L2: DNA packing and storage

Question 1

What is the primary function of DNA?

Answer 1

DNA serves as the blueprint for life, carrying genetic instructions for the development, growth, and reproduction of all living organism

Question 2

How is genetic information stored within DNA?

Answer 2

Genetic information is stored in sequences of nucleotides (A, T, C, G) arranged into genes, which code for specific proteins

Question 3

What are the purines and pyrimidines in DNA?

Answer 3

Purines have two rings (adenine and guanine), while pyrimidines have one ring (cytosine and thymine in DNA; uracil replaces thymine in RNA).

Question 4

What is the difference between euchromatin and heterochromatin?

Answer 4

Euchromatin is decondensed chromatin that allows gene expression, while heterochromatin is tightly packed, restricting gene expression.

Question 5

Describe the structure and components of a DNA molecule

Answer 5

DNA has a double-helix structure, with a sugar-phosphate backbone and nitrogenous bases that form hydrogen bonds, creating a ladder-like structure

Question 6

What role do histones play in DNA packaging?

Answer 6

Histones are positively charged proteins around which DNA wraps to form nucleosomes, stabilizing the DNA structure and reducing repulsion between negative charges on DNA.

Question 7

How and why is DNA organized during cell division?

Answer 7

During cell division, DNA condenses into chromosomes to prevent entanglement, ensuring stable and orderly separation of genetic material into daughter cells.

Question 8

What is a nucleosome?

Answer 8

A nucleosome is a unit of DNA wrapped twice around a core of eight histone proteins (2 of each: H2B, H2A, H3, H4), helping organize DNA into chromatin.

Question 9

What is the primary structural difference between RNA and DNA?

Answer 9

DNA is double-stranded and contains deoxyribose sugar, while RNA is single-stranded and contains ribose sugar with uracil instead of thymine.

Question 10

What is the organisation level of DNA?

Answer 10

DNA, nucleosome, Solenoid, chromatin, loops, Chromosome

Question 11

State the purins and pyrimidines

Answer 11

Purins: Adenine, Guanine
Pyrimidines: Cytosine, Thymine, Uracil

Question 12

Benefits of DNA packing?

Answer 12

1. Compartmentalisation of genes within DNA
2. structural stability of chromosomes during cell division

Question 13

State the properties of DNA double helix (i.e. back bone and bases)

Answer 13

Hydrophobic bases
Hydrophilic backbone

Question 14

state the location of DNA and RNA

Answer 14

DNA: Only in the nucleus (except when cell division)
RNA: Nucleus and can travel to cytoplasm

Question 15

Stability of DNA and RNA

Answer 15

DNA:
1. deoxyribose sugar less reactive than ribose sugar.
2. Double strand– protection of hydrophobic bases
RNA:
1. 2 C-OH group of ribose makes it more reactive
2. Single-stranded, more susceptible to attack