Lecture 11 Cytoskeleton and Energy

Question 1

cytoskeleton

Answer 1

• system of filaments
• dynamic and adaptable
• shape, structure, robustness, rearranging of internal components, movement, growth, division
• examples: swimming of sperm, structure of the membrane, vesicular traffic, pulling of chromosomes during the division (moving of things around, in the cell)

Question 2

3 different protein groups, which make 3 different type of filaments:

Answer 2

actin filaments (microfilaments) microtubules intermediate filaments

Question 3

actin filaments

Answer 3

• microfilaments
• 2 stranded helical structure
• polymer of protein actin
• networks mostly concentrated under the plasma membrane

Question 4

Microtubules

Answer 4

• long hollow cylinders
• made of protein tubulin
• long, rigid, strait
• attached at one end to the centrosom

Question 5

Intermediate filaments

Answer 5

ropelike fibers family of proteins (nuclear lamina) (strength of tissue)

Question 6

Actin filaments rearrangement can be used to …

Answer 6

make cells move

Question 7

Cell division: interplay of microtubules and actin filaments

Answer 7

Actin: ring construction
microtubules: pulling chromosomes

Question 8

How microtubules pull chromosomes?

Answer 8

By shrinking at one end

Question 9

How to kill a rapidly dividing cell (cancer cell)?

Answer 9

Stabilization of microtubules (including the mitotic spindle) by taxol

Question 10

Requirements for efficient ATP production

Answer 10

membranes
transferring of electrons
proton gradient

Question 11

Mitochondria

Answer 11

Thanks to mitochondria, more complex eukaryal cells (Metazoa), could develop. Mitochondria allow cells to produce 15 times more ATP per unit of glucose or fat. Mitochondria localize with microtubules. They are dynamic, fusing, branching, fragmenting and changing shape and position in the cell. Mitochondria have circular genomes, their proteins are encoded by the nuclear DNA and mtDNA.

Question 12

Electrons produced in the … are being carried around in the mitochondrion and the end result is the production of …

Answer 12

TCA (citric acid cylce)

ATP, CO2 and H2O

Question 13

Biological oxidation extracts the energy …

Answer 13

step-wise

Question 14

Electron-driven pumps export protons, on their return protons drive the …

Answer 14

ATP synthesis

Question 15

How does the electron transfer work?

Answer 15

1. NADH -> NAD+, 1 proton H+ and 2 electrons e-
2. electron carriers, eg NAD+, (metal ions), electrons loose energy
3. three respiratory enzyme complexes
4. The terminal acceptor of electrons is O2

Question 16

NADH dehydrogenase complex

Answer 16

passes 2 electrons from NADH to ubiquinone

Question 17

Cytochrome c reductase complex

Answer 17

receives 1 electron from ubiquinol

passes the electron to cytochrome C oxidase

Question 18

Cytochrome oxidase complex

Answer 18

receives 1 electron from the cytochrome C the last complex receives 1 electron at the time and ”collects” them before donating 4 electrons to O2 (forming H20)

Question 19

Pumping of protons to the intermembrane space creates a … and …

Answer 19

pH gradient

a voltage gradient (electric potential).

Question 20

Th e protons are on the outer side of the inner membrane. The gradient transfers them back to the matrix. But, they will go via the …

Answer 20

F0F1 ATP-synthase

Question 21

Rotary catalysis

Answer 21

flow of protons changes the conformations of subunits, creating mechanical energy that is then converted to chemical energy during the formation of the phosphate bond: 3 ATP/rotation

Question 22

Inhibition of ATP production and thermogenesis

Answer 22

thermal energy instead of ATP production