4.16-4.22 Flashcards
What is the cytoskeleton?
Network of protein fibers throughout the cell.
What does the cytoskeleton do?
Organizing structures and activities: structural support, internal movement of cell parts. *In motile cells, they help with the crawling and swimming.
What are the three types of fibers in the cytoskeleton, from thickest to thinnest?
microtubules, intermediate filaments, and microfilaments. (25, 10 and 7 nanometers respectively)
A nanometer is ______ of a meter
one billionth.
What is the shape and material of microtubules?
Straight, hollow tubes made of GLOBULAR proteins called tubulins. Easily dissembled and moved to other parts of the cell.
Where do microtubules create in animal cells?
A centrosome, which is made of two centrioles. Surrounds the nucleus? (Plant cells organize their microtubules by other means)
What are some of the functions of microtubules?
- They are the “tracks” for motor organelles to get to one place from another.
- Guide movement of chromosomes during cell division (centrosomes).
- Make up cilia and flagella (motor)
Where are intermediate filaments found?
In most animal cells.
What are intermediate filaments made of?
Cable-like and coiled fibrous proteins
What are the function of intermediate filaments?
- Secure organelles (ex.
nucleus) in place. They are not as easily dissembled as microtubules.
Where are microfilaments found?
Just inside the plasma membrane.
What are microfilaments made of/what are they like?
Made of globular proteins called actin which create a twisted double chain.
What are the function(s) of microfilaments?
- Supports cell shape in the plasma membrane (esp. imp for animal cells which lack cell walls)
- Actin interaction with the motor protein myosin causing contracting of muscle cells. Help amoeboid (crawling) movements of Amoeba and white blood cells.
What component of the cytoskeleton is most important in 1. holding the nucleus in place 2. guiding transport vesicles from the Golgi to the plasma membrane 3. contracting muscle cells?
- intermediate filaments 2. microtubules 3. microfilaments.
How were biologists able to see the cytoskeleton for the first time in 1974?
Immunofluorescence microscopy. Antibody proteins that attack to actin and glow when they bond.
What was the technique that immunofluorescence microscopy created?
Molecular cytochemistry. Allowed them to watch cells change in real time?
Difference between molecular cytochemistry and immunofluorescence microscopy
In the former, fluorescently labeled antibodies show the locations of specific molecules. In the latter, the molecules themselves are labeled, and their behavior within a living cell can be tracked.
Where are cilia found?
On the outside of protist cells.
What is the function of cilia?
- Short and numerous “legs” that move the protist.
- Signal receiving antenna (If inmotile). Called the primary cilia, important to embroyonic development.
What is a flagella?
A tail like version of cilia for swimming. Many less.
Example of cilia?
In the trachea, cilia on cells sweep off mucus.
Example of flagella?
sperm.
What are cilia and flagella made of?
microtubules wrapped in an extension of the plasma membrane.
What is the 9+2 pattern?
In eukaryotic cells, this is how microtubules in flagella and cilia organize themselves. pg. 67
How is the 9+2 pattern anchored in a cell?
By a basal body very similar to a centriole.
How do cilia and flagella move?
Dynein proteins walk between pairs of microtubules. One side has feet, the other a body. This causes bending…I’m confused
What hold the microtubules in their place?
Proteins
What makes a cilia nonmotile?
lacking central pair of microtubules.
Primary ciliary dyskinesia (PCD), also known as immotile cilia syndrome, is a fairly rare disease in which cilia and flagella are lacking motor proteins. PCD is characterized by recurrent respiratory tract infections and immotile sperm. How would these seemingly unrelated symptoms be explain?
Without motor proteins, microtubules cannot bend. Thus cilia cannot cleanse the trachea, and sperm cannot swim.
Where is the extracellular matrix found?
Outside the cell.
What is the extracellular matrix made up of?
Mainly collagen, a glycoprotein. Collagen is 40% of protein in body. Collagen weaves itself into thick fibers, and is surrounded in the ECM with other glycoproteins.
What is the function of the extracellular matrix.
- Holds cells together in tissues.
- Protects and supports plasma membrane
Shortening for extracellular matrix?
ECM
add all groups,
endomembrane
What is the name of the protein responsible for binding the ECM to the cell?
Integrins.
What do integrins bind to on the inside of a cell? What do they do?
The cytoskeleton. Transmit signals between the ECm and cytoskeleton.
Don’t forget
to add notes about cell-cell bonding.
How does the integrins connection between the ECM and the cytoskeleton affect the cell?
ECM can regulate cell behavior: direct the movement of embryonic cells, changing activity of genes.
What structures provide support for the plasma membrane?
The membrane is attached through membrane proteins (integrins) to microfilaments in the cytoskeleton and collagen fibers of the ECM.
What are the three types of cell-cell junctions?
Tight junction, anchoring junction and gap junction.
Describe the qualities of a tight junction.
Plasma membranes knit together by tight junctions. prevents leakage of fluid between cells.
Describe the qualities of an anchoring junction.
Intermediate filaments act as the anchors between cells here. They make cells into strong sheets. They can stretch, as skin and muscle.
Describe the qualities of a gap junction.
AKA communicating junctions. Allows for passage of ions. These ions cause the heart to contract, and this type of junction is commonly found in embryos.
A muscle tear injury would probably involve the rupture of which type of cell junction?
Anchoring junction.
Where is the cell wall found?
ONLY plant cells.
What are the functions of the cell wall?
- Protects cell
- Skeleton support
- Keeps plants upright on land.
What is the cell wall made up of?
Cellulose fibers embedded with other polysaccharides and proteins. It is like steel reinforced concrete.
How does the cell wall grow and develop?
When the cell is still growing, the wall is more flexible. After it stops growing, it hardens
Function of pectins in a cell wall?
Sticky polysaccharides between cells, glue the cells together.
What is lignin (cell wall)
A secondary wall of strength in plant cells. Wood uses
Even with there thick cell walls, what is the name of the process which connects plant cells?
Plasmodesmata.
Define plasmodesmata and their function.
Channels that allow water cytosol and other small molecules through. Essential to nourishment and chemical messaging.
Which animal cell junction is analogous to a plasmodesma?
A gap junction.
What are the four functional groups within a cell?
The Genetic Control, the Manufacturing, distribution and breakdown, the energy processing, and the structural support and communication between cells.
What organelles are within the genetic control group? What do they do?
Nucleus and ribosomes that create the proteins from genetic instructions.
What organelles are within the manufacturing, distribution and breakdown group?
The endomembrane system; ER, Golgi Body, lysosomes, vacuoles, and a couple others??
What organelles are within the energy processing group?
mitochondria and chloroplasts
What organelles are within the structural support, movement and communication between cells group?
Cytoskeleton, ECM.
Remember that structure mirrors
function
How do mitochondria, smooth ER and the cytoskeleton all contribute to the contraction of a muscle cells?
Mitochondria supply energy in the form of ATP. The smooth ER helps regulate contraction by the uptake and release of calcium ions. Microfilaments function in thee actual contractile apparatus.
