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____ [38]
4 years ago
13

When two adjacent bases in the same strand of DNA dimerize (form a covalent bond between them), what happens to the DNA?

Biology
1 answer:
kondaur [170]4 years ago
4 0

The DNA of every higher organism consists of two strands which are joined together through bonding between nitrogenous bases. We know well that the base of one strand forms hydrogen bond between the base of the other strand to hold the DNA intact. Thymine always pairs with Adenine and Guanine always pairs with Cytosine, this way an intact and normal DNA structure is formed.

However, sometimes the Ultra violet (UV) rays cause serious damage to DNA. When UV rays are absorbed by DNA, where the bases are thymine or cytosine they add energy at that point. This energy causes the formation of covalent bond between adjacent cytosine- cytosine or thymine-thymine bases of same DNA strand (Please see attached figure). This abnormal process is called the formation of Pyrimidine dimers.  

What harm they can incur to us?

Our body cells have excellent DNA proofreading mechanisms that correct the errors in DNA. But sometimes when DNA has to replicate, the dimers don’t let the DNA polymerase enzyme to correctly read DNA strand because there are abnormal structures. The enzyme incorporates wrong base, at the position of dimers for example if C-C dimer is present, adenine instead of guanine will be added at that position. This causes the presence of incorrect base in newly synthesized DNA.  

This process leads to mutation in the cells which is very common cause of increased risk of cancers nowadays.


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Katen [24]

Answer:

Symptoms

Signs and symptoms of hemophilia vary, depending on your level of clotting factors. If your clotting-factor level is mildly reduced, you may bleed only after surgery or trauma. If your deficiency is severe, you may experience spontaneous bleeding.

Signs and symptoms of spontaneous bleeding include:

  • Unexplained and excessive bleeding from cuts or injuries, or after surgery or dental work
  • Many large or deep bruises
  • Unusual bleeding after vaccinations
  • Pain, swelling or tightness in your joints
  • Blood in your urine or stool
  • Nosebleeds without a known cause
  • In infants, unexplained irritability

Bleeding into the brain

A simple bump on the head can cause bleeding into the brain for some people who have severe hemophilia. This rarely happens, but it's one of the most serious complications that can occur. Signs and symptoms include:

  • Painful, prolonged headache
  • Repeated vomiting
  • Sleepiness or lethargy
  • Double vision
  • Sudden weakness or clumsiness
  • Convulsions or seizures

Causes

When you bleed, your body normally pools blood cells together to form a clot to stop the bleeding. The clotting process is encouraged by certain blood particles. Hemophilia occurs when you have a deficiency in one of these clotting factors.

There are several types of hemophilia, and most forms are inherited. However, about 30% of people with hemophilia have no family history of the disorder. In these people, an unexpected change occurs in one of the genes associated with hemophilia.

Acquired hemophilia is a rare variety of the condition that occurs when a person's immune system attacks clotting factors in the blood. It can be associated with:

  • Pregnancy
  • Autoimmune conditions
  • Cancer
  • Multiple sclerosis

Treatment

Several different types of clotting factors are associated with different varieties of hemophilia. The main treatment for severe hemophilia involves receiving replacement of the specific clotting factor that you need through a tube placed in a vein.

This replacement therapy can be given to combat a bleeding episode that's in progress. It can also be administered on a regular schedule at home to help prevent bleeding episodes. Some people receive continuous replacement therapy.

Replacement clotting factor can be made from donated blood. Similar products, called recombinant clotting factors, are manufactured in a laboratory and aren't made from human blood.

Other therapies may include:

  • Desmopressin. In some forms of mild hemophilia, this hormone can stimulate your body to release more clotting factor. It can be injected slowly into a vein or provided as a nasal spray.
  • Clot-preserving medications. These medications help prevent clots from breaking down.
  • Fibrin sealants. These medications can be applied directly to wound sites to promote clotting and healing. Fibrin sealants are especially useful in dental therapy.
  • Physical therapy. It can ease signs and symptoms if internal bleeding has damaged your joints. If internal bleeding has caused severe damage, you may need surgery.
  • First aid for minor cuts. Using pressure and a bandage will generally take care of the bleeding. For small areas of bleeding beneath the skin, use an ice pack. Ice pops can be used to slow down minor bleeding in the mouth.
  • Vaccinations. Although blood products are screened, it's still possible for people who rely on them to contract diseases. If you have hemophilia, consider receiving immunization against hepatitis A and B
6 0
3 years ago
Which type of macromolecule is the monosaccharide made by plants called fructose?
Taya2010 [7]
I think the most suitable answer is carbohydrates as it can be monosaccharide, disaccharide or polysaccharide.
8 0
4 years ago
Why does DNA replication have such accuracy ?
USPshnik [31]
Because human DNA is so very long (with up to 80 million base pairs in a chromosome) it unzips at multiple places along its length so that the replication process is going on simultaneously and more accurately.
5 0
3 years ago
Which one could it be ?
Dafna1 [17]

Answer:

Size of pot

Explanation:

The size of the pot is the only variable changed from the control group in this experiment.

4 0
3 years ago
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Suppose that a cell has 20 chromatids at prophase of mitosis. After mitosis and cytokinesis end, the two resulting daughter cell
EleoNora [17]

Answer:

20

Explanation:

Mitosis is a process in which a cell produces an exact copy of itself. The 2 daughter cells produced from mitosis have the same number of chromatids as the parent cell.

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