Download Chromosomal Structure HWK

Chromosomal Structure HWK Solutions (pg. 267, #1-5)
1. (a) A histone is a positively charged protein that DNA is bound to in a chromosome; a nucleosome is a complex of eight histones
enveloped by DNA
(b) A telomere is a long sequence of repetitive, noncoding DNA that is found at the end of chromosomes, while a centromere is a
constricted region of a chromosome that holds two replicated chromosome strands together
(c) A LINE is a DNA sequence of 5000 to 7000 nucleotides that are repetitive and alternate with other DNA sequences within the
genome of higher organisms. A SINE differs from a LINE by the length of nucleotides. SINEs are approximately 300 nucleotides
long.
2.
2.
CHROMOSOME
HISTONES
DNA
Exons
Introns
Variable Number
Tandem Repeats
Pseudogenes
LINEs
SINEs
Connections
3. (a) If a SINEMaking
were found
within an exon and it was not excised during the posttranscriptional modifications made to the mRNA
3. (a) If
a SINE were
within
an exonamino
and it acids
was not
during the posttranscriptional modifications made to the
transcript, the protein
expressed
wouldfound
contain
extraneous
andexcised
be dysfunctional.
mRNA
transcript,
the there
protein
expressed
contain
amino acids and be dysfunctional.
(b) If a SINE were found
within
an intron,
would
be no would
effect in
terms extraneous
of protein synthesis.
(b)
If
a
SINE
were
found
within
an
intron,
there
would
be
no
effect
in
terms of protein synthesis.
(c) If a SINE were found within a telomeric region, there would be no effect.
(c) If a SINE were found within a telomeric region, there would be no effect.
The field
forensics
can exploitofthe
variability
VNTRs
found among
individuals.
DNAindividuals
from different
individuals can
4. The field of4.forensics
can of
exploit
the variability
VNTRs
foundofamong
individuals.
DNA
from different
can be
be compared
theirDNA
VNTR
regions usingHumans
DNA fingerprinting.
Humans
very similar
their
coding the
regions.
compared in their VNTR
regionsinusing
fingerprinting.
are very similar
in theirare
coding
regions.inFor
example,
gene For
example,
gene
forenzymes
collagen,are
insulin,
amylase,
andhumans;
other enzymes
arewould
identical
between
hence, it would be
for collagen, insulin,
amylase,the
and
other
identical
between
hence, it
be futile
to tryhumans;
to differentiate
futile at
to these
try to sites.
differentiate
between
two individuals
at these
sites. from
The DNA
in noncoding
regions
varies greatly
from
between two individuals
The DNA
in noncoding
regions varies
greatly
individual
to individual.
Noncoding
regions
individualcombinations
to individual.ofNoncoding
regions
ofregion.
VNTRs.
Different
of VNTRs
exist for a specific
consist of VNTRs. Different
VNTRs exist
for aconsist
specific
For
example,combinations
the DS180 region
of chromosome
1 can
Forofexample,
the DS180
region ofThis
chromosome
can
have anywhere
1 repeat
of that
the sequence
to 45
have anywhere fromregion.
1 repeat
the sequence
to 45 repeats.
variability1far
outweighs
the twofrom
or three
alleles
are possible
forrepeats.
This
variability
far
outweighs
the
two
or
three
alleles
that
are
possible
for
most
genes
found
in
coding
regions.
For
most genes found in coding regions. For this reason, noncoding DNA comprising VNTRs is used to differentiate among individuals inthis
reason, noncoding DNA comprising VNTRs is used to differentiate among individuals in the field of forensics.
the field of forensics.
5. Telomeres and centromeres play specific roles in maintaining the integrity of DNA in an organism. Telomeres protect a
genome from
thespecific
degradation
results fromthe
theintegrity
process of
of DNA
DNA in
replication.
It would
be disadvantageous
for an exon
5. Telomeres and centromeres
play
rolesthat
in maintaining
an organism.
Telomeres
protect a genome
to that
be found
the telomeric
region,
because
the telomeric
regions
are degraded over
time
to preserve
the in
genome.
If the
from the degradation
resultsinfrom
the process
of DNA
replication.
It would
be disadvantageous
for an
exon
to be found
the
exon coded
for a protein,
thatare
protein
would
eventually
cease to the
be expressed
nucleotide
sequencethat
would be
telomeric region, because
the telomeric
regions
degraded
over
time to preserve
genome. Ifbecause
the exonitscoded
for a protein,
destroyed.
same
reasoning
applies
centromeres.
Centromeres
a role inThe
keeping
chromosomes
protein would eventually
ceaseThe
to be
expressed
because
its to
nucleotide
sequence
would beplay
destroyed.
samehomologous
reasoning applies
to
togetherplay
during
cellindivision.
an exon were
found in thistogether
region,during
it may cell
not be
expressed.
centromeres. Centromeres
a role
keeping If
homologous
chromosomes
division.
If an exon were found in
this region, it may not be expressed.
INVESTIGATION 5.4.1 PROTEIN SYNTHESIS AND INACTIVATION OF ANTIBIOTICS
(Page 268)
Question
Ensure that students write their predictions while still in the classroom.
Prediction
(a) Student answers will vary. Most students will correctly predict that E. coli MM294/pAmp will survive on ampicillin-rich
media, while E. coli MM294 will not.
Sample Results
E.coli MM294/pAmp will grow on the LB/amp plate while E. coli MM294 will not. Both strains of E. coli will grow on the
LB plates. The growth should be plentiful with a few individual colonies being isolated.