Organelles: Lysosomes and Mitochondria

Function of lysosomes

Intracellular digestion

How do lysosomes carry out their function

Acid hydrolysis

How is a cell protected from lysosomal function

Lysosomal membrane proteins are highly glycosylation

How does a cells pH protect against lysosomes

PH of lysosome environment makes hydrolytic enzymes non-functional at cellular pH

How is lysosomal pH maintained

Via vacuolar H+ ATPase that pumps hydrogen ions into lysosome

Where do lysosomal hydrolases first go to

Endosomes and finally end up in lysosomes

Wat do lysosomes carry

Mannose-6-phosphate group attached in N-linked oligosaccharide

How is lysosome shipped from Golgi to lysosome

Receptor for M6P on trans-Golgi then put into Cathrine coated pit, then sent to lysosome

Autophagy

Deletion of obsolete cell parts via lysosomal digestion; unclear how they get to lysosome

Exocytosis

Proteins destined for cell export are in trans Golgi transport vesicles that fuse with the plasma membrane of the cell

Constitutive secretory pathway

Operates continuously in unpolarized cells, no signals required for protein to leave

Regulated secretory pathway

In cells that secrete proteins rapidly to different domains of the cell surface

Where are secretory proteins first aggregated

In vesicles

Where do secretory vesicles bud from

Trans Golgi network

Mitochondrion

Organelles that generate most of the cells supply of ATP

Structure of mitochondria

Outer membrane, inter membrane space, inner membrane, cristae and matrix

What is the mitochondria involved in

Formation of hydrogen gradient using fat and sugar and producing water and CO2

What does the outer membrane of mitochondria do/have

Proteins that form channels through which molecules and ion some through

What does the inner membrane of the mitochondria have

5 complexes of integral membrane proteins

Complex I

NADH dehydrogenase

Complex II

Succinate dehydrogenase

Complex III (cytochrome c)

Cytochrome c reductase

Complex IV

Cytochrome c oxidase

Complex V

ATP synthase

Mitochondrial matrix

Complex mixture of soluble enzymes that catalyze respiration of pyruvic acid and other small molecules

What does the mitochondria use and produce

Pyruvic acid is oxidized and decarboxylated to produce CO2 and acetate donated to oxaloacetate to form citric acid

What does each turn of the CAC make

2 CO2

3 NADh

1 GTP

1 FADH2

How many genes in mitochondrial DNA

37 genes

What kind of genes do mitochondrial DNA have

Ribosomal RNA

Transfer RNA

13 polypeptides

What happens when mitochondria does not function properly

Not enough energy

Cells and organs do not function

What must happen for symptoms to be seen in a mitochondrial disease

Critical number of mito must be affected

What kind of tissues are most affected by mito diseases

Tissues that are highly dependent on oxidative respiration (brain, heart, muscle)

From whom do we inherit our mitochondrial DNA

Mother