PHYA is the only gene that encodes a Type I phytochrome and predominantly perceives far-red light.

Phytochrome B predominantly perceives red light

TLS Online TPP Program

#Id: 3537

#Unit 2. Cellular Organization

The fivefold discrepancy in size between the S. cerevisiae (84 kb) and mammalian (16.6 kb) mitochondrial genomes indicates the fact that there must be a great difference in their genetic organization in spite of their common function.

TLS Online TPP Program

#Id: 3538

#Unit 2. Cellular Organization

The chloroplast genome in land plants encodes 4 rRNAs, 30 tRNAs, and 60 proteins.

TLS Online TPP Program

#Id: 3539

#Unit 2. Cellular Organization

The chloroplast genome is generally similar to that of mitochondria, except that there are more genes.

TLS Online TPP Program

#Id: 3683

#Unit 2. Cellular Organization

There are 6000 genes in yeast; 21,700 in a nematode worm; 17,000 in a fly; 25,000 in the small plant Arabidopsis; and probably 20,000 to 25,000 in mice and humans

TLS Online TPP Program

#Id: 3684

#Unit 2. Cellular Organization

The “introns early” hypothesis is the proposal that introns have always been an integral part of the gene.  Genes originated as interrupted structures, and those now without introns have lost them in the course of evolution.

TLS Online TPP Program

#Id: 3685

#Unit 2. Cellular Organization

The “introns late” hypothesis is the proposal that the ancestral protein-coding sequences were uninterrupted and that introns were subsequently inserted into them