Molecular Basis of Inheritance: DNA Structure and Packaging

Practice flashcards covering DNA structure, chemical components, the Double Helix model, genetic information flow, and DNA packaging based on the lecture transcript.

DNA is a long polymer of __________.

deoxyribonucleotides

The bacteriophage known as $\phi \times 174$ has __________ nucleotides.

$$5386$$

The haploid content of human DNA is __________ bp.

$$3.3 \times 10^9$$

A nucleotide has three components: a nitrogenous base, a __________ sugar, and a phosphate group.

pentose

The two types of nitrogenous bases are Purines (Adenine and Guanine) and __________ (Cytosine, Uracil and Thymine).

Pyrimidines

In RNA, __________ is present at the place of Thymine.

Uracil

A nitrogenous base is linked to the OH of $1'\,C$ pentose sugar through a __________ linkage to form a nucleoside.

N-glycosidic

Two nucleotides are linked through __________ phosphodiester linkage to form a dinucleotide.

$$3'-5'$$

The backbone of a polynucleotide chain is formed due to __________ and phosphates.

sugar

In RNA, every nucleotide residue has an additional __________ group present at $2'\text{-position}$ in the ribose.

$$-OH$$

DNA was first identified as an acidic substance in the nucleus by __________ in 1869, who named it ‘Nuclein’.

Friedrich Meischer

James Watson and Francis Crick proposed the Double Helix model in 1953 based on X-ray diffraction data produced by __________ and Rosalind Franklin.

Maurice Wilkins

According to __________, the ratios between Adenine and Thymine and Guanine and Cytosine are constant and equals one for double-stranded DNA.

Erwin Chargaff

Guanine is bonded with Cytosine with __________ H-bonds.

three

The two chains of the DNA double helix are coiled in a __________ fashion.

right-handed

The pitch of the DNA helix is __________ nm.

$$3.4$$

The distance between a base pair in a helix is approximately __________ nm.

$$0.34$$

The __________ states that the genetic information flows from $DNA \rightarrow RNA \rightarrow \text{Protein}$.

Central dogma

In prokaryotes, DNA is held with some positively charged proteins in a region termed as __________.

nucleoid

Histones are rich in the basic amino acid residues __________ and arginine.

lysine

Negatively charged DNA wrapped around a histone octamer forms a structure called a __________.

nucleosome

A typical nucleosome contains __________ bp of DNA helix.

$$200$$

The repeating unit of chromatin seen as ‘beads-on-string’ under an electron microscope is the __________.

nucleosome

Packaging of chromatin at higher levels requires a set of proteins collectively referred to as __________ proteins.

Non-histone Chromosomal (NHC)

__________ is the transcriptionally active, loosely packed region of chromatin that stains light.

Euchromatin

The densely packed, dark-staining, transcriptionally inactive chromatin is called __________.

Heterochromatin

In 1928, __________ conducted the Transforming Principle experiments using Streptococcus pneumoniae.

Frederick Griffith

In Griffith's experiment, the __________ strain bacteria have a mucous (polysaccharide) coat and are virulent.

S