The nucleus

Question 1

How many genes do bacteria have?

Answer 1

1000-6000

Question 2

What roles does the nucleus undertake?

Answer 2

• separates transcription from translation
• it enables alternative splicing
• allows for multicellular organisms with different cell population

Question 3

Why doesn’t alternative splicing occur in bacteria?

Answer 3

No nucleus

Question 4

What are the 2 hypothesis of the origin of the nucleus?

Answer 4

1. Invagination
2. Endosymbiosis

Question 5

Describe the process of invagination as an origin of the nucleus

Answer 5

The DNA is in the cell, with the ribosomes bound to the membrane. The membrane then invaginates and eventually forms around the DNA.

Question 6

Describe the process of endosymbiosis as an origin of the nucleus

Answer 6

The engulfment of bacteria resulting in organelles such as mitochondria, chloroplast.

Question 7

Describe where mitochondria has come from

Answer 7

Bacteria (bacteria that has been engulfed)

Question 8

How many proteins is a histone octamer made of?

Answer 8

8

Question 9

DNA is wrapped around histones to form what?

Answer 9

nucleosides

Question 10

What is heterochromatin?

Answer 10

DNA material of a high density staining

Question 11

What is euchromatin?

Answer 11

DNA material of a less dense staining

Question 12

What is the nucleolus (think staining)?

Answer 12

DNA material that stains densely

Question 13

What is chromosome called when not in a dividing stage?

Answer 13

Chromatin

Question 14

What technique can be used to view specific chromosomes?

Answer 14

Chromosomal painting

Question 15

What is the nucleolus’ function?

Answer 15

Ribose synthesis

Question 16

What is the speckles’ function?

Answer 16

Pre-mRNA processing

Question 17

What is the function of the Cajal bodies?

Answer 17

Splicing

Question 18

What is the function of PML (promyelocytic leukemia protein) bodies?

Answer 18

Storage depot

Question 19

What is Fen1-GFP?

Answer 19

damage repair protein

Question 20

What is micro-radiation?

Answer 20

Laser used to introduce damage at a specific point in cell

Question 21

Why is micro-radiation useful?

Answer 21

allows ability to observe repair factories

Question 22

How does the nucleolus synthesize ribosomes?

Answer 22

through the production of rRNA, which is then processed and assembled into the nucleus

Question 23

Does the nucleolus have a membrane?

Answer 23

NO

Question 24

When does the nucleolus dissociate?

Answer 24

during mitosis

Question 25

How many membranes does the nuclear envelope have?

Answer 25

2 - inner & outer

Question 26

What is the outer membrane of the nuclear envelope's composition?

Answer 26

Continuous membrane with the ER (endoplasmic reticulum) & contains ribosomes

Question 27

What is the inner membrane of the nuclear envelope's composition?

Answer 27

Contains proteins that anchor the chromatin

Question 28

What is the function of the nuclear lamina ?

Answer 28

maintains the structure of the nuclear envelope on the inner membrane

Question 29

How does the nuclear envelope disassemble during mitosis?

Answer 29

the nuclear envelope becomes detached from the NPCs (nuclear pore complexes)

Question 30

What type of staining allows us to visualise the nuclear envelope?

Answer 30

DAPI staining

Question 31

What is the nuclear envelope made up of?

Answer 31

Lamins

Question 32

What are laminopathies?

Answer 32

defects in nuclear lamins that can cause conditions such as Hutchinson-Golford progeria syndrome

Question 33

What roles can laminas be said to play, as a result of the defects caused by laminopathies?

Answer 33

- gene regulation - structural rigidity

Question 34

What is transported into the nuclear pore?

Answer 34

proteins

Question 35

What is transported out the nuclear pore?

Answer 35

tRNA & mRNA

Question 36

How many proteins are there that are nucleoporins?

Answer 36

30

Question 37

What technique has allowed research into NPCs (nuclear pore complex)?

Answer 37

Electron microscopy

Question 38

How does water & water-soluble molecules travel into the nucleus?

Answer 38

NPCs (nuclear pore complex)

Question 39

What method is used to transfer proteins larger than 60,000 Da across the NPC (nuclear pore complex)?

Answer 39

Active transport

Question 40

What are nuclear localisation signals (NLS) used for?

Answer 40

when proteins are imported into the nucleus, they use NLSs to reach their target destination

Question 41

What amino acids are Nuclear Localisation Signals (NLS) rich in?

Answer 41

lysines & arginines

Question 42

What type of proteins belong in the nuclear transport receptor family?

Answer 42

Nuclear Import proteins (NIPs) - importins Nuclear Export proteins (NEPs) - exportins