Structure and function of cells

Question 1

Nucleus.

Answer 1

Functions: contains the genetic information of the cell, controls the cell (responsible for the instructions of the protein synthesis and for transmitting the DNA to the daughter cells).

Structural features: largest organelle, double-layered nuclear doeble-membrane (nuclear envelope - continuous with the endplasmic reticulum), nuclear pores, chromosomes/chromatin (DNA), nucleoplasm, nucleolus (composed of rRNA and proteins).

Question 2

Ribosomes.

Answer 2

Dense particles composed of rRNA and proteins.

Site of protein synthesis.

Free-floating in cytoplasm or bound (attached) to outer-surface of endoplasmic reticulum.

Question 3

ER.

Answer 3

Rough ER manufactures and modifies proteins. The membrane-system enclosing a cavity (the cisterna), externally studded with ribosomes. Sugar groups are attached to the proteins within the cisternae. Proteins are bound in vesicles for transport t the Golgi apparatus and ther sites. The external face synthesizes phspholipids and cholesterol.

Smoth ER synthesizes and metabolizes lipids, packages the proteins, and detoxifies. A membranous system of sacs and tubules.

Question 4

Golgi apparatus.

Answer 4

Refines, packages (into vesicles), and ships synthesized products.

Question 5

Vesicles.

Answer 5

Storage and shipping vesicles.

Secretory vesicles.

Endocytic vesicles.

Peroxisomes contain detxification (oxidase) enzymes. Catalase breaks down hydrogen peroxide.

Lysosomes contain digestive enzymes (acid hydrolases).

Question 6

Mitochondria.

Answer 6

Rod-like, double-membreane structures. The inner membrane is folded into cristae (projections). The site of ATP synthesis.

Question 7

Cell structures for support and movement.

Answer 7

Cytoskeleton: microtubules and microfilaments (contract muscles).

Many short cilia (found on cells lining airways).

Single long flagella (enable spermatozoa to swim).

Centrioles, composed of none triples of microtubules, organize a microtubule network during mitosis to form the spindle, asters, and the bases of cilia and flagella.

Question 8

Energy storage in animals.

Answer 8

Long-term: triglycerides.

Short-term: glycogen.

Question 9

Anabolism and catabolism.

Answer 9

Both require enzymes.

Anabolism assembles large molecules (cell components), may require ATP, stores energy.

Catabolism breaks down nutrients, recycles cell components, may release energy, accesses energy storage.

Question 10

Cellular respiration.

Answer 10

C6H12O6 + 6O2 + 36ADP + 36Pi -> 6CO2 + 6H2O + 36ATP.

Releases energy to do cellular work: anabolism, transport, and muscle contraction.

Glycolysis: 10 reactions: glucose + 2ATP -> 2 pyruvate + 4ATP + e- + H+ => NAD+ -> NADH.

Preparatory step: 2 pyruvate -> CO2 + e- + H+ + acetyl group => NAD+ -> NADH, acetyl group -(Coenzyme A)-> 2 Acetyl CoA.

Citritc acid (Krebs) cycle: 2 Acetyl CoA -> CO2 + 2ATP + 2e- => NAD+ -> NADH, FAD -> FADH2.

Electron transport chain (inner mitochondrial membrane): 6O2 + 2ATP + 8NADH + 2FADH2 -> 6H2O + NAD+ + FAD + 34ATP.

Question 11

Anaerobic pathways of making energy available.

Answer 11

Pyruvate -> lactic acid.

When O2 is available, lactic acid is metabolized.

Question 12

Additional energy sources.

Answer 12