Midterm Exam 2

Question 1

Glycolysis

Answer 1

Cytosol, whole glucose molecule, net 2 ATP, 2 NADH, and 2 pyruvates

3 Stages: Energy investment, cleavage, and energy liberation

Question 2

Breakdown of Pyruvate

Answer 2

Mitochondria, 2 pyruvates and coenzyme A, net 2 NADH, 2 CO2, and 2 acetyl CoAs

Question 3

Citric Acid Cycle

Answer 3

Mitochondrial matrix, 2 acetyl CoAs and oxaloacetate, net for both acetyls 4 CO2, 2 ATP, 6 NADH, and 2 FADH reproduces oxaloacetate

Question 4

Oxidative Phosphorylation

Answer 4

Mitochondrial membrane, generates 30-34 ATP via chemiosmosis through the electron transport chain, chemiosmosis, and ATP synthase

Question 5

Positron Emission Topography (PET)

Answer 5

Identifies locations within the body using glycolytic enzymes at a higher rate than the adjacent tissue, useful for identifying tumors (Warburg Effect)

Question 6

Electron Transport Chain

Answer 6

Uses NADH to form H+ gradient, by exporting the protons, which are then let back in by rotating ATP synthase (discovered by Yoshida and Kinosita)

Question 7

How is a chloroplast internally structured?

Answer 7

An inner and outer membrane separated by an intermembrane space, with an inner space (stroma), where the Calvin cycle occurs, and is occupied in part by the thylakoids, which are in stacks called grana, the lumen of which is where the light reaction of photosynthesis occurs (3 membranes from cytosol)

Question 8

Light Reactions

Answer 8

Photosystem II (pigment molecule (chlorophyll) absorbs light energy, transfers high energy electron to P680, water splits to make O2), then ETC (contributes to H+ gradient formation, cytochrome), then Photosystem I (light enters and highly energetic electrons transfer to P700), NADP+ reductase protein then protonates NADP forming NADPH and H+ outside of thylakoid membrane (contributing to gradient) before ATP synthase utilizes gradient to release ATP into stroma

Question 9

Estrogen Receptor

Answer 9

An internal cell receptor functioning as a transcription factor

Question 10

Plasma Membrane Receptors

Answer 10

G-Protein Coupled, Enzyme-Linked Receptors, and Ligand-Gated Ion Channels

Question 11

3 Phases of the Calvin Cycle

Answer 11

1. Carbon Fixation: CO2 added to RuBP, breaks down to form two 3C molecules
2. Reduction/Carbohydrate Synthesis: ATP, NADPH oxidized to reduce the new 3C molecules
3. Regeneration of RuBP: ATP is used to regenerate RuBP

Question 12

3 Conformational States of ATP Synthase

Answer 12

1. ADP and Pi bind with good affinity
2. ADP and Pi bind so tightly they fuse to make ATP
3. ATP binds weakly to protein, released

Question 13

C4 Plants

Answer 13

Conduct C4 cycle in Mesophyll cell on surface, Calvin cycle occurs within a bundle-sheath cell to avoid photorespiration

Question 14

CAM Plants

Answer 14

Shut their stomata during the day to prevent water loss, running the Calvin cycle and light reactions, generating energy. The stomata open at night while the plants carry out the C4 cycle, using the energy collected during the day

Question 15

Animal Cell ETC

Answer 15

Begins with NADH and NADH dehydrogenase exporting protons out of the mitochondrial matrix and into the cytosol, followed by ubiquinone, and succinate which takes FADH2 and deprotonates it to FAD and 2H+ which add to the gradient via cytochrome. The H+ reenter the matrix through ATP synthase, where ATP is used to rotate the protein as the energy of the gradient generates more

Question 16

3 Mechanisms Producing H+ Gradient in Light Reactions

Answer 16

Chemiosmosis along the ETC, oxidation of water in PSII, and synthesis of NADPH from PSI

Question 17

Cell Signaling Types

Answer 17

Direct, Contact Dependent, Autocrine, Paracrine, and Endocrine

Question 18

3 Stages of Cellular Response

Answer 18

1. Receptor activation
2. Signal transduction
3. Cellular response

Question 19

Advantages of Secondary Messengers

Answer 19

Signal amplification and speed

Question 20

Crosstalk

Answer 20

One or more components of a cell signal transduction pathway affect another, can be inhibitory or activate proteins. This enables cells to respond to hormones in complex ways

Question 21

Extracellular Matrix (ECM)

Answer 21

Composed of macromolecules such as adhesive and structural proteins, as well as gel-like polysaccharides to resist compression

Question 22

Plant Cell Walls

Answer 22

Provide rigidity and mechanical support to cell, helping it maintain shape and direction of growth.

Primary cell wall develops first, flexible for growth and made mainly of cellulose. The secondary cell wall is deposited between the primary and cell membrane, and is often more variable in structure in accordance with the function of the cell

Question 23

Animal Cell Junctions

Answer 23

Anchoring Junctions: Attach cells to each other and ECM via cell adhesion molecules such as integrin
Tight Junctions: Form tight seals between cells through occludin and cloudin proteins
Gap Junctions: Allow for a small gap between adjacent cells at the junction, where 6 connexin proteins from each cell align and form a connexon channel, allows for quick signaling (1000 Daltons)

Question 24

Plant Cell Junctions

Answer 24

Middle Lamella: Form outside of cell wall, cement cells together, rich in pectin which provides structure
Plasmodesmata: Functionally similar to animal cell gap junction, differing in that they are open channels where cell membranes of adjacent cells are continuous, desmotubules can connect the adjacent cells’ ER membranes