2.4 - Eukaryotic Cell Structure

Question 1

Describe the structure of the nucleus

Answer 1

• has a double nuclear envelope that has a double membrane to protect it from damage in the cytoplasm
• has nuclear pores that allows molecules to move into and out of the nucleus
• dense nucleolus made of RNA and proteins assembled ribosomes

Question 2

Describe the function of the nucleus

Answer 2

• contains DNA coiled around chromatin into chromosomes
• controls cellular processes eg. gene expression determines specialisation and is the site of mRNA transcription, mitosis and semi- conservative replication

Question 3

Describe the structure and function of the Endoplasmic reticulum

Answer 3

Structure = network of membrane enclosing flattened sacs called cisternae that extends from the cell membrane and connects to the nuclear envelope

Function :
Rough ER - many ribosomes attached for protein synthesis and transport
Smooth ER - lipid synthesis

Question 4

Describe the structure and function of the Golgi apparatus

Answer 4

Structure = planar stick of membrane bound , flattened sacs , cis face aligns with rough endoplasmic reticulum
Molecules are processed in the cisternae
Vesicles bud off trans face via exocytosis

Function =
Modifies and packaged proteins for export
Synthesizes glycoproteins

Question 5

Describe the structure and function of ribosomes

Answer 5

Structure - formed of protein and rRNA
Function - have large subunit which joins amino acids and small subunit with mRNA binding site

Question 6

Describe the structure of a mitochondrion

Answer 6

•surrounded by a double membrane
•Folded inner membrane forms cristae : site of electron transport chain
•The fluid interior is called matrix and contains mitochondrial DNA , respiratory enzymes , lipids , proteins

Question 7

What is the cytoskeleton?

Answer 7

•Network of fibers necessary for the shape and stability of a cell
•The organelles are held together by the cytoskeleton and it controls cell movement of organelles within cells

Question 8

What are the 3 compartments of the cytoskeleton?

Answer 8

1. Micro filaments
2. Microtubules
3. Intermediate fibers

Question 9

What are microfilaments ?

Answer 9

• contractile fibers formed from the protein actin
• responsible for cell movement and cell contraction during cytokinesis

Question 10

What are microtubules?

Answer 10

• globular tubulin proteins to polymerise to form tubes that are used to form a scaffold like structure that determines the shape of a cell
• acts as tracks for the movement of organelles including vesicles around the cell

Question 11

What are intermediate fibres?

Answer 11

Give mechanical strength to cells and help maintain their integrity