1. The document is Issue 13 of Big Picture magazine, published in January 2011. The issue focuses on cells and cell biology. 2. It contains articles on the structure and function of cells, how cells divide and develop, how cells interact with their environment, the lifespan of cells and what happens when they die, stem cells and their roles in development and medical research. 3. The issue also includes "real voices" interviews with three people discussing how cells impact their lives.

1. ISSUE 13 jANUARY 2011
Big THE CELL
Picture
bRiNgiNg CUTTiNg-EDgE SCiENCE iNTo THE CLASSRooM
Insider
knowledge
Revealing the secrets of your cells
What are cells for?
How do cells divide, develop
and communicate?
What are stem cells and
why are they important?
What happens when cells die?
fo r t e a c h
ce e
© David S Goodsell, 2000
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A res o
a n d le a r n e
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2. Big
Picture
CoNTENTS
Big Picture Introducing the cell
A close-up look at the structure of animal cells.
3
Big Picture is a free resource for teachers, Beginnings and basics
How do cells divide, develop and grow into complex organisms?
4–5
school and college students, and learners
of any age. Published twice a year, each Cells and their surroundings
How do cells interact with their environment?
6–7
issue comes as a printed magazine with
accompanying online articles and other A matter of life and death
How long do cells live? What happens when they die?
8–9
content. Here’s how to get the most from
your issue. Stem cells and development
What are stem cells and how are they used in medical research?
10–11
Stem cells and the future
What might developments in stem cell science mean for us?
12–13
Real voices
Three people’s stories about the roles of cells in their lives.
14–15
How to use Big Picture magazine How to use the Big Picture website
Each issue of Big Picture focuses on a topic that is current, As well as twice-yearly magazines, there’s loads of other
relevant to the biology curriculum, rooted in science, and that has useful material available on the Big Picture website
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– including Annie Cavanagh
for studying specific diseases
muscular dystrophy
Big Using stem cells Huntington’s, Parkinson’s,
and type 1 diabetes –
have been made by
Picture You seem different… Stem cells hold great
potential for reprogramming adult cells
from patients into a
stem cells would
for their roles? treating disease. pluripotent state. Pluripotent
How are cells specialised give researchers the chance
to test drugs
cells and
range of hormones and
digestive
If we can learn how to
control the but only if they can
on different types of cell,
1 Stem ment
Each cell type is specialised enzymes. Small regions
of the cells we might be able how and when
c differentiation of stem develop ways of controlling
for the role it plays; specifi pancreas known as the
Islets of of cell damage in the cells.
from to remedy many kinds these stem cells differentiate. Scanning electron micrograph
of embryonic kidney
characteristics range Langerhans contain four
different
body. Embryonic stem
cells are pluripotent,
Adult stem cells (those
found in
develop
general
making key proteins to cell types, which each
make
and so the most versatile,
but their use organs) are . This approach
Red blood (for more, see differentiated tissues and involved in cell differentiation
properties like shape. different hormones. The
most in drugs for, in this
small is not without controversy potentially useful too. Researchers single adult can also be used to screen
cells, for example, are common cells there – beta cells are using tissues.
shape pages 12–13).
companies use Cambridge, for example, instance, repairing damaged
biconcave discs. This – make insulin and amylin. Some pharmaceutical the biological signals
area, skin stem cells to explore
– not gives a large surface cells specialise? test new drugs. Stem cells
Stem cells are very special stem cells to
How do
2
oxygen
helping the cells to ship
Getting some culture
a signal
s but A stem cell will receive
only can they renew themselve ted from the lungs to the
tissues,
from its surroundings
that
differentia and a little of the carbon
dioxide grown
they can also become an embryo Many types of cell are
pattern
triggers a change in the
in the other way. on and
cells. Stem cells found The shape also gives
of genes that are turned
off, directing the cell towards
a in the lab for research.
cells found
can become any of the hold great
1
flexibility, helping the
cells be kept alive outside
more specialised state.
Having Many kinds of cell can
dish. If they grow and
in the body and, as such,
smallest
squeeze through the a detailed understandin
g of the body in a laboratory
g replacement red blood cell culture. Many cell
capillaries. Developing these changes and how
they reproduce, you have a
promise for generatin cells begin with a nucleus
and us to culture ‘lines’ (or types)
are used in research.
a number are triggered may allow
tissues and cells to treat , including
4
before substitute for whole
organelles, but lose them control them. To some extent, they can
for animal testing of
of diseases and disorders
in effect
they start work, which organisms, particularly
disease and full However, cultures
diabetes, Parkinson’s reduces the cells to bags
of haemoglobin, the protein
EM Unit, UCL Medical
toxicity or drug effects.
(a layer one cell
usually consist of a monolayer the mix of cells
multiple sclerosis. that carries oxygen and
carbon School, Royal Free Campus
thick) of a single type of
cell, not
distorted, also lack the three-
dioxide. If the shape is found in real tissues. They
2
disease can result. For
example, of tissues and organs,
dimensional structure
sickle- and support their
in the inherited disease which have defined shapes
Stem cells cell anaemia, some red
blood
cells in carefully ordered
arrangements.
stem cells? is as much art
What do we mean by cells become sickle-shaped Successful tissue culture
owing to abnormal haemoglobin carefully controlled
all its descendants will
be as science. Cells need
If a differentiated cell divides, the right
do more, molecules clumping together. conditions to grow, including
other. A stem cell can growth factors in
identical to it and each Organs often contain temperature, gas mix and
differentiated cells. They’re
producing stem cells and on sub-populations of cells.
The blood cells. the medium they grow
in. The longest-lived
means that they can go makes a Sickled and normal red cancer cells, which
also self-renewing, which pancreas, for instance, cultures often derive from
normal controls
and on dividing.
potency – how much they
can have found ways to override
4
Stem cells vary in their lines have to be
egg and the products
of on cell division. Such cell
differentiate. A newly fertilised totipotent cells. These cancerous cells may
made of checked continually. The
its first few divisions are do in a tumour that’s
cell type in the body, including go on changing, as they
cells can give rise to any easy for cultures to
University of Edinburgh
produce a whole organism. still in the body. It is also
the placenta, and so can by other cells. If this
a few steps beyond the
egg in become contaminated
3
Embryonic stem cells, may not be
– they can become any goes unnoticed, experiments
development, are pluripotent think.
but not a whole organism. testing what the investigators
type of specialised cell, of
can make just a few types
Multipotent cells, which red
marrow that can generate
cell, include those in bone found
adult stem cells (those
or white blood cells. Most
www.nucleusinc.
Art, all rights reserved.
in differentiated tissues
and organs) are multipotent.
just one
Medical illustration copyright
© 2010 Nucleus Medical
FAST FACT
those in the skin, make are
Unipotent cells, such as Stem cell therapies
fully differentiated cell type,
usually where lots of new
micrograph of epithelial
(skin) cells. More, and bigger already in use in the
Transmission electron form of bone marrow
cells are needed regularly.
focuses on the transitions
between Organs can grow by transplants – the first
of
A lot of research getting more cells,
these states. A basic question
is whether pluripotent
by default, or need some
This way up and function. or larger ones.
which was performed
in cells’ development
in 1956. Source:
cells carry on as they are
continuing signal to remind
them to stop differentiating.
cells
Direction is important An organ can grow in
two ways. www.biotechlearn.org.nz
that embryonic stems absorption. The cell keeps
track
Adding more cells makes
it
Research strongly suggests cells, as – including
keep making more stem A cell’s development of which end is which,
so that
bigger. But so can increasing
Munich
are self-sustaining, and protein
signals from a particular its direction – is constantly molecules go the right
way.
the size of individual cells
(called
long as they receive no
influenced by the cells A more complex example
is
‘hypertrophy’). We use
both
Medical Art Service,
3
that triggers cell differentiation.
surrounding it. An epithelial found in the ear, where
a type
methods. The embryonic
heart
sheet, for example, is of epithelial cell in the
inner ear
increases in size by adding
extra
– the
asymmetric. One face turns vibrational signals
into
cells, but after birth, our
hearts too thick
to Heart muscle becomes
apical surface – is exposed electrical messages so
we can
grow by hypertrophy. Normal heart (cut section). (hypertrophy).
the gut,
the watery contents of hear. These hair cells,
which
By exercising, we stimulate
The In this
or to the air in the lungs. have a bundle of fine
cilia, have
this process, and the
hearts of which stimulates hypertrophy.
surface again. In heart failure, case, despite the increase
in
opposite face – the basal a top and bottom, but
have to
athletes can grow much
larger things
of can result from many actually
– sits on supporting layers be arranged in the right
direction
still. This so-called physiological diet and size, heart performance Cross-section of bone.
tissue. well. If they such as infection, poor
collagen and connective along another axis as hypertrophy is normal;
when is an worsens.
into high blood pressure, there
Cells that secrete molecules lose this orientation, or
planar
you stop training, your
heart heart that
membrane increased load on the
the gut need different polarity, the sense of
hearing
will adapt and slowly
reduce
bottom,
proteins at the top and may be impaired. JANUARY 2011 • 11
for
and so do those specialised
THE CELL
10 • Big Picture 13:
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2 • Big Picture 13: THE CELL

3. introducing the cell
are poised to break down the material into
smaller molecules.
Cell theory was put forward in the
1830s, soon after the cell nucleus was first
join us as we explore the building block of life. identified in eukaryotes. It recognised that
living things are made of cells, that cells
are the basic units of life, and that new
The cell is the smallest unit of life. Some eukaryotic organisms are multicellular. cells are created by old ones dividing into
simple organisms consist of just one cell, The intricately organised insides of two. Viruses – simple entities of genes and
whereas more complex beasts, like us, have eukaryotic cells allow them to have different protein – need to get into a cell and hijack its
vast numbers of them. Humans are among things happening in different compartments. cytoplasmic machinery to copy themselves.
the organisms built up from eukaryotic Keeping a cell going depends on getting We describe these as acellular, and they are
cells, which have their DNA parcelled the right molecules to the right place at the not considered to be living.
up in a nucleus, and lots of subcellular right time. Having distinct spaces does half In this issue, we’ll be focusing on animal
compartments, called organelles. Prokaryotic the job, but it also requires sophisticated cells – how they reproduce, grow, move,
organisms (such as bacteria) are simpler: machinery to ensure the right things get communicate and die. So join us to explore
cells still with DNA, but having no nucleus into each section. Only material the cell has what we know – as well as what we still don’t
or membrane-bound structures. The vast finished with, for example, can be allowed understand – about the cells that are the
majority of these are unicellular, while most into a lysosome, where powerful enzymes basis of all of us.
microtubules – small, tubular assemblies of lysosomes – membrane-bound
protein, made from repeating tubulin subunits, organelles that are the cell’s rubbish
which help maintain the cell’s internal structure disposal and recycling units; contain
and move organelles and cytoplasm using hydrolytic enzymes extracellular matrix – the
molecular motors. Part of the cytoskeleton material in between cells that
vacuoles – internal bags, holds tissues together, usually
surrounded by a membrane, made of scaffolding proteins
which cells use for storage such as collagen
of food or waste
nucleus – the information centre
microfilaments – smaller
of the eukaryotic cell, where the
than microtubules, these are
DNA is stored, replicated and
made from repeating actin
copied into RNA (transcribed)
subunits. Responsible for
cell movement and changes
in shape, and make muscle nuclear envelope –
contraction possible. Part of double membrane that
the cytoskeleton separates the contents
of the nucleus from the
cytoplasm
centrioles – a pair of
organelles that organises
microtubules into spindles
on which chromosomes nuclear pores – gaps
are separated when in the nuclear envelope
cells divide that allow substances
to move in and out of
the nucleus
Golgi apparatus –
one of the wondrously
complex membrane
systems in the cytoplasm, nucleolus – part of the
which modifies, packages nucleus that produces
and directs newly made ribosomes
proteins to where they
are needed
endoplasmic reticulum
(ER) – an extensive network
cytoplasm – everything in
of membranes. Rough ER is
the cell outside the nucleus;
studded with ribosomes and
a viscous fluid containing
is a site where proteins are
proteins, other organic
made, modified and processed
and inorganic molecules,
for shipping. The roles of
membranes and organelles
smooth ER include lipid and
steroid synthesis and drug
detoxification
mitochondria (singular: ribosomes – molecular machines,
mitochondrion) – rod-shaped plasma membrane – a phospholipid built from RNA and protein, that
bodies in the cytoplasm that bilayer that contains cholesterol make new proteins. They are found
supply chemical energy to the and proteins. it surrounds the cell and in the cytoplasm and bound to the
rest of the cell enables it to communicate with its rough endoplasmic reticulum
neighbours and detect and respond
to changes in the environment
JANUARY 2011 • 3