Question

cell organization- sc.912.l.14.2: relate structure to function for the components of plant and animal cells. explain the role of cell membranes as a highly selective barrier.

1. basic eukaryotic cell structure consists of an outer membrane, cytoplasm filled with organelles and a nucleus. describe and give the function of each of the following:

• cell membrane:
• cytoplasm:
• organelles:
• nucleus:

1. how is a cell like a factory?
2. in this space draw a nucleus. label and give the function of the following: nuclear membrane, chromatin, chromosomes, and nucleolus.

Answer:

1. Describing and giving functions:

• Cell membrane:
• Description: A thin, flexible barrier that surrounds the cell, made of a phospholipid bilayer with embedded proteins.
• Function: It acts as a selectively permeable barrier, controlling the entry and exit of substances (like nutrients and waste) into and out of the cell, and also provides structural support.
• Cytoplasm:
• Description: A jelly - like substance (cytosol) that fills the cell and contains the organelles.
• Function: It is the site of many chemical reactions in the cell, and it helps to suspend and move organelles within the cell.
• Organelles:
• Description: Specialized structures within the cell, each with a specific shape and composition.
• Function: Each organelle has a unique function, for example, mitochondria produce energy (ATP), ribosomes are involved in protein synthesis, and the endoplasmic reticulum is involved in protein and lipid synthesis and transport.
• Nucleus:
• Description: A large, spherical or oval - shaped organelle, usually located near the center of the cell (in animal cells) or may be pushed to the side (in plant cells due to the large vacuole). It is surrounded by a nuclear membrane.
• Function: It is the control center of the cell. It contains the cell's genetic material (DNA) in the form of chromatin (which condenses into chromosomes during cell division). It controls cell growth, reproduction, and the synthesis of proteins by regulating the transcription of DNA.

2. How is a cell like a factory?

A cell can be compared to a factory in the following ways:

• The cell membrane is like the factory's security gate or entrance/exit. It controls what raw materials (nutrients) enter the cell and what finished products (waste or secreted substances) leave the cell, just as a factory gate controls the entry of raw materials and the exit of finished goods.
• The cytoplasm is like the factory floor. It is the space where all the work (chemical reactions and organelle - mediated processes) happens, similar to how the factory floor is where manufacturing processes take place.
• Organelles are like the different machines and departments in a factory. For example, mitochondria (the "powerhouses" of the cell) are like the power generators of the factory, providing energy (ATP) for the cell's activities, just as a factory's power generator provides energy for the factory's machinery. Ribosomes, which make proteins, are like assembly lines that produce products (proteins) in the factory.
• The nucleus is like the factory's management office. It contains the instructions (DNA) for making products (proteins) and controls the overall operations of the cell (factory), just as a management office controls the operations of a factory.

3. Drawing a nucleus and labeling components:

• Nuclear membrane:
• Description: A double - layered membrane that surrounds the nucleus. It has pores that allow the passage of certain molecules (like RNA and proteins) between the nucleus and the cytoplasm.
• Function: It acts as a barrier, protecting the genetic material inside the nucleus and regulating the exchange of substances between the nucleus and the cytoplasm.
• Chromatin:
• Description: A complex of DNA and proteins (histones) that is in a relatively uncoiled state during most of the cell's life cycle (interphase).
• Function: It contains the cell's genetic information and is the material from which chromosomes are formed during cell division.
• Chromosomes:
• Description: Highly condensed structures of chromatin that are visible during cell division (mitosis or meiosis). They are made up of DNA and proteins and carry the genetic information in the form of genes.
• Function: They ensure the accurate distribution of genetic material to daughter cells during cell division.
• Nucleolus:
• Description: A dense, spherical structure within the nucleus, not surrounded by a membrane. It is composed of RNA, proteins, and DNA.
• Function: It is the site of ribosome synthesis. It produces ribosomal RNA (rRNA) and assembles ribosomal subunits, which are then transported to the cytoplasm to participate in protein synthesis.

(For the actual drawing of the nucleus: Draw a large circle to represent the nucleus. Inside the nucleus, draw a smaller, dense - looking circle or oval to represent the nucleolus. Represent the nuclear membrane as a double line around the nucleus. Draw wavy or thread - like structures to represent chromatin, and if showing chromosomes (for example, during cell division - related context), draw more condensed, rod - like structures. Then label each component as described above.)