10 Questions
What is the primary function of cyclins in the cell cycle?
To trigger or activate CDKs
What is the role of G1/S-cyclins in the cell cycle?
To activate G1/S-Cdk in late G1
What happens to the levels of G1/S-cyclins during the S phase?
They lessen in number
What is the role of S-cyclins in the cell cycle?
To stimulate DNA replication
What is the mechanism by which cyclins trigger cell cycle events?
Protein phosphorylation
What is the role of Taga in the cell cycle?
To 'convince' G1-Cyclin
When do M-cyclins increase in production?
During the G2/M transition
What is the result of high levels of G1/S-cyclins?
The cell commits to entering the cell cycle
What is the role of cyclins in the regulation of the cell cycle?
To trigger or activate CDKs
What happens to the levels of M-cyclins between metaphase and anaphase?
They lessen in number
Study Notes
Historical Background of Genetics
- Father of modern genetics: studied 20,000 pea plants and gathered data that was later verified by modern scientists
- Data was found to be perfect, with a probability of less than 0.001% of occurring by chance, leading to suspicions of falsification
Discovery of DNA
- 1870s: observation of nuclei of male and female gametes fusing during fertilization, leading to the recognition of the importance of cell nucleus in inheritance
- 1880s-1890s: discovery of chromosomes in the nucleus using light microscopy
- 1900s: discovery of nuclein (later found to be DNA) within the nucleus
- Albrecht Kossel (1910): discovery of nucleobases, finding that nuclein is made up of monomers (building blocks) called nucleotides
- Phoebus Levene (1910): discovery of the structure of a nucleotide, including a sugar, phosphate group, and nitrogenous base
Griffith Experiment (1928)
- Studied transformation of bacteria using two types of bacteria: non-virulent rough and virulent smooth
- Experiments:
- Control: mouse + rough strain → mouse lived
- Exp 1: mouse + heat-killed smooth strain → mouse lived
- Exp 2: mouse + rough strain + smooth strain (heat-killed) → mouse died, with transformation of rough strain to smooth strain
- Exp 3: cultured virulent strain from dead mice, infecting another mouse which died
- Implications: DNA is the transforming molecule, not protein
Avery, MacLeod, and McCarthy Experiment (1944)
- Used radioactive sulfur to label bacteriophage DNA, infecting E. coli
- Results: pellet (E. coli) was radioactive, supernatant was not, concluding that DNA is the blueprint for life
Cell Cycle
- Three main stages: G1, S, and M
- G1: prepared to replicate DNA, receives signal, and prepares for S phase
- S phase: DNA replication, cell cannot do anything else
- G2/M transition: replenishes resources, checks for DNA replication errors, and prepares for mitosis
- M phase: metaphase, anaphase, and telophase leading to cytokinesis
Regulation of Cell Cycle
- Cyclins and CDKs regulate the cell cycle
- G1/S-cyclin: activates G1/S-Cdk, triggering commitment to the cell cycle entry
- S-cyclin: stimulates DNA replication
- M-cyclin: stimulates the enter into the mitotic phase
Test your knowledge of genetics and biotechnology with this quiz. Learn about the father of modern genetics, the importance of biotechnology, and more. Discover interesting facts about DNA and species revival.
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