AP Bio Insta-Review Topic 4.7*: Regulation of Cell Cycle

Front

Which checkpoint determines whether the cell will divide? Options: G₁, S, G₂, M

Back

G₁

Answer explanation

The G1 checkpoint occurs in the G1 phase. This is the go-ahead signal. If a cell passes this checkpoint, it will usually complete cell division.

Front

Which checkpoint inhibits nondisjunction? Options: G₁, S, G₂, M

Back

M

Answer explanation

Nondisjunction is the process where sister chromatids or homologous chromosomes do not segregate to opposite poles. The M checkpoint ensures that all chromatids/chromosomes are attached to a microtubule for anaphase.

Front

Which checkpoint verifies DNA has “no errors” and replicated? Options: G₁, S, G₂, M

Back

G₂

Answer explanation

The G2 checkpoint occurs prior to mitosis. This will ensure the DNA has copied with “no errors” and the cell is large enough for division.

Front

What phase is the M checkpoint located in?

Back

Metaphase

Answer explanation

The M checkpoint is during metaphase when the sister chromatids are on the metaphase plate. This will check to ensure all microtubules are attached to chromatids to ensure equal division of chromosomes.

Front

How does the level of cyclin and CdK vary during cell cycle?

Back

Cyclin increases, CdK remains the same

Answer explanation

CdK is the cyclin dependent kinase. This enzyme will remain at a constant level throughout the cell cycle. The cyclin will build up through interphase. Once it reaches the optimal level, the enzyme will be activated.

Front

Proto-oncogenes can mutate into oncogenes.

Back

True

Answer explanation

Proto-oncogenes are normal cell division genes. When the proto-oncogene is mutated, it will cause the normal growth to be overactivated thus causes an increase in cell divison with causes abnormal cell growth.

Front

If the cell doesn’t get the go ahead signal in G1, where does it go?

Back

G₀

Answer explanation

If the cell does not get the signal at G0, they will exit the cell cycle. Example cells include: nerve, muscle, or liver cells

Front

What is the function of the M checkpoint?

Back

Check DNA is undamaged

Answer explanation

The M checkpoint is during metaphase when the sister chromatids are on the metaphase plate. This will check to ensure all microtubules are attached to chromatids to ensure equal division of chromosomes.

Front

What could result if the cell bypasses the M checkpoint?

Back

Nondisjunction

Answer explanation

The M checkpoint is during metaphase when the sister chromatids are on the metaphase plate. This will check to ensure all microtubules are attached to chromatids to ensure equal division of chromosomes. If this phase is bypassed, the sister chromatids might not segregate to opposite cells.

Front

What stimulates progression from the G₂ checkpoint?

Back

Cyclin level rises to specific level to bind with CdKs

Answer explanation

The G2 checkpoint occurs prior to mitosis. This will ensure the DNA has copied with “no errors” and the cell is large enough for division. As the cell goes through interphase, the cyclin level will rise while the CdK level stays the same.