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- https://bio.libretexts.org/Courses/Prince_Georges_Community_College/PGCC_Microbiology/02%3A_Chemistry_of_Microbiology/2.03%3A_Chemical_Reactions/2.3.03%3A_Energy_and_Biochemical_ReactionsIn fact, each chemical reaction - the chemical reactions that allow the cellsin those ants to do the work - needs energy to get started. The energy needed to start a chemical reaction is calledactivat...In fact, each chemical reaction - the chemical reactions that allow the cellsin those ants to do the work - needs energy to get started. The energy needed to start a chemical reaction is calledactivation energy. A chemical reaction that releases energy is an exothermic reaction, and a chemical reaction that absorbs energy is an endothermic reaction. The energy needed to start a chemical reaction is the activation energy.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/13%3A_Human_Biology/13.70%3A_Adulthood_and_AgingHeart disease is the number one killer of Americans, and one of the main killers of people the world over. This makes it harder for blood to get to all the parts of the body that need it, including th...Heart disease is the number one killer of Americans, and one of the main killers of people the world over. This makes it harder for blood to get to all the parts of the body that need it, including the heart itself. The size of the four chambers of the heart also change, as do the valves between the chambers. The resting heart rate does not change as you age, but the heart cannot beat as fast when you are physically active or stressed, as it did when you were younger.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/11%3A_Invertebrates/11.03%3A_Invertebrate_Classification
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/13%3A_Human_Biology/13.33%3A_BloodTypes of blood cells in plasma include red blood cells, white blood cells, and platelets (see Figure below). For example, white blood cells called phagocytes swallow and destroy microorganisms and deb...Types of blood cells in plasma include red blood cells, white blood cells, and platelets (see Figure below). For example, white blood cells called phagocytes swallow and destroy microorganisms and debris in the blood, neutrophils engulf bacteria and other parasites, and lymphocytes fight infections caused by bacteria and viruses. Red blood cells carry oxygen, white blood cells defend the body, and platelets help blood clot.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/04%3A_Molecular_Biology/4.13%3A_Eukaryotic_Gene_RegulationIn eukaryotic cells, the start of transcription is one of the most complicated parts of gene regulation. This is a regulatory element that is part of the promoter of most eukaryotic genes. It is only ...In eukaryotic cells, the start of transcription is one of the most complicated parts of gene regulation. This is a regulatory element that is part of the promoter of most eukaryotic genes. It is only when all of the appropriate proteins are bound to the TATA box that RNA polymerase recognizes the complex and binds to the promoter. To see a video showing the role of the TATA box in the initiation of transcription, go to this link: http://www.youtube.com/watch?v=6tqPsI-9aQA.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/13%3A_Human_Biology/13.52%3A_ImmunityAs long as the memory cells survive, the pathogen will be unable to cause a serious infection in the body. Immunization is the deliberate exposure of a person to a pathogen in order to provoke an immu...As long as the memory cells survive, the pathogen will be unable to cause a serious infection in the body. Immunization is the deliberate exposure of a person to a pathogen in order to provoke an immune response and the formation of memory cells specific to that pathogen. However, only part of a pathogen, a weakened form of the pathogen, or a dead pathogen is typically used. Passive immunity results from the transfer of antibodies to a person who has not been exposed to the pathogen.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/13%3A_Human_Biology/13.39%3A_Digestive_System_OrgansFood enters the mouth, passes through the other organs of the GI tract, and then leaves the body through the anus. The organs of the GI tract are lined with mucous membranes that secrete digestive enz...Food enters the mouth, passes through the other organs of the GI tract, and then leaves the body through the anus. The organs of the GI tract are lined with mucous membranes that secrete digestive enzymes and absorb nutrients. The digestive system has three main functions: digestion of food, absorption of nutrients, and elimination of solid food waste. The waste later passes out of the body through the anus in the process of elimination.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/06%3A_Ecology
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/13%3A_Human_Biology/13.56%3A_HIV_and_AIDSIn the process the T cell is destroyed, and the virus copies go on to infect other helper T cells. The graph in Figure below shows how the number of T cells typically declines over a period of many ye...In the process the T cell is destroyed, and the virus copies go on to infect other helper T cells. The graph in Figure below shows how the number of T cells typically declines over a period of many years following the initial HIV infection. As the number of T cells decreases, so does the ability of the immune system to defend the body. The rate of spread of the infection is higher Africa than in the U.S., yet the U.S.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/07%3A_Prokaryotes_and_Viruses/7.11%3A_Virus_ReplicationSome RNA viruses carry enzymes which allow their RNA genome to act as a template for the host cell to a form viral mRNA. Reverse transcriptase, a viral enzyme that comes from the virus itself, convert...Some RNA viruses carry enzymes which allow their RNA genome to act as a template for the host cell to a form viral mRNA. Reverse transcriptase, a viral enzyme that comes from the virus itself, converts the viral RNA into a complementary strand of DNA, which is copied to produce a double stranded molecule of viral DNA. This viral DNA is then transcribed and translated by the host machinery, directing the formation of new virions. The DNA of DNA viruses is transcribed into mRNA by the host cell.
- https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Introductory_Biology_(CK-12)/03%3A_Genetics/3.13%3A_BiotechnologyGene cloning is the process of isolating and making copies of a gene. During ligation, the enzyme DNA ligase combines the isolated gene with plasmid DNAfrom bacteria. (A plasmid is circular DNA that i...Gene cloning is the process of isolating and making copies of a gene. During ligation, the enzyme DNA ligase combines the isolated gene with plasmid DNAfrom bacteria. (A plasmid is circular DNA that is not part of a chromosome and can replicate independently.) Ligation is illustrated in Figure below. Biotechnology is the use of technology to change the genetic makeup of living things for human purposes. Gene cloning is the process of isolating and making copies of a DNA segment such as a gene.
