The Structure of the Universe :Challenge to the Plasma Theory (Part-IV)

    Author : Rumana Reza    

Previously particle physics and some basic biological terms were discussed on The Structure of the Universe :Challenge to the Plasma Theory (Part-III),
The Structure of the Universe :Challenge to the Plasma Theory (Part-II) andThe Structure of the Universe :Challenge to the Plasma Theory . Today this post is about biology too as an  extension .

DNA

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.

DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.

An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.

DNA is a double helix formed by base pairs attached to a sugar-phosphate backbone.

Mitochondrial DNA

Mitochondria are structures within cells that convert the energy from food into a form that cells can use. Each cell contains hundreds to thousands of mitochondria, which are located in the fluid that surrounds the nucleus (the cytoplasm).

Mitochondria produce energy through a process called oxidative phosphorylation. This process uses oxygen and simple sugars to create adenosine triphosphate (ATP), the cell’s main energy source. A set of enzyme complexes, designated as complexes I-V, carry out oxidative phosphorylation within mitochondria.

In addition to energy production, mitochondria play a role in several other cellular activities. For example, mitochondria help regulate the self-destruction of cells (apoptosis). They are also necessary for the production of substances such as cholesterol and heme (a component of hemoglobin, the molecule that carries oxygen in the blood).

Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function. Thirteen of these genes provide instructions for making enzymes involved in oxidative phosphorylation. The remaining genes provide instructions for making molecules called transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), which are chemical cousins of DNA. These types of RNA help assemble protein building blocks (amino acids) into functioning proteins.

Gene

A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make molecules called proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases. The Human Genome Project has estimated that humans have between 20,000 and 25,000 genes.

Every person has two copies of each gene, one inherited from each parent. Most genes are the same in all people, but a small number of genes (less than 1 percent of the total) are slightly different between people. Alleles are forms of the same gene with small differences in their sequence of DNA bases. These small differences contribute to each person’s unique physical features.

Genes are made up of DNA. Each chromosome contains many genes.

Chromosome

In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.

Chromosomes are not visible in the cell’s nucleus—not even under a microscope—when the cell is not dividing. However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope. Most of what researchers know about chromosomes was learned by observing chromosomes during cell division.

Each chromosome has a constriction point called the centromere, which divides the chromosome into two sections, or “arms.” The short arm of the chromosome is labeled the “p arm.” The long arm of the chromosome is labeled the “q arm.” The location of the centromere on each chromosome gives the chromosome its characteristic shape, and can be used to help describe the location of specific genes.

DNA and histone proteins are packaged into structures called chromosomes.

Proteins 

So many times at so many places we have heard about protein. But do all of us know about what actually protein is?let's have a look on the images bellow :




Proteins are large, complex molecul





Protines that play many critical roles in the body. They do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs.

Proteins are made up of hundreds or thousands of smaller units called amino acids, which are attached to one another in long chains. There are 20 different types of amino acids that can be combined to make a protein. The sequence of amino acids determines each protein’s unique 3-dimensional structure and its specific function.

Proteins can be described according to their large range of functions in the body, listed in alphabetical order:

Examples of protein functions Function Description Example Antibody Antibodies bind to specific foreign particles, such as viruses and bacteria, to help protect the body. Immunoglobulin G (IgG)  Enzyme Enzymes carry out almost all of the thousands of chemical reactions that take place in cells. They also assist with the formation of new molecules by reading the genetic information stored in DNA. Phenylalanine hydroxylase  Messenger Messenger proteins, such as some types of hormones, transmit signals to coordinate biological processes between different cells, tissues, and organs. Growth hormone  Structural component These proteins provide structure and support for cells. On a larger scale, they also allow the body to move. Actin  Transport/storage These proteins bind and carry atoms and small molecules within cells and throughout the body. Ferritin
Relations between genes and proteins  Most genes contain the information needed to make functional molecules called proteins. (A few genes produce other molecules that help the cell assemble proteins.) The journey from gene to protein is complex and tightly controlled within each cell. It consists of two major steps: transcription and translation. Together, transcription and translation are known as gene expression. During the process of transcription, the information stored in a gene’s DNA is transferred to a similar molecule called RNA (ribonucleic acid) in the cell nucleus. Both RNA and DNA are made up of a chain of nucleotide bases, but they have slightly different chemical properties. The type of RNA that contains the information for making a protein is called messenger RNA (mRNA) because it carries the information, or message, from the DNA out of the nucleus into the cytoplasm. Translation, the second step in getting from a gene to a protein, takes place in the cytoplasm. The mRNA interacts with a specialized complex called a ribosome, which “reads” the sequence of mRNA bases. Each sequence of three bases, called a codon, usually codes for one particular amino acid. (Amino acids are the building blocks of proteins.) A type of RNA called transfer RNA (tRNA) assembles the protein, one amino acid at a time. Protein assembly continues until the ribosome encounters a “stop” codon (a sequence of three bases that does not code for an amino acid). The flow of information from DNA to RNA to proteins is one of the fundamental principles of molecular biology. It is so important that it is sometimes called the “central dogma.” Through the processes of transcription and translation, information from genes is used to make proteins. Movements of  Genes  Each cell expresses, or turns on, only a fraction of its genes. The rest of the genes are repressed, or turned off. The process of turning genes on and off is known as gene regulation. Gene regulation is an important part of normal development. Genes are turned on and off in different patterns during development to make a brain cell look and act different from a liver cell or a muscle cell, for example. Gene regulation also allows cells to react quickly to changes in their environments. Although we know that the regulation of genes is critical for life, this complex process is not yet fully understood. Gene regulation can occur at any point during gene expression, but most commonly occurs at the level of transcription (when the information in a gene’s DNA is transferred to mRNA). Signals from the environment or from other cells activate proteins called transcription factors. These proteins bind to regulatory regions of a gene and increase or decrease the level of transcription. By controlling the level of transcription, this process can determine the amount of protein product that is made by a gene at any given time.

Now have a look on our blood. Here are the basics about the life-sustaining fluid called blood.

Blood Basics

Two types of blood vessels carry blood throughout our bodies:

1. Arteries carry oxygenated blood (blood that has received oxygen from the lungs) from the heart to the rest of the body.
2. Blood then travels through veins back to the heart and lungs, so it can get more oxygen to send back to the body via the arteries.

As the heart beats, you can feel blood traveling through the body at pulse points — like the neck and the wrist — where large, blood-filled arteries run close to the surface of the skin.
The blood that flows through this network of veins and arteries is whole blood, which contains three types of blood cells:

1. red blood cells (RBCs)
2. white blood cells (WBCs)
3. platelets

In babies and young kids, blood cells are made within the bone marrow (the soft tissue inside of bones), particularly in the long bones like the humerus (the upper arm bone) and femur (the thigh bone). But, as kids get older and approach adulthood, blood cells are made mostly in the bone marrow of the vertebrae (the bones of the spine), ribs, pelvis, skull, sternum (the breastbone).
The cells travel through the circulatory system suspended in a yellowish fluid called plasma, which is 90% water and contains nutrients, proteins, hormones, and waste products. Whole blood is a mixture of blood cells and plasma.

Illustration depicting formed elements of blood   Blausen.com staff. Blausen gallery 2014Wikiversity  

Red Blood Cells

Red blood cells (RBCs, also called erythrocytes) are shaped like slightly indented, flattened disks. RBCs contain the iron-rich protein hemoglobin. Blood gets its bright red color when hemoglobin picks up oxygen in the lungs. As the blood travels through the body, the hemoglobin releases oxygen to the tissues.
The body contains more RBCs than any other type of cell, and each has a life span of about 4 months. Each day, the body produces new RBCs to replace those that die or are lost from the body.

White Blood Cells

White blood cells (WBCs, also called leukocytes) are a key part of the body's system for defending itself against infection (this system is called the immune system). They can move in and out of the bloodstream to reach affected tissues.
Blood contains far fewer WBCs than red blood cells, although the body can increase WBC production to fight infection. There are several types of WBCs, and their life spans vary from a few days to months. New cells are constantly being formed in the bone marrow.
Several different parts of blood are involved in fighting infection. White blood cells called granulocytes and lymphocytes travel along the walls of blood vessels. They fight germs such as bacteria and viruses and also may attempt to destroy cells that have become infected or have changed into cancer cells.
Certain types of WBCs make antibodies, which are special proteins that recognize foreign materials and help the body destroy or neutralize them. The white blood cell count (the number of cells in a given amount of blood) in someone with an infection often is higher than usual because more WBCs are being produced or are entering the bloodstream to battle the infection.
After the body has been challenged by some infections, lymphocytes "remember" how to make the specific antibodies that will quickly attack the same germ if it ever enters the body again.

Platelets

Platelets (also called thrombocytes) are tiny oval-shaped cells made in the bone marrow. They help in the clotting process. When a blood vessel breaks, platelets gather in the area and help seal off the leak. Platelets survive only about 9 days in the bloodstream and are constantly being replaced by new cells.
Important proteins called clotting factors are critical to the clotting process. Although platelets alone can plug small blood vessel leaks and temporarily stop or slow bleeding, the action of clotting factors is needed to produce a strong, stable clot.
Platelets and clotting factors work together to form solid lumps (called blood clots) to seal leaks, wounds, cuts, and scratches and to prevent bleeding inside and on the surfaces of our bodies. The process of clotting is like a puzzle with interlocking parts. When the last part is in place, the clot happens — but if even one piece is missing, the final pieces can't come together.
When large blood vessels are cut, the body may not be able to repair itself through clotting alone. In these cases, dressings and stitches are used to help control bleeding

Blood plasma 

Blood plasma is the pale yellow liquid component of blood that normally holds the blood cells in whole blood in suspension; this makes plasma the extracellular matrix of blood cells. It makes up about 55% of the body's total blood volume. It is the intravascular fluid part of extracellular fluid (all body fluid outside of cells). It is mostly water (up to 95% by volume), and contains dissolved proteins (6–8%) (i.e.—serum albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes (Na⁺, Ca²⁺, Mg²⁺, HCO₃⁻, Cl⁻, etc.),hormones, and carbon dioxide (plasma being the main medium for excretory product transportation). Plasma also serves as the protein reserve of the human body. It plays a vital role in an intravascular osmotic effect that keeps electrolytes in balanced form and protects the body from infection and other blood disorders.

A unit of donated frozen plasma DiverDave - Own work

Blood plasma is prepared by spinning a tube of fresh blood containing an anticoagulant in a centrifuge until the blood cells fall to the bottom of the tube. The blood plasma is then poured or drawn off.Blood plasma has a density of approximately 1025 kg/m³, or 1.025 g/ml.

Blood serum is blood plasma without clotting factors; in other words, "pure" blood.Plasmapheresis is a medical therapy that involves blood plasma extraction, treatment, and reintegration.

To be continued..........

Copyright © 2015 by Rumana Reza (Aurny)