Lecture 9: Mitochondria, Chloroplasts, Cytoskeleton & Cell Adhesion Flashcards
What are plastids? Examples?
Small organelles such as mitochondria or chloroplast
Are the chloroplast and mitochondria part of the end-membrane system?
No
How many membranes does the mitochondria have?
The mitochondria has two membranes, an inner membrane and an outer membrane
What are Christae?
Christae are formed when the inner membrane of the mitochondria is further invaginated
- Christae contains the enzymes for respiration
What is the matrix and where is it?
The matrix is the space inside the mitochondria.
-It is full of enzymes that catalyze the citric acid cycle
- It also contains DNA that is transcribed into RNA
-Does contain some ribosomes and RNA and circular DNA
Where are mitochondria found?
In all eukaryotes(plants, animals, fungi, protists)
What are mitochondria essential?
They provide our daily ATP needs
Where are chloroplasts found?
Found in plants and other eukaryotes but never in animals
How many membranes do chloroplasts have?
Two, an inner membrane and an outer membrane
What are thylakoids?
A stack of membranes separated from the inner membrane inside chloroplasts
- Help absorb sunlight for photosynthesis
-All photosynthetic enzymes are found within the thylakoids
What is the storma?
The space that fills the rest of the interior of the chloroplast similar to the matrix of mitochondria)
-Stroma contains enzymes that mediate carbon fixation
What is carbon fixation?
Conversion of atmospheric carbon dioxide into sugars
What is found inside chloroplasts?
-RNA
-DNA
-Ribosomes
-Circular DNA
Plastids are endosymbiotic, what does that mean?
They live inside other organisms and both mutually benefit
What is phagocytosis?
An event where one cell eats another one
What went through phagocytosis?
Both the mitochondria and chloroplasts went through phagocytosis which is how they ended up inside of cells
Prove of the endosymbiosis theory due to membranes of chloroplasts and mitochondria ?
-Both chloroplasts and mitochondria have double membranes
-Their outer membranes also have slightly different compositions than their inner membranes(out membrane is similar to a cell membrane, inner membrane is similar to a bacterial membrane)
How does the importation of lipids and proteins contribute to the endosymbiosis theory?
Lipids and proteins are imported completely different into chloroplasts and mitochondria compared to the endomembrane system(have a unique machinery for protein importation)(completely different from the ER, proteins are not made in the ER but instead in the cytosol and then enter into the mitochondria with their own machinery)(some are even made inside the mitochondria and chloroplasts)
What is the most important piece of evidence for the endosymbiosis theory?
Mitochondria and chloroplasts have their own genome, a circular genome which is typically found in bacteria
Additional pieces of evidence that are in favour of the endosymbiosis theory?
-They have ribosomes that look more bacterial
-Size of the mitochondria and chloroplast are similar to that of bacteria
Are the Golgi and ER from the same ancestor as the chloroplasts and mitochondria?
NO
What is a cytoskeleton?
-Any type of internal structure that gives cells their typical shape
-Normally huge protein complexes made up of many individual proteins that provide stability and shape and even allow cells to move around
What are the three components that make up the cytoskeleton?
- Actin Filaments
- Intermediate Filaments
- Microtubules
What are actin filaments?
-Made up of actin monomers that polymerize into actin filament
-Actin monomer refers to an entire protein
-Long chains
From largest to smallest name the three components of the cytoskeleton?
-Microtubules
-Intermediate Filaments
-Actin Filaments
Is the polymerization of actin filaments covalent bonds?
No, instead it is protein-protein interactions
What causes actin filaments to have polarity?
-Actin filaments have a positive and negative end because they are not perfectly round
Do proteins interact with actin filaments, if yes how?
- Proteins do interact with actin filaments
- Proteins can help them depolymerize, grow or can cut the actin filaments
-Some actin binding proteins will bind actin filaments together into big bundles of actin filaments
How do actin filaments work in gut cells?
- The actin is cortical in the gut cells(right below the membrane)
- The actin makes villi in gut cells(they stick out and increase the surface area of gut cells to help increase food that the body intakes)
What is myosin?
-A motor protein that can bind to and walk along the actin filaments
-It can only walk in one direction