The Nucleus and Ribosomes

1
The Nucleus and Ribosomes
2
(No Transcript)
3
Eukaryotic vs. Prokaryotic Cells

• Similarities to Prokaryotes
• Plasma membrane
• Cytoplasm (cytosol)
• Ribosomes.

4
Eukaryotic vs. Prokaryotic Cells

• Larger
• Membrane-bounded true nucleus
• Structurally more complex
• organelles
• cytoskeleton.
• Belong to domain eukarya Kingdoms fungi,
  animalia, plantae, and protista

5
(No Transcript)
6
(No Transcript)
7
Structure of the Nucleus

• Diameter of about five micrometers (?m).
• Chromatin
• Contains DNA, protein, and some RNA.
• Threadlike
• Coils into chromosomes
• DNA and determines characteristics of the cell
  by coding for rotein.

8
The Nucleus

• Chromosomes
• rodlike
• formed during cell division
• coiled or folded chromatin.

9
(No Transcript)
10
The Nucleus

• Nucleoplasm
• semifluid medium of nucleus.

11
The Nucleus

• Nucleoli dark-stained spherical bodies in
  nucleus where rRNA and proteins join to form
  ribosomes.

12
The Nuclear Envelope

• double membrane
• separates nucleoplasm from cytoplasm.

13
Nuclear Pores (100 nm)
protein
ribosomal subunits
14
Ribosomes

• Cooridinate assembly of amino acids into
  polypeptide chains (i.e. protein synthesis).

15
(No Transcript)
16
Ribosomes

• Ribosomes attached to ER depend on an ER signal
  sequence to bind to a receptor protein.

17
Ribosomes

• Eukaryotic slightly larger than prokaryotic
• Composed of a large and a small subunit.
• Each subunit has its own mix of protein and rRNA.

18
Ribosomes
19
Polyribosomes
Several ribosomes synthesizing Same protein may
be attached to or may lie free.