Gr 11 Nucleic Acid structure

DNA Replication

Protein Synthesis

What are DNA and Genes? <watch>

The stringy stuff in the test tube is DNA. But you can't tell which one of these organisms it came from just by looking at it. That's because DNA looks exactly the same in every organism on Earth. All living things have DNA. And whether it comes from you, a pea plant, or your pet rat, it's all the same molecule. It's the order of the letters in the code that makes each organism different.

The order of building blocks in a strand of DNA makes up a "sequence." We can read a DNA sequence like letters in a book. In fact, we know the sequence of the entire human genome—all 3 billion letters. That's enough information to fill roughly 1,000 200-page books! Contained within the 3 billion letters of the human genome are about 21,000 genes. Most of our known genes code for proteins, but some code for RNA molecules.

The Big Picture

By the end of this unit, you will be able to explain the mechanisms shown in the animation, with great detail.

The central dogma

The central dogma of molecular biology explains that DNA codes for RNA, which codes for proteins. DNA is the molecule of heredity that passes from parents to offspring. It contains the instructions for building RNA and proteins, which make up the structure of the body and carry out most of its functions.

Inside the cells of all living things, tiny molecular machines are constantly reading the information in DNA and using it to build proteins. In exploring the activity below, you will learn about the three types of RNA are essential to this process: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).

DNA Structure

The nucleic acids DNA and RNA are polymers of nucleotides
DNA differs from RNA in the number of strands present, the base composition and the type of pentose
DNA is a double helix molecule made of two antiparallel strands of nucleotides linked by hydrogen bonding between complementary base pairs

Nucleotides

Nucleic acids are the genetic material of the cell and are composed of recurring monomeric units called nucleotides

Each nucleotide is comprised of three principal components:

5-carbon pentose sugar (pentagon)
Phosphate group (circle)
Nitrogenous base (rectangle)

Both the phosphate group and nitrogenous base are attached to the central pentose sugar

The nitrogenous base is attached to the 1’– carbon atom (right point)
The phosphate base is attached to the 5’– carbon atom (left point)

Video about DNA structure, and the different bonds within the molecule

Note: It is kind of confusing because it uses all the key words I have discussed with you, (without explanation) so watch this as a summary to check your understanding of the topic.

Can you invent a question based on any information presented here?

RNA Structure

The key to RNA's versatility is its chemical structure. It's made from just 4 simple building blocks, yet RNA can take on a nearly infinite variety of shapes. And its three-dimensional shape in part determines what an RNA molecule can do.

Even though RNA is single-stranded (unlike DNA, which is made up of two strands), it can still form complementary base pairs. Complementary sections within a single strand of RNA can base-pair with each other, causing the molecule to fold in on itself and form a complex, three-dimensional shape.

The sequence of bases along the RNA strand determines how it will fold. In this way, the sequence of bases determines the strand's three-dimensional shape. Changing the bases will change both the molecule's shape and its function. It is this flexibility that makes RNA such a versatile molecule.

Types of RNA

The Role of RNA

The disovery of the structure of DNA

Watson

Crick

Chargaff

Franklin

It's important to know these scientists, all of their individual discoveries played a part in determining the structure of DNA

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