DNA replication is the process by which DNA copies itself for cell division. It ensures each new cell has the full set of instructions to function properly. Mutations can occur during replication if there are errors in copying the DNA sequence of adenine, thymine, guanine, and cytosine bases. Mutations can lead to diseases or provide genetic diversity to make organisms healthier over time. The key components of replication include telomeres, Okazaki fragments, DNA ligase, and telomerase.

1. DNA Replication
By: Danielle Bowser

67. More Information
• DNA replication needs to happen for new cells to divide. The cells need
a copy of the DNA or instructions to function and know what to do.
• Mutations can occur when there is an error in the DNA sequence
(adenine, thymine, guanine, and cytosine). Errors in the sequence are
things such as a missing sequence piece, the bases are paired up
wrong, or duplication (a piece of DNA is copied one or more times).
• Mutations can lead to diseases, cancer, color blindness, sickle cell, and
many more. Some mutations are inherited from the parent
organisms, some mutations happen due to environmental factors, and
of course some happen due to cell division.
• Not all mutations are bad. Mutations can happen to make an organisms
healthier over time by creating genetic diversity.

68. More Information
• Telomeres: when talking about chromosomes the telomeres are the long parts
of the chromosome pinched in the middle by what is called the centromere.
Telomeres keep other chromosomes in the cell from becoming attached to one
another.
• Okazaki Fragments: a section of the lagging complementary strand that
synthesizes off of the RNA primer and is later bonded together by DNA ligase
• DNA Ligase: “stiches” the Okazaki fragments together by forming phospodiester
bonds
• Telomerase: an enzyme that makes DNA from a RNA template. Telomerase is
generally found in stem cells and unicellular eukaryotes
• Cancer: cancer cells can grow indefinitely and contain telomerase. Cancer is a
type of bad mutated cell that harms organisms.

69. More Information
• Transplanted Cells: removing cells from an organism, changing the cells
with the gene that the organisms was unable to make, and returning
the improved cell back to the organism
• Cloning: creating the same organism from the nucleus of a cell from an
adult organism
• Aging: progressive loss of mental functions that increase the chance of
death. Aging of course starts in the cells. When cells are not produced
as efficiently or do not work as smoothly it is generally due to aging
but, it could also be cause of mutations, disease, and environmental
factors.

70. THE END!