Cell Biology

Question 1

List the methods of gene expression control.

Answer 1

chromatin remodelling
regulation of transcription
alternative mRNA processing
microRNA regulation 
mRNA transport
translation control
post-translational modification
rate of protein degradation

Question 2

Describe transcription regulation.

Answer 2

transcription factors bind to promoter or enhancer region

activated by environmental stimuli/hormones

Question 3

Describe alternative mRNA processing.

Answer 3

pre-mRNA converted into multiple types of mature mRNA

Question 4

Describe microRNA regulation of gene expression.

Answer 4

microRNA (small non-coding) bind to 3’ untranslated region

represses/degrades target mRNAs

Question 5

Describe post-translational modification.

Answer 5

methylation/phosphorylation etc.

regulate everything

Question 6

How can genome changes cause disease?

Answer 6

mutations of gene
gene expression changes
modification of mRNA
changes in protein

Question 7

How does PCR work?

Answer 7

selected DNA sequence is amplified & purified

allows detection of a specific sequence & comparative analysis between sequences

Question 8

How does in-situ hybridization work?

Answer 8

labelled complementary RNA/DNA localize specific sequence
shows location of sequence within tissue sample
fluorescence can be applied for ease of recognition

Question 9

Describe DNA microarrays.

Answer 9

different genes attached to probe at fixed locations
can identify multiple genes at the same time
assay gene expression within one sample or compare between
fluorescence can indicate level of regulation
tissue microarray uses clinical tissue not just genetic material

Question 10

Describe western blots.

Answer 10

identifies specific proteins
electrical current moves proteins through gel
antibody attaches to target protein
secondary antibody attaches to primary antibody
enzyme substrate creates detection signal

Question 11

Describe immunohistochemistry.

Answer 11

labelled antibodies attached to antigens in tissue sample
locate biomarkers with colour change
uses primary & secondary labelled antibodies

Question 12

Describe immunofluorescence.

Answer 12

fluorescence labelled antibodies attach to antigens in tissue sample to locate biomarkers w/ fluorescence microscopy

Question 13

Describe GFP-fusion proteins.

Answer 13

location of proteins within a cell via green fluorescent tags on gene of interest
can see how proteins move around in living cells

Question 14

What are stem cells?

Answer 14

archetypal cells
self-renewing
differentiate into diverse specialized cells

Question 15

How do stem cells differentiate?

Answer 15

use symmetric (identical daughter cells) and asymmetric division (identical & progenitor daughter cells)

Question 16

Describe the difference between progenitor & stem cells.

Answer 16

progenitor - limited self renewal

identical - same potential as parent stem cell

Question 17

Describe the difference between adult and embryonic stem cells.

Answer 17

adult - multipotent - “repair system” in tissues already partially differentiated (tissue specific)
embryonic - pluripotent, can differentiate into any type of tissue & potentially infinite propagation

Question 18

How are ESCs acquired?

Answer 18

ICM of blastocyst removed, cultured, proliferated w/o differentiation

Question 19

Describe the changes in cell colony morphology as pluripotent ESCs differentiate.

Answer 19

start with enlarged nucleus & distinct nucleoli - culture is compact colony of spherical cells
differentiation leads to flattened cells at edges of colony start to migrate out

Question 20

List potential uses for ESCs.

Answer 20

developmental biology research
drug discovery/development
cell replacement therapy

Question 21

Describe somatic cell nuclear transfer (SCNT).

Answer 21

donor 1 - remove nucleus
egg cell from donor 2 - remove nucleus
fuse donor 1 nucleus with donor 2 cell, apply electrical current
embryo implanted into surrogate
offspring born with same DNA as donor 1 (clone)

Question 22

Describe induced pluripotent stem cells (iPS).

Answer 22

somatic cells reprogrammed into ECS via somatic nuclear transfer or ectopic expression of pluripoency-specific transcription factors

Question 23

How can iPS potentially be used?

Answer 23

differentiate into all 3 germ layers

provide autologous cell source for individualized medicine

Question 24

Describe haematopoietic stem cells.

Answer 24

both multipotent & able to self-renew

hierarchical differentiation

Question 25

Describe mesenchymal stem cells.

Answer 25

originates from mesoderm & neural crest
bone marrow derived
in connective tissue
self-renewal, differentiation, transdifferentiation

Question 26

Describe cardiac stem cells.

Answer 26

potential for cardiac progenitor cells w/ stem cell characteristics

Question 27

Describe cellular plasticity.

Answer 27

capacity for a cell to transform into another type of cell

dedifferentiation/transdifferentiation

Question 28

Describe a stem cell niche.

Answer 28

stem cells within a fixed compartment
controls signals to stem cells - controls rate of proliferation, determines specialization, protects from exhaustion/death

Question 29

Describe cancer stem cells.

Answer 29

cells within tumours responsible for initiation, growth & metastasis
can produce heterogeneous lineages -> bulk of tumour
resistant to treatment

Question 30

What is senescence?

Answer 30

state of permanent growth arrest in G1
metabolically active
resistant to apoptosis
unresponsive to growth factors

Question 31

Describe the cancer-ageing hypothesis

Answer 31

tissue regeneration increases chance of acquiring mutations

apoptosis & tumour suppressor mechanisms lead to aging (atrophy)

Question 32

Describe the clonal evolution model of cancer.

Answer 32

DNA damage to stem cell -> mutated progenitor -> mutated somatic cell -> tumour growth
individual somatic cell becoming tumorigenic is unlikely d/t short lifespan

Question 33

List key characteristics of cancer stem cells.

Answer 33

.

Question 34

Describe the cancer stem cell model of cancer.

Answer 34

cancer stem cells initiate & maintain tumour growth
long lived w/ self-renewal & differentiation
get mutated progenitor & mutated somatic cells