Quiz: Nucleic Acids

Dr. Z @Trinity

What is the monomer of a nucleic acid?

What are its 3 components?

The nucleotide!

A phosphate group (OPO₃^2-), a pentose (5-carbon) sugar, and a nitrogenous base

What are the different types of nucleic acids?

DNA → deoxyribonucleic acid → deoxyribose sugar missing an oxygen, protects genetic instructions

RNA → ribonucleic acid → ribose sugar has the oxygen, transports the instructions (in the case of mRNA)

ATP → adenosine triphosphate → energy, three phosphates, a pentose sugar and an adenine (nitrogenous base)

What kind of bonds connect the 3 components of a nucleotide?

Covalent bonds

Differentiate between the two types of sugars.

Differentiate between the 5 types of nitrogenous bases.

Deoxyribose is missing an oxygen and is used in DNA, ribose has that oxygen and is used in RNA.

Cytosine, Uracil (in RNA) and Thymine (in DNA) are pyrimidines, meaning they have a single ring. REMEMBER: CUT = Pyrimidines

Purines are the rest: Guanine and Adenine. They have double rings.

Chargaff’s Rules

The proportion of A always equals that of T

The proportion of G always equals that of C

A = T and G = C

What components make the sides of the “ladder” in deoxyribonucleic acid?

What is the name of the bonds that hold those components together?

Alternating phosphate groups and pentose sugars

Covalent bonds

What comprises the rungs of the “ladder”?

What kind of interaction holds the rungs together?

Nitrogenous bases

Hydrogen bonds

What is the advantage of DNA being double-stranded instead of single-stranded?

Because it is double-stranded, it offers better protection to the rungs — that precious genetic information.

What is easier to do: separate two strands of DNA or disassemble the nucleotides in a single strand? Why?

Separate two strands of DNA, because they are connected by hydrogen bonds. It is easier to unzip in order to transfer genetic information with the help of an enzyme (helicase) during replication and transcription.

Why is it necessary to mash the strawberries to extract DNA?

This is to break the cell wall, allowing the extraction solution to get through.

What is the purpose of the detergent?

The detergent pokes holes through the cell membrane (interferes with the phospholipid bilayer).

What is the purpose of the salt?

The salt makes the DNA clump up together!

Name a liquid that DNA is not soluble in.

Alcohol; DNA is in solution in the strawberry mush, but once alcohol is added, DNA was no longer in solution!

Is the DNA you extracted pure? What else might be attached to the DNA?

Not pure, it might be mixed up with proteins.

Can you see a single strand of DNA without a microscope? Explain how you were able to see the DNA in this experiment without magnification.

No, you need a microscope. We could see the DNA of strawberries because they are octoploid, meaning they have 8 sets of chromosomes, and as such, a lot more DNA than (for example) the DNA of a human cheek cell, which is diploid.

What is polyploidy and what effect would it have on the procedure?

Multiple sets of chromosomes (more than 2)

More types make it more visible (more massive)

Why is extraction of DNA important and what can it be used for? (3)

Studying genetic diseases

Forensics

Paternity testing

What are the three types of RNA? Expand on mRNA only.

mRNA (messenger RNA) → involved in protein synthesis, the copy of protein-making instructions that travels to the ribosome

tRNA (transfer RNA)

rRNA (ribosomal RNA)

What is the ribosome?

The protein-making factory, reads the code of mRNA and produces new proteins using amino acids from the cytoplasm.

Transcription

Translation

Transcription is the process of creating a copy mRNA from the original DNA in the nucleus. Uracil replaces thymine.

After transcription, the mRNA leaves the nucleus into the cytoplasm, ready to travel to the ribosome.

Translation is the process of “translating” the genetic language of nitrogenous bases into protein languages. Every three bases are a codon, which corresponds to 1 of 20 amino acids. This happens within the ribosome; after receiving an mRNA, it produces a polypeptide chain based on the genetic instructions… which becomes a protein!

What bond links together nucleotides?

Phosphodiester bonds

List four differences between DNA and RNA.

List three similarities between DNA and RNA.

DNA has the sugar deoxyribose, which is missing an oxygen, while RNA has the sugar ribose. DNA is double-stranded, while RNA is single-stranded. DNA only stays in the nucleus, while RNA can travel outside of the nucleus. Lastly, DNA has thymine, while RNA has uracil.

DNA and RNA are both example of nucleic acids. They both consist of nucleotides. Lastly, both DNA and RNA can carry genetic information.