Question

what is the main function of the ribosomes in * a cell?
energy production
protein synthesis
dna replication
lipid storage
which of the following structures disappears * in prophase and reappears in telophase?
centromeres
chromosomes
nuclear membrane
spindle fibres
the proper sequence of mitosis is *
prophase, anaphase, metaphase, telophase
prophase, telophase, anaphase, metaphase.
metaphase, prophase, anaphase, telophase
prophase, metaphase, anaphase, telophase.

Explanation:

• Ribosomes are organelles that read mRNA (messenger RNA) and assemble amino acids into polypeptide chains, which is the process of protein synthesis. Energy production is mainly done by mitochondria, DNA replication occurs in the nucleus (with enzymes like DNA polymerase playing key roles), and lipid storage is associated with structures like lipid droplets.
• During prophase of mitosis, the nuclear membrane breaks down. In telophase, as the two new daughter nuclei are forming, the nuclear membrane reforms around each set of chromosomes. Centromeres are part of chromosomes (they hold sister chromatids together), chromosomes condense in prophase (but don't disappear in the sense of losing their structure - they become more visible) and de - condense in telophase, and spindle fibers form in prophase and disassemble in telophase.
• The correct sequence of mitosis: In prophase, chromosomes condense, the nuclear membrane breaks down, and spindle fibers form. In metaphase, chromosomes line up at the equatorial plane. In anaphase, sister chromatids are pulled apart to opposite poles. In telophase, the nuclear membrane reforms, chromosomes de - condense, and cytokinesis (cell division) usually follows.

Answer:

1. Protein synthesis
2. nuclear membrane
3. prophase, metaphase, anaphase, telophase.