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First, glaucophyte chloroplasts have a peptidoglycan wall, a type of cell wall otherwise only in bacteria (including cyanobacteria). [Note 2] Second, glaucophyte chloroplasts contain concentric unstacked thylakoids which surround a carboxysome – an icosahedral structure that contains the enzyme RuBisCO responsible for carbon fixation.
Diagram of the plant cell, with the cell wall in green. Cell walls serve similar purposes in those organisms that possess them. They may give cells rigidity and strength, offering protection against mechanical stress. The chemical composition and mechanical properties of the cell wall are linked with plant cell growth and morphogenesis. [11]
Each of the envelope membranes is a lipid bilayer that is between 6 and 8 nm thick. The lipid composition of the outer membrane has been found to be 48% phospholipids, 46% galactolipids and 7% sulfolipids, while the inner membrane has been found to contain 16% phospholipids, 79% galactolipids and 5% sulfolipids in spinach chloroplasts.
English: A simple diagram of a plant leaf cell, labelled with numbers. It shows the cytoplasm, nucleus, cell membrane, cell wall, mitochondria, permanent vacuole, and chloroplasts. Note going down the left the numbers are not sequential, this is to match the numbering on others in the series.
The cell wall consists of peptidoglycan in bacteria and acts as an additional barrier against exterior forces. It also prevents the cell from expanding and bursting from osmotic pressure due to a hypotonic environment. Some eukaryotic cells (plant cells and fungal cells) also have a cell wall.
The structure of peptidoglycan Bacterial cell walls. The cell envelope is composed of the cell membrane and the cell wall.As in other organisms, the bacterial cell wall provides structural integrity to the cell.
Cells come in a variety of different shapes. The cell wall may be smooth or ornamented with spines, granules, scrobiculations (pits), or pores. Cells are generally flattened. [6] Cells usually have one or two chloroplasts filling the cell; each chloroplast contains pyrenoids, typically one or two. [3]
Green algae have chloroplasts that contain chlorophyll a and b, giving them a bright green colour, as well as the accessory pigments beta carotene (red-orange) and xanthophylls (yellow) in stacked thylakoids. [12] [13] The cell walls of green algae usually contain cellulose, and they store carbohydrate in the form of starch. [14]