4.Stem cells and apoptosis

Question 1

what are stem cells

Answer 1

Stem cells are non-specialised cells that can divide and differentiate into different specialised cells

Question 2

what is meant by stem cell ‘potency’

Answer 2

the varying capacity into which stem cells are able to differentiate into

Question 3

two main types of stem cells

Answer 3

-adult stem cells
-embryonic stem cells

Question 4

identify the order of stem cell potency from most to least potent

Answer 4

-totipotent
-pluripotent
-multipotent

Question 5

what is meant by totipotent

Answer 5

the capacity to differentiate into all possible cell types, including extra embryonic tissue

Question 6

what is meant by pluripotent

Answer 6

the ability to differentiate into all cell types, except those that make up the placenta

Question 7

what is meant by multipotent

Answer 7

the potential to give rise to cells from multiple, but a limited number of lineages

Question 8

what is the potency of adult stem cells

Answer 8

multipotent

Question 9

source of adult stem cell

Answer 9

adult stem cells are isolated from tissue samples

Question 10

examples of adult stem cell for medical use

Answer 10

-bone marrow transplantation
-regenerative medicine

Question 11

examples of adult stem cell use in research

Answer 11

-testing new drugs for safety and effectiveness
-model for studying how diseases develop

Question 12

what is the potency of embryonic stem cells

Answer 12

pluripotent

Question 13

source of embryonic stem cells

Question 14

ethical issues raised by stem cells

Answer 14

-human embryos are destroyed when stem cells are extracted

-offering unproven stem cell therapies to those who are desperate

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Question 14

ethical issues raised by stem cells

Answer 14

-human embryos are destroyed when stem cells are extracted

-offering unproven stem cell therapies to those who are desperate

Question 15

What is the term that is used to refer to an embryo that is 5 days old and consists of two groups of cells: Trophoblast and Inner cell mass?

Answer 15

blastocyst

Question 16

define apoptosis

Answer 16

apoptosis is the natural and controlled death of cells in the body. It’s also known as programmed cell death

Question 17

what is the purpose of apoptosis

Answer 17

-allows old and/or damaged cells to be removed in your body
-allows infected cells to be removed in your body
-allows unnecessary/unwanted cells to be removed during embryonic development

Question 18

two pathways that can initiate apoptosis

Answer 18

-mitochondrial pathway (intrinsic)
-death receptor pathway (extrinsic)

Question 19

step 1 of apoptosis

Answer 19

a damaged cell or unwanted cell receive signals that initiate apoptosis

Question 20

step 2 of apoptosis

Answer 20

once signals are received by the cell, it leads to activation of capsazes

Question 21

what are capsaze enzymes

Answer 21

group of enzymes that can cleave intracellular proteins

Question 22

step 3 of apoptosis

Answer 22

as the digestion of cell contents continues, the cell starts to shrink and its membrane starts to bulge out, forming blebs

Question 23

step 4 of apoptosis

Answer 23

the cell will eventually be broken down into small chunks called apoptotic bodies

Question 24

apoptosis vs necrosis

Answer 24

-programmed and regulated cell death vs unexpected cell damage/death -cell shrinks and contents are held in apoptotic bodies vs the cells contents swell and burst -no inflammation vs inflammation

Question 25

too much apoptosis

Answer 25

can lead to degenerative diseases -eg alzheimers

Question 26

briefly describe alzheimers disease

Answer 26

neurones begin to die leading to brain shrinkage. Because of increased apoptosis

Question 27

too little apoptosis

Answer 27

-reduced cell death -can lead to tumours

Question 28

what is a tumour

Answer 28

a mass of abnormal cells -in the sense that they divide uncontrollably and lack normal shape and structure -cant undergo apoptosis naturally instead are flagged by the immune system

Question 29

G1 checkpoint

Answer 29

-inspects for DNA damage and cell size

Question 30

metaphase checkpoint

Answer 30

confirms that spindle fibres have correctly attached to the centromeres of replicated chromosomes

Question 31

G2 checkpoint

Answer 31

confirms that DNA has correctly replicated in the s phase

Question 32

important proteins involved in apoptosis

Answer 32

-capsaze enzymes -death receptors

Question 33

what happens if DNA damage isn't repaired

Answer 33

-may lead to mutations in genes that code for proteins -mutated genes may code for less or non functional proteins -hence a reduced rate of apoptosis -mutated cells are able to go through the cell cycle with further mutations to their DNA leading to formation of tumours

Question 34

two classifications of tumours

Answer 34

-benign tumours -malignant tumours (aka cancers)

Question 35

characteristics of benign tumours

Answer 35

-relatively slow growing masses of cells that tend to stay together within a capsule -hence they can't seperate and invade other parts of the body -benign tumours can be removed by radiation therapy, often successful

Question 36

characteristics of malignant tumours

Answer 36

-benign tumours cells can mutate further and become malignant when they gain the ability to invade nearby tissue and/or enter the bloodstream or lymphatic system

Question 37

metastasis

Answer 37

malignant tumour cells can travel to other parts of body and grow into new malignant tumours

Question 38

why are cancers (malignant tumours) dangerous

Answer 38

-these tumours can grow in amongst healthy tissues and affect the structure of the healthy tissues -if the structure of an organ is compromised by a tumour then then the function if the organ will be compromised too.

Question 39

what causes cancer

Answer 39

carcinogens-are any substance that can increase the likelihood of developing malignant tumours eg uv light increases risk of skin cancer