Chapter 3 The Cell (part 2)

Golgi complex Stacked sacs Receive proteins from ER Modifies them and packages them up

FIGURE 3.16 The Golgi complex.

Lysosomes Contain hydrolytic enzymes that: Bkdn old, worn out, or defective parts Digest foreign invaders (e.g., bacteria) engulfed by phagocytosis Helps with cell suicide (apoptosis)

FIGURE 3.17 Lysosome formation and function in intracellular digestion. Lysosomes, released from the Golgi complex, digest a bacterium engulfed by the cell (see pathway on right). Lysosomes also digest obsolete parts of the cell itself (see pathway on left).

Vesicles Ship and Store Cellular Products Vesicles: membrane-bound spheres Used for secretion and storage Examples: neurotransmitters, hormones, lysosomes Figure 3.18

FIGURE 3.20a Microtubules serve as tracks along which organelles or vesicles move.

Cytoskeleton Supports the Cell Microtubules Microfilaments

FIGURE 3.20b Microtubules serve as tracks along which organelles or vesicles move.

FIGURE 3.21 Centrioles may help organize microtubules.

FIGURE 3.22a Microtubules are responsible for the movement of cilia and flagella.

FIGURE 3.22c Microtubules are responsible for the movement of cilia and flagella.

FIGURE 3.22b Microtubules are responsible for the movement of cilia and flagella.

FIGURE 3.25 Formation of pseudopodia. Microfilaments form pseudopodia, extensions of the cell that produce movement across a surface.

Table: 03-T05 Title: Structures and functions of cytoskeletal elements. Caption:

FIGURE 3.19 Mitochondria are sites of energy conversion in the cell.

Mitochondria: Provide Energy to the Cell Produce ATP Contain chromosomes (DNA) Evolved from prokaryote (bacteria-like organism) through symbiosis

TABLE 3.4 REVIEW OF MAJOR ORGANELLES AND THEIR FUNCTIONS

Our Cells Use Cellular Respiration to Generate ATP Cellular respiration: Cells use glucose and oxygen to synthesize ATP Three stages of respiration Glycolysis: in cytoplasm Citric Acid Cycle: in mitochondria Electron Transport System: in mitochondria

Overview of Respiration C6H12O6 + O2  CO2 + H2O + ATP

FIGURE 3.30 Summary of cellular respiration. Cellular respiration produces 36 ATP per molecule of glucose (2 ATP from glycolysis, 2 ATP from the citric acid cycle, and 32 ATP from the electron transport chain).

Cellular Respiration Glycolysis occurs in the cytoplasm splitting glucose into two pyruvate molecules generating a net gain of two ATP and two NADH molecules

Figure: 02-15a Title: Monosaccharides are simple sugars. Caption: (a) Three representations of the monosaccharide glucose.

FIGURE 3.26 Glycolysis is a several-step sequence of reactions in the cytoplasm. Glucose, a six-carbon sugar, is split into two threecarbon molecules of pyruvate.

Cellular Respiration The transition reaction occurs within the mitochondria. CO2 is removed from each pyruvate forming 2 acetyl CoA molecules

FIGURE 3.27 The transition reaction takes place inside the mitochondrion and is the link between glycolysis and the citric acid cycle.

Cellular Respiration Electrons are removed from Acetyl CoA in the citric acid cycle releasing two ATP, two FADH2 and six NADH molecules CO2 is also released in this process

FIGURE 3.28 The citric acid cycle is a cyclic series of eight chemical reactions that occurs inside the mitochondrion and yields two molecules of ATP and several molecules of NADH and FADH2 per molecule of glucose.

Cellular Respiration The electron transport chain is the final step where the electrons of FADH2 and NADH are transferred from one protein to another, until they reach oxygen This process releases energy that results in 32 ATP

FIGURE 3.29 The electron transport chain is the final phase of cellular respiration. This phase yields 32 ATP per molecule of glucose.

Cellular Respiration: An Overview

TABLE 3.5 REVIEW OF CELLULAR RESPIRATION

Brown Fat Fat fires up. PET/CT scans of a person exposed to cold (left) and at room temperature (right) show the dark signature of brown fat.