Cellular Level Of Organization (Questions)

Question 1

What is the basic structural and functional unit of the body?

Answer 1

The cell is the basic structural and functional unit of the body.

Question 2

What are the three principal parts of a cell?

Answer 2

The three principal parts are the cell membrane (plasma membrane), cytoplasm, and nucleus.

Question 3

What is the function of the cell membrane (plasma membrane)?

Answer 3

The cell membrane acts as a boundary between the inside and outside of the cell.

Question 4

What is the cell membrane composed of?

Answer 4

The cell membrane is composed of a phospholipid bilayer, cholesterol, membrane proteins, membrane carbohydrates, and microvilli.

Question 5

What are the components of the phospholipid bilayer?

Answer 5

The phospholipid bilayer consists of hydrophilic phosphate head groups and hydrophobic fatty acid (FA) tails.

Question 6

What are the two types of membrane proteins?

Answer 6

The two types of membrane proteins are integral proteins and peripheral proteins.

Question 6

What is the function of the phospholipid bilayer in the cell membrane?

Answer 6

The phospholipid bilayer divides the intracellular fluid (ICF) inside the cell from the extracellular fluid (ECF) outside the cell.

Question 7

What role does cholesterol play in the cell membrane?

Answer 7

Cholesterol is scattered throughout the membrane and adds stability to the cell membrane.

Question 8

What is the difference between integral and peripheral proteins in the cell membrane?

Answer 8

Integral proteins are embedded within the membrane and may extend across the entire membrane (transmembrane proteins), while peripheral proteins are attached to the surface of integral proteins.

Question 8

What are the functions of membrane proteins?

Answer 8

Membrane proteins function as enzymes, transporters, channels, receptors, anchors, and identity markers for the immune system.

Question 9

Where are membrane carbohydrates located, and what are their functions?

Answer 9

Membrane carbohydrates are found only on the outer surface of the membrane. They function in cell recognition (e.g., sperm recognizing egg cells) and anchoring cells together.

Question 10

What are microvilli, and what is their function?

Answer 10

Microvilli are small projections of the cell membrane that increase surface area. They are best seen on cells of the small intestine and kidney.

Question 11

What is the Fluid Mosaic Model of the cell membrane?

Answer 11

The Fluid Mosaic Model describes the cell membrane as being fluid, meaning its constituents can move around, and a mosaic, where proteins dot the surface like tiles in a mosaic.

Question 12

What is cytoplasm?

Answer 12

Cytoplasm is the area between the inside of the cell membrane and the outside of the nucleus.

Question 13

What are the two divisions of the cytoplasm?

Answer 13

The two divisions of the cytoplasm are cytosol and organelles.

Question 14

What is cytosol, and what does it contain?

Answer 14

Cytosol is the gel-like intracellular fluid containing water, ions (e.g., K+, Na+), and a suspension of carbohydrates, proteins, and lipids. It may also contain inclusions such as melanin and glycogen.

Question 15

What are organelles, and how are they categorized?

Answer 15

Organelles are structures that perform specific functions and are essential for life. They can be categorized as non-membranous or membranous organelles.

Question 16

What is the function of ribosomes, and what are the two types?

Answer 16

Ribosomes are the sites for protein synthesis. The two types are free ribosomes (which float in cytosol) and ribosomes attached to the endoplasmic reticulum (ER).

Question 17

What is the centrosome, and what are its components?

Answer 17

The centrosome consists of a pair of centrioles and the pericentriolar matrix. It organizes microtubules, including the spindle apparatus for cell division and the cytoskeleton.

Question 18

What are the three types of cytoskeletal structures, and their functions?

Answer 18

• The three types of cytoskeletal structures are:
  1. Microfilaments – made of actin, involved in muscle contraction, cell movement, and cytokinesis.
  2. Intermediate filaments – tissue-specific proteins (e.g., keratin), provide structural support.
  3. Microtubules – made of tubulin, form centrioles, spindle apparatus, cilia, and flagella, and help in organelle movement.

Question 19

What is the function of mitochondria?

Answer 19

Mitochondria are the site of ATP synthesis and contain their own DNA, RNA, and proteins.

Question 20

What are the two types of endoplasmic reticulum (ER), and their functions?

Answer 20

1. Rough ER (RER) – has ribosomes attached and synthesizes secretory, lysosomal, and membrane proteins.
2. Smooth ER (SER) – lacks ribosomes, synthesizes lipids and steroid hormones, and is continuous with the RER.

Question 21

What is the function of the Golgi apparatus?

Answer 21

The Golgi apparatus modifies, sorts, packages, and delivers proteins to the cell membrane, lysosomes, or for secretion.

Question 22

What are lysosomes, and what do they do?

Answer 22

Lysosomes are filled with digestive enzymes that digest bacteria, viruses, and worn-out organelles, providing a clean-up function for the cell.

Question 23

What are the parts of the nucleus?

Answer 23

• The nucleus has three main parts:
  1. Nuclear envelope – a double membrane with nuclear pores, connected to the ER.
  2. Nucleolus – a dense, non-membranous region where ribosomes are made.
  3. Chromosomes/Chromatids – contain DNA and histone proteins, either dispersed (chromatin) or condensed during cell division.

Question 24

What is the nucleolus, and what is its function?

Answer 24

The nucleolus is a non-membranous, dense region within the nucleus where ribosomes are made and assembled.

Question 25

What are chromosomes, and when are they condensed?

Answer 25

Chromosomes contain DNA and histone proteins. They are condensed and individually visible during cell division (mitosis or meiosis).