2.5 Ultrastructure of Plant Cells
First review @September 25, 2023
Practise Q's Done
plant cells have all the same components as animals cells plus a few extras
Function of plant cell organelles
Vacuoles
membrane-bound sacs that contain cell sap
many plants have permanent vacuoles which help to maintain the turgidity of the cell
by pushing the other organelles against the cell wall — this makes the cell rigid
made of a membrane called tonoplast which is selectively permeable (only certain
molecules can pass through it)
vacuoles may appear in animals cells, however they are transient and small
Chloroplasts
organelles responsible for photosynthesis in a plant
contain a green pigment called chlorophyl
only found in stems and leaves, since roots do not get sunlight so photosynthesis
doesn’t occur in that part of the cell
the have a double membrane like mitochondria
the fluid enclosed within the membrane is called the stroma
they have a network of membranes also which form flattened sacs called
thylakoids — several thylakoids stacked together are called grana (granum
singular)
the grana are joined by membranes called lamellae and they contain the pigment
chlorophyll
the starch formed by chloroplasts are stored as starch grains
like mitochondria, chloroplasts also have their own DNA and ribosomes so that they
can make their own enzymes
2.5 Ultrastructure of Plant Cells 1
First review @September 25, 2023
Practise Q's Done
plant cells have all the same components as animals cells plus a few extras
Function of plant cell organelles
Vacuoles
membrane-bound sacs that contain cell sap
many plants have permanent vacuoles which help to maintain the turgidity of the cell
by pushing the other organelles against the cell wall — this makes the cell rigid
made of a membrane called tonoplast which is selectively permeable (only certain
molecules can pass through it)
vacuoles may appear in animals cells, however they are transient and small
Chloroplasts
organelles responsible for photosynthesis in a plant
contain a green pigment called chlorophyl
only found in stems and leaves, since roots do not get sunlight so photosynthesis
doesn’t occur in that part of the cell
the have a double membrane like mitochondria
the fluid enclosed within the membrane is called the stroma
they have a network of membranes also which form flattened sacs called
thylakoids — several thylakoids stacked together are called grana (granum
singular)
the grana are joined by membranes called lamellae and they contain the pigment
chlorophyll
the starch formed by chloroplasts are stored as starch grains
like mitochondria, chloroplasts also have their own DNA and ribosomes so that they
can make their own enzymes
2.5 Ultrastructure of Plant Cells 1
