NCEA Level 3 Science (90729) 2011 — page 1 of 3
Assessment Schedule – 2011
Science: Describe genetic processes (90729)
Assessment Criteria
Q
Evidence
ONE
The three forms of RNA are messenger
RNA (mRNA), transfer RNA (tRNA)
and ribosomal RNA (rRNA).
They are all made up of RNA
nucleotides, which consist of a
phosphate, a ribose sugar and a
nucleotide (A, G, C or U).
mRNA is a single stranded RNA
which is a copy of the DNA. Its
purpose is to carry the code from the
nucleus (DNA) to the cytoplasm via a
nuclear pore.
rRNA is the RNA component of the
ribosome that is folded up with
proteins to form the two subunits.
Together they make the ribosome,
which ‘reads’ the mRNA strand and
matches the tRNA. It then joins the
amino acids together with a peptide
bond to form the polypeptide chain.
tRNA is a strand of RNA that is folded
into a clover like shape.
http://en.wikipedia.org/wiki/File:TRN
A-Phe_yeast_1ehz.png
It carries an amino acid at one end and
has an anticodon at the other end. It
carries a specific amino acid that
matches the anticodon.
The order of bases on the codon
(mRNA) and the anticodon (tRNA)
determines the order of the specific
amino acids in the protein being made.
Achievement
Description of the
structure for TWO
forms of RNA.
OR
Description of the
function for TWO
forms of RNA.
Eg: mRNA is a
single strand of
RNA that is made
up of C, G, A and
U nucleotides.
rRNA is the RNA
found in a ribosome
and it is folded up
with proteins to
complete the
structure.
tRNA is a folded
(clover leaf) shape
of RNA with three
bases (anticodon)
and a specific
amino acid.
Note: if described
all RNA as single
stranded in a
general statement
this feature is not
needed in answer
for specific forms of
RNA
Achievement with
Merit
Achievement with
Excellence
Full explanation of
the structure and
function for TWO
forms of RNA
AND
a link between the
genetic code and the
protein being
produced for
EITHER mRNA or
tRNA
Full discussion of
how TWO forms of
RNA interact,
including their
structure linked to
their function.
Eg: mRNA is a single
strand of RNA that is
made up of C, G, A
and U nucleotides; its
function is to carry
the transcribed code
from the DNA in the
nucleus to the
ribosome in the
cytoplasm.
rRNA is the RNA
found in a ribosome
and it is folded up
with proteins to
complete the
structure. Its function
is to help ‘read’ the
mRNA sequence..
tRNA is a clover leaf
shaped molecule with
an anticodon and a
specific amino acid
attached.
The ribosome is made
up of two sub units
which attached to the
mRNA strand
allowing one codon to
be read at a time. This
allows for a specific
tRNA molecule to
come into place. The
bases on the codon
and the anticodon are
complementary (base
pair). The specific
amino acid is brought
into place and is able
to bond (peptide
bond) to the
polypeptide chain.
Eg: mRNA is a single
strand of RNA that is
made up of C, G, A
and U nucleotides; its
function is to carry
the transcribed code
from the DNA in the
nucleus to the
ribosome in the
cytoplasm. The order
of the codon codes
for the amino acids
that make up the
protein.
rRNA is the RNA
found in a ribosome
and it is folded up
with proteins to
complete the
structure; its function
is to help ‘read’ the
mRNA sequence.
tRNA is a folded
molecule with a
clover leaf shape. It
carries an amino acid
at one end and has an
anticodon (3 bases).
The different
anticodons code for
the specific amino
acids that make up
the protein.
NCEA Level 3 Science (90729) 2011 — page 2 of 3
TWO
A point mutation is when one base
changes, which results in a base pair
change. It can have little or no effect
on the polypeptide chain, depending on
where the mutation occurs in the
sequence.
A protein is produced from the DNA of
an organism. The order of nucleotides
gives the sequence of codons, which
will result in the order of the amino
acids. The polypeptide chain then folds
up according to the properties of the
specific amino acids.
Some amino acids have several
different codon sequences that code for
them, usually the third base in the
codon is irrelevant. This means that if a
mutation occurs, the same amino acid
could still be coded for.
Also some amino acids have similar
properties to others. This means that if
the mutation codes for a different
amino acid that has similar properties
to the original amino acids, then the
polypeptide chain could still function,
as it still folds in a similar way.
Description of a
point mutation.
OR
Description of
protein synthesis.
Eg: A point
mutation is where a
single base changes
in the DNA
sequence.
Explanation of how a
point mutation has
little effect or no
effect on the amino
acids produced.
Full discussion a
point mutation can
have little effect and
no effect on the
protein produced.
Eg: A point mutation
is where a single base
changes in the DNA
sequence. It can have
little or no effect on
the amino acid
produced, because
amino acids have
more than one
possible codon
sequence for them.
This means that if
there was a point
mutation, then the
same amino acid
could still be coded
for.
Eg: A point mutation
is where a single base
changes in the DNA
sequence. It can have
little or no effect on
the amino acid
produced, because
amino acids have
more than one
possible codon
sequence for them.
This means that if
there was a point
mutation, then the
same amino acid
could still be coded
for.
This would then
result in the exact
same protein being
produced; it would
still fold up in the
same way and
therefore still
function the same.
NCEA Level 3 Science (90729) 2011 — page 3 of 3
THREE
A DNA profile is made by collecting a
sample of DNA.
If the sample is too small to test, then
PCR can be carried out to create more
identical copies of the original DNA.
Restriction enzymes are then added to
the sample. The restriction enzymes cut
the DNA at specific sequences,
depending on the enzyme used. This
results in the DNA being cut into
different sized fragments, depending
on the sequence.
Electrophoresis then separates out the
cut DNA, depending on the size of the
fragments. It works by using an electric
charge to move the fragment through a
gel. Because DNA is negatively
charged, the DNA will move towards
the positive end of the container.
Shorter fragments will travel further
than longer fragments.
Description of use
restriction enzymes.
OR
Description of how
PCR is used to
amplify the DNA
ready for profiling.
OR
Description of use
of DNA profiling.
OR
Description of how
relatedness can be
shown.
Eg: The DNA
profile produced
can show how
closely related the
birds are by looking
at the banding
pattern. If they are
similar, then they
are closely related.
Once it is run through, an image is
created and the order of bands is
compared. If two organisms are closely
related, there will be similar banding
pattern. The more distantly related
organisms are, the greater the
difference in the banding patterns.
Explanation of the
use of DNA profiling
using restriction
enzymes.
OR
Explanation of the
use of DNA profiling
using PCR.
OR
Explanation of the
use of DNA profiling
and how it can show
relatedness.
Eg: A DNA profile is
made by using the
lengths of the cut
DNA to run an
electrophoresis gel.
The gel uses an
electric charge to
separate out the
strands of DNA; the
shorter strands travel
further than the
longer strands. Once
the gel is run, then an
image is made of the
gel and the order and
sizes of the bands are
compared. More
closely related birds
will have more bands
in common than
distantly related
birds.
Full discussion of the
use of DNA profiling
using restriction
enzymes, and/or PCR
and how this can be
used to show how
closely related the
organisms are.
Eg: A DNA profile is
made by using the
restriction enzymes to
cut the DNA sample
into various sized
lengths. The
restriction enzyme
used will cut at
certain sequences of
DNA and will
therefore cut the
birds’ DNA in
different places,
depending on the
sequence of DNA.
The lengths of cut
DNA are then run in
an electrophoresis
gel. The gel uses an
electric charge to
separate out the
strands of DNA; the
shorter strands travel
further than the
longer strands. Once
the gel is run, then an
image is made of the
gel and the sizes of
the bands are
compared. More
closely related birds
will have more bands
in common than
distantly related birds.
Judgement Statement
Achievement
Achievement with Merit
Achievement with Excellence
2A
2M
2E