1. Concept of gene

Central Dogma

Fig 1.1

Exceptions to Central Dogma

1. RNA viruses (RETROVIRUSES) & REVERSE TRANSCRIPTASE

RNA ssDNA

2. Gramicidin S, antibiotic produced by strains of Bacillus brevis

produced by enzymatic joining of 10 aa using 2 enzymes, not by ribosomal protein synthesis
 
 

What is a gene?
How are genes arranged in genomes?
How can genes change over time?
How can genes be transmitted through space and time?
How can genes recombine?
Definitions of the gene

1. The unit of function. That piece of genetic material that controlled the inheritance of one character or one aspect of the phenotype.

2. The unit of structure defined by recombination. The smallest unit of inheritance that cannot be disrupted by recombination. The RECON.

3. The unit of structure defined by mutation. The smallest unit of inheritance that can undergo mutational change independent from other forms of inheritance. The MUTON.

Are these all THE GENE? (1940s)

Exceptions:

1. INTRAGENIC recombination

2. The recon is actually a SINGLE NUCLEOTIDE PAIR

3. The muton is also a single nucleotide pair.

Hence recon & muton do not apply to the gene and are no longer in use as definitions of gene.

The gene is a unit of function: The unit of inheritance that codes for one polypeptide chain and that can be defined by the CIS-TRANS test, i.e.

GENE = CISTRON. (more later.)
 
 

Genome Organisation

Classical concept was BEADS ON A STRING

each gene could undergo recombination relative to the others and could undergo mutation. these concepts already described as erroneous.

• Syllabus

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