Lecture 10 - Nucleus Flashcards
What are ribosomes?
Complexes made of ribosomal RNAs & proteins
What are the two types of ribosomes?
Bound ribosomes and free ribosomes
Where are ribosomes found?
Bound ribosomes - Attached to the rEr
Free ribosomes - In the cytoplasm
What are the function of ribosomes?
Carry out translation
What is the nucleus?
The cell’s control centre
- Contains most of the cell’s genes
- Serves as repository of inherited genetic information
What is the size of the nucleus?
5-10 µm diameter
What is the structure of the nucleus?
Nuclear envelope, nuclear pores, DNA and nucleolus
What is the structure of the nuclear envelope?
Two membranes (outer and inner) each containing a phospholipid bilayer
What is the outer membrane of the nuclear envelope continuous with?
The ER
What is the nuclear lamina?
Lining of the inner surface of the nuclear envelope
What is the role of the nuclear lamina?
- Maintain shape of nucleus
- Helps organise the packing of the DNA within the nucleus
What is the nuclear lamina composed of?
Intermediate filaments
What happens if the nuclear
lamina is defective?
- Cells cannot produce a normal nuclear lamina
- Thus their nuclei are unable to retain a spherical shape
- This limits the ability of affected cells to divide
Results in abnormal features
and premature aging
What are nuclear pores?
Channels made of proteins
(nucleoporins) that form the
Nuclear Pore Complex
Where are nuclear pores found?
Spanning nuclear envelope
How many nuclear pores are there per cell?
Approx 1000
What is the role of nuclear pores?
Controls the movement of
molecules out of, or into, the
nucleus (nucleo-cytoplasmic
exchange)
What moves from the nucleus to the cytoplasm? (3)
mRNA, tRNA and
ribosomal subunits
What is the role of mRNA (messenger RNA)?
Carries information from a gene
What is the role of tRNA (transfer RNA) and ribosomal subunits?
Needed to build proteins
What moves from the cytoplasm to the nucleus? (3)
Control signals, building
materials and energy
T or F
The nuclear envelope consists of a
single membrane
False
The nuclear envelope has two membranes (inner and outer)
T or F
The nuclear pore complex allows mRNA and tRNA to move out of the nucleus
True
T or F
The nuclear lamina is made of
microtubules
False
The nuclear lamina is made of intermediate filaments
