(39-40) Peroxisome and mitochondria

Organelle

membrane bound unit within a cell with a specific function

Peroxisomes look like — however they are involved in — instead of —

lysosomes; oxidation/detoxification; digestion

series of enzymes found in peroxisomes. What activities are all of these enzymes involved in?

peroxidases, d-amino oxidases, and catalases; oxidative activities (production and destruction of hydrogen peroxide [H2O2])

t/f you may tell the difference between peroxisomes and lysosomes using a light microscopy

false

Similarities in lysosomes and peroxisomes

shape and size

Differences in lysosomes and peroxisomes

fewer peroxisomes than lysosomes in cell, lysosomes are made in the golgi and peroxisome membrane components are made in the ER while other components come from the cytosol

Where are peroxisomes made?

the membrane components comes from the ER and many other proteins are moved from the cytosol/cytoplasm

What is considered the most important enzyme in the peroxisome? This protein consists of — percent of proteins in a peroxisomes

catalase; 40

Catalase

tetrameric proteins (4 different protein subunits) with a heme group to help oxidize various compounds. Monomeric units are synthesized in the cytoplasm and come together inside the peroxisome. Primarily involved in destroying hydrogen peroxide.

t/f catalase monomers have a leader sequence on their mRNA (explain answer)

false, they are made in the cytoplasm, not the rough ER

How is catalase formed in peroxisomes?

monomeric units of catalase are moved from the cytoplasm into the peroxisome. They then form a tetramer and bind with a heme ring to form functional catalase within the peroxisome.

Toxic compounds are typically highly (reduced or oxidized)

reduced

t/f hydrogen peroxide is not toxic to our cells, which makes it ok to clean wounds with.

false, it kills all cells (both bacteria and our cells)

Show the reaction equations of how peroxisomes typically breakdown toxic compounds.

RH2 represents a reduced toxic compound, DAO= D-amino oxidase

The first reaction step that peroxisomes use to breakdown toxins is a — reaction while the second step is a — reaction

oxidative; peroxidative

Glutathione peroxidase

enzyme found in the cytoplasm responsible for destroying any hydrogen peroxide that may escape a peroxisome

When is the only time you will normally see hydrogen peroxide in a cell?

apoptosis

Mitochondria is a Greek term meaning what? What was its old name?

thread and granule; bioclast

How are mitochondria unique from other organelles?

It has its own DNA

t/f mitochondria make all of their own proteins

false, they make some but not all

Some proteins in the mitochondria are under nuclear control. What does this mean?

they are synthesized in the cytoplasm from mRNA that comes from the nucleus. These proteins have a leader sequence which makes them transport to the mitochondria.

Where do the lipids of the mitochondria come from?

the ER

Why are mitochondria referred to as dynamic?

they are constantly moving

Cytoplasmic streaming

the way in which cytoplasm moves in a cell. Mitochondria often use this to go where they are needed

Mitochondria may accumulate anywhere in the cell where there is —

a need for energy

Although the — and — of a mitochondria may vary, the — stays roughly uniform

length and shape; width

Average mitochondria width

0.5 microns (500 nm)

Range of lengths of mitochondria

5-7 microns (5,000-7,00 nm)

What do mitochondria do as the cell is about to divide?

they align themself with the spindle apparatus so that the mitochondria are divided approximately evenly between the two new cells

Amount of mitochondria found in a normal cell (ie liver cell)

1000- 1600

Egg cells may have upwards of — mitochondria within them

300,000

Mitochondrial crests/cristae

folds in the inner membrane of the mitochondria which increases its surface area

At its closest, the inner membrane and outer membrane of the mitochondria are — nm apart

6-8

Contact zones

locations in which the inner membrane of the mitochondria fuses with the outer membrane. Represents a region where the molecules may be moved into the mitochondrial with ease ( they only need to pass through one membrane)

Porin

29,000 dalton channel protein on the outer membrane of the mitochondria. Found only on mitochondria and gram negative bacteria. Supports the hypothesis that mitochondria’s origins are that of a bacteria which eventually became the mitochondria

The mitochondrial outer membrane is about —% lipid while the inner membrane is about —% lipid. What does this difference mean?

40;20; the outer membrane allows for much easier movement of solutes while the inner membrane acts much more like a barrier which requires a transport or channel protein to move in

What makes mitochondrial DNA unique??

mitochondrial DNA comprises of a singular circular chromosome with a high G-C content

Why is mitochondrial DNA “heavier”?

it has a higher G-C content

If there is more than one mitochondrial chromosomes this indicates what?

that the chromosomes has been replicated in preparation for formation of new mitochondria

Granules

associated with the mitochondrial matrix, either calcium or phospholipid granules. Storage form for calcium or phospholipids.

What type of ribosome is found within mitochondria? What are its subunits?

55s ribosomes with 35s and 25s subunits

F1 ATPase

lines the matrix side of the inner membrane of the mitochondria. Responsible for producing ATP from the flow of protons from the inner membrane space into the matrix.

F1 ATPase is Spaced at about — nm apart and they look like a — in shape

10; cone

In order for ATP to be made, — precursors are required which most move through specific — proteins

ADP; channel

— moves out of the mitochondria through specific —

ATP; channels

Beta oxidation

the process by which fatty acids are broken down into acetates which are then used to produce NADH and GTP. This process occurs within both the mitochondria and peroxisomes.

Similarities in mitochondria and peroxisomes

both are oxidative and both include the process of beta-oxidation

Draw and label a mitochondria