(HER) DNA Lesson

DNA Lesson

DNA is a type of nucleic acid, a long molecule made up of the elements carbon, nitrogen, oxygen, hydrogen, and phosphorus. Nucleic acids contain the genetic information in the cell that is responsible for carrying out all of its life's functions.  That means our DNA contains the blueprints to make proteins.  Why are proteins important?  Here is a list of a few things that proteins do in our bodies.

• Digestive enzymes are protein molecules that break down food. 
• Pepsin and lactase are digestive enzymes. Pepsin breaks down proteins in food molecules found in your stomach. 
• Lactase breaks down sugar molecules in milk.
• Antibodies are the proteins of the immune system that defend the body against foreign substances.
• Myosin and actin are contractile proteins that aid in movement by helping muscles to contract.
• Hemoglobin is a protein that transports oxygen in the blood.
• Structural proteins provide support for connective tissues found in tendons and ligaments.

 

How Are Proteins Made?

Proteins are made up of a chain or sequence of amino acids. There are 20 different types of amino acids. The combination of these amino acids determines the type of protein that will be made inside the cell. DNA contains the instructions to make proteins but RNA helps connect amino acids together to make proteins.  

In 1951, Rosalind Franklin took X-ray images of DNA. Her photographs revealed the shape of a helix. In 1953, Francis Crick and James Watson used these photographs to propose that the structure of DNA resemble a double helix. DNA contains two strands of molecules that are combined together to form the shape of a spiral staircase or twisted ladder.  The sides of the DNA ladder are made up of the sugar, deoxyribose, and phosphates. These rungs or steps of the DNA ladder represent the four types of nitrogen bases in a DNA molecule. The four nitrogen bases are adenine (A), thymine (T), cytosine(C), and guanine (G). Each strand of DNA contains nitrogen bases that are connected to the nitrogen bases on the adjacent DNA strand. Adenine always pair with thymine and guanine only pairs with cytosine. Each base is a part of a nucleotide. The nucleotide in DNA consists of a phosphate, a five carbon sugar (deoxyribose), and one of the four nitrogen bases. 

 

Watch the video below to learn more about DNA.

 

 

The DNA sequence is the order of nucleotides within a DNA molecule. The order of the nucleotides in a DNA molecule helps distinguish one organism from another organism.

The DNA sequence in a chimpanzee is about 96% similar to the DNA sequence in humans. The DNA sequence in a frog or zebra fish is very different from the order of nucleotides in a human.

There is another name for these two strands of DNA molecules that are made up of nucleotides.

They are called chromosomes. Just like a pair of shoes consists of two shoes, a right and a left, our chromosomes come in pairs too.

Our body has 23 pairs of chromosomes.

How many individual chromosomes are inside each cell? The nucleus in the human body has to fit a lot of information inside a tiny cell.

See description of diagram Links to an external site.

 

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