+
you
Canbelieve
it?
10
THE
BIG
QUESTIONS
AARON CASEY
Let’s talk about sex
PUB: ADVERTISER
Q
HOW did life
evolve on Earth?
A
8/11/11 28 STATE
FOR life to continue and evolve,
organisms must
successfully
reproduce.
Did you know that not all
organisms do this in the
same way?
Single cell organisms, such
as bacteria, mainly reproduce using asexual reproduction, where the cell
duplicates its genome
(DNA) and then divides into
two so that each cell has one
copy of the genome.
In this case the daughter
cells are identical – they
are clones.
Multicellular organisms,
including humans, generally
reproduce via sexual reproduction, a process which requires the production of gametes (sperm and eggs in
animals) and their fusion
(usually from two different
parents) to form offspring.
Sex requires attracting
partner(s) and mating, both
complex procedures that require lots of energy.
For example, the colourful
plumage of the male peacock
might attract a mate but it
also reduces camouflage,
making it an obvious target
for predators.
To understand why sex is
so successful despite coming
at a great cost, we need to
look at the genetics of sex.
DNA is wrapped up in
chromosomes. In a sexually
reproducing species, an individual will have two copies of each chromosome in
each cell – one from
each parent.
However, there is one exception. The gametes, which
DID YOU KNOW?
■ Sexual reproduction requires
two parents, while asexual
reproduction requires only one.
■ Sexual reproduction requires
the expenditure of vast amounts
of energy compared with
asexual reproduction.
■ In a sexually reproducing
species, each individual has
its own unique combination
of traits, while in an
asexually reproducing species
each individual is a clone of
its parent.
COL: C M Y K
are produced in the testes
and ovaries, have only one
copy of each chromosome as
a result of a special process
known as meiosis.
At the start of meiosis,
chromosomes from the father pair with the
chromosomes from the
mother and DNA is exchanged between the pairs
creating a unique set
of chromosomes.
Two subsequent cell divisions result in cells that
have half the number of
chromosomes, which are
now slightly different from
their parents’ chromosomes
because of the swapping of
DNA between the
chromosomes when
they pair.
After mating, sperm and
egg cells will fuse with each
other to restore the
chromosome number and
create a new organism with
a completely unique set of
chromosomes.
This is why so much variation is created with each
generation, and why children look different from
their parents.
So sex results in variation
between parents and off-
EducationNow contacts
NEW LIFE: Sexual reproduction leads to offspring with a unique set of chromosomes.
spring, but why is this
important?
We live in an everchanging environment and
sometimes these changes are
sudden and dramatic, so
much so that sometimes individuals cannot survive in
the changed environment.
Sexual reproduction provides variation so there are
some individuals that are
able to survive in the new
environment, an outcome
that would not be possible if
the species were all clones.
SHERADYN HOLDERHEAD
NIE MANAGER/JOURNALIST: Martina
Simos, phone 8206 2613,
email: [email protected]
SCIENCE REPORTER: Clare Peddie,
phone 8206 2204,
email: [email protected]
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+
28 The Advertiser
www.adelaidenow.com.au
Molecular & Biomedical
Sciences, and the Research
Centre for Reproductive Health,
Robinson Institute, University
of Adelaide.
To find out more about the 10
Big Questions, go to: http:/
/ua.edu.au/sciences/10bq
Students bring dreaming to life
EDITOR: Sheradyn Holderhead,
phone 8206 2300, email:
[email protected]
Published by The Advertiser Newspapers,
31 Waymouth St, Adelaide, SA 5000.
GPO Box 339 Adelaide, SA 5001.
Sex is the key to understanding the huge variation
that makes humans so different and also to why our
environment is so
wonderfully complex.
■ Aaron Casey is a PhD student
in the Grutzner Lab, School of
ACHIEVEMENT: Computer science students Dominic Smart, Dennis
Hsieh and Ke Liu with Marra Dreaming artist Samantha Snow.
Tuesday, November 8, 2011
UNISA students are helping to
promote the work of a community organisation which teaches
and sells Aboriginal art to reduce social isolation.
Students studying professional writing and computer science
have been working on the redevelopment of the Marra Dreaming website as part of the Hands
Working Together project.
In collaboration with AGL
they have also replaced the ailing IT infrastructure for the
organisation and secured computers to replace those that had
become outdated.
UniSA acting-pro vice chancellor Associate Professor
Brenton Dansie said it was part
of the Community Service
Learning Project course offered
by the university which taught
students how their skills could
meet community need.
‘‘It’s one thing to gain profes-
sional skills through a university degree, but it is another to
learn how these skills can be
used for the betterment of society,’’ he said.
‘‘The result of the collaboration has seen a distinct lift in
morale among the volunteers in
the organisation which runs on
a very limited yearly budget and
it has given our students particular experience in helping to
achieve something tangible.’’
Computer science student
Dennis Hsieh worked with two
fellow UniSA students to upgrade the Marra Dreaming computer network.
‘‘We made it a wireless structure so they can print using
their laptop wirelessly. . . (and)
set up a file sharing so they can
share files within the business
itself which will save time as
well,’’ he said.
Go to the website
www.marradreaming.com.au
for more information.