Biology is designed for multi-semester biology courses for science majors. It is grounded on an evolutionary basis and includes exciting features that highlight careers in the biological sciences and everyday applications of the concepts at hand. To meet the needs of today’s instructors and students, some content has been strategically condensed while maintaining the overall scope and coverage of traditional texts for this course. Instructors can customize the book, adapting it to the approach that works best in their classroom. Biology also includes an innovative art program that incorporates critical thinking and clicker questions to help students understand—and apply—key concepts.

By the end of this section, you will be able to:Understand RNA splicing and explain its role in regulating gene expressionDescribe the importance of RNA stability in gene regulation

By the end of this section, you will be able to:Describe the structure of nucleic acids and define the two types of nucleic acidsExplain the structure and role of DNAExplain the structure and roles of RNA

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Many chronic diseases lead to organ fibrosis due to repeated tissue damage and repair cycles. Fibrosis stiffens the organs and causes inflammation that worsens disease, so new ways to diagnose and mitigate organ fibrosis are urgently needed. Circular RNAs (circRNAs) alter protein levels by binding to microRNAs and causing them to degrade. They also regulate transcription, interact with proteins, and even encode proteins themselves, as well as mediating crosstalk among organs as cargo in exosomes. Different circRNAs have a variety of roles in organ fibrosis, and exosomal circRNAs are potentially useful biomarkers and therapeutic targets. Aberrant circRNA expression is involved in fibrotic diseases including cardiac, liver, pulmonary, renal, and skin fibrosis. Although finding precise circRNA targets and developing treatments will require additional research, interfering with these circRNAs and delivering synthetic circRNAs is a promising strategy to reduce organ fibrosis in the future..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Exosomes are tiny membrane-bound vesicles that could be cutting-edge tools for cancer diagnosis and treatment. Exosomes are released by nearly every cell type to transport biomolecule cargo between cells and can be found in most body fluids. Among exosome cargos, microRNAs have draw significant attention for their role in the development of various diseases. MicroRNAs are small non-coding RNA molecules that can regulate the expression of protein-encoding genes. Exosomal microRNAs have shown promise as diagnostic biomarkers and as therapeutic targets or even therapeutics themselves. Studies have suggested that the microRNAs in cancer cell exosomes resemble the microRNA pool from their parent cancer cell. Exosomal microRNAs may be of particular use for the detection and treatment of hematologic neoplasms, which include cancers like lymphoma and multiple myeloma. However, there are several barriers than need to be addressed before exosomal microRNAs can be used in clinical settings..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Mesenchymal stem cells (MSCs) are multifunctional cells with the ability to reduce inflammation and repair tissue when injected directly. But MSC use is controversial, especially in patients with cancer or in cancer remission, as MSCs can release growth factors that can promote tumor growth. Fortunately, new research is showing that certain MSC contents can exert targeted beneficial effects without these drawbacks, most notably, microRNAs packaged inside exosomes. These loaded exosomes can accumulate at sites of tissue damage, and many studies suggest that MSC exosomes can be applied to cancer therapy, gene therapy, drug delivery, regenerative medicine, and other biomedical applications. Further research could reveal new and more effective ways of packaging and transferring exosomes from MSCs to recipient cells, and thereby lead to new methods of treating and monitoring various diseases..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"In laying hens, the cecal microbiota is important for digestion and metabolism. However, it also produces hydrogen sulfide gas, an odorous and harmful pollutant that is released in large amounts from poultry houses. Host microRNAs (miRNAs) can regulate the gut microbiota, but whether they affect hydrogen sulfide production in hens is unclear. To clarify this issue, a recent study analyzed the cecal content of two laying hen breeds, Hy-line Gray and Lohmann Pink, with naturally different hydrogen sulfide production. Differential expression of several microbial genes was related to the difference in hydrogen sulfide production between breeds, miRNA-containing exosomes were present in the cecal contents, and the differentially expressed host miRNA gga-miR-222a regulated two of the altered microbial genes encoding methionine synthases. During in vitro fermentation, gga-miR-222a upregulated the two methionine synthase genes..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Alpha-1 antitrypsin deficiency (AATD)-mediated liver disease is a form of toxic inflammation associated with the retention of mutant alpha-1 antitrypsin within cells. Patients with this disease typically show fibrosis and cirrhosis of the liver. Unfortunately, the mechanism of AATD-mediated liver disease is not well understood. To gain some insight, researchers recently explored the role of extracellular vesicles in the progression of AATD-mediated liver disease. They isolated vesicles from the plasma of individuals with both AATD and liver disease and compared them with vesicles from healthy individuals in terms of cytokine and chemokine expression as well as miRNA expression. Vesicles from individuals with AATD were shown to activate hepatic stellate cells in vitro, which is believed to be one of the first steps of fibrosis. a process mediated by the NF-κB and JAK/STAT signaling pathways..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Hematopoietic stem cells (HSCs) are immature cells that can develop into all types of blood cells, making them critical regulators of blood composition. However, during aging, HSCs undergo a process called senescence, in which their functionality starts to fade, leading to issues like reduced immune cell populations or leukemia. HSC senescence is influenced by various age-related factors, like accumulated DNA damage or epigenetic (non-DNA-altering) changes in gene expression, and it’s regulated by small RNA molecules known as microRNAs (miRNAs). For example, the miR-212/132 cluster binds to the FOXO3 gene to affect HSC life cycles, function, and survival and is upregulated with aging, while miR-125b, which can help HSCs resist stress and cell death, is downregulated in aging HSCs..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Lung cancer is the leading cause of cancer-related deaths globally. Tyrosine Kinase Inhibitors (TKIs) are a common treatment for lung cancer, but TKI resistance is widespread. TKI treatment also has serious side effects like hair loss, anemia, and hypothyroidism, meaning it is important to identify which patients will benefit from the treatment. MicroRNAs may be a way to do that. MicroRNAs regulate gene expression by blocking transcription or promoting the breakdown of messenger RNA, and because microRNAs are stable in body fluids, they can be particularly useful as diagnostic or prognostic indicators in many applications. In the context of anti-cancer drugs, microRNAs are frequently directly involved in the cellular response. Profiling their expression could be used to predict the response to anti-cancer drugs like TKIs. The research to date has described numerous microRNAs and their roles in TKI response by lung cancer cells. However, most previous research did not measure microRNAs in serum samples..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Exosomes are extracellular vesicles that can be transferred from cancer cells to surrounding cells in the tumor microenvironment. Despite their tiny size, exosomes have a huge effect on cell-to-cell communication, facilitating tumor progression and contributing to metastasis. Their widespread effects have drawn the attention of scientists hoping to develop new cancer therapies. A recent study focused on a specific type of exosome cargo – microRNAs (miRNAs), which can act as nucleic acid messengers between cells. Certain miRNAs are known to be enriched in cancer cell exosomes, but how this enrichment occurs is unclear. Using a pancreatic cancer cell line, researchers identified RNA-binding proteins that could bind to a common cancer-associated miRNA, miR-1246. They found that the protein SRSF1 could bind strongly with miR-1246. Reducing SRSF1 expression decreased the enrichment of miRNAs in exosomes, while overexpressing SRSF1 enhanced the enrichment..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Breast cancer is the most common cancer among women, and metastatic breast cancer remains highly lethal. During metastasis, cancer cells migrate from the breast to areas called pre-metastatic niches, which are favorable for cancer growth. These niches are created with the help of small extracellular vesicles (sEVs) released by breast cancer cells. Via their protein and RNA cargoes, sEVs encourage inflammation in the niches and suppress immunity, allowing arriving cancer cells to escape immune detection. By promoting new blood vessel formation and leakage of existing blood vessels, sEVs ensure a supply of nutrients for cancer growth in the niches. They can also transform certain cell types in the niches into cancer-supporting cells called cancer-associated fibroblasts. The expression patterns of proteins called integrins in sEVs help determine exactly where metastatic cancer cells will settle, such as in the lungs, liver, or brain..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Ulcerative colitis is a painful inflammatory disease that is associated with an increased risk of colorectal cancer, but the mechanisms linking these diseases are not well understood. There is mounting evidence that the receptor TLR4 (Toll like receptor 4) is a key bridge molecule linking the two. TLR4 is the receptor for endotoxins from gram-negative bacteria, including colitis-associated pathogens. This receptor is overexpressed in both colitis and colitis-associated cancer and may promote tumorigenesis by facilitating cell proliferation and protecting malignant cells against apoptosis. It may also accelerate invasion and metastasis while helping create a tumor-favoring microenvironment. More recently, research has suggested that the microRNA miR-155 may also play a role. The expression changes and cancer promoting properties of miR-155 in colitis-associated cancer development mirror those of TLR4..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Mesangial proliferative glomerulonephritis (MsPGN) is a condition involving cell proliferation and tissue deposition in the kidney mesangium. MsPGN is a major cause of chronic kidney disease and kidney failure, but few treatment options are available. To explore new therapies, a recent study investigated the effects of extracellular vesicles from umbilical cord mesenchymal stem cells (ucMSC-EVs) on MsPGN in rats. The ucMSC-EVs reduced mesangial enlargement and fibrosis in rats in a dose-dependent manner, while suppressing mesangial cell proliferation. A mechanistic study revealed that the microRNA miR-378 was markedly upregulated by ucMSC-EV treatment, suggesting that the vesicles delivered miR-378 to the kidney tissues. Further analyses showed that miR-378 exerted beneficial anti-MsPGN effects by inhibiting the protein PSMD14, which in turn induced degradation of the protein TGFBR1, thereby suppressing the TGF-β1/Smad2/3 pathway..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"Non-Hodgkin lymphoma (NHL) is one of the most common cancers worldwide. To better understand factors involved in carcinogenesis, a recent study examined the contribution of one class of proteins. MicroRNAs (miRNAs) are small non-coding RNAs that regulate the expression of target genes. The study focused on one miRNA family member: miR-1250, which is embedded in the second intron of its host gene, apoptosis-associated tyrosine kinase (AATK). Researchers studied the methylation status of AATK/miR-1250 in healthy controls compared to that in lymphoma cell lines and 120 primary lymphoma samples. They found that while AATK/miR -1250 was not methylated in healthy peripheral blood and tonsils. in NHL cell lines and patient samples, methylation was detected, correlating with repression of miR-1250-5p and AATK expression. Restoring miR-1250-5p resulted in decreased cell proliferation as well as enhanced apoptosis and cell death..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.

This resource is a video abstract of a research paper created by Research Square on behalf of its authors. It provides a synopsis that's easy to understand, and can be used to introduce the topics it covers to students, researchers, and the general public. The video's transcript is also provided in full, with a portion provided below for preview:

"MicroRNAs (miRNAs) are small RNA molecules that can modulate gene expression to affect numerous biological processes. One such molecule, miRNA-93, is dysregulated in various diseases and might be a valuable marker of prognosis. For example, it’s generally upregulated in lung cancer, prostate cancer, glioma, osteosarcoma, and hepatocellular carcinoma, where it promotes cell proliferation, migration, and invasion to drive cancer progression. It can also induce the development of chemotherapy resistance. Furthermore, miRNA-93 contributes to coronary artery blockage, Parkinson’s disease, postmenopausal osteoporosis, and acute kidney injury. However, it’s not always upregulated in disease. In fact, it’s downregulated in gastric, bladder, cervical, and renal cancer, sometimes exerting anti-tumor effects. These differences emphasize the need to truly understand miRNA-93’s role in a specific disease before using miRNA-93 as a prognostic marker or treatment target..."

The rest of the transcript, along with a link to the research itself, is available on the resource itself.