Non Membranous Organelles

Question 1

Location of cilia

Answer 1

It is found on the free surfaces of the epithelium lining of the respiratory system and parts of female and male genital tract

Question 2

Cilia under L.M

Answer 2

• Each cilium has basal body shaft and rootlet —> formed of a single centrioles —> which migrate to surface of the cell to form the basal body of the cilium
• the basal body of the cilium is formed of 27 microtubules —> 9 bundles —> each bundle is formed of 3 microtubules ( triple tubule )
• the shaft of the cilium ( axoneme ) —> contain 2 single microtubules
• rootlet of the cilium —> formed of minute rootlet fibers —> extend underneath the basal body into the cytoplasm to fix the basal body to underlying cytoplasm

Question 3

Function of cilia

Answer 3

• pushing fluids or small bodies in one direction over the surface of the ciliated cells , the movement of the cilia is initiated by energy which is released from ATP
• each rod and cone in the retina of the eye is covered by a single modified cilium which acts as a photoreceptors

Question 4

Structure of flagella

Answer 4

• Similar in structure to the cilium , but it is rather longer , and present in a single form
• in man the only cell with a single flagellum is the spermatozoon

Question 5

Function of centrioles during cell division

Answer 5

• The two centrioles develop another two daughter centrioles
• each pair of centrioles migrates to both sides of the dividing cell
• then each pair becomes surrounded by an area of cytoplasm rich in protein called —> micro-tubular organizer centre - MTOC -

Question 6

Function of centrioles in relation to cilia and flagella

Answer 6

Each centriole divided into procentrioles which can form cilia and flagella

Question 7

Centrioles under E.L

Answer 7

• each centriole is a hollow cylinder ; its wall is formed of 27 microtubules embedded in a protein matrix
• it is arranged in the wall of the cylinder in the form of 9 bundles
• each bundle is formed of 3 microtubules called triplets

Question 8

Centrioles under L.M

Answer 8

• small dark body surrounded by a clear zone known as microcentrum , followed by dense zone called centrospheres

Question 9

Staining of centrioles

Answer 9

Stained with iron hematoxylin

Question 10

Location of centrioles

Answer 10

Centrioles are not present in erythrocytes and mature nerve cells

Question 11

Structure if centrioles

Answer 11

The pair of centrioles is tubular structures ; each centriole is a hollow cylinder , closed at one end while the other end is opened

Question 12

Centrioles

Answer 12

Centrioles it is a zone of cytoplasm present near the nucleus in an area called centrioles , it is contains a pair of centrioles

Question 13

Function of ribosomes

Answer 13

• Synthesis protein —> which used for building up the cells
• as hemoglobin of RBCs
• this protein is secreted by the cells as a secretory products in the form of hormones or enzymes

Question 14

Ribosomes under E.M

Answer 14

• composed of 2 subunits , one is large while the other is small
• the large one is formed of 2 parts , between these two parts there is a polypeptide chain
• the polypeptide chain segregate the protein which is formed or synthesized by ribosomes

Question 15

Which type of ribosomes are responsible for the basophilia of the cytoplasm

Answer 15

Free ribosomes “ which scattered freely in the cytoplasm “

Question 16

Their number may increase in growing cells , secretory cells , cancer cells and during normal cell division, what is it ?

Answer 16

The free ribosome

Question 17

Location of free ribosomes

Answer 17

Find in all kinds of cells except in mature RbCs

Question 18

Position of free ribosomes

Answer 18

• Scattered freely in the cytoplasm so they are not attached to membrane
• arranged in groups usually of 5 ribosomes

Question 19

The attached ribosomes are called

Answer 19

Ribosomal RNA

Question 20

Function of attached ribosomes

Answer 20

They are responsible for protein synthesis

Question 21

Location of attached ribosomes in the cytoplasm

Answer 21

They are attached to outer surface of R.E.R

Question 22

Types of ribosomes

Answer 22

1 - ribosomes in form of small fragments “ are rich glucose 6 phosphate enzyme “ “ are called microsomes “
2 - ribosomes attached to each other “ forming spiral - shaped structure or rosette shaped structure “ “ are called polysomes “
3 - ribosomes with R.E.R “ form isolated bodies in nerve cells” and “ are called nissls granules “
4 - attached ribosomes
5 - free ribosomes

Question 23

Staining if ribosomes

Answer 23

• Basophilic in staining due to their content of r - RNA

- stain “ hematoxylin , toluidin blue , and methylene blue .

Question 24

Ribosomes Site of formation

Answer 24

They are formed at nucleolus

Question 25

Shape of ribosomes

Answer 25

They are rounded or oval cytoplasmic bodies

Question 26

Structure of ribosomes

Answer 26

Ribosomes are formed of ribo-nucleoprotein

Question 27

The pathway of ribosomes after formation in the nucleolus

Answer 27

They pass through the nuclear pores to reach the cytoplasm