Lecture 4 Flashcards
What did Merion Thomas observe about Crassulacean plants?
They could simultaneously take up both oxygen and carbon dioxide in the dark
What did Benjamin Heyne note when chewing plants?
He described a daily acid taste cycle in certain plants in thr Indian gardens in 1813
Give 3 example of species that can exhibit CAM
Cactuses
Agaves
Ephphytes
What are the key characteristics of CAM syndrome?
Succulent photosynthetic organs
Stomata open at night
High abundance of the enzymes PEPC and MDH
Diurnal fluctuation of malic acid
What does MDH stand for?
Malate dehydrogenase
What does PEPC stand for?
Phosphoenolpyruvate carboxylase
When are a CAM plants levels of malic acid at it’s highest?
Night
Do PEPC and Rubisco compete for carbon dioxide?
No as they are diurnally regulated?
When is PEPC active?
Night
When is Rubisco active?
Daytime
What does RuBisCo stand for?
Ribulose-bisphosphate carboxylase
Why do CAM cells have such large vacuoles?
To enable storage of large quantities of malic acid
What is the main advantage of the CAM pathway?
It increases water efficiency
How much water is lost for each carbon dioxide molecule assimialted in a CAM plant?
125
What are the energy costs associated with CAM plants?
Pumping malate into the cytoplasm
Generation of PEP for carboxylation
Temporal regulation of PEPC
Where is starch made?
In chloroplasts
How is the amount of carbon stored regulated in CAM plants?
The carbon from the day is stored as starch in chloroplasts for the following night. The photosynthetic partitioning is finely regulated dependent on environmental conditions particularly day length.
What are the 6 types of plastids?
Proplastid Etioplast Chromoplast Chloroplast Leucoplast Proteinoplast Elaioplast Amyloplast
What is a chromoplast responsible for?
Pigmentation
What is an amyloplast responsible for?
Making and storing starch
What is an elaioplast responsible for?
Lipids
What is a proteinoplast responsible for?
Proteins
What is endosymbiotic gene transfer?
When there is genetic exchange between the endosymbiont and the host
How do plastids survive when they only have about 10% of the required genes for metabolic capacity?
Endosymbiotic gene transfer.
Proteins encoded by genes in the nucleus are sent to the plastid
What are stromules?
Plastids which can change shape
