Neutral theory of molecular evolution

Developed by Motoo Kimura, who argued that most of the evolution of DNA sequences occurs by chance (genetic drift) rather than by natural selection. 

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#Unit 2. Cellular Organization

Matrix-targeting sequences

sequences for localizing proteins to mitochondria

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#Unit 2. Cellular Organization

Matrix-targeting sequences

Located at the N-terminus

Usually 20–50 amino acids in length

Rich in hydrophobic amino acids, positively charged basic amino acids (arginine & lysine), and hydroxylated ones (serine and threonine)

Amphipathicity of matrix-targeting sequences is critical to their function

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#Unit 2. Cellular Organization

Mitochondrial protein import requires: 

Tom proteins (Tom 20/22/70)

General import pore (Tom40)

Tim proteins (Tim23/17)

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#Unit 2. Cellular Organization

Energy inputs are needed to Import proteins into mitochondria

Chaperone proteins (Hsp70& Hsp90)

An H+ electrochemical gradient, or proton-motive force

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Brown Adipose Tissue

is brown because of the presence of large numbers of mitochondria (high concentrations of cytochromes), with heme groups that are strong absorbers of visible 

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#Id: 7918

#Unit 2. Cellular Organization