B1- Cell Biology Flashcards
(243 cards)
1
Q
What cells are eukaryotic?
A
Animals and plants
2
Q
What cells are prokaryotic?
A
Bacteria, single cell organisms
3
Q
What type of cell is complex?
A
Eukaryotic
4
Q
Organelle definition:
A
Things inside cells e.g nucleus
5
Q
What organelles are in an animal cell?
A
- Nucleus
- Cytoplasm
- Cell membrane
- Mitochondria
- Ribosomes
6
Q
Define nucleus:
A
Contains genetic material that controls the activities of the cell
7
Q
Define Cytoplasm:
A
Gel-like substance where most of the chemical reactions happen. It contains enzymes that control these chemical reactions happen.
8
Q
Define mitochondria:
A
These are where most of the reactions for aerobic respiration take place. Respiration transfers energy that the cell needs to work.
9
Q
Define Ribosomes:
A
These are where proteins are made in the cell.
10
Q
Define cell wall:
A
Made of cellulose. It supports the cell and strengthens it.
11
Q
Define vacuole:
A
Contains cell sap,a week solution the cell and strengthens it.
12
Q
Define chloroplasts:
A
These are where photosynthesis occurs, which makes food for the plant. They contain a green substance called chlorophyll, which absorbs the green light needed for photosynthesis.
13
Q
What are the organelles of a plant cell?
A
- Cytoplasm
- Cell membrane
- Cell wall
- Plasmids (sometimes)
14
Q
What organelles does a eukaryoctic cell have that a bacteria doesn’t?
A
- Chloroplasts
- Mitochondria
- Nucleus
15
Q
What does a bacteria cell have instead of a nucleus?
A
Single circular strand of DNA
16
Q
Define plasmids:
A
Small ring of DNA
17
Q
What do microscopes let us do?
A
Let us see thing that we can’t see with the naked eye
18
Q
What do light microscopes use?
A
light and lenses
19
Q
What do electron microscopes use instead of light?
A
Electrons
20
Q
Do electron microscopes have a higher or lower magnification than light microscopes?
A
Higher
21
Q
Do electron microscopes have a higher resolution than a light one?
A
Yes
22
Q
What does resolution mean?
A
The ability to distinguish
23
Q
What is the equation for magnification?
A
magnification=image size/real size
24
Q
1.7 x 10^-2
A
0.017
25
Examples of a specimen
plant or animal cells
26
How are some cells different to others?
In structure and function
27
Define differentiation
The process by which a cell changes to become specialised for its job
28
What happens as cells change?
- They develop different subcellular structures
| - Turns into different types of cells ( this allows them to carry out specific functions)
29
When does most differentiation occur in an organism?
When the organism develops
30
In animal cells is the ability to develop lost at an early or late stage ( before or after they become specialised)?
Early (before)
31
Do plant cells ever lose their ability to differentiation?
No
32
What are cells that differentiate in mature animals mainly for?
Repairing and replacing cells e.g skin or red blood cells.
33
What are undifferentiated cells called?
Stem cells
34
What are sperm cells specialised for?
reproduction
35
What is the function of a sperm cell?
To get the male DNA to the female DNA
36
What is the point of a tail and a streamline head in a sperm cell?
To help it swim
37
Why to sperm cells have a lot of mitochondria?
To provide a lot of energy
38
Why do sperm cells also carry enzymes in its head?
To digest through the egg cell membrane
39
What are nerve cells specialised for?
Rapid signalling
40
What is the function of a nerve cell
To carry electrical signals from one part of the body to another
41
Why are nerve cells long?
To cover more distance
42
What do nerve cells have at the end of them?
branched connections
43
What are branched connections on a nerve cell used for?
To connect other nerve cells and form a network throughout the body
44
What are muscle cells specialised for?
Contraction
45
Are muscle cells long or short?
Long
46
Why are muscle cells long?
So they have space to contract
47
Why do muscle cells have lots of mitochondria?
To generate energy to contract
48
What are root hair cells specialised for?
Absorbing water and minerals
49
What cells are on the surface area of plant cells?
Root hair cells
50
What are phloem and xylem cells specialised for?
Transporting substances
51
What do phloem and xylem cells form?
Phloem and xylem tubes
52
What do phloem and xylem tubes transport?
Food & water
53
Where do the long phloem and xylem cells join to form the tubes?
End to end
54
Are xylem tubes hollow in the center?
yes
55
Do phloem cells have a lot of subcellular structures and why?
No,so stuff can travel through them
56
Why do cells have to able to divide?
In order to grow and survive
57
Do most cells in your body have a nucleus?
Yes
58
Does cytoplasm contain genetic material in the form of chromosomes?
No, it is the nucleus
59
True or false: Chromosomes are coiled up lengths of DNA molecules.
True
60
Do each chromosome carry a small number of genes?
No, it is a large number
61
What do different genes control?
The development of different characteristics e.g hair
62
How many copies do body cells normally have and why?
2. One from the mother and one from the Father.
63
True or false?
| Body cells in multicellular organisms divide to produce new cells as part of stages called the cell cycle.
True
64
What is the stage of the cycle called when the cells divide?
Mitosis
65
What do multicellular organisms mitosis to do?
Grow ad replace cells that have been damaged
66
What does the end of the cell cycle result in?
Two identical cells to the original cell with the same number of chromosomes
67
In a cell that is not dividing how is the DNA spread out?
Long strips
68
What does the cell have to do before it divides?
Grow and increase the amount sub cellular structures such as mitochondria and ribosomes
69
What does the cells do before they divide
It duplicates its DNA so there's one copy for each new cell
70
Each 'arm' of the chromosome isn't a duplicate of the rest. True/False
False it is an exact duplicate
71
When everything inside the cell and DNA has been copied what is the cell ready for?
Mitosis
72
What does the chromosomes line up and cell fibers at the middle of the cell?
Pull the apart
73
The two arms of each chromosome go to opposite ends of the cell. True/False
True
74
Where do membranes form?
Around each of the sets of chromosomes
75
How are the nuclei of the new cells made
Membranes form around chromosomes
76
What happens in the last stage of mitosis?
The cytoplasm and cell membrane divide
77
What is the term called for the cell that is produced in the last stage of mitosis?
Daughter cells
78
the daughter cell contains the exact same DNA as each other and the parent cell. True/False
True
79
What is the term for how prokaryotic cells reproduce?
Binary fission
80
How many does the cell split into in binary fission?
2
81
In binary fission what do the circular DNA and plasplasmid(s) do
Replicate
82
What do the circular DNA do when the cell gets bigger in binary fission?
Move to opposite 'poles' (ends) of the cell
83
What is the 3rd step of binary fission?
The cytoplasm begins to divide and new cell walls begin to form
84
What happens when the cytoplasm divides
Two daughter cells are produced
85
How many copies does each daughter cells have of circular DNA (binary fission)?
1
86
Each daughter cell has a variable amount of plasmid(s) (binary fission). True/false
True
87
Is bacteria fast at dividing (in the correct conditions)
Yes
88
What will happen to the bacteria cells if the condition are not ideal?
They will stop dividing and die
89
Do embryonic or adult stem cells have the ability to turn into any type of cell?
Embryonic
90
What is differentiation?
The process of where a cell becomes specialised for a certain job
91
What are undifferentiated cells called?
Stem cells
92
Can stem cells divide to make more stem cells?
Yes
93
undifferentiated cells can differentiate into different types of cell depending on the instruction given: True/false
True
94
Where are stem cells found?
In early human embryos
95
Why are embryonic stem cells exciting to doctors and medical researchers?
Because they have the potential to turn into any kind of cell
96
Where have all different cells in the human body have come from?
Few embryonic stem cells.
97
Where is one place adult stem cells are found?
Bone marrow
98
Can adult stem cells turn into any type of cell?
No
99
Name one cell adult stem cells can turn into?
Blood cells
100
Stem cells from embryos and bone marrow can't be grown in a lab and produce clones.:True/False
False, they can
101
Can medicine use adult stem cells to cure diseases?
Yes, they currently do.
102
Can embryonic stem cells be used to replace faulty cells?
Yes
103
What is therapeutic cloning?
A nucleus of a cell is inserted into a fertilised egg who's nucleus has been removed
104
What is a risk of using stem cells in medicine?
Stem cells that grow in a lab can become contaminated and and then make the patient sicker
105
Why are some people against stem cell research ?
They believe that it is wrong to experiment with
| human embryos because they have the potential to human life
106
Why do some people think that we should still use human embryos despite he potential of human life?
Because they feel that curing existing patients is more important than the rights of embryos
107
What is a reason that using human embryos isn't taking a life away?
The embryos usually experimented on are unwanted ones from fertility clinics that wouldn't normally be used anyway. However campaigners for the rights of embryos want this banned too.
108
Stem cell research is allowed?
It is banned in some countries but is allowed in the UK(with strict guide lines)
109
Where are stem cells found in plants?
Meristems
110
How much of a plants life can cell tissue in the meristems turn into any type of plant cell?
The plants entire life.
111
Plants stem cells can be used to produce clones of whole plants cheaply and easy:True/False
True
112
What is a benefit of using stem cells of plants?
- You can grow rare species of plants to prevent them from being wiped out
- You ca grow identical plant with a desired feature e.g resistance to a disease
113
What is diffusion?
The spreading out of particles from an area of higher concentration to an area of lower concentration
114
What states does diffusion happen?
Gas and liquids
115
Why can't diffusion happen in solids?
The particles aren't free to move randomly
116
What is the simplest type of diffusion?
When two gasses diffuse through each other
117
The smaller the concentration gradient the faster the diffusion rate:True/False
False. The bigger the concentration gradient the faster the diffusion rate
118
How will temperature impact the rate of diffusion and why?
A higher premature will increase the rate because the particles have more energy to move around faster
119
What does a cell membrane do?
Hold a cell together and let stuff in and out too
120
How do dissolved substances get in and out of the cell?
Diffusion
121
What is the only type of molecules that can pass through the cell membrane?
Small ones
122
With diffusion through a cell membrane the particles move from an area of higher concentration to lower concentration but they sill have random movement but what is the overall effect called?
Net movement
123
How does the surface area of a of the membrane effect the diffusion rate?
The bigger the surface area the faster the rate of diffusion because more particles move through at once
124
What is osmosis?
The movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
125
What is a partially permeable membrane?
A membrane with small holes in it
126
What is an example of something that can fit through the holes in a partially permeable membrane.
Water
127
What is an example of something that can't fit through the holes in a partially permeable membrane
sucrose
128
Does water pass through both ways through osmosis and why?
Yes, water particles move randomly
129
Is there a net flow with osmosis?
Yes
130
Because of net flow would a strong sugar solution get more or less diluted?
More
131
Is osmosis a type of diffusion?
Yes
132
What is passive movement?
The movement of water particles from an area of higher water concentration to an area of lower concentration
133
What is active transport?
When a substance needs to be absorbed against the concentration gradient
134
What type of cells take in minerals and water?
Root hair cell
135
How many hairs are on each branch of a root hair cell?
Millions
136
How big are the hairs on root hair cells?
Microscopic
137
What is the point of a root hair cell having a big surface area?
Absorbing more water and mineral ions from cell
138
What are mineral ions used for with plants?
Healthy growth
139
What concentration of minerals usually higher in root hair cells or the soil?
Root hair cells
140
Can root hair cells use diffusion to take up minerals from the soil?
No
141
Why should minerals cells move out of the root hairs?
If they follow the rule of diffusion
142
What method is used to minerals move out of root hair cells?
Active transport
143
Where does active transport get the energy to use?
From respiration
144
What is an example of how active transport used in the human body?
Taking glucose from the gut and from kidney tubels
145
What changes how quickly stuff moves from an organism and its environment?
Surface area to volume ratio
146
What do organisms exchange substances with?
Their environment
147
What process do cells use to take in substances and get rid of waste products?
Diffusion
148
What process is it when oxygen and carbon dioxide are transferred between cells and their environment?
Gas exchange
149
What is urea?
A waste product produces from the breakdown of proteins
150
In humans what diffuses cells into blood plasma for removal from the body by kidneys ?
Urea
151
Do multi cellular organisms need exchange surfaces?
Yes
152
How do gasses or dissolved substances get in or out of a singular cell organism?
Diffused across the cell membrane
153
How are exchange surfaces adapted to maximise effectiveness
-They have a thin membrane
, so substances only have a short distance to diffuse.
-They have large surface area so lots of substance can diffuse at once
-Exchange surfaces in animals have lots of blood vessels, to get stuff into and out of the blood quickly.
Gas exchange surfaces in animals (e.g alveoli) are often ventilated too- air moves in and out
154
What is the job of the lungs?
To transfer oxygen to the blood and to remove waste carbon dioxide from it
155
What are the millions of little air sacks called in the lungs?
Alveoli
156
Where does gas exchange take place within the lungs?
Alveoli
157
What are the alveoli specialised to do?
Maximise the diffusion of oxygen and carbon dioxide
158
What features does the alveoli have to maximise diffusion?
- An enormous surface area( about 75 m^2 in humans)
- A moist lining for dissolving gases
- Very thin walls
- A good blood supply
159
Where does carbon dioxide in a leaf diffuse into?
Air spaces within the leaf then into cells where photosynthesis happens
160
The underneath of the leaf is used as an exchange surface:True/False
True
161
What is the stomata?
Biddly little holes on the bottom of the leaf which carbon dioxide diffuses through
162
What two things diffuse in and out of the stomata?
Water vapour and oxygen
163
What controls the size of the stomata?
Guard cells
164
When would the guard cells close the stomata?
If it is losing water faster then it is being replaced y the roots?
165
What is a good reason for the flattened shape of the leaf?
It increases the area of this exchange surface so that it's more efficient`
166
What do the walls of the cells inside the leaf form?
Another exchange surface
167
How are exchange surfaces adapted to maximise effectiveness?
- They have a thin membrane, so substances only have a short distance to diffuse
- They have a large surface area so lots of substances can diffuse at once
- Exchange surfaces in animals have lots of blood vessels,to get stuff into and out of the blood quickly
- Gas exchange surfaces in animals (e.g alveoli) are often ventilated too - air moves in and out
168
What are the two types of cells?
● Eukaryotic (plant and animal)
| ● Prokaryotic (bacteria)
169
What are the differences between eukaryotic and
| prokaryotic cells?
Prokaryotic cells are much smaller than
eukaryotic cells.
Eukaryotic cells contain membrane
bound-organelles and a nucleus containing
genetic material, while prokaryotes do not.
170
What is the prokaryotic cell wall composed of?
Peptidoglycan
171
How is genetic information stored in a prokaryotic
| cell?
Found free within the cytoplasm as:
● Chromosomal DNA (single large loop of circular DNA)
● Plasmid DNA
172
What are plasmids?
● Small, circular loops of DNA found free in the
cytoplasm and separate from the main DNA.
● Carry genes that provide genetic advantages
e.g. antibiotic resistance.
173
What is order of magnitude?
A power to the base 10 used to quantify
| and compare size.
174
What is a micrometre (µm)?
1 × 10-6 metres
175
What is a nanometre (nm)?
1 x 10-9 metres
176
What is the difference in order of magnitude between
a human hair (length = 100 µm) and the HIV virus
(length = 100 nm)?
100 µm = 10-4 m
100 nm = 10-7 m
-4-(-7) = -4 + 7 = 3
177
List the components of both plant and animal cells
| 5
```
● Nucleus
● Cytoplasm
● Cell membrane
● Mitochondria
● Ribosomes
```
178
List the additional cell components found in plant
| cells (3)
● Chloroplasts
● Permanent vacuole
● Cell wall
179
```
Other than storing genetic information, what is the
function of the nucleus?
```
Controls cellular activities
180
Describe the structure of the cytoplasm
● Fluid component of the cell.
● Contains organelles, enzymes and dissolved
ions and nutrients.
181
What is the function of the cytoplasm?
Site of cellular reactions e.g. first stage
of respiration.
Transport medium.
182
What is the function of the cell membrane?
Controls the entry and exit of materials
| into and out of the cell
183
What is the function of the mitochondria?
Site of later stages of aerobic respiration
| in which ATP is produced
184
What is the function of the ribosomes?
Joins amino acids in a specific order
during translation for the synthesis of
proteins
185
What is the plant cell wall made of?
Cellulose
186
What is the function of the plant cell wall?
● Provides strength.
● Prevents the cell bursting when water
enters by osmosis.
187
What does the permanent vacuole
| contain?
```
Cell sap (a solution of salts, sugars and
organic acids).
```
188
What is the function of the permanent vacuole?
Supports the cell, maintaining its
| turgidity.
189
What is the function of chloroplasts?
Site of photosynthesis
190
Describe how sperm cells in animals are adapted to
| their function
● Haploid nucleus contains genetic information.
● Tail enables movement.
● Mitochondria provide energy for tail movement.
● Acrosome contains enzymes that digest the egg cell
membrane.
191
Describe how nerve cells in animals are
| adapted to their function
● Long axon allows electrical impulses to be transmitted all over
the body from the central nervous system.
● Dendrites from the cell body connect to and receive impulses
from other nerve cells, muscles and glands.
● Myelin sheath insulates the axon and speeds up the
transmission of impulses along the nerve cell.
192
Describe how muscle cells in animals
| are adapted to their function
● Arrangement of protein filaments allows them to
slide over each other to produce muscle contraction.
● Mitochondria to provide energy for muscle
contraction.
● Merged cells in skeletal muscle allow muscle fibre
contraction in unison.
193
Describe how root hair cells in plants are adapted to
| their function
● Large surface area to absorb nutrients and
water from surrounding soil.
● Thin walls that do not restrict water
absorption.
194
Describe how xylem cells in plants are adapted to
| their function
● No upper or lower margins between cells
to provide a continuous route for water to flow.
● Thick, woody side walls strengthen their
structure and prevent collapse.
195
Describe how phloem cells in plants are adapted to
| their function
● Sieve plates let dissolved amino acids and
sugars be transported up and down the stem.
● Companion cells provide energy needed for
active transport of substances along the
phloem.
196
What is cell differentiation?
The process by which cells become
| specialised.
197
Why is cell differentiation important?
Allows production of different tissues and
organs that perform various vital
functions in the human body.
198
At what point in their life cycle do most
| animal cells differentiate?
Early in their life cycle
199
For how long do plant cells retain the
| ability to differentiate?
Throughout their entire life cycle
200
What is the purpose of cell division in
| mature animals
Repair and replacement of cells
201
What changes does a cell go through as
| it differentiates?
Becomes specialised through acquisition
of different sub-cellular structures to
enable a specific function to be
performed by the cell.
202
Define magnification
The number of times bigger an image
appears compared to the size of the real
object.
203
Define resolution
The smallest distance between two
| objects that can be distinguished.
204
How does a light microscope work?
Passes a beam of light through a specimen
which travels through the eyepiece lens,
allowing the specimen to be observed.
205
What are the advantages of light
| microscopes? (4)
● Inexpensive
● Easy to use
● Portable
● Observe both dead and living specimens
206
What is the disadvantage of light
| microscopes?
Limited resolution
207
How does an electron microscope work?
It uses a beam of electrons which are
focused using magnets. The electrons hit
a fluorescent screen which emits visible
light, producing an image.
208
Name the two types of electron microscope
Transmission electron microscope (TEM)
| Scanning electron microscope (SEM)
209
What is the advantage of electron
| microscopes?
Greater magnification and resolution.
210
Why do electron microscopes have a
| greater magnification and resolution?
They use a beam of electrons which has
a shorter wavelength than photons of
light.
211
How have electron microscopes enabled scientists
| to develop their understanding of cells?
● Allow small sub-cellular structures (e.g. mitochondria,
ribosomes) to be observed in detail.
● Enable scientists to develop more accurate
explanations about how cell structure relates to
function.
212
What are the disadvantages of electron
| microscopes? (4)
● Expensive
● Large so less portable
● Require training to use
● Only dead specimens can be observed
213
How can the magnification of an image be
| calculated?
magnification = size of image / size of real object
214
How do bacteria multiply?
Binary fission (simple cell division)
215
How often do bacteria multiply?
Once every 20 minutes if enough
nutrients are available and the
temperature is suitable.
216
State 2 ways in which bacteria can be
| grown
● Nutrient broth solution
| ● Colonies on an agar gel plate
217
What nutrients make up a nutrient broth solution?
All nutrients required for bacteria to grow
including nitrogen for protein synthesis,
carbohydrates for energy and other
minerals.
218
What are uncontaminated cultures of
| microorganisms needed for?
Investigating disinfectant and antibiotic
| action.
219
Describe the preparation of an
uncontaminated culture using aseptic
technique
1. Use pre-sterilised plastic Petri dishes or sterilise glass Petri dishes and agar gel before using an autoclave.
2. Pour the sterile agar gel into the Petri dish and allow time to set.
3. Sterilise the inoculating loop by passing it through a Bunsen burner flame.
4. Dip the inoculating loop into the solution of microorganisms and make streaks
with the loop on the surface of the agar.
5. Put the lid on the Petri dish and secure it with tape. Label accordingly then
turn and store upside down.
6. Incubate the culture at 25oC in school laboratories.
220
Why must Petri dishes and culture media before
| sterilised before use?
To kill any bacteria already present.
221
Why must inoculating loops be sterilised
by passing them through a Bunsen
burner flame?
To kill any bacteria present on the
| inoculating loop.
222
Why must the Petri dish lid be secured with adhesive
| tape and the whole dish stored upside down?
Stops bacteria in the air contaminating the culture.
The lid is not fully sealed to prevent the growth of
anaerobic bacteria in a lack of oxygen.
Upside down to prevent condensation from forming
and dripping down onto the colonies.
223
Why are cultures incubated at 25oC in
| school laboratories
Harmful pathogens are less likely to to
| grow at this temperature.
224
What is the formula used to calculate
cross-sectional area of a bacterial colony
or clear area around a bacterial colony?
```
πr2 = 3.14
r = radius (diameter/2)
```
225
How is the number of bacteria in a
population after a certain time calculated
from the mean division time?
1. Calculate the number of times the bacteria will divide in the given time period
from the mean division time.
2. Use the following equation to calculate the number of bacteria:
Number of bacteria in population at end of time period = number of bacteria at
the beginning of the time period x 2number of divisions in the time period .
Express the answer in standard form if possible.
226
Calculate the number of bacteria that will
be present after 3 hours for a population
that divides every 15 mins and has 5
bacterium present now
15 minutes = 0.25 hours
3/0.25 hours = 12 divisions
5 x 212 = 20480 or 2.048 x 104
227
What are chromosomes made up of
Chromosomes consist of DNA molecules
combined with proteins. They contain
genes which provide the instructions for
protein synthesis.
228
What is a gene?
A section of DNA which codes for a
| protein.
229
How many chromosomes are found in
| the nucleus of human body cells?
46
230
How many chromosomes are found in the
| nucleus of gametes?
23
231
How are chromosomes arranged in the nucleus
| of a body cell?
Arranged in pairs - 46 chromosomes
| form 23 pairs.
232
What are the three main stages of the cell
| cycle?
1. Replication of DNA and synthesis of
organelles
2. Mitosis
3. Division of cell
233
Why is mitosis important?
● Produces identical cells which all have the
same genetic information.
● Produces additional cells for growth and
repair.
234
Describe the first stage of the cell cycle
Longest stage - cells grow and increase
in mass, replicate DNA and synthesise
more organelles (eg. mitochondria,
ribosomes).
235
Describe the second stage of the cell cycle
Each chromosome in a pair is pulled to
opposite poles of the cell, then the nucleus
divides.
236
Describe the third stage of the cell cycle
The cytoplasm and cell membrane divide -
| two identical daughter cells are produced.
237
What is a stem cell?
An unspecialised cell which is capable of
differentiating into other cell types and of
self-renewal.
238
What is the function of stem cells in embryos
Embryonic stem cells can replicate themselves and
differentiate into many other types of cells.
Embryonic stem cells may be able to treat conditions
such as paralysis and diabetes by dividing to replace
damaged cells.
239
What is the function of stem cells in adult bone
| marrow?
Adult stem cells can differentiate into several cell
types to replace dead or damaged tissues. For
example, bone marrow stem cells can form many
different types of blood cell.
240
What is the function of stem cells in plant
| meristems?
Meristem stem cells retain the ability to
differentiate into any type of plant cell throughout
their lifespan - they can differentiate into any cell
which is required by the plant.
241
What is therapeutic cloning?
A cloning method where an embryo is produced
with the same genetic makeup as the patient.
The stem cells which originate from the embryo
will not be rejected by the patient’s immune
system, so can be used to treat certain medical
conditions.
242
What are the advantages of cloning plants using
| meristem stem cells?
● Can prevent rare plants from becoming extinct.
● Can produce large numbers of plants with a
favourable characteristic.
● Can produce identical plants for research.
243
What are issues are associated with the use
| of embryonic stem cells?
● Many embryonic stem cells are sourced from aborted embryos -
some people have an ethical/religious objection.
● Development of stem cell therapies is slow, expensive and difficult.
● Adult stem cells infected with viruses could transfer infections to
patients.
● If donor stem cells do not have a similar genetic makeup to the
patient, an immune response could be triggered.
