Subtractive process is used to form sculpture is by removing material from a block or mass of wood, stone, or any other material. This is usually done with sharpened tools.
Carving is one of the oldest sculptural techniques. Whereas, casting, modeling, and assembling are the other three techniques.
Sculptural materials that are soft, pliable, and are easily manipulated possess ephemeral property. Examples of such materials are plaster of Paris, wax, unfired clay, and plasticine<span>.</span>
4 daughter cells
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Answer/Explanation:
DNA polymerase is the enzyme responsible for replicating DNA. It is hugely important that is performs its functions accurately, as if incorrect bases are incorporated this can lead to mutations that disrupt the structure and function of genes. It adds nucleotides in a 5' - 3' direction only.
DNA polymerase III also has high processivity, which means that for every time it binds DNA, it is able to add many bases before it becomes dissociated.
A. DNA polymerase avoids the incorporation of improperly paired nucleotides in two ways:
- The first way depends on the structure of the enzyme. If the nucleotide that the enzyme is in the process of adding is not complementary to the template, then the nucleotide will not align with the template, and thus it is more inefficient to add. This inefficiency means the nucleotide is more likely to leave the active site before it is added, and DNA polymerase can replace it with the correct nucleotide.
- It also has proofreading capabilities. This means, when an incorrect base is added, it recognises the error and can fix this. It can do this because it possesses 3'-5' exonuclease activity. That means, it can chop out incorrectly added bases.
B. Ribonucleotides are the nucleotides that are incorporated into a growing RNA molecule. They are different from deoxyribonucleotides because of the differences in the sugar backbone (ribose vs deoxyribose). Their incorporation would disrupt the structure and function of the DNA, leading to problems with transcription and replication.
DNA polymerase avoids incorporating these nucleotides primarily because of the structure of the enzyme. Ribonucleotides cannot fit into the active site of DNA polymerase due to what is called a "steric filter" or "steric gate". This gate/filter function is performed by specific amino acid residues which usually have a bulky side chain and thus block the incorporation of the 2'OH of the ribose sugar (which is lacking in the deoxyribose sugar)
The first organ that receives nutrients from the small intestine is the liver. To better understand this, check out the process flow of the digestive system up to how the liver becomes the first organ to benefit from the nutrient absorption by the small intestines. 1. Esophagus - After chewing, the food is pushed down the esophagus and then out of the esophageal sphincter, which is a ring-like muscle at the junction of the esophagus and stomach that controls the passage of food and liquid between the esophagus and stomach.2. Stomach - Swallowed food and liquid are stored in the stomach. The stomach then mixes the food and liquid with digestive juices that it produces. The mixed food and gastric juices will then be called chyme. The chyme is then slowly emptied into the small intestine. 3. Small intestine - The muscles of the small intestine mix food with digestive juices from the pancreas, liver, and intestine and push the mixture forward to help with further digestion. The small intestine has multiple parts: the duodenum, the jejunum and the ileum. The ileum mix and push food towards the large intestines. Located within the ileum are villi that increase the surface area for absorption. The nutrients absorbed here are transferred to the blood stream and liver.
Scientists
can also glimpse the awful effects of Alzheimer's disease when they look at
brain tissue beneath the microscope:
Alzheimer's tissue has numerous fewer nerve
cells and synapses than a well brain.
<span>
<span>Plaques, unusual
clusters of protein particle, which are construct up between nerve cells.</span>
</span>
<span>
<span><span>Dead and dying nerve cells contain tangles,</span> which
are produce of twisted strands of a further protein.</span>
</span>
<span>Scientists
are not absolutely sure what causes cell death and tissue deficiency in the
Alzheimer's brain, but plaques and tangles are key suspects.</span>
