The Cell — Short Questions

i. It is selectively-permeable
ii. It allows very few molecules to pass through it while blocks many other molecules.

Function of Golgi apparatus
i. It modifies molecules coming from rough ER and packs them into small membrane-bound sacs called Golgi vesicles.
ii. These sacs are kept in cell or are transported to exterior in the form of secretions.

Functions of Lysosomes
i. Lysosomes bud off from Golgi apparatus.
ii. Cell engulfs the food material in the form of food vacuole.
iii. Lysosome fuses with food vacuole and its digestive enzymes break down the food present in vacuole.
iv. Lysosomes also have enzymes for breaking cellular water.
v. They also engulf the damaged organelles and break them.
vi. Lysosomes can store certain molecules for later use.

i. Smooth endoplasmic reticulum involved in lipid metabolism.
ii. It also detoxifies the harmful chemicals that have entered the cells.

i. It lacks ribosomes.
ii. It is involved in lipid metabolism and in the transport of materials from one part of the cell to the other.
iii. It also detoxifies the harmful chemicals that have entered the cell.
iv. In muscle cells, the SER is also involved in contraction process.

Vacuoles in an Animal cell | Vacuole in a Plant Cell
i. Animal cell may have many small temporary vacuoles. | i. Most mature plant cells have a single, large, central vacuole.
ii. They contain water and food substances. | ii. It is formed by the fusion of many small vacuoles.
iii. Some freshwater organisms like amoeba and sponges have contractile vacuoles which collect and pump out extra water and other wastes. | iii. The membrane of plant vacuole is called tonoplast and the sap inside plant vacuole is called cell sap.
iv. Some cells ingest food by forming food vacuoles. Food vacuoles also store food. | iv. It is a watery solution of salts.

If lysosomal enzymes stop working properly, they do not digest food and cells accumulate waste and eventually die.

Cristae are important for cellular respiration because they increase the surface area of the inner mitochondrial membrane which allows the cell to produce more energy.

i. Chromosomes are composed of chromatin and chromatin is a fibrous mass made up of DNA and proteins.
ii. Chromatin material condenses during cell division to form chromosomes.
iii. Chromosomes are visible only during cell division while during interphase (non-dividing phase) of cell they are in the form of thread like structures known as chromatin.

Neurons are the specialized cells of nervous system which are responsible for sending nerve signals (nerve impulses) throughout the body.

Function of mesophyll
i. They are specialized for photosynthesis.
ii. They contain large number of chloroplasts, which contain the green pigment chlorophyll necessary for capturing light energy.
iii. Their shape and arrangement in leaves is suitable for maximum absorption of light.

i. Unspecialized cells that have ability to differentiate into a variety of specialized cell types is called stem cell.
ii. The zygote is an unspecialized cell but it has the ability to make new cells which can differentiate into specialized cells.

(a) Cell membrane is composed of proteins and lipids and small quantities of carbohydrates.
(b) The cell wall of fungi is made of chitin.
(c) Plant cell wall is made of cellulose.
(d) The cell wall of prokaryotes is made of peptidoglycan.
(e) Ribosomes are composed of proteins and ribosomal RNA (rRNA).
(f) Chromosomes are composed of proteins and DNA.

Animal Cell | Plant Cell
1. Mitochondria | 1. Golgi apparatus
2. Cell membrane | 2. Nucleus
3. Cytoskeleton | 3. Rough endoplasmic reticulum
4. Smooth endoplasmic reticulum | 4. Vacuole
5. Lysosome | 5. Mitochondria
6. Golgi apparatus | 6. Cytoskeleton
7. Vacuole | 7. Chloroplast

Mitochondria produce energy in the form of ATP that is why they are called power house of cell.

Following structures are present in all cells of all kingdoms.

Structures present in all cells | Functions
1. Cell membrane | It stops the cell contents from escaping and also controls the substances which are allowed to enter or leave, the cell.
2. Chromosome | It contains DNA which is the genetic material of the cell.
3. Cytoplasm | It contains all the organelles. Many biochemical reactions take place in it.
4. Ribosomes | Ribosomes are the sites of protein synthesis.

Chloroplast is a type of a plastid bound by a double membrane. It is found in plant cells. Chloroplasts are the sites of photosynthesis in eukaryotes. They contain chlorophyll, the green pigment necessary for photosynthesis.

It was discovered by Italian scientist Camillo Golgi in 1898. Golgi apparatus is also known as Golgi complex. It modifies the materials coming from rough ER and enclose them into golgi vesicles.

Mitochondria are spherical, rod-like or elongated tiny organelles.
It produce energy for the cell.
Structure
Under EM a mitochondrion is a double membrane structure. The outer membrane is smooth. The inner membrane is folded to form cristae. Cristae provide a much greater area. Mitochondrial solution is called matrix.

It is located in central region in animal cells. Nucleus consists of a double nuclear membrane, nucleoplasm, nucleolus and chromosomes. It acts as control center of the cell.
Structure
Nuclear envelope: The surface of the nucleus is bounded by a double nuclear membrane called nuclear envelope. The nuclear membrane has many pores.
Nucleoplasm: The fluid inside the nucleus is called nucleoplasm.
Nucleolus: The darkly stained region in the nucleus is called nucleolus.
Chromosomes: The thread like structures in the nucleus are called chromosomes.
Chemical Composition of Chromosomes: Chemically chromosomes consist of deoxyribonucleic acid (DNA) and protein.
Centromere: The centromere is a constriction in chromosome.

Red blood cells have a noticeable biconcave disc shape which means they are curved inward on both sides. This shape gives them more surface area and carry oxygen and carbon dioxide more efficiently.

(a)There are special epidermal cells on leaves called guard cells. These cells surround small opening called stomata and help to control gas exchange and transpiration from the plants.
(b)In roots, certain epidermal cells extend into long "roots hairs" that vastly increase the surface area for water and nutrient absorption from the soil.

Mitochondria produce energy (ATP) needed for all cellular activities, called power house of cell. Without functional mitochondria, the cell lacks energy, disrupting processes in other organelles like the endoplasmic reticulum (ER) and Golgi apparatus, which need ATP to function. They disrupted the ion balance especially calcium regulation slowing down protein synthesis. Mitochondrial dysfunction also weakened the cell defense, waste management, harming other organelles and overall cell health. This can trigger apoptosis lead to diseases, impaired cell function, or even cell death.

If the nucleus and ribosomes don't work together properly, problems can happen because the nucleus gives instructions for making proteins, and ribosomes are responsible for protein synthesis. Without coordination, ribosomes cannot produce the proteins needed for cell growth and repair, leading to malfunctioning of cell processes. Proteins control most cellular activities like enzyme production, transport, and cell division. It causes disrupted cell function triggering diseases like cancer or neurodegenerative disorders. So, lack of coordination between the ribosomes and the nucleus might lead to cell malfunction or death.