Meera looks at an electron micrograph of a thin section of a mitochondrion…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Meera looks at an electron micrograph of a thin section of a mitochondrion. Name its two membranes and its two compartments. Where should she look for the cristae, and where for the mitochondrial DNA?
Need a reminder? The key ideaShow
A mitochondrion has an outer membrane and an inner membrane folded into cristae, an outer compartment and a matrix. The matrix holds circular DNA and 70S ribosomes. Plastids: chloroplasts (chlorophyll), chromoplasts (carotene, xanthophylls), and leucoplasts: amyloplasts (starch), elaioplasts (oils and fats), aleuroplasts (proteins).
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The membranes. A smooth outer membrane forms the boundary. Inside it lies the inner membrane.
Step 2. The compartments. The outer compartment lies between the two membranes. The inner compartment, the matrix, lies inside the inner membrane.
Step 3. The cristae. They are the infoldings of the inner membrane, reaching into the matrix.
Step 4. The DNA. A single circular DNA molecule lies in the matrix, with the 70S ribosomes.
Answer: outer and inner membranes; outer compartment and matrix; cristae are folds of the inner membrane; the DNA is in the matrix.
Discussion (0)
Log in to join the discussion.
Loading…