Oragnelles II

Question 1

Peroxisome

Answer 1

• Membrane bound
• Generates hydrogen peroxide
• performs B-oxidation of long chain fatty acids

Question 2

Peroxisomal Fission

Answer 2

• Different from prokaryote division

- gets larger and larger and splits into two daughter peroxisomes

Question 3

Evidence for Porkaryote Origin of Mitochondria

Answer 3

1. Contains its own small circular chromosome of DNA
2. Originates by fission from pre existing mitochondria
3. Double Membrane- host membrane and symbiotic prokaryote
4. Closest relative is Rickettsia bacteria

Question 4

Proton Pump

Answer 4

• facilitates the synthesis of ATP
• H+ ions cause the rotor to spin. Mechanical energy is converted to chemical energy in the form of synthesis of ATP.
• H+ ions are then pumped back into intermembrane space

Question 5

Melanosomes

Answer 5

membrane bound cytoplasmic inclusions.

• contain melanin
• gives rise to pigmentation of the skin

Question 6

Lipfuscin

Answer 6

Membrane bound cytoplasmic Inclusions

• Lipid containing residues of lysosomal digestion
• residual body (tertiary lysosome)

Question 7

Glycogen

Answer 7

non membrane bound cytoplasmic inclusions

- stores of glucose

Question 8

Lipid

Answer 8

non membrane bound cytoplasmic inclusions

- triglycerides in storage form

Question 9

Microfilaments

Answer 9

• Actin Filaments- globular monomers that assemble in the presence of K and Mg into a double stranded filamentous actin

Question 10

Actin

Answer 10

Functions

• Intracellular movement and muscle contraction by forming stress fibers
• Membrane structures like microvilli and stereocilia
• locomotion (filopodia)

Question 11

Microtubules

Answer 11

• wider than actin

- Heterodimer of alpha and beta subunits.

Question 12

Microtubule Fibers

Answer 12

• individual microtubules
• mitotic spindle of dividing cells
• axons of neurons

Question 13

axoneme

Answer 13

• doublet of microtubules

- core of cilia and the sperm tail

Question 14

centriole

Answer 14

• organization of microtubules into triplets.

- 2 centrioles constitute a centrosome.

Question 15

basal Body

Answer 15

a centriole that nucleates the axoneme of cilia

Question 16

Motile Cilia

Answer 16

Contain a central doublet of microtubules

Question 17

Primary cilia

Answer 17

Lack a central doublet of microtubules.

• nonmotile
• used for sensory function

Question 18

Keratin

Answer 18

Intermediate Filament

• attach to desomosmes to form a framework within the cytoplasm
• expression can be useful in grading tumor cells
• provides barrier to dehydration

Question 19

Zonula occludens

Answer 19

tight junctions

• Form a band encircling the apical end of the cell
• prevent movement between the lumen and intercellular space
• facilitates polarity
• zip lock seal is formed

Question 20

Zonula Adherens

Answer 20

Intermediate Junctions

• directly under tight junctions
• Anchors cells to one another

Question 21

Cadherin proteins

Answer 21

mediate cell adhesion

• bind catenin to actin filaments
• this forms the terminal web that help anchor actin filaments originating from microvilli at the apical pole of epithelial cells

Question 22

Macula Adherens

Answer 22

Desmosomes
- consists of transmembrane proteins, desmoglein and desmocollin that insert into a dense attachment plaque of anchoring proteins that then binds keratin

Question 23

Gap Junctions

Answer 23

• pores between adjacent cells
• rapid communication between cells
• 6 connexin proteins froms a connexon
• 2 aligned connexons froms an open channel between cells