Lecture 12: Unique plant structures Flashcards
What is the protoplast?
A plant cell minus the cell wall.
What are plasmodesmata?
Narrow channels between two cell walls.
How many membranes surround the vacuole?
One.
What is the tonoplast?
The single membrane around the vacuole. It is highly selective.
How many vacuoles do plant cells usually have?
Young plant cells often have many small vacuoles, but mature plant cells typically have one large vacuole.
How are vacuoles produced?
Vacuoles are produced by the golgi associated endoplasmic reticulum.
What are the three main functions of a vacuole?
Storage - Primary and secondary metabolites
Breakdown of macromolecules and organelles
Regulation of cell turgor
Where are metabolites stored in plant cells?
In the vacuole.
Which metabolites are growth associated?
Primary metabolites are growth associated, Secondary metabolites are not growth associated.
The tonoplast is a __________ membrane that controls the movement of substances into and out of the vacuole.
The tonoplast is a selective membrane that controls the movement of substances into and out of the vacuole.
What are the 6 main primary metabolites in vacuoles?
Inorganic ions Organic acids Sugars Amino acids Proteins Lipids
Can water pass through the tonoplast freely?
Yes.
What are two types of secondary metabolites?
Molecules for defence
Molecules for signalling
What are 3 examples of defence molecules?
- Rubber tree (Hevea brasiliensis)
- Raphides in vacuoles (Raphides are needle shaped crystals of calcium oxalate)
- Alkaloids. Have a toxic effect on animals. Used in drugs e.g., cocaine, morphine, codeine, quinine
What is an example of signalling molecules?
Catharanthus roseus pigment. Used in Vincristine &/or Vinblastine
How are plant cells produced artificially?
Using a cell culture (can be genetically modified). Economical (efficient) and ecological benefits.
What is Anthocyanin?
A pigment used for attracting animals and pollinators to plants.
Where are anthocyanins stored?
In the vacuole.
Where are organelles and macromolecules digested in a plant cells?
In the vacuole. (Digestion of cytoplasmic constituents)
Vacuoles are ALKALINE/ACIDIC and contain ________ enzymes similar to the lysosomal enzymes of animal cells
Vacuoles are acidic and contain hydrolytic enzymes similar to the lysosomal enzymes of animal cells
What decides what enters and exits the vacuole?
The tonoplast. Tonoplast control can vary depending on the environment and cell type.
Because they contain water and
make up such a large portion of the
protoplast, vacuoles can play a role
in the ____________ __ _____ _______.
Because they contain water and
make up such a large portion of the
protoplast, vacuoles can play a role
in the regulation of cell turgor.
How is turgor developed?
High concentrations of solutes in the vacuoles have a negative osmotic potential, resulting in water up take. The plant cell wall enables water up
take without bursting.
Loss of water from vacuoles _________ turgor pressure
Loss of water from vacuoles decreases turgor pressure
What is wilting?
A loss of turgor pressure.
What the 4 steps in the plastid origin theory?
- Non-photosynthetic eukaryote
- Engulfing of Photosynthetic prokaryote
- Chloroplast becomes a semi-autonomous organelle
- Photosynthetic eukaryote
What is the DNA in chloroplasts called and what shape does it have?
ctDNA, circular.
Although \_\_\_\_\_\_\_ contains information for the formation of many chloroplast proteins, some proteins found in the chloroplast are encoded by genes present in the \_\_\_\_\_\_\_ of the cell.
Although ctDNA contains information for the formation of many chloroplast proteins, some proteins found in the chloroplast are encoded by genes present in the nucleus of the cell.
What is the function of chloroplasts?
photosynthesis: Capture light energy and convert it to chemical energy
What is the function of chromoplasts?
synthesis and storage of coloured pigments
What is the function of leucoplasts?
storage of assimilates (starch)
What is the function of proplastids?
precursors to the other plastids
What are 4 similarities between chloroplasts and mitochondria?
- bounded by two membranes
- contain nucleic acids
- outer membrane highly permeable
- inner membrane more selective
What is a unique feature of chloroplasts in terms of its membranes?
It has a third membrane system.
Where are the thylakoid membrane systems found?
In the chloroplast.
Where are lumens found?
Inside of thylakoid
What are the 3 membranes of the chloroplast?
Inner, out, thylakoid
What are the 3 compartments of the chloroplast?
Stroma, thylakoid space, and intermembrane space.
Where do dark reactions take place in the chloroplast?
In the stroma.
Where do light reactions take place in the chloroplast?
On the thylakoid membranes.
As fruit ripens _____________are converted to __________.
As fruit ripens chloroplasts are converted to chromoplasts.
What are the major structural differences between chloroplast and chromoplasts?
Chromoplasts have increased carotenoids (pigments) and decreased thylakoid membranes.
What do leucoplasts store?
Pigments, protein, lipids or starch.
