Cells, Photosynthesis, Respiration Practice Questions E
1. Describe binary fission.
Binary fission is the process by which most prokaryotic cells divide.
It can be broken down into a series of three steps.
Step 1: DNA Replication
Step 2: Chromosome Segregation
Step 3: Cytokinesis
2. What is mitosis?
Mitosis is the process by which eukaryotic cells divide.
It is a multi-phase process in which the nucleus of the cell divides.
3. Identify the phases of the eukaryotic cell cycle.
It can be categorized mainly into two phases.
Each can be subdivided into the following.
Mitotic phase (mitosis and cytokinesis)
Interphase (growth phase 1, synthesis phase, and growth phase 2)
4. What happens during interphase?
The following three phases occur during interphase.
Growth Phase 1 (G1): during this phase, the cell grows rapidly, while
performing routine metabolic processes. It also makes proteins needed for
DNA replication and copies some of its organelles in preparation for cell
division.
Synthesis Phase (S): during this phase, the cell's DNA is copied in the
process of DNA replication.
Growth Phase 2 (G2): during this phase, the cell makes final preparations to
divide. It makes additional proteins and organelles.
5. Define cancer.
Cancer is a disease that occurs when the cell cycle is no longer regulated.
6. How might the relationship between cancer and the cell cycle be used in
the search for causes of cancer?
The cell cycle of cancer is no longer regulated because the cell's DNA
becomes damaged. When the cell's DNA is damaged, it cannot produce
proper regulatory proteins. These proteins control the cycle by signaling
the cell to either start or delay the next phase of the cycle. This means
that cancerous cells generally keep dividing at a much faster rate than
normal cells do. Those rapidly dividing cells take up nutrients and space that
normal cells need.
7. Cells go through a series of events that include growth, DNA synthesis,
and cell division. Why are these events best represented by a cycle
diagram?
Because these events are repetitive and they are a continuous process.
Moreover, a cycle diagram can show the length of time each event generally
takes.
8. Contrast cell division in prokaryotes and eukaryotes. Why are the two
types of cell division different?
Most prokaryotes use the process of binary fission, whereas eukaryotes use
the process of mitosis. They use different cell division methods. This is
because the structure of prokaryotes is much simpler than that of
eukaryotes. (The size is smaller, too.) The chromosome of prokaryotes such
as bacteria is single and circular. The chromosomes of eukaryotes such as
humans, in contrast, are multiple and its shapes are complex.
9. Explain how the cell cycle is regulated.
The cell cycle is regulated mainly by regulatory proteins. These proteins
control the cycle by signaling the cell to either start or delay the next
phase of the cycle. They ensure that the cell completes the previous phase
before moving on. Regulatory proteins control the cell cycle at key
checkpoints of the cycle.
10. Why is DNA replication essential to the cell cycle?
DNA contains genetic information. DNA replication is essential to the cell
cycle because when the cell divides, each daughter cell has to have its own
chromosomes (including DNA) that are genetically identical to each other
and to the parent cell.