Nucleus

Question 1

Nucleus structure and function

Answer 1

Large round of structure command

center of sale command center

contains code for protein synthesis

Has machinery to replicate DNA and synthesizes RNA

Question 2

Components of nucleus

Answer 2

Nuclear envelope 
nuclear lamina 
nucleolus 
nuclear pores 
chromatin

Question 3

Nuclear envelope structure and function

Answer 3

Selective barrier between cytoplasm and nucleus

has two membranes and peri-nuclear space in between

Outer membrane continuous with rER

Inner membrane associated with meshwork of proteins called lamins in region underneath membrane called nuclear lamina which stabilize it maintains shape of nucleus

Question 4

Lamins function

Answer 4

They bind to membrane proteins of inner membrane and chromatin in non-dividing cells

Question 5

Nuclear pore structure and function

Answer 5

Made of proteins called nucleoporins
-Display eight Ford symmetry around lumen

Bridge outer and inner membranes and allow exchange exchange of materials between cytoplasm and nucleus

Question 6

Mechanism for proteins to be segregated into nucleus

Answer 6

The mechanism is the same is that of the RER

specific sequences are encoded by the five end of mRNA

Sequence bound by transport proteins “importins and exportins which interact with proteins of Pore complex to translocate peptide into nucleus

Question 7

Chromatin structure and types

Answer 7

Chromatin is DNA and it’s associated proteins which compact it

• in people chromatin is linear and divided into 46 chromosomes after replication but before division each chromosome is two chromatids attached at the centromere
• divided into euchromatin and heterochromatin

Question 8

Euchromatin structure and function

Answer 8

Finely dispersed and lightly basophilic

Rich in genes prominent in synthesizing cells found deep in the nucleus

Question 9

Heterochromatin function and structure

Answer 9

Condensed dense chromatin and darkly basophilic

more compact shows little or now transcriptional activity

Question 10

Types of heterochromatin function and structure

Answer 10

1 constitutive - Mainly repetitive Gene poor sequences including at Centromere and telomere

2 facultative - Other regions of DNA with transcription is in activated by epigenetic mechanisms but can undergo transitions from compact to transcriptionally active conformations
prominent in non-synthesis cells

Question 11

Barr body structure and function and contrast to other chromosome

Answer 11

This is a small dense sec chromatin one of the large X chromosomes in females but not in males
Tightly coiled and other is transcriptionally active and less visible
-Can be used to determine the sex of infants or of individuals

Question 12

Location of hetero and euchromatin

Answer 12

Hetero is found near the lamina connected to the membrane by the lamins and euchromatin is deeper in the nucleus

Question 13

Homologous pairs

Answer 13

These are a pair of chromosomes one from either parent but although from different parents contain the same alleles

Question 14

Nucleous structure and function

Answer 14

Spherical large part of nucleus Highly basophilic in synthesis cells due to rRNAso which is associated with proteins from cyto to form subunits