Chapter 3The Cell (part 2)

Golgi complex

• Stacked sacs

• Receive proteins from ER

• Modifies them and packages them up

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)

Vesicles Ship and Store Cellular Products

• Vesicles: membrane-bound spheres– Used for secretion and storage

– Examples: neurotransmitters, hormones, lysosomes

Figure 3.18

Cytoskeleton Supports the Cell

• Microtubules

• Microfilaments

Mitochondria: Provide Energy to the Cell

• Produce ATP• Contain chromosomes

(DNA) • Evolved from

prokaryote (bacteria-like organism) through symbiosis

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

Cellular Respiration

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

Cellular Respiration

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

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

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

Cellular Respiration: An Overview

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.