L19 - Growth & Reproduction of Mitochondria

Mitochondria

= make ATP & synthesis of heme from calvin cycle in mito

• 2 membranes

• semi-autonomous organelle

• abundant

• grow & divide independently of the cell - reproduce during ALL of interphase

• mitochondria are moving around + change their shape

other functions:

→ initiate apoptosis = programmed cell death

→ mutations in mtDNA genes cause blindness (retina)

Growth of Mitochondria

Components

1. phospholipids - in both membranes

2. proteins - in both membranes + matrix

→ replenish phosphlipids in its membrane using phospholipid exchange proteins for lateral diffusion b/w mito & the ER

→ most proteins are made by free ribosomes in cytosol, THEN imported by translocates into the mito (same as chloroplasts)

• using signal for cytosol → mito import

→ some proteins are made INTERNALLY using genes of mtDNA (circular dsDNA)

• mito make 13 out of their 1000 proteins, including their ETC & ATP synthase proteins

• requires: gene on DNA -RNA pol→ mRNA -ribosme→ protein

→ import of nucleotides & AA into mitochondria

via: porin → specific transporters

• porin (b-barrels) : protein CANT pass thru, only nucleotides & AA + in the outer mito membrane

• specific transporters are found in the inner mito membrane

Reproduction of Mitochondria

• fission by ER wrapping around the mitochondria

seen here:

• procedure: TEM tomography

Heme Synthesis of Mitochondria

• done by Calvin cycle in the mitochondria

Path of Iron:

1. enters cell with RME

2. exits lysosome into the cytosol thru DMT1

3. enters mitochondria thru porin then specific transporter (mitoferrin)

4. Krebs cycle occurs in mito matrix → produces heme

5. heme exits mito thry spefiic transporter (FLvR1b) then porin

How are new DMT1 proteins delivered to lysosomes?

a). cytosol → lysosome

b). ER → lysosome

c). ER → Golgi → lysosome

c). ER → Golgi → lysosome w a M6P signal

How are new Mfrn1 proteins delivered to mitochondria?

a). made inside mitochondria

b). cytosol → porins → transporters

c). cytosol → TOMS → TIMS

c). cytosol → TOMS → TIMS

• bc Mfrn1 is a protein that imported into mito, THUS uses translocates

examinable content