Ultrastructure of Eukaryotic Cells

Question 1

Ultrastructure of Animal Cells?

Answer 1

Nucleus 
Cell Membrane 
rER
sER
Cytoplasm 
Mitochondria 
Centrioles 
Golgi Body Apparatus 
Secretory Vesicle 
Glycogen/Lipid Droplets
80s Ribosomes 
Lysosome 
Nucleolus

Question 2

Function of Centrioles?

Answer 2

Control spindle fibres which are required in all cell division.

Question 3

Function of rER?

Answer 3

Involved in production and transport of proteins through the cell.

Question 4

Function of Golgi?

Answer 4

Involved in transport and modification of proteins through the cell.

Question 5

Function of Lysosome?

Answer 5

Contains digestive enzymes that breaks defunct organelles, food particles or pathogens.

Question 6

Function of Nucleolus?

Answer 6

Darkly stained region of the nucleus. Where ribosomes are synthesised.

Question 7

Function of sER?

Answer 7

Involved in the production and transport of lipids throughout the cell.

Question 8

Ultrastructure of Plant Cells?

Answer 8

Nucleus 
rER
sER
Cell Wall
Cell Membrane
Mitochondria 
Golgi 
Chloroplasts 
Vacuole 
Tonoplast 
Starch Granules 
Plasmodesmata

Question 9

Mitochondria Structure + Function?

Answer 9

Double Membrane (or Envelope), Inner mitochondrial membrane highly infolded to form cristae. Stalked particles on cristae.

The site of respiration and ATP production.

Question 10

Chloroplasts Structure + Function?

Answer 10

Double membrane (or envelope), thylakoid containing chlorophyll in stacks called grana. Stroma in centre of inner membrane where grana are found. Starch granules.

Chlorophyll in thylakoids absorb light energy needed for photosynthesis/site of photosynthesis.

Question 11

Centrioles Structure + Function?

Answer 11

Pair of hollow cylinders in different orientation (perpendicular to each other). Each centriole consist of 9x3 microtubules.

Forms spindle fibres which separates chromosomes during cell division.

Question 12

Nucleus Structure + Function?

Answer 12

Envelope with pores. Nucleolus is a darkly stained region in the centre; largest organelle; nuclear envelope is often linked with the rER.

Site of transcription. Ribosomes are synthesised in nucleolus. Contains genetic material.

Question 13

Ribosomes Structure + Function?

Answer 13

80s in size (in eu); smallest organelle; not membrane bound; consist of two subunits; made of RNA (ribosomal RNA); some free but majority attached to rER.

Ribosomes attach to mRNA; holds two tRNA molecules in place during translation allowing for formation of a peptide bond between two adjacent amino acids.

Question 14

rER Structure + Function?

Answer 14

Continuous network of membrane sacs called cisternae ; 80s ribosomes on surface; each cisternae has single membrane; rER often continuous with nuclear membrane.

Involved in transport of proteins; polypeptides are folded into their specific structures; then transported to Golgi.

Question 15

sER Structure + Function?

Answer 15

Continuous network of membrane sacs called cisternae; each cisternae has single membrane.

Involved in the transport and production of lipids (triglycerides)

Question 16

Golgi Structure + Function?

Answer 16

Consists of a stack of flattened membranes called cisternae; cis and trans face; vesicles budding from and into Golgi.

Where proteins are modified (e.g. additional groups added), involved in transport and packaging of proteins into vesicles.

Question 17

What is the Protein Secretion Pathway?

Answer 17

1) mRNA leaves nucleus - copy of instructions for specific protein.
2) Goes to ribosomes on rER. Translation: proteins produced and folded into specific structures in rER.
3) Protein leaves rER in secretory vesicle.
4) Protein enters Golgi on trans face.
5) Protein modified then packaged in vesicles and leaves on cis face.
6) Vesicle fuses with cell surface membrane and cell contents released (only some proteins)