Shownotes
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 protrusions
- Used by cells and microorganisms for movement
- Specialized flagella in some organisms used as sensory organelles that can detect changes in temperature and pH
- Eukaryotic
- Very similar to cilia
- Have 1+ (generally many) flagella which move in a whiplike way
- Core is a bundle of 9 pairs of microtubules surrounding 2 central microtubules like cilia, sliding of microtubules cause movement, etc.
- Depend on ATP for energy
- Prokaryotic/Bacterial
- Helically shaped structures that contain the protein flagellin
- Base of flagellum near the cell surface is attached to the basal body and the flagellum rotates in a clockwise or counterclockwise direction
- Get energy from this proton motive force across the cell membrane
Segment 2: More About Cilia and Flagella
- Cilia Function
- Important in movement of cell itself or of substances that go past the cell
- In ciliates, cilia responsible for the movement of the whole organism such as the unicellular protist Paramecium (cilia responsible for the movement and feeding)
- Help to remove contaminants from organs or tissues by helping to move fluids over the cell
- Lining of the nasopharynx and trachea covered in cilia - ciliated epithelial cells remove mucus, bacteria, and other debris from the lungs
- Present in the lining of the fallopian tubes - help in fertilization by movement of the egg towards the uterus
- Non-motile cilia
- Sensory apparatus for cell - detect signals
- Play roles in sensory neuron
- Found in the kidneys to sense urine flow
- In eyes on the photoreceptors of retina where they function to transport vital proteins from the inner segment of the photoreceptor to outer segment through sense and initiating movement
- Provide habitats for symbiotic microbiomes in animals
- Known to filter, clear, localize, select, and aggregate bacteria and control adhesion for ciliated surfaces
- Flagella Function
- Used to propel a cell (ex: bacteria and sperm) through liquid
- Specialized functions
- Some eukaryotic cells used flagellum to increase reproduction rates
- Eukaryotic and bacterial flagella are used to sense changes in the environment, such as temperature or pH disturbances
- Found in sponges and other aquatic species to help move water for respiration
- Eukaryotic flagella can serve as sensory organelles
- Flagella may be used as a secretory organelle
Segment 3: Connection to the Course: Cell Structure and Function
- Prokaryotic and eukaryotic cells contain cilia and flagella - aid in cell movement and movement of substances around cells and along tract
- Consequences of lack of cilia/flagella
- Cells unable to move to attain food and nutrients
- Cell cycle affected - proteins would not be able to function properly
- Reproduction would likely not occur
- Cell communication would be affected
- Contaminants may not move past cell and could negatively harm the cell
- Cell can’t swim away from non ideal conditions or invaders
- Transport of certain proteins and bacteria would not occur
- Cells may not be able to detect signals - reaction to stimuli would be affected
Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!
Music Credits:
- “Ice Flow” Kevin MacLeod (incompetech.com)
- Licensed under Creative Commons: By Attribution 4.0 License
- http://creativecommons.org/licenses/by/4.0/
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