DNA

DNA

 

Deoxyribonucleic acid is what DNA stands for. Quite a mouthful isn't it? Hey Epicraptor here and I am going to talk about DNA. Everybody has a unique DNA. DNA is located in the chromosomes which are present inside the nucleus.It's arranged in a spiral shape called a double helix. The sides of the ladder are made of sugar and phosphate molecules and the rungs are made up of nitrogen base pairs. The base pairs are cytosine, thymine, adenine and guanine. Since the DNA chain is so long, the base pairs can arrange themselves in millions of sequences. The base pairs have a specific code for arranging themselves. Thymine can only pair with adenine and cytosine and guanine can only pair up together. So why is DNA so important? Because DNA is basically a blue print for you. DNA contains information for an organism's growth and function.

As stated in my previous mitosis blog chromosomes reproduce by mitosis.When chromosomes are duplicated before mitosis, the amount of DNA inside the nucleus is doubled. The two sides of DNA helix unwind and separate from each other. Each side then becomes a pattern of which a completely new side forms.The new DNA has bases that are exactly identical to those of the original DNA and are in the same order. In 1952 scientist Rosalind Franklin discovered that DNA is two chains of molecules in a spiral shape. In 1953 James Watson and Francis Crick made the first DNA model.

You may or may not have seen a crime in a movie where the Crime scene investigators find some DNA left behind. DNA can be found in blood, sweat, hair strands and fingerprints. Since no two people in the world have the same DNA, crime investigators try to analyze the DNA. The DNA found at the crime scene is then matched with the suspects DNA. If it is a match then the suspect can be arrested for the crime.

This has been Epicraptor and I hope you learned more about DNA today.

Sources

Source 1

Source 2

 Source 3

Cell division and Mitosis

Hey everyone! Epicraptor here ready to discuss mitosis. Cell division is the division of a dying cell to form two new cells. Mitosis is when the nuclei divide into two new identical nuclei. Mitosis ensures that each cell offspring will have a complete set of chromosomes like the parent cell. Chromosomes are two DNA molecules held together by a circular structure called a centromere. Every human cell has 46 chromosomes. Mitosis has four steps, prophase, metaphase, anaphase and telophase.

A chromosome

During the prophase chromosomes are visible. Structures called centrioles appear on opposite ends of the cell. Thread-like spindle fibers begin to stretch across.

Prophase

In metaphase the chromosomes line up in the middle of the cell. Each centromere attaches to two different spindle fibers.

Metaphase

In Anaphase the centromeres divide. Each half of the chromosomes separate and move to opposite ends of the cell.

Anaphase

The last phase is telophase. In telophase Spindle fibers start to disappear. Chromosomes uncoil and it becomes harder to see them. Each mass of chromosomes develops it's own nuclear membrane to make a new nucleus.

Telophase



A cell about to divide

 

 

 

 

 

 

 

 

 

 

Ninja Kick!

Links
If you have a brainpop account, watch this.

The T-rex had a predator!

 

The Tyrannosaurus rex  was one of the most fearsome predators. Everyone knows what a T-rex is. I think? Anyways scientists have wondered why its ancestors remained relatively small for millions of years. Now, the discovery of a new meat eater may offer some answers. This newfound predator may have preyed on T. rex’s ancestors. That should have kept them small and on the run. Scientists call the new dino Siats meekerorum. Like the T-rex, Siats walked on two legs, but Siats was an Allosaurs. S. meekerorum ruled what is now western North America about 98.5 million years ago.  Some predator usually dominates every ecosystem. Such an apex, or top predator usually is so tough that no other creature attempts to tackle it. And as long as the top predator remains healthy, no other creature will prey on it. (Think of an apex predator as the schoolyard’s biggest, meanest bully.)Zanno and her team estimate that Siats weighed more than 3,900 kilograms (8,600 pounds). Most of the fossil remains they found came from an individual that likely measured more than 9 meters (about 30 feet) long. But it also was only a juvenile when it died. Its towering size makes Siats the third-largest known predator to ever prowl western North America.

Links

More Info