Biology Lecture 4: Cell Cycling
Base pairing is always anti-parallel.
DNA synthesis is bidirectional (replication forks going in both directions).
o The inheritance of sameness:
DNA (stable double helix structure)
o Replication “bubble” arises from two “forks” created at one “origin”.
o When it’s said that “DNA synthesis is bidirectional” it means that the replication forks
are headed out in both directions.
o Strand that is replicated continuously is leading. The one that is discontinuous is
lagging. Leading and lagging strands depend on replication forks.
***Be able to draw replication fork and bubble.
Bacterial Cell Cycle:
o Bacteria are immortal and continuously divide. Chromosomes are actively partitioned in
the daughter cells, and are split due to binary fission.
o Binary fission ensures that daughter cells get one original copy of the chromosome.
o Found in almost all of our tissues.
o Self-renewing population.
o Progeny are progressively more differentiated.
o When a stem cell divides, you are left with one daughter cell, but the daughter cell
continuously divides further and differentiates into other blood cells.