Chapter 6

Question 1

Define a membrane-bound organelle, giving examples.

Answer 1

Membrane bound organelles are cellular structures that contain their own membranal sac/envelope. eg nucleus, mitochondria, chloroplasts.

Question 2

Define cytoplasm and cytosol, explaining the difference between the two.

Answer 2

Cytosol is the semifluid, jelly like substance which the cell’s organelles are suspended in. The cytoplasm is the interior of the cell between the nucleus and plasma membrane.

Question 3

Define Chromatin and chromosomes. Explain the relationship and difference between the two.

Answer 3

Chromatin is the complex form of the genetic material of an organism. However, DNA strands are long and can be great in length. Therefore the are tightly packed and condensed into chromosomes.

Question 4

What is the lumen. State its function

Answer 4

To transport substances within cells.

Question 5

What is a vesicle? State its function.

Answer 5

A tiny membranal sac that aids in transportation of cell contents/secretion of necessary enzymes.

Question 6

Explain the structure and function of collagen

Answer 6

Collagen is a protein made of many fibers that provides strength and elasticity to cells.

Question 7

What are proteoglycans? What do they do?

Answer 7

Proteoglycans are small core proteins bounded to chains of carbohydrates, acting as fillers between cells.

Question 8

What are integrins?

Answer 8

Integrins are cell surface receptor proteins that help cells by notifying them of stimuli in the environment, ‘integrating changes within and outside the cell.” They link cytoskeletons with the extracellular matrix.

Question 9

What are laminins?

Answer 9

Laminins are glycoproteins that link the integrins to the extracellular matrix.

Question 10

What are common characteristics of cells?

Answer 10

All cells have cytosol, cytoplasm, plasma membranes and ribosomes.

Question 11

What is the major type of microscopy used to identify cells?

Answer 11

Light microscopy. This utilizes focused light to magnify the image of the specimen.

Question 12

What are some differences between prokaryotic and eukaryotic cells?

Answer 12

See bio scio.

Question 13

What is the function of the nuclear envelope?

Answer 13

A double membrane that encloses the nucleus and protect the organism’s DNA.

Question 14

What is the function of the nuclear lamina?

Answer 14

The nuclear lamina supports (mechanically) the nuclear envelope . It is a netlike structure of protein filaments.

Question 15

What does the nucleolus do?

Answer 15

The nucleolus is responsible for the manufacture of ribosomal subunits which leave through the nuclear pores and join to form ribosomes in the cytosol.

Question 16

What are nuclear pores? what is their function?

Answer 16

Nuclear pores are perforated holes in the nuclear envelope that allow for the net traffic of proteins and RNA within the nucleus and cytoplasm, done by its pore complex. They tend to be about 100nm in diameter.

Question 17

How are ribosomes made? Explain their importance and function.

Answer 17

Ribosomes are the cellular components that carry out protein synthesis (Translation). They are made via the rRNA produced by the nucleolus. They are important as they aid in the specialization of proteins.

Question 18

What is the main function of mitochondria?

Answer 18

Mitochondria are the main/major manufacturers of ATP in most organisms. While respiration can occur anaerobically, without oxygen, aerobic respiration that occurs in the mitochondria produces much more energy and ATP molecules, and therefore is much more efficient.

Question 19

What is the main function of chloroplasts? Where are they found?

Answer 19

Chloroplasts are the sites of photosynthesis found primarily in the palisade layer of plant cells. They contain photosystems which trap light energy from the sun, converting it to usable chemical energy. This is important as the sun is the earth’s major energy source, and without chloroplasts, we wouldn’t be able to access this energy.

Question 20

What is the rough ER? What is the smooth ER? State the functions of both and explain their differences.

Answer 20

The rough ER has bound ribosomes attached to its outer membrane. Its major function is the specialization of proteins (specifically secretory proteins).
The smooth ER has no outer ribosomes. It is responsible for a variety of functions: lipid synthesis, detoxification, storage of Ca2+ ions, metabolism of carbohydrates.

Question 21

What is glycosylation? Where does it occur?

Answer 21

Glycosylation is the addition of a carbohydrate molecule. It occurs in the golgi apparatus

Question 22

What is the Golgi apparatus? Why do we say its ‘directional’?

Question 23

What are lysosomes? Why are their pH regulated to a certain number? What is the average pH in a lysosome?

Answer 23

Lysosomes are membranal sacs of digestive enzymes that aid in the breakdown of waste materials of the cells. Due to the presence of its enzymes, they need to have a regulated pH, to prevent the denaturation of these enzymes. Their pH range is usually between 4.5-5.

Question 24

What are cytoskeletal filaments? What is meant by ‘dynamic’ filaments?

Answer 24

Cytoskeletal filaments are intermediate fibers that are wrapped together, producing shape and holding organelles in place. It is referred to as dynamic as they can be rearranged to change the cell shape and allow for cell movement.

Question 25

What are the functions of the 3 cytoskeletal filaments?

Answer 25

Actin Filaments/Microfilaments: maintains cell shape and aids in muscle contraction and cell movement.
Microtubules: maintains structure and aids in the transport of macromolecules.
Intermediate Filaments: anchors the nucleus and other organelles in place, forms the nuclear lamina.

Question 26

What are the functions of cilia and flagella? Explain their differences.

Answer 26

Cilia and flagella are both cellular extensions containing microtubules. They both aid in the movement/ removal of -unwanted/unnecessary-substances from an area. However, cilia tends to be congested in large amounts while flagella are usually few in number. Cilia are shorter than flagella and tend to have recovery strokes and alternating power.

Question 27

What is the function of the extracellular matrix? What is the connection to cells?

Answer 27

The extracellular matrix consists of glycoproteins and integrins attached on the membranes of cells that aid in cell reception. They help a cell respond to stimuli in the environment/matrix.

Question 28

What are the 3 types of cell to cell junctions? What are their structures? How does it relate to their functions? Where do we find them?

Answer 28

Gap Junctions: are like plasmodesmata in plants whereby they allow small substances (ions, sugars, amino acids) to easily pass through adjacent cells through perforated connections. eg embryos
Desmosomes: aid in packing adjacent cells tightly together into strong, sturdy sheets. eg muscle cells
Tight Junctions: help compact adjacent cells through binding proteins to prevent the leakage of substances through cell perforations(desmosomes). eg. skin cells