Check Your Knowledge
Title of the Article: Your Cells Are My Cells
Author and Year of the article: J. Lee Nelson, 2007
Write 2-3 paragraphs summarizing the article:
The article discusses microchimerism, the phenomenon where cells from one individual live
inside another. During pregnancy, cells cross the placenta in both directions, a mother’s cells
can take root in her child, and fetal cells can remain in the mother. Surprisingly, many of
these foreign cells persist for decades, sometimes integrating into tissues like the heart,
pancreas, or liver. Scientists now know that these cells are often stem cells or stemlike cells,
meaning they can survive long-term and even transform into specialized tissues.
Researchers are uncovering that microchimerism has both positive and negative effects. In
some cases, the foreign cells may trigger autoimmune diseases, such as juvenile
dermatomyositis or neonatal lupus, by causing the immune system to mistakenly attack
tissues. On the other hand, these cells can sometimes help repair damage. For example,
maternal cells found in the pancreas of diabetics may be trying to regenerate
insulin-producing cells. Because of this, microchimerism is now seen as a potential avenue
for developing new therapies that could either prevent immune disorders or encourage tissue
regeneration.
List 5 things you did not know but learned from reading this article:
1. During pregnancy, cells pass both ways, from mother to child and from child to
mother.
2. These “foreign” cells can survive for decades and even become part of organs like the
heart or pancreas.
3. The condition is called microchimerism, named after the mythological chimera that
combines different animals.
4. Microchimerism may explain some autoimmune diseases, since the immune system
could be attacking foreign cells rather than the body’s own cells.
5. These transferred cells can sometimes help heal tissues, opening up possibilities for
future medical treatments.
Title of the Article: Mitochondrial DNA in Aging and Disease
Author and Year of the article: Douglas C. Wallace, 1997
Write 2-3 paragraphs summarizing the article:
The article explains how tiny defects in mitochondrial DNA (mtDNA) can cause serious
diseases and may even play a role in aging. Unlike the familiar DNA in the nucleus,
mitochondria have their own circular DNA with 37 genes that help produce energy for the
cell. Mutations in these genes can harm energy production, leading to disorders that often
affect organs with high energy needs, such as the brain, muscles, heart, and kidneys. For
example, conditions like Leber’s hereditary optic neuropathy (blindness), mitochondrial
myopathy (muscle weakness), and MELAS (a multi-system disorder) have all been linked to
mtDNA mutations.
One key difference from nuclear DNA is inheritance: mitochondrial DNA is passed down
only from the mother, since sperm do not contribute mitochondria. Mutations can be
heteroplasmic (a mix of normal and mutant DNA) or homoplasmic (all copies mutated). This
makes the symptoms unpredictable, two people with the same mutation may experience very
different diseases depending on how much of their mitochondria carry the defect.
Researchers have also found that mtDNA damage builds up over a person’s lifetime, partly
from harmful molecules called free radicals, which may explain why mtDNA is connected
not just to rare inherited diseases but also to common problems like diabetes, heart failure,
and even Alzheimer’s disease.
List 5 things you did not know but learned from reading this article:
1. Mitochondria have their own DNA with 37 genes separate from nuclear DNA.
2. Mitochondrial DNA mutations are inherited only from the mother.
3. These mutations can cause diseases such as blindness, muscle weakness, seizures,
kidney failure, and even Alzheimer’s disease.
4. Cells can have a mix of normal and mutant mitochondrial DNA (heteroplasmy),
which makes symptoms vary in severity.
5. Damage to mitochondrial DNA accumulates with age, possibly contributing to aging
and late-life diseases like diabetes and heart disease.
Title of the Article: The New Code of Life (RNA)
Author and Year of the article: Philip Ball, 2024
Write 2-3 paragraphs summarizing the article:
For a long time, scientists thought DNA’s main job was to make proteins, with RNA acting
only as a messenger between DNA and protein-making ribosomes. But research from
projects like ENCODE has revealed that most of our DNA actually makes noncoding RNAs
(ncRNAs), which do not build proteins but instead regulate genes in complex ways. Some
ncRNAs, like long noncoding RNAs (lncRNAs), can silence entire chromosomes (such as
XIST turning off one X chromosome in females) or act as scaffolds to organize proteins and
control chromatin structure. Others, like microRNAs (miRNAs) and small interfering RNAs
(siRNAs), can block or destroy messenger RNAs, preventing proteins from being made.
These discoveries represent an “RNA revolution” because they show that genetic
programming is far more complex than just “DNA → RNA → protein.” Noncoding RNAs
may explain how cells fine-tune which genes are active, help organisms adapt more flexibly
through evolution, and even play roles in diseases like cancer. Scientists are now studying
whether ncRNAs could be used in medicine, either as drug targets or as treatments
themselves. This new understanding shifts the view of RNA from being a passive messenger
to being an active “computational engine” of the cell.
List 5 things you did not know but learned from reading this article:
1. Most of our genome makes noncoding RNA, not just protein-coding RNA.
2. Long noncoding RNAs (lncRNAs) can silence entire chromosomes, like XIST does in
females.
3. MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) regulate genes by
blocking or destroying messenger RNAs.
4. Noncoding RNAs can act as scaffolds, organizing proteins and chromatin to control
gene activity.
5. Some ncRNAs are linked to diseases like cancer, and researchers hope to use them in
new medical treatments.
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