Lecture 12 Flashcards
What are the vacuoles produced by?
Produced by the Golgi associated endoplasmic reticulum
What is the structural feature of the Vacuole? (1)
It is enclosed by a single membrane called the tonoplast
What are the three main differences between a plant cell and an animal cell?
- Cell Wall
- Chloroplasts
- Central Vacuole
How many vacuoles per plant?
Depends. Mature plant cells typically have a single large vacuole and younger plants have many small vacuoles.
What are the functions of the vacuole?
Storage
Breakdown of macromolecules
Regulation of Cell Turgidity
What are the type of substance that vacuoles store? What are each of their characteristics?
Primary Metabolites - growth associated
Secondary Metabolites - Not growth associated
What are some examples of Primary metabolites?
Inorgainc ions Organic acids Sugars Amino acids Proteins Lipids
What are some the two sections of Secondary metabolites?
Molecules for Defence
Molecules for signalling
What are some examples of molecules for defence?
Small latex containing vacuoles - rubber tree
Specialised cells called Raphides
Alkaloids- nitrogen containing bases
What are Raphides?
Needle shaped crystals of calcium oxalate
Whats the tonoplast?
It’s a selective membrane that controls the movement of substances into and out of the vacuole (has proteins in the membrane eg transport proteins)
Molecules for signalling? - explain
Pigments to attract animals for seed dispersal to give petals colour/attract insects e.g. anthocyanins - purple dots are concentrated areas of anthocyanins and light purple is vacuole
Secondary metabolites can now be produced in ___ ___ Why is it better to produce it in these conditions?
Cell cultures- this way it is more efficient than extracting it form harvested material and ecologically less damaging.
Vacuoles: Degradation
- What it is described to be?
- What characteristics does the vacuole have to help degradation?
- Digestion of cytoplasmic constituents
2. Vacuoles are acidic and contain hydrolytic enzymes similar to the lysosomal enzymes of animal cells.
Why do vacuoles play a large part in regulation of cell turgor?
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.
What are the pathways that cause the cells to lose/gain turgor pressure?
- Due to this high solute concentration within the vacuole, this means that there is a NEGATIVE OSMOTIC PRESSURE, resulting in the WATER UPTAKE.
The plant cell wall enables the uptake of water without bursting.
- Loss of water means the decrease in turgor pressure, and thus will result in WILTING.
What are plastids?
Plastids are double membrane bound organelles found inside plants, which are responsible for activities related to making and storing food.
Describe the origin of Plastids
- A non-photosynthetic eukaryote engulfs a photosynthetic prokaryote.
- The prokaryote forms a relationship between the eukaryotic cell.
- The prokaryote then becomes semi-autonomous. (The prokaryote cannot survive without the host cell fully)
- The non-photosynthetic eukaryote then turns into a photosynthetic eukaryote cell.
What are the main features of Chloroplast DNA?
- Chloroplast DNA is circular
- Most of the genome encoding for chloroplast proteins are in the chloroplast DNA, some of the genes that code for chloroplast proteins are also in the nucleus of the cell.
What are the functions of the chloroplasts? Which reactions take place where?
The function of the chloroplasts are to capture of light energy and convert it to chemical energy.
The dark reactions take place in the stroma
The light reactions take place in the thylakoid membranes
What are the 4 features that chloroplasts have in common with mitochondria?
- Both bounded by two membranes
- Contains nucleic acids
- Outer membrane is highly permeable
- Inner membrane is more selective.
What is the unique feature about the chloroplasts that differs from the mitochondria?
There is a third membrane system in the thylakoid membrane.
What is the thylakoid lumen (space) used for?
Used to build up gradients of molecules for ATP.
What are the structures of the Chloroplasts?
- 3 membranes (thylakoid, inner, outer)
- There are three compartments (stroma, thylakoid space, inter membrane space)
- These compartments and the membranes that separate them are for isolation of different photosynthetic reactions.
What do chromoplasts do?
They attract animals - give colour to many flowers and fruits. They have increased carotenoids (pigments) and decreased thylakoid membranes.
What is the conversion of chromoplasts as fruit ripens?
Chloroplasts are converted to chromoplasts.
What do leucoplasts store?
Pigments
Protein
Lipids
Starch
What are proplastids?
All plastids are derived from proplastids. I.e the proplastids can differentiate and turn into any of the 3 plastids (leucoplasts, chromoplasts, chloroplasts)
