Challenge: What role do chromosomes play in the inheritance of genes? Act 63 – Show Me the Genes Challenge: What role do chromosomes play in the inheritance of genes?

Stopping to Think 1 How is the function of cell division in single –celled organisms different from cell division in multicellular organisms? Cell division is the method of asexual reproduction in single-celled organisms, but it is also the process that enables growth and replenishment of dead cells in multi-cellular organisms.

Stopping to Think 2 What would happen to the number of chromosomes in each cell if copies of them were not made before cell division? The number of chromosomes would be cut in half for each new cell if the chromosomes did not copy.

Stopping to Think 3 Why must the number of chromosomes in the sperm and egg be half the number of chromosomes in the other cells of an organism? The number of chromosomes would double with each generation if the egg and sperm both gave 46 chromosomes.

Stopping to Think 4 Consider two children with the same two parents. Would you expect them to have the same sets of chromosomes? Explain why or why not. Do not expect siblings to have the same sets of chromosomes. Genes are present on chromosomes and only one chromosome of each pair is given to each offspring.

Stopping to Think 5 How exactly does a mutation change the form of an organism? When do such mutations occur? Mutations are random changes in the DNA sequence of genes. Mutations can occur at any cell division during the copying of the DNA. Mutations that change the entire form of an organism occur only during the formation of sex cells in the parents of that organism.

Analysis #1 46 Chromosomes inside a cell 1 chromosome   46 Chromosomes inside a cell 1 chromosome gene on a chromosome l DNA Each gene is on a chromosome, which is made of a tightly coiled double-strand of DNA.

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