Molecular Basis of Inheritance Flashcards

Vocabulary flashcards based on Molecular Basis of Inheritance lecture notes.

Nucleic Acids

Building blocks of genetic material (DNA & RNA).

DNA

The genetic material in most organisms.

RNA

Functions mostly as messengers; genetic material in some viruses.

Polynucleotide

Polymer of nucleotides; DNA and RNA are polynucleotides.

Nucleotide

Composed of a nitrogenous base, a pentose sugar, and a phosphate group.

Purines

Nitrogenous bases including Adenine (A) and Guanine (G).

Pyrimidines

Nitrogenous bases including Cytosine (C), Thymine (T), and Uracil (U). Thymine is only in DNA, Uracil only in RNA.

N-glycosidic linkage

Linkage between a nitrogenous base and a pentose sugar to form a nucleoside.

Nucleoside

Nitrogenous base + sugar.

Nucleotide (deoxyribonucleotide)

Nitrogen base + sugar + phosphate group.

3'-5' phosphodiester bond

The bond through which 2 nucleotides are linked together to form dinucleotide.

Friedrich Miescher

Identified DNA in 1869 and named it 'Nuclein'.

Watson & Crick

Proposed the double helix model of DNA in 1953, based on X-ray diffraction data from Wilkins & Franklin.

Anti-parallel polarity

The two DNA chains run in opposite directions (5'-3' and 3'-5').

Base pairs (bp)

Bases in 2 strands are paired through H-bonds (A=T, C=G).

Erwin Chargaff's rule

In DNA, [A]=[T] and [G]=[C].

Nucleoid

In prokaryotes, DNA (negatively charged) held with positively charged proteins.

Histones

Positively charged, basic proteins rich in lysines and arginines. Organize DNA in eukaryotes.

Histone octamer

Formed by 8 histones.

Nucleosome

Negatively charged DNA wrapped around a histone octamer.

Chromatin

Thread-like stained bodies constituted by repeating units of nucleosomes.

Euchromatin

Loosely packed, transcriptionally active chromatin that stains light.

Heterochromatin

Densely packed, inactive region of chromatin that stains dark.

Griffith's Transforming Principle

Experiment using mice & Streptococcus pneumoniae demonstrating genetic transformation.

S-strain (Smooth)

Virulent strain of Streptococcus pneumoniae with a polysaccharide mucus coat; causes pneumonia.

R-strain (Rough)

Non-virulent strain of Streptococcus pneumoniae lacking a mucus coat; does not cause pneumonia.

Reverse transcription

Flow of information from RNA to DNA in some viruses.

Semi-conservative model of replication

Parental DNA strands act as template for synthesis of new complementary strands.

Origin (ori)

A point at which DNA replication starts

Replicon

A unit of replication with one origin

Helicase

An enzyme that unwinds and separates the 2 strands by breaking H-bonds.

Replication fork

The 'Y'-shaped structure formed by the unwinding of the DNA molecule.

Primase

Enzyme that synthesizes a small RNA primer to start DNA replication.

DNA dependent DNA polymerase

Enzyme that adds nucleotides to the primer strand.

Leading strand

New DNA strand formed continuously in the 5'-3' direction.

Okazaki fragments

Small stretches of DNA formed discontinuously on the lagging strand.

DNA ligase

Enzyme that joins Okazaki fragments together.

Lagging strand

The new strand is formed in small stretches (Okazaki fragments) in 5'-3' direction (Discontinuous synthesis).

Transcription

Process of copying genetic information from one strand of DNA into RNA.

Transcription Unit

It is the segment of DNA between the sites of initiation and termination of transcription.

Promoter

Transcription start site; binding site for RNA polymerase.

Structural gene

The region between promoter and terminator where transcription takes place.

Terminator

The site where transcription stops.

Template strand

3'-5' strand that acts as template for transcription.

Coding strand

5'-3' strand with the same sequence as the RNA transcript (except T instead of U).

Induction

Switching on a set of genes to metabolize a substrate added to growth medium of bacteria.

Repression

Is when a metabolite (product) is added, the genes to produce it are turned off.

Operon

A set of genes regulating a metabolic reaction.

Lac Operon

Operon controlling lactose metabolism in E. coli.

Negative regulation

Regulation of lac operon by repressor.

Genome

The entire DNA in the haploid set of chromosomes of an organism.

Human Genome Project (HGP)

Project (1990-2003) to identify the sequence of nucleotides and mapping of all the genes in human genome.

Expressed Sequence Tags (ESTs)

Approach of HGP focused on identifying all the genes that are expressed as RNA

Sequence annotation

Sequencing whole set of genome containing all the coding & non-coding sequence and later assigning different regions in the sequence with functions.

Bioinformatics

Application of computer science and information technology to the field of biology & medicine.

DNA Fingerprinting (DNA Profiling)

Technique to identify individuals based on their DNA.

VNTR probe

Hybridization using radioactive labelled VNTR probe.