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LekaFEV [45]
3 years ago
6

MUST BE at least 350 WORDS 50 POINTS

Biology
1 answer:
Alona [7]3 years ago
3 0

Answer:

Sickle cell disease (SCD) affects millions of people around the globe and is the 4th leading cause of deaths in children in many developing countries. It causes a number of health problems, such as attacks of pain, anaemia, swelling in the hands and feet, bacterial infections and stroke. Sickle-cell contributes to a low life expectancy in the developed world of 40 to 60 years.  

The disease results in abnormal haemoglobin - the oxygen-carrying protein found in red blood cells – giving the blood cell a rigid, sticky, sickle-like shape that hinders its oxygen-binding properties. These irregularly shaped cells can get stuck in small blood vessels, which can slow or block blood flow and oxygen to parts of the body. A blood and bone marrow transplant is currently the only cure for sickle cell disease, but only a small number of patients are eligible. For the rest, there's no cure but effective treatments can relieve pain, help prevent problems associated with the disease and prolong life.

70 years ago, researchers found a genetic connection to the anatomical abnormalities seen in blood cells. A mutation seemed to be causing the moon-shaped blood cells. The most severe form of the disease occurs when two copies of the mutation are inherited. However, patients with one sickle cell gene, referred to as sickle cell trait, usually do not have any of the signs of the disease and live a normal life, but they can pass the trait on to their children.

As with all inherited genetic diseases, you’d expect natural selection to weed out a gene that has such unpleasant consequences but with sickle cell disease, that doesn’t seem to be the case. Indeed, as of 2015, about 4.4 million people have sickle cell disease, while an additional 43 million have sickle cell trait. So what makes the disease stay in the human population?

Researchers found the answer by looking at where the disease was most prevalent. As it turns out, 80% of sickle cell disease cases occur in Sub-Saharan Africa or amongst populations having their ancestors in this region, as well as in other parts of the world where malaria is or was common. There was a long standing theory that the sickle cell trait – having only one sickle cell gene – didn’t cause discomfort and provided a bonus trait of preventing patients from contracting severe forms of malaria. Later confirmed - associating sickle cell to a 29% reduction in malaria incidence - this working theory would explain why the mutation stuck around in evolution. In 2011, researchers used mice to confirm the assumption.

Miguel Soares and Ana Ferreira of the Gulbenkian Institute of Science in Oeiras, Portugal, and colleagues found that haem – a component of haemoglobin – is present in a free form in the blood of mice with sickle cell trait, but largely absent from normal mice. By injecting haem into the blood of normal mice before infecting them with malaria, researchers found it could help guard against malaria. The mice did not develop the disease. Their results also showed that the gene does not protect against infection by the malaria parasite, but prevents the disease taking hold after the animal has been infected.

Explanation:

Sorry if I did or got anything wrong:(

I actually tried on this tho:)

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Delicious77 [7]

Answer:

b.

Explanation:

8 0
3 years ago
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Match the following terms and definitions.
nlexa [21]

Answer:

<em>1. Oblong cells with unevenly thickened walls for support in young stems  →</em>

<em>Collenchyma </em><em>.</em>

<em>2. a waxy substance covering most surface areas of plants; helps to retain water  → </em><em>Cuticle</em><em>. </em>

<em>3. The youthful, undifferentiated cells of root and shoot tips and other plant parts that produce new cells for growth  → </em><em>Meristem </em><em>.</em>

<em>4. The most common plant cell, found in practically all parts of the plant body; important for food production, food storage, lateral transport, and other life processes; an almost round cell in some tissues  → </em><em>Parenchyma</em><em> .</em>

<em>5. Dermal layer made of dead cork cells  → </em><em>Periderm</em><em> .</em>

<em>6. Tiny holes in a cell wall which allow the passage of chemicals between cells  → </em><em>Plasmodesmata</em><em>.</em>

Explanation:

<em>This all refers to tissues found in plant organisms.</em>

  • In plants, the colenchyma is a supporting tissue, composed mainly of elongated, irregularly walled living cells with a large amount of cellulose. Their composition and the way they are arranged - with longitudinal interlacing - give the tissue strength and resistance. It represents one of the three basic tissues of plants.
  • Cuticles of plant tissue are formed by an oily secretion from the epidermal cells, forming a waxy, impermeable and protective layer, which prevents the entry of foreign organisms and reduces the loss of water from the plant. The cuticles are mainly composed of cutin molecules associated with wax.
  • Meristematic tissue represents a group of undifferentiated cells with great capacity to multiply, differentiate and provide growth and development to a plant. It is a tissue with unlimited growth capacity, which allows the plant to always replace the damaged tissue and grow indefinitely.
  • Parenchyma of plant organisms are tissues that are found in most of these organisms, allowing multiple functions, such as the drying of substances, storage and photosynthesis. The parenchyma is generally formed by thin-walled living cells that can adapt to any vital function of plants.
  • Periderm constitutes the outer coating of a plant or bark, functionally replacing the epidermis. This tissue is located after the secondary phloem, and is composed of cork, specifically phellem, phellogen and phelloderm.
  • Plasmodesmata are a type of microscopic channel that crosses the plant wall, being a link for intercellular communication, as well as the transport of nutrients.

4 0
3 years ago
Help on this question please
bezimeni [28]

Answer:

they should just contain the same considering they are still sperm sells. so c.

7 0
3 years ago
What are the two methods used together to demonstrate the Earth is at least 3.8 billion years old? List and briefly describe the
gregori [183]

Answer:

The three primary methods are Radiation Measurement.

Explanation:

5 0
2 years ago
What theme is featured in Machiavelli’s The Prince?
mrs_skeptik [129]
<h2>Answer:</h2>

B. the importance and limits of political power

<h2>Explanation:</h2>

Niccolo Machiavelli was an eminent Italian author and statesman who in his best-known work, The Prince, described the means by which government may gain and maintain its power. He believed in gain of power by whatever means and to maintain it for long period of time. He said that gaining power is the only way to live with honor because the world is a place for the fittest people and not the weak ones. This famous theory is known as Realism in Political Science.

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3 years ago
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