that connect the central microtubule to the outer doublet microtubules.
• Nexin is a protein connecting outer doublet microtubules.
• Microtubule structure shows the $\alpha$ and $\beta$ tubulin molecules.
• Trypsinized axoneme is an image of microtubule movement.
• Cells move using a power stroke and recovery stroke (sequential bending).

Mitosis

• Mitosis is cell division.
• Cytokinesis is the division of the cytoplasm.
• Mitosis in tissue-cultured lung cells is recorded with a microscope (Pol-scope)
• Different stages of mitosis are shown in the images, including interphase, prophase, prometaphase, metaphase, anaphase, and telophase.
• The diagrams show the progression of the cell cycle.
• Checkpoints in the cell cycle ensure DNA replication and environment favorability.
• Spindle checkpoints are involved in regulation of the cell's success in division.

Cyclin Dependent Kinase (CDK)

• Cyclin-dependent kinases (CDKs) control cell cycle progression.
• The video shows different checkpoints (G1, S, G2, M checkpoint).
• Regulation of whether the cell enters G1 or continues to S phase depends on the type of signals given by the environment.
• Various cyclins and CDKs regulate the cell cycle.

Centrosome Duplication

• Centrosomes are microtubule-organizing centers.
• Regulation of the cell cycle through centrosome duplication is shown.
• Centrioles are duplicated during interphase.
• Different stages of centrosome duplication/separation are represented by the images.
• The cell cycle ensures the duplication of centrosomes.

Organelle Inheritance

• Organelles are distributed during cell division.
• Cytoskeletal filaments distribute organelles between daughter cells.
• Specific types of organelles need to be segregated in distinct ways to ensure that daughter cells obtain the correct number and type of organelle.
• Mitochondrial inheritance is addressed.
• Bundled actin filament inheritance is addressed.

Chromosome Movement and Spindle Pole Separation

• Chromosome movement is addressed during anaphase.
• Spindle pole separation during anaphase is shown in figures including pulling and pushing forces.
• Microtubule motors drive chromosome movement and spindle elongation.

Microtubule Organising Centres

• Microtubule organizing centres (MTOCs) such as centrosomes organize microtubules.
• Duplication of centrosomes and their movement are essential in proper cell division.
• Microtubules elongate and shorten to contribute to movement of chromatids.