My AP Biology Thoughts  Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Saarim and I am your host for episode 54 called Unit 2 Cell Structure and Function: Movement Organelles. Today we will be discussing cilia and flagella, which are known as the movement organelles of the cell due to their importance in the movement and locomotion of cells through different means. I’ll be starting off by giving an introduction to Cilia and Flagella (so, talking about their structure and what they both are exactly). Afterwards, I’ll go through the variety of functions that cilia and flagella partake in and take on. Finally, I will place cilia and flagella into the broader scope of “cell structure and function” and expand a little bit on their importance and finish off by quickly presenting the consequences if cilia and flagella were absent.

Segment 1: Introduction to Cilia and Flagella

•  Cilia and flagella overview
• Tube like appendages that allow for motion in eukaryotic cells
• Cilia - found in both animals and microorganisms, but not in most plants
• Flagella - mostly used for motility in bacteria and gametes of eukaryotes
• Cilia structure
• Small hair-like protuberances on the outside of eukaryotic cells
• Responsible for locomotion of cell itself or of fluids on cell surface
• Involved in mechanoreception - detection/response of animals to stimuli
• Structure
• Made up of microtubules coated in plasma membrane
• Microtubules - small hollow rods made of protein tubulin
• Contains 9 pairs of microtubules forming the outside of a ring; two central microtubules (axoneme) - microtubules held together by cross-linking proteins
• Dyneins - motor proteins between the 9 outer pairs - allow cilia to be motile
• Proteins (hydrolyze ATP for energy) undergo conformational changes which allow for complex movements - cause the bending in the cilium as microtubules slide
• Cilia - 0.25 micrometers in diameter and 20 micrometers in length 
• Found on cell surface and beat back and forth to create movement
• Non-motile cilia
• Don’t have the center microtubule structure or dynein arms - can’t move
• Flagella structure
• Hair life organelles - longer and less numerous...