Question

Activity 1: Observation of Mitosis in an Onion and a Whitefish Instructions: View the images in Table 1 and Table 2 of the Activity 1 Page to complete blanks below Table 1: Stages of the Cell Cycle in Onion Root Tip Table 2: Stages of Mitosis in Whitefish Blastula *Name Each Stage *Name Each Stage (a) (b) (b) (c) (c) (d) (d) (e) *To name the stages above, choose from: Interphase, Prophase. Metaphase, Anaphase or Telophase/Cytokinesis Identify the number in the image that is pointing to the following (Omit #15): Spindle microtubules Nuclear membrane Sister chromatids (Duplicated chromosomes) Single chromosomes Plasma membrane Cleavage or cell furrow Hint: Sister chromatids (duplicated chromosomes) are pulled apart in anaphase and become single chromosomes. Post-Lab Questions 1. Why must DNA replicate or copy itself before a cell divides? In which phase of the cell cycle does this occur? ONA replicates before a cell divides to give a complete of genetic instructions to each daughter ceil. DNA replicates in so phase. 2. What are sister chromatids? ntromere, and are distributed to daughter nuclei during Sister Chronnanias are duplicated chromosomes attached at the 3. What event must occur after telophase to complete the process of cell division? The division of the cytoplasm to form 2 daughter cells, otherwis known as cytokinesis. 4. What is the role or purpose of mitotic cell division in the root tip of a plant and in the blastula stage of an animal?

Answer 1

Post lab questions.

4. role or purpose of mitotic cell division in plants and animals....

Blastula cells represent the reproductive cells which undergo mitosis at a regular interval as the embryo increases its complexity and number of cells for development. In the case for plants, the root tip is more dense and contains an apical meristem that will make the root lengthening and enlarging an easier and faster process.

8. two different pop-it beads for a chromosome

To identify the centromere in the chromosome from the other parts/ structure: the long and short arms, and chromatid

9. two types of molecules found in chromatin

Chromatin is composed of mostly DNA, proteins called histones, and ribonucleic acids.

10. what actually moves sister chromatids and separates them in mitosis

In mitosis, sister chromatids movement and separation occurs in the anaphase; the replicated chromosomes are split / break at centromeres and split and move to the opposites poles of the cell. What helps them perform the action is the three types of microtubules that are involved in making the adequate force for separation. These are: kinethocore, interpollar and astral.

11. How many homologous pairs of chromosomes in the two daughter cells at the end of cytokinesis? Are they identical to the parent cell?

two diploid (46 chromosomes) daughters at the end of mitosis with the same original number of chromosomes, they are identical.

12. diploid number of each daughter cell

2 ⁿ = 23 pairs of chromosomes.= total of 46 chromosomes

PHASES IN MITOSIS

• chromosomes are pilled to opposite poles -- E
• growth phase between cell division ---A
• two identical nuclei are formed in the cell --- G
• sister chromatis are alligned in the equator-- D
• spindle fibers attach to sister chromatids- -- C
• organelles and rest of cytoplasm are divided--F
• chromatin condenses and nuclear memnrane fragments---B