Muscarinic acetylcholine receptor is coupled to a Gαi protein.

TLS Online TPP Program

#Id: 3184

#Unit 3. Fundamental Processes

In some situations a mitochondrion has both paternal and maternal alleles. This has two requirements: that both parents provide alleles to the zygote (which of course is not the

case when there is maternal inheritance.

TLS Online TPP Program

#Id: 3185

#Unit 3. Fundamental Processes

Mitochondrial DNA replicates by increasing the number of genomes in proportion to mitochondrial mass, but without ensuring that each genome replicates

the same number of times.

TLS Online TPP Program

#Id: 3186

#Unit 3. Fundamental Processes

Mitochondria use different origin sequences to initiate replication of each DNA strand

Replication of the H strand is initiated in a D loop.

Replication of the L strand is initiated when its origin is exposed by the movement of the first replication fork.

TLS Online TPP Program

#Id: 3187

#Unit 3. Fundamental Processes

Replication starts at a specific origin in the circular duplex DNA. Initially, though, only one of the two parental strands (the H strand in mammalian mitochondrial DNA) is used as a

template for synthesis of a new strand. 

Synthesis proceeds for only a short distance, displacing the original partner (L) strand, which remains single-stranded,

TLS Online TPP Program

#Id: 3188

#Unit 3. Fundamental Processes

A single D loop is found as an opening of 500 to 600 bases in mammalian mitochondria.

TLS Online TPP Program

#Id: 3189

#Unit 3. Fundamental Processes

Some mitochondrial DNAs possess several D loops, reflecting the use of multiple origins. The same mechanism is employed in chloroplast DNA, where (in complex plants) there are two D loops.