nucleus (lecture 9)

Question 1

describe the basic structure of the nucleus

Answer 1

• double membrane of 2 phospholipid bilayer surrounding called the nuclear envelope, lined by the nuclear lamina
• nuclear pore channels running through to the exterior of the nuclear envelope (controls nucleo-cytoplasmic exchange)
• contains tightly packed DNA
• contains nucleolus, prominent darker area in the middle

Question 2

describe the basic function of the nucleus

Answer 2

• contains most of the cells genes
• organisation of DNA within the nucleus

Question 3

describe the basic structure of the nuclear pore complex

Answer 3

• channels made of proteins (nucleoporins) form the complex
• allows for control of molecule movement in/out of the nucleus

Question 4

explain nucleo-cytoplasmic exchange (specifically the nuclear pore complexes role)

Answer 4

• movement of mRNA, tRNA and ribosomal subunits to the cytoplasm
• moving control signals, building materials and energy in to the nucleuas

Question 5

describe the organisation of DNA within the nucleus

Answer 5

• DNA interaction with histone proteins to form fibres
• increasing complexity of DNA interacting with more proteins, condensing the packing of DNA

Question 6

state the functional differences between euchromatin and heterochromatin

Answer 6

euchromatin - less electron opaque - lighter and less tightly packed
heterochromatin - more electron opaque - darker and more dynamic