Protoplasmic astrocytes produce substances that are tropic to neurons, & they help maintain the appropriate concentration of ions & neurotransmitters by taking up K+ & neurotransmitters glutamate & γ-aminobutyrate (GABA)

TLS Online TPP Program

#Id: 3534

#Unit 2. Cellular Organization

Animal cells have small mitochondrial genomes 16.6 kb in mammals. There are several hundred mitochondria per cell and each mitochondrion has multiple copies of the DNA.

TLS Online TPP Program

#Id: 3535

#Unit 2. Cellular Organization

Mitochondrial genomes have genes encoding (mostly complex I–IV) proteins, rRNAs, and tRNAs

TLS Online TPP Program

#Id: 3536

#Unit 2. Cellular Organization

Human mitochondrial DNA has 22 tRNA genes, 2 rRNA genes, and 13 protein-coding regions. 

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.