VII. Read the text with the help of the dictionary and translate it into Russian.

The Cell

Life is both wonderful and majestic. Yet for all of its majesty, all organisms are composed of the fundamental unit of life, the cell. The cell is the simplest unit of matter that is alive. From the unicellular bacteria to multicellular animals, the cell is one of the basic organizational principles of biology. Let's look at some of the components of this basic organizer of living organisms.

There are two primary types of cells: eukaryotic cells and prokaryotic cells. Eukaryotic cells are called so because they have a true nucleus. The nucleus, which houses DNA, is contained within a membrane and separated from other cellular structures. Prokaryotic cells, however, have no true nucleus. DNA in a prokaryotic cell is not separated from the rest of the cell but coiled up in a region called the nucleoid.

Eukaryotes grow and reproduce through a process called mitosis. In organisms that also reproduce sexually, the reproductive cells are produced by a type of cell division called meiosis. Most prokaryotes reproduce through a process called binary fission. During binary fission, the single DNA molecule replicates and the original cell is divided into two identical daughter cells.

DNA and Evolution

Deoxyribonucleic acid (or DNA) is the scheme for all inherited characteristics in living things. It is a very long sequence, written in code that needs to be transcribed and translated before a cell can make the proteins that are essential for life. Any sort of changes in the DNA sequence can lead to changes in those proteins, and in turn, they can cause changes in the traits those proteins control. Changes at a molecular level lead to microevolution of species.

The DNA in living things is highly conserved. DNA has only four nitrogenous bases that are responsible for all differences in living things on the Earth. Adenine, cytosine, guanine, and thymine line up in a specific order and a group of three, or a cordon, code for one of 20 amino acids found on the Earth. The order of those amino acids determines what protein is made.

It is really fantastic that only four nitrogenous bases that make only 20

amino acids explain all diversity of life on the Earth. There has not been any other

code or system found in any living, or once living, organism on the Earth. Organisms from bacteria to humans to dinosaurs all have the same DNA system as a genetic code. This may be evidence of the fact that all life developed from a single common ancestor.

Pectoral and Pelvic Girdles

The pectoral girdle connects the upper limb (arm) bones to the axial skeleton and consists of the left and right clavicles and left and right scapulae.

The humerus is the bone of the upper arm. It forms the ball and socket joint of the shoulder with the scapula and the elbow joint with the lower arm bones. The radius and ulna are the two bones of the forearm. The ulna is on the medial side of the forearm and forms a hinge joint with the humerus at the elbow. The radius allows the forearm and hand to turn over at the wrist joint.

The lower arm bones form the wrist joint with the carpals, a group of eight small bones that give added flexibility to the wrist. Formed by the left and right hip bones, the pelvic girdle connects the lower limb (leg) bones to the axial skeleton.

The femur is the largest bone in the body and the only bone of the thigh (femoral) region. The femur forms the ball and socket hip joint with the hip bone and forms the knee joint with the tibia and patella.

The tibia and fibula are the bones of the lower leg. The tibia is much larger than the fibula and bears almost all of the body’s weight. The tibia and fibula form the ankle joint with the talus, one of the seven tarsal bones in the foot.

The tarsals form the posterior end of the foot and heel. The tarsals form joints with the five long metatarsals of the foot.

Types of Bones

All of the bones of the body can be divided into five types: long, short, flat, irregular, and sesamoid.

Long. Long bones have greater length than width and are the major bones of the limbs. Long bones grow more than the other classes of bone throughout childhood. A hollow medullary cavity is found in the centre of long bones and serves as a storage area for bone marrow. Examples of long bones include the femur, tibia, fibula, metatarsals, and phalanges. 

Short. Short bones have almost the same length and width and are often cubed or round in shape. The carpal bones of the wrist and the tarsal bones of the foot are examples of short bones.

Flat. Flat bones vary greatly in size and shape, but have the common feature of being very thin in one direction. Because they are thin, flat bones do not have a medullar cavity like the long bones. the ribs and hip bones are examples of flat bones.

Irregular. Irregular bones have a shape that does not fit the pattern of the long, short, or flat bones. The vertebrae, sacrum, and coccyx of the spine—are all irregular bones.

Sesamoid. The sesamoid bones are formed after birth inside of tendons that run across joints. The patella and the pisiform bone of the carpals are the only sesamoid bones that are counted as part of the 206 bones of the body.

Three Reasons Why Fast Food Is Bad For You

Eating too much fast food is considered to be a leading cause of obesity, hypertension, and heart disease.

Fast food restaurants are popular because they serve tasty convenient foods for a reasonable price. Many people visit these restaurants often to eat their main meals. They don't realize that these types of food items are bad for health.

1. Fast food contains more calories. Large portion size and high fat content are the main reasons for the high energy content. An average person needs to consume about 400-600 calories in a mealtime. (If he takes three main meals and two snacks.) The calorie content of many items is far more than that level.

2. Fast food contains more unhealthy fat. Most of the convenient foods contain high levels of saturated fat. This type of fat is mostly derived from animal products such as meat, eggs and butter. Palm oil and coconut oil also contain significant amounts of saturated fat.

3. Fast foods are high in sodium. Sodium plays several important roles in our body. We need to consume certain amount of sodium every day.However, taking too much salt is bad for the body. It can cause high blood pressure, obesity, and osteoporosis. In addition, experts believe that over-consumption of salt is linked to increased risk of developing bowl cancer.