DC Biology-Cell Cycle Regulation Quiz

Coordination of cell division is critical for…

Normal growth, development and maintenance

What are the two irreversible points in cell cycle?

1. Replication of genetic material

2. Separation of sister chromatids

Checkpoints:

Cell cycle controlled by stop and go chemical signals at critical points

What are the three major checkpoints?

1. G1/S

2. G2/M

3. Spindle

Which checkpoint is the most critical?

G1/S

If cells receive go signal in G1/S, what do they do? If they receive stop?

Divides; exits cycle and switches to G0 phase

How do cells know when to divide?

Cell communication signals/chemical signals

Go signals promote…

Cell growth and division

Internal go signals:

Promoting factors

External go signals:

Growth factors

What is go signal primary mechanism of control?

Phosphorylation

Cell cycle controls (three):

1. Cyclins

2. Cyclin-dependent kinases (Cdks)

3. Cyclin-dependent kinase cyclin complex

The interaction between ________ and ________ triggers the stages of cell cycle

Cyclins & Cdks

Growth factors coordinate between ______

Cells

Density-dependent inhibition (external):

Crowded cells stop dividing

Anchorage dependance (external):

To divide, cells must be attached to substrate

What does proto-oncogenes normally do? What about if switched on?

Activate cell division; cause cancer

What does tumor-supressor genes normally do? What about if switched off?

Inhibit cell division; cause cancer

P53 protien:

Halts cell division if detects damaged DNA

Mutagen:

Changes genetic material of an organism

Examples of physical, chemical and biological mutagens:

Radiation, metals, viruses or bacteria

Mutagens that lead to the formation of cancer are further classified as….

Carcinogens

Mitotic index:

The ratio of cells undergoing mitosis to the number of cells not undergoing mitosis

Each cell type will have a different ____________ based on division rate

Mitotic index

Traditional treatments for cancers:

Radiation & chemotherapy

Why are most cell lines not immortal?

Telomeres, hayflick limit, senescence

Hayflick limit:

Normal cell can only divide 40-60 times before it cant anymore

Senescence:

Aging/retirement

Telomere structure:

Regions of repetitive DNA located at each end of a chomatid

Telomere function:

Prevent chromosomal deteriation

Telomeres can be lengthened by enzyme ___________

Telomerase

HeLa cells:

A cell type in an immortal cell lines used in scientific research; oldest and most commonly used human cell line

G1/S checkpoint checks for…

Cell size, nutrients, growth factors, DNA damage

G2/M checkpoint checks for:

DNA damage, DNA replication completeness

Spindle checkpoint checks for…

Chromosome attachment to spindle at metaphase plate