Question

bio 1 - ck12 reading notes #14 - chromosomes & mitosis
chromosomes - ck12 2.31

1. what is mitosis?
2. what event must occur before mitosis begins, and why is it necessary?
3. draw the model of the chromosome below, correctly labeling the centromere and one of the chromatids.
4. explain what sister chromatids are.
5. what is a gene, and how are they related to chromosomes?
6. human cells have __ chromosomes, from mom and __ from dad.
7. what is a homologous pair of chromosomes?

Explanation:

1. Mitosis is a type of cell - division where a single cell divides into two identical daughter cells. It is crucial for growth, repair, and asexual reproduction.
2. DNA replication must occur before mitosis begins. This is necessary so that each daughter cell receives a complete set of genetic information.
3. A chromosome consists of two sister chromatids joined at the centromere. The centromere is the constricted region, and each half of the chromosome is a chromatid.
4. Sister chromatids are two identical copies of a single replicated chromosome that are joined together by a centromere. They are formed during DNA replication.
5. A gene is a segment of DNA that contains the instructions for making a particular protein or RNA molecule. Genes are located on chromosomes.
6. Human cells have 46 chromosomes, 23 from mom and 23 from dad.
7. A homologous pair of chromosomes consists of two chromosomes, one from the mother and one from the father, that have the same genes at the same loci but may have different alleles.

Answer:

1. Mitosis is a type of cell - division resulting in two identical daughter cells.
2. DNA replication; to ensure each daughter cell has a full set of genetic info.
3. Draw a structure with two parallel parts (chromatids) joined at a constricted region (centromere).
4. Two identical copies of a replicated chromosome joined by a centromere.
5. A gene is a DNA segment with instructions for making proteins/RNA; located on chromosomes.
6. 46; 23; 23
7. A pair of chromosomes, one from each parent, with the same genes at the same loci.