Topic I

Question 1

cell necrosis

Answer 1

injured cells rupture and damage neighbouring cells (to be avoided)

Question 2

apoptosis

Answer 2

cells that 1) are no longer required or 2) are a threat are dismantled and provide nutrients for other cells (preferred way)

Question 3

examples of cells that perform apoptosis

Answer 3

• cells holding leaves to branches
• tails of tadpoles
• human cells that are cancerous or infected with viruses

Question 4

preparation for apoptosis

Answer 4

• procaspases are present - Bcl2 protects mitochondria
• DNases are inactive
• phosphatidylserines are hidden

Question 5

(Apoptosis) step 1: the trigger

Answer 5

• damage to mitochondria
• damage to DNA
  (severe DNA damage has p53 turn on PUMA gene)
• absence of survival signals (eg cell death of overproduced neurons to match # of neurons to # of target cells)
• death signal from a T cell (uses its Fas Ligand memb. proteins to trigger apoptosis)

Question 6

The T cell using its Fas Ligand memb. proteins is ____ signalling

Answer 6

contact dependent

Question 7

(Apoptosis) Step 2: Activation of procaspases

Answer 7

• procaspases when brought together are activated by proteolysis
• damage to mitochondria releases Cyt c and procaspases are brought together
• damage to DNA -> p53 -> PUMA -> Bcl2 inhibited -> Cyt c release
• no survival signals -> no Bcl2 -> Cyt c release
• death signal from a T-cell (Fas ligand -> Fas receptors -> procaspases brought together)

Question 8

(Apoptosis) Step 3: Caspase cascade

Answer 8

caspases activate other procaspases = caspase cascade

Question 9

caspases also ____ target proteins

Answer 9

cleave

Question 10

(Apoptosis) Step 4: Cell Destruction

Answer 10

• chromosomes destroyed (caspases indirectly activate DNases)
• nuclear envelope dismantled (caspases directly destroy nuclear lamins)
• cells round up and become apoptopic bodies

Question 11

what technique labels apoptotic cells?

Answer 11

TUNEL technique

Question 12

(Apoptosis) Step 5: Phagocytosis

Answer 12

apoptotic bodies consumed by neighbour cells (non-professional phagocytes) or macrophages (professional phagocytes)

Question 13

why does phagocytosis happen

Answer 13

apoptotic bodies display phosphatidylserine phospholipids (“eat me” signal)

Question 14

why chop up DNA?

Answer 14

to make apoptosis irreversible and to make apoptotic bodies safe to eat (destroy virus/cancer genes)

Question 15

how many cell types are in the human body (mammals)

Answer 15

200

Question 16

when do cells become specialized

Answer 16

when transcription cells turn on/off specific genes

Question 17

when does cell differentiation begin in mammals

Answer 17

early in development

Question 18

stem cells

Answer 18

cells that both reproduce & differentiate

Question 19

are embryonic stem cells multipotent or pluripotent?

Answer 19

pluripotent - can become any cell type

Question 20

where are stem cells found?

Answer 20

in tissues and organs where cell reproduction occurs

Question 21

types of stem cells

Answer 21

• blood (hematopoietic)
• skin (epidermis)
• gut (small intestine)

Question 22

blood stem cells

Answer 22

produced in the blood marrow, adult stem cells are multipotent (can become one or more related cells)

Question 23

skin stem cells

Answer 23

can reproduce (make another stem cell) or become differentiated (mature skin cell)

Question 24

gut stem cells at the base of villi can become what?

Answer 24

absorptive and goblet cells

Question 25

what can embryonic stem cells be used for?

Answer 25

- research (eg. adding heart TFs) | - scams (stem cell therapy)

Question 26

what can skin stem cells be used for?

Answer 26

to treat burns and wounds using autograph transplantation (person A -> person A)

Question 27

what can bone marrow stem cells be used for?

Answer 27

treat blood and bone marrow diseases using allograft transplantation (person A -> person B), donor = a family member or related stranger

Question 28

where are the bone marrow stem cells harvested from a donor?

Answer 28

the pelvis which has the most blood stem cells

Question 29

what can umbilical cord blood stem cells be used for?

Answer 29

- research - allograft for another child - scams (private cord blood banks that promote autographs which won't work)

Question 30

what can induced pluripotent stem (iPS) cells be used for?

Answer 30

- research | - potential treatment (eg. to replace damaged neurons)

Question 31

cancer

Answer 31

cancer cells reproduce and spread inappropriately, risk of cancer goes up with age

Question 32

benign cells

Answer 32

reproduce when they are not supposed to

Question 33

malignant/cancer cells

Answer 33

reproduce when they are not supposed to and go where they are not supposed to

Question 34

what cancer is the most common cause of cancer deaths in mem and women?

Answer 34

lung cancer

Question 35

stages of cancer

Answer 35

- initiation - progression - spread (metastasis)

Question 36

initiation

Answer 36

one mutation in one cell causes it and its offspring, to divide inappropriately.

Question 37

progression

Answer 37

more random mutations that increase reproduction, survival and spreading of the cancer

Question 38

spread (metastasis)

Answer 38

cells leave the primary tumour and establish secondary tumours

Question 39

are cancer cells 'trying' to get worse?

Answer 39

no, this is a misconception. Mutations are random and are detrimental or have no effect

Question 40

do cancer cells reproduce quickly?

Answer 40

no, a misconception. Cancer cells are defective and reproduce ~100 days per cell cycle (vs ~25 days for a healthy cell)

Question 41

are cancer cells in a tumour identical?

Answer 41

no, a misconception. Cells have different properties and vulnerabilities

Question 42

are cells in a tumour cancer cells?

Answer 42

most cells in a tumour are not cancer cells, cancer cells recruit normal cells for support

Question 43

what are three main reasons why cells become cancerous?

Answer 43

- cancer critical genes - new (somatic) mutations - inherited (germline) mutations - viral infection -

Question 44

cancer critical genes

Answer 44

encode proteins involved in the cell cycle. Tumor suppressor genes that inhibit cell cycle and proto-oncogenes that promote cell cycle can have mutations occurring

Question 45

new (somatic) mutation

Answer 45

mutation happens within the person

Question 46

inherited (germline) mutations

Answer 46

mutation is inherited from a parent

Question 47

viral infection

Answer 47

some viruses deliberately cause cancer to facilitate their own reproduction. Viral proteins inhibit or activate the proteins made by critical cancer genes

Question 48

(initiation) unregulated cell reproduction due to loss of tumour supressor genes

Answer 48

normal function: inhibit cell proliferation cause cancer when non-functional (eg. RB1 gene, without Rb proteins, cells can't pause at the G1 checkpoint)

Question 49

(initiation) unregulated cell reproduction due to proto-oncogene -> oncogene

Answer 49

normal function: stimulate cell cycle cause cancer when the normal proto-oncogene becomes an over active oncogene (eg. HER2 gene)

Question 50

(progression) genetic instability

Answer 50

cancer cells acquire new mutations at more than the spontaneous rate (eg. mutations in the TP53 tumor suppressor gene)

Question 51

(progression) no apoptosis

Answer 51

some cancer cells do not perform apoptosis because genes such as TP53, PUMA, BCL2 have mutations

Question 52

PUMA is a _____ because too ___ PUMA proteins is dangerous

Answer 52

tumour suppressor gene... few

Question 53

BCL2 is a ___ because too __ BCL2 proteins is dangerous

Answer 53

proto-oncogene... many

Question 54

what proportion of human cancers have mutations in TP53?

Answer 54

> 50%

Question 55

(spread) induce angiogenesis

Answer 55

tumours cannot grow beyond 1-2mm in diameter without recruiting blood vessels

Question 56

(spread) invade neighbouring tissue

Answer 56

cancer cells spread if some of them dismantle the extracellular matrix (as if they were fibroblasts)

Question 57

(spread) metastasis to new cites

Answer 57

0.1% of cells survive to reach new sites to make a secondary tumour

Question 58

what proportion of human cancers are due to viral infection?

Answer 58

> 10%