Cellular Ultrastructure

Question 1

2 major components of cells

Answer 1

cytoplasm
-contains organelle
-contains inclusions
nucleus 
-is the largest organelle within the cell, making visualization  with light microscopy fairly easy

Question 2

Nucleus

Answer 2

function
-storage and use of the genome
light microscopy features
-largest organelle within a cell
-very distinct boundary 
-may have visible nucleoli 
EM features
-nuclear envelope is a double membrane
-chromatin may have regionalized condensation

Question 3

Nucleolus

Answer 3

function
-synthesis of rRNA
-ribosomal production and assembly
Light microscopy features
-roughly circular region within the nucleus
-may be visible in some cell types or at certain points during the cell cycle (interphase)

Question 4

Mitochondria

Answer 4

Function: aerobic energy supply-oxiative phosphorylation, ATP
Light microscopy features
-can sometimes be observed as small dark dots

Question 5

Rough Endoplasmic Reticulum (rER)

Answer 5

Function: involved in protein synthesis and modification of newly synthesized proteins

Light microscopy features:

• can be observed as a basophilic region of cytoplasm
• found localized in the cytoplasm

Question 6

Smooth Endoplasmic Reticulum (sER)

Answer 6

Function:
-mediates many biochemical reactions including detox  
-involved in lipid and steroid synthesis
Light microscopy features 
-not visible

Question 7

Golgi

Answer 7

Responsible for modifying, sorting and packaging proteins

Light microscopy features:
-sometimes observed as a negative golgi image adjacent to the nucleus

Question 8

Ribosomes

Answer 8

Synthesis of proteins

Light Microscopy features:
-not visible

EM features
-minute dark dots in the cytoplasm (free) or associated with the rER

Question 9

Cytoskeletal elements

Answer 9

includes microfilaments and microtubules and centrioles
Function- cell motility, cell adhesion, transport (intracellular and extracellular)
Light microscopy features
-only visible when organizing into larger structures or utilizing a special stain
EM Features
-long, linear
-specific features and width are characteristic of function