Chapter 4, Problem 1CC

Label the structures in this diagram of an animal cell. Review the functions of each of these organelles.

Summary Introduction

To review: The structures and functions of each of the organelles in the given animal cell.

Introduction:

A cell is the fundamental structural and functional unit of living organisms. It is bounded by a cell membrane. Cells contain different organelles. Each organelle has its own specific features and functions. Each cellular organelle possesses different structural peculiarities.

Explanation of Solution

Pictorial representation:

Fig. 1 shows various structural organelles of an animal cell.

Fig. 1: Structure of an animal cell

The functions of various organelles are very specific.

1. a. Rough ER: It is a network of membranous sacs and tubes; its external surface is attached with the ribosome. It helps in protein processing and secretion. Also, the addition of carbohydrate with protein occurs to produce glycoprotein, which helps in the production of a new membrane within the cell.
2. b. Nucleus: It is a membrane-bound organelle covered by the nuclear envelope. The nucleus contains the nucleolus and chromatin material. The chromatin material consists of DNA and proteins.
3. c. Nucleolus: It is a core region in the nucleus where components of the ribosome assemble.
4. d. Ribosome: It is a non-membranous structure found in the cytoplasm of the cell. It is the core organelle for protein synthesis. It can be found free or attached with the rough endoplasmic reticulum.
5. e. Peroxisome: It is a specialized single membrane–bound vesicle found in the cytoplasm of the cell. It produces hydrogen peroxide as a by-product and converts it to water.
6. f. Centrosome: The formation of microtubules initiates at the centrosome. It contains a pair of centrioles.
7. g. Cytoskeleton: It consists of a network of fibrous substances within the cytoplasm of a cell. The cytoskeleton consists of three main fibers called microtubules, microfilaments, and intermediate filaments. It helps in providing rigidity and gives structural support to the cell.
8. h. Mitochondrion: It is double membrane–bound organelle. It is important for cellular respiration and energy generation in the form of ATP. The two phospholipid bilayer membranes enclosed with the mitochondria play a great role in functioning of mitochondria. It is also called as the “power house” of the cell.
9. i. Plasma membrane: It is the protective compartment of the cell. It is composed of a lipid bilayer.
10. j. Lysosome: It is a single membrane–bound organelle. It is the storage unit of hydrolytic enzymes. Breakdown of indigested substances takes place in lysosomes, and cell organelles are recycled here.
11. k. Golgi apparatus: It is a single membrane–bound organelle stack of the flattened membranous sac. It is the active unit of modification, sorting, and secretion of cell products.
12. l. Smooth ER: It is a network of membranous sacs and tubes but not attached with the ribosome. It helps in detoxification and lipid synthesis. It helps in folding of protein and transferring of the synthesized protein.