1: L4-5

Question 1

What ‘shines’ on a light micrscope

Answer 1

combined or specific light wavelengths

Question 2

What ‘shines’ on a electron micrscope

Answer 2

electrons

Question 3

What does microscopy begin with

Answer 3

What ‘shines’ on a light micrscope

Question 4

what are 2 methods for fixation of cells

Answer 4

• Physical + solvents- strip out water

* Chemical- Formation of chemical cross links

Question 5

2 ways to section tissue before immunostaining

Answer 5

Cryostat

Parafin

Question 6

what is a confocal microscopy compared to flourescence

Answer 6

• Fluorescence method to get rid of out of focus light (a disadvantage of fluoresces= light above and below focal plain)
• Uses pinholes to prevent unwanted wavelengths

Question 7

what are the 2 types of electron microscope + what measure

Answer 7

• 2 type: transmission (TEM) (what got blocked) and surface (SEM) (bounced off surface of sample // surface contours)

Question 8

Can electron or fluorescent be conducted on living cells

Answer 8

Flor= on living cells
electron= in vacuum

Question 9

name the cell cycle phases

Answer 9

1. Interphase (G1, S, G2)

2. Mitosis (prophase, metaphase, anaphase, telophase)

Question 10

describe G1 phase and S phase

Answer 10

G1 phase (gap phase 1) 
- growth & normal 
- cellular activity 
S phase (synthetic phase) 
-DNA replication - 6-8 hours

Question 11

2 ways cells die

Answer 11

• accidental
• programmed cell death (apoptosis) (occurs if the cell is abnormal in some way eg dividing too rapidly or infected by virus)

Question 12

what processes is cell proliferations needed for

Answer 12

development and homeostasis

Question 13

what is asymmetric mitosis

Answer 13

allows the stem cell population to replenish itself too

Question 14

why is G1 not a fixed duration but the other phases are

Answer 14

variable as cell cycle can enter optional G0 resting phase
• Some cells, rapidly dividing (eg embryo) have no G0 phase
• Some differentiated cells are in G0 for remainder of their natural lives

Question 15

what cell cycles do stem cells fluctuate between

Answer 15

G0 and cell-division cycle

Question 16

what cues do most cells have/turn off

Answer 16

C. Most cells= signals to survive but no proliferation, no growth but also not dying = does not progress through cell cycle

Question 17

what cues do cancer cells have/turn off

Answer 17

D. Cancer cell ignore or not receive death or growth inhibition cues, will make own proliferation and survival cues

Question 18

What factors control cell cycle checkpoint transitions

Answer 18

A. Cyclin proteins accumulate at different stages

B. Cyclins combine w/ CDKs (cyclin dependant kinases) @ G2 > MPF = enable checkpoints to be passed

Question 19

how do molecules move through the nucleus

Answer 19

must pass through nuclear pores
• Passive diffusion for small molecules <20-30 kilodaltons i.e. RNA
• Large protein have nuclear ‘export’ and ‘import’ signals
• Cargoes bigger than pores > partly unfolded to allow entrance

Question 20

what is a territory of nucleus

Answer 20

• The defined location of each chromosome in the nucleus = it’s territory
• Territories: periphery (on lamina) or others at the centre,
o This can change with cell type, or shape

Question 21

Describe FISH

Answer 21

• Short fragments of DNA that complement your sequence of interest + hybridises with them
• Add flourescent molecule

Question 22

Where are large/small chromosomes typically for mammalian cells

Answer 22

o larger chromosomes tend to be at the periphery, smaller - centre

Question 23

where are nuclear bodies and 3 examples

Answer 23

in space between the territories (interchromatin spaces/territories)
o i.e. nucleospeckle, paraspeckle, nucleolus

Question 24

what do nuclear bodies do

Answer 24

• Nuclear body role: make the processing of RNA more efficient + DNA repair

Question 25

what is the densest part of cell

Answer 25

nucleolus

Question 26

what does the nucleolus do

Answer 26

• Site of ribosome production (ribosomal RNA)

Question 27

what is paraspeckles built around

Answer 27

long noncoding rna NEAT1

Question 28

What do paraspeckles do

Answer 28

• Regulate gene expression by sequestration (‘trapping’) of paraspeckle proteins including transcription factors - stops them from doing things, alters regulation of genes when cell becomes stress

Question 29

how to measure movement rate of molecules in living cell

Answer 29

• Using a fluorescent protein fusion> photodynamics:

• Bleach the protein (turn black)
• Image the recovery of fluorescence
• Bleach recovery speed = how fast moving

Question 30

why are nuclear bodies in centre

Answer 30

chromatin moves from periphery to centre to be transcriped // nuclear bodies there so they can aid in this process in appropriate location