16th October 2019
What are thymine dimers and what causes them to form?
thymine dimer definition. A pair of abnormally chemically bonded adjacent thymine bases in DNA, resulting from damage by ultra-violet irradiation. The cellular processes that repair this lesion often make errors that create mutations.
If DNA never replicated, meiosis and mitosis would slowly halve the size of the genome until each cell would die, which probably would not take long. Therefore, it is important that DNA doubles itself to account for the cells splitting during mitosis/meiosis. DNA replication is similar to RNA transcription.
DNA replicates before a cell divides so that each daughter cell receives a complete set of genetic information. Semiconservative replication means that only one strand of a DNA molecule is newly formed. The other strand is original DNA from the parent cell.
Explanation: DNA replication needs to occur because existing cells divide to produce new cells. Each cell needs a full instruction manual to operate properly. So the DNA needs to be copied before cell division so that each new cell receives a full set of instructions!
Some mutations don't have any noticeable effect on the phenotype of an organism. This can happen in many situations: perhaps the mutation occurs in a stretch of DNA with no function, or perhaps the mutation occurs in a protein-coding region, but ends up not affecting the amino acid sequence of the protein.
Normal healthy cells replicate themselves when a neighbor cells dies and then stop replicating. A cancer cells continues to replicate itself endlessly. The process of copying the DNA is incredibly complex. Cancer cells are created in the body every day in the process of copying the DNA in cell replication.
Why is it advantageous to have weak hydrogen bonds between complementary bases and strong covalent bonds between phosphate and deoxyribose groups in a DNA molecule? The hydrogen bonds break easy making it easy for DNA to separate. The covalent bonds make sure nucleotides stay in each strand.
Mutations that are harmful may increase a person's chance, or risk, of developing a disease such as cancer. Overall, inherited mutations are thought to play a role in about 5 to 10 percent of all cancers. Cancer can sometimes appear to “run in families” even if it is not caused by an inherited mutation.
Some people are born with a gene mutation that they inherited from their mother or father. This damaged gene puts them at higher risk for cancer than most people. When cancer occurs because of an inherited gene mutation, it is referred to as hereditary cancer .
Sometimes, certain types of cancer seem to run in some families. In some cases, this might be because family members share certain behaviors or exposures that increase cancer risk, such as such as smoking. Cancer risk might also be affected by other factors, like obesity, that tend to run in some families.
In recent years, scientists have discovered a number of mutations that can contribute to a person's risk of developing certain cancers, including breast, ovarian, colorectal, and prostate cancer, as well as some other, less common cancer types. Genetic testing is now available for some hereditary cancers.
Most cancers are not inherited -- they just happen. Sometimes you can inherit an increased risk of cancer. And very rarely certain types of cancer can be passed down through generations.
The most common types of skin cancer in the United States are basal cell carcinoma and squamous cell carcinomas. These are referred to as non-melanoma skin cancers and are generally the result of sun exposure. However, about 5-10% of melanoma cases are inherited in an autosomal dominant fashion.
Genetic factors likely play some role in high blood pressure, heart disease, and other related conditions. However, it is also likely that people with a family history of heart disease share common environments and other potential factors that increase their risk.
Control your blood pressure. Take steps, including lifestyle changes, to prevent or control high blood pressure. Keep your cholesterol and triglyceride levels under control. High levels of cholesterol can clog your arteries and raise your risk of coronary artery disease and heart attack.
Many cardiac disorders can be inherited, including arrhythmias, congenital heart disease, cardiomyopathy, and high blood cholesterol. Coronary artery disease leading to heart attack, stroke, and heart failure can run in families, indicating inherited genetic risk factors.
When arteries are narrowed, less blood and oxygen reaches the heart muscle. This is also called coronary artery disease and coronary heart disease. This can ultimately lead to heart attack. Ischemia often causes chest pain or discomfort known as angina pectoris.
The CDC's report found that about 80 percent of deaths from coronary artery disease -- a name for heart disease caused by narrowing of the arteries which leads to reduced blood flow to the heart -- can be attributed to preventable factors like obesity, poor physical activity, heavy drinking, eating unhealthy foods and
Treatment for coronary heart disease (CHD) usually is the same for both women and men. Treatment may include lifestyle changes, medicines, medical and surgical procedures, and cardiac rehabilitation (rehab). (Blood clots can cause a heart attack.) Widen or bypass plaque-clogged coronary (heart) arteries.
Plaque buildup thickens and stiffens artery walls, which can inhibit blood flow through your arteries to your organs and tissues. Atherosclerosis is also the most common cause of cardiovascular disease. It can be caused by correctable problems, such as an unhealthy diet, lack of exercise, being overweight and smoking.