Animal Cells

what is the properties of the nucleus?

• 🔬 Location: Found at the centre of the atom.

• ⚛ Size: Very small compared to the overall size of the atom (about 1/10,000th of the atom’s diameter).

• ⚡ Density: Extremely dense — almost all the atom’s mass is concentrated in the nucleus.

• ➕ Charge: Positively charged because it contains protons (positive) and neutrons (neutral).

• 🧪 Mass: Contains almost all the atom’s mass, since electrons have negligible mass.

• 💥 Stability: Can be stable or unstable — unstable nuclei may undergo radioactive decay.

what is the function of the nucleus?

• 🧬 Stores genetic material (DNA): The nucleus contains the cell’s DNA, which carries instructions for making proteins and controlling cell activities.

• 🧠 Controls cell functions: It regulates growth, metabolism, reproduction, and protein synthesis.

• ⚙ Coordinates cell division: The nucleus ensures that DNA is copied and passed on correctly during cell division (mitosis and meiosis).

what are the properties of the nucleolus?

• 📍 Location: Found inside the nucleus of a eukaryotic cell.

• 🔬 Structure: A dense, round, and dark-staining region with no membrane around it.

• 🧪 Composition: Made up of RNA, proteins, and DNA.

• ⚙ Activity: One of the most active parts of the cell in terms of producing RNA and proteins.

• 🧬 Number: Most cells have one nucleolus, but some may have more.

In simple terms, the nucleolus is a dense structure inside the nucleus that plays a key role in making ribosomes.

What are the functions of the nucleolus?

• 🧪 Ribosome production: Its primary job is to make ribosomal RNA (rRNA) and combine it with proteins to form the subunits of ribosomes.

• 📦 Assembly site: It assembles ribosome subunits before they are transported out of the nucleus into the cytoplasm.

In short, the nucleolus is essential because it builds ribosomes, which are needed to make proteins — vital for all cell functions.

What are the properties of a centriole?

• 📍 Location: Found near the nucleus in animal cells, usually in pairs inside a region called the centrosome.

• 🔬 Structure:

  • Cylindrical shape.

  • Made of microtubules arranged in a 9 + 0 pattern (nine groups of microtubule triplets arranged in a ring, with none in the centre).

• 🧬 Size: Very small — about 0.2 µm in diameter and 0.4 µm long.

• ⚙ Number: Usually found in pairs positioned at right angles to each other.

• 🐾 Presence: Present in animal cells and some lower plant cells, but absent in most plant cells.

In short, centrioles are tiny, tube-like structures made of microtubules that sit near the nucleus and play a key role during cell division.

What are the functions of a centriole?

• 🏗 Organisation of microtubules: Centrioles help organise the cell’s cytoskeleton by forming and anchoring microtubules.

• 🌱 Formation of cilia and flagella: They give rise to structures called basal bodies, which develop into cilia and flagella for cell movement.

In short, centrioles are crucial for cell division, microtubule organisation, and the formation of cilia and flagella.

What is the property of the Golgi apparatus?

1. 🏗 Structure:

   • Made up of a stack of flattened, membrane-bound sacs.

   • Usually located near the endoplasmic reticulum (ER) and nucleus.

   • Has a cis face (receiving side) and a trans face (shipping side).

2. 📦 Function (Main Property):

   • Modifies, sorts, and packages proteins and lipids received from the ER.

   • Adds molecules like carbohydrates (glycosylation) or phosphates (phosphorylation).

   • Packages products into vesicles for transport inside or outside the cell.

3. 🚚 Secretion Role:

   • Plays a major role in secretion (exocytosis) by releasing materials out of the cell.

   • Essential for producing lysosomes, cell membrane components, and hormones.

✅ In short: The Golgi apparatus is a membrane-bound organelle that processes, modifies, packages, and transports proteins and lipids, acting like the cell’s “post office.”

What is the function of the Golgi apparatus?

• 🧪 Modifies proteins and lipids (e.g. adds sugars to make glycoproteins).

• 📦 Packages them into vesicles for transport.

• 🚚 Transports them to their correct destinations inside or outside the cell.

• 🧫 Produces lysosomes (organelles with digestive enzymes).

✅ In short: The Golgi apparatus acts like the cell’s “post office,” preparing and delivering molecules to where they are needed.

What are the properties of the lysosomes?

1. 🔬 Structure:

   • Small, spherical, membrane-bound organelles found in animal cells.

   • Contain powerful digestive enzymes (hydrolytic enzymes).

2. 🧪 Function:

   • Break down worn-out organelles, food particles, and engulfed bacteria.

   • Help with digestion and recycling of cell materials (a process called autophagy).

3. 🧫 Environment:

   • Inside is acidic (low pH), which is ideal for the enzymes to work.

4. 🔐 Protective Membrane:

   • Surrounded by a single membrane to prevent enzymes from damaging the rest of the cell.

✅ In short: Lysosomes are small, enzyme-filled sacs that digest and recycle waste materials inside the cell, acting like the cell’s “waste disposal system.”

What are the functions of the lysosomes?

1. 🦠 Break down waste:

   • Digest and remove worn-out organelles, cell debris, and damaged cell parts.

2. 🍽 Digest food particles:

   • Break down large molecules and food particles brought into the cell.

3. 🧬 Destroy harmful invaders:

   • Break down bacteria or viruses that enter the cell.

4. 🔄 Recycle materials (autophagy):

   • Reuse useful materials from broken-down cell parts.

5. ☠ Programmed cell death (apoptosis):

   • Help the cell self-destruct safely when necessary.

✅ In short: Lysosomes act as the cell’s “recycling and waste disposal system”, breaking down unwanted materials and keeping the cell clean and healthy.