DNA and Nucleic Acids

Question 1

What really is a nucleotide?

Answer 1

• This is a molecule containing a 5 carbon pentose sugar. a nitrogenous base and a phosphate group!

Question 2

How can we group the 4 bases that we have?

Answer 2

1. THYMINE and CYTOSINE: These are pyramidines with a single ring structure
2. ADENINE and GUAMINE: These are purines with a double ring structure!

Question 3

How do pyramidines and purines bond together?

Answer 3

• as they will bond via complementary base pairing, a PYRAMIDINE will always bons to a PURINE!
• Hence, Adenine bonds to Thymine, and Cytosine bonds to Guamine!

Question 4

What is DNA?

Answer 4

• This is a hereditary macromolecule in cells of ALL living organisms, with the role of stroing genetic information, instructions for protien manufacture and growth for entire organism

Question 5

What can complementary base pairing bring to DNA?

Answer 5

• This will bring EQUAL SIZED RUNGS on DNA DOUBLE HELIX SHAPE!!!
• This will also brong molecular stability and base-information protection for such a large macromolecule…

Question 6

Give the 4 main differences between DNA and RNA

Answer 6

1. D = Double stranded sugar-phosphate backbone
R = Single-stranded
2. D = Made of deoxyribose
R = Made of ribose
3. D = Extremely long molecule#
R = relitavly short molecule
4. D = Found in chromosomes
R = Found in the cytoplasm

Question 7

What is the anti-parralel structure in DNA?

and give the number of HYDROGEN BONDS FOR EACH BOND!!

Answer 7

• This is when complementary bas pairing occurs between purines and pyramidines
• Can be unzipped via RNA Polymerase!

***2 HYDROGEN BONDS = Aden

3 HYDROGEN BONDS = Cytosine and Guanine
2 HYDROGEN BONDS = Adenine and Thymine

Question 8

What are the Phosphodiester Bonds?

Answer 8

• These are the bonds that form between a A SINGLE PHOSPHATE GROUP bonded to 2 PENTOSE SUGAR GROUPS of the neighbouring nucleotide

Like with literally all biological molecules, a CONDENSATION REACTION and with HYDROLYSIS to break apart….

Question 9

Where in the nucleotide does the Phosphodiester bond form?

*

Answer 9

• This will form at carbon 3 and carbon 5 at the pentose sugar molecules!

Question 10

What is the difference between ribose and deoxyribose???

Answer 10

1. RIBOSE: Will contain URACIL over THYMINE in its structure
   Will also contain 2 hydroxyl groups in molecule
2. DEOXYRIBOSE: Will be the normall bases that it contains, but with having only 1 hydroxyl group in molecule

Question 11

How can we describe the direction of bonding in a DNA molecule?

Answer 11

1. This will occur from the 3’ to the 5’
2. This will stands for the number on the carbon atoms in the pentose sugar.
3. Thid will mean the opposing sides of the nucleotides wil be of reverse of each other (like a mirror image)

Question 12

How is DNA organised in Eukaryotic Cells?

Answer 12

1. Each molecule of DNA is tightly wound around a histone protien, forming chomosomes!
2. Hence, each chromosome = 1 DNA Molecule!

Question 13

How is DNA organised in Prokaryotic Cells?

Answer 13

• DNA loop is free floating in the cytoplasm, not enclosed in a membrane-bound nucleus?

Question 14

Why are the hydrogen bonds inportant in DNA?

Answer 14

THIS ALLOWS THE MOLECULE TO BE UNZIPPED BY RNA POLYMERASE FOR DNA TRANSRIPTION and REPLICATION!!!!!!

instead of bieng held in a very rigid, bond-like structure e.g. : COVALENT or IONIC………..