DNA & Biotechnology/ Patterns of Genetic Inheritance

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22 Οκτ 2013 (πριν από 4 χρόνια και 17 μέρες)

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DNA &

Biotechnology
/ Patterns of Genetic Inheritance



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T
ask 1: DNA Structure and Replication

1.

Read
“Introduction”

(pg 213
) and section
16
.1 “DNA Structure and
Replication”

(pg 214
)
.

2. Complete

F
igure 16
.1

“Overview of DNA structure”

(pg 214
)

3.

Read and

complete
“Observation:
DNA Structure”
,

questions 3
-
7 (pg 215
). In
T
able 16
.1

“Base Colors”

skip the “in you
r

kit” section.

4. Read and complete
“Observation:
DNA Replication”
, questions 1
-
5 (pgs

216
-
217
), and
T
able 16
.2

“DNA Replication”

(pg 216
).



Do n
ot continue until your TA checks your progress.

Task 2: RNA Structure

1.

Complete
Figure 16
.3 “Overview of RNA Structure”

(pg 217
),


2.

Answer questio
ns 1
-
3
and complete
T
able 16
.3

“DNA and RNA Bases”

(
pg
217
).

3
.

Perform
“Observation: RNA Structure”

and c
ompl
ete
Table 16.4

“Base
Colors” (
skip the “in your kit” section)

and
Table 16.5
“DNA Structure

Compares with RNA Structure”

(pg. 218
).



Do not continue until your TA checks your progress.

Task 3: DNA and Protein Synthesis

1.

Read section
16
.3 "
DNA and
Protein Synthesis
"

(pg. 218
) and

Transcription


(pg 219
). Complete
F
igure 16
.4

“Messenger RNA (mRNA)”

and
T
able 16
.6

“Transcription”

(pg 219
).

2. Read

Translation


(pg 220
)

and complete
Figure 16.5 “Transfer RNA”
(pg.
220)
.

3.
Perform
“Observation: Tr
anslation”
, answer question 1
-
2 and c
omplete
F
igure
16
.6
“Transfer RNA diversity”
(pg 220
).

4
. Complete
T
able 16
.7

“Translation”

and
F
igure 16
.7

“Protein synthesis”

(pg
221
).

5
.

Read section

16
.4

“Isolation of DNA”

(pg 223
). Perform

Experimental
Pro
cedure:

“Isolation of DNA”

following this procedure (
Note: Do not follow the
manual’s instructions
):


1. Cut the onion into several small pieces and place in the mortar.


2. Ad 10ml of detergent solution.


3. Gently grind the onion with the pestle until yo
u obtain a mushy mixture.


4. Place a piece of cheesecloth in the funnel and filter the onion mixture into a
beaker.


5. Decant as much of the onion mixture as possible int
o the beaker, trying to
leave mo
st of the foam behind.


6. Add 3ml of the protease
solution to the beaker containing the clean, filtered
onion solution. Swirl gently to mix.


7. Slowly and gently add 3
-
5ml of ice cold ethanol to the onion/protease solution.
Disperse it slowly against the side of the beaker so that it flows over the surfa
ce
of the solution. The purpose is to maintain two separates layers. If the layers mix
you will not get a good DNA isolation.


8. Let the solution sit for about 3 minutes. Don not disturb it
in any way. You
should see
the DNA begin to precipitate into the

alcohol layer.


9. Collect the DNA by gently spooling them onto the glass Pasteur pipette.

4. An
swer question 6 (pg 223
).



Do not continue until your TA checks your progress.

Task 4: DNA Fingerprinting
(Adopted from Sylvia S. Mader. 2008. DNA and
Biote
chnology. In: Human Biology Laboratory Manual, 10
th

ed. Boston: McGraw
-
Hill).


1. DNA Fingerprinting:

A genome is all
the
genetic material in a set of chromosomes. The genome
contains portions of DNA (i.e. genes) that code for the various proteins and spec
ialized
RNAs (tRNAs and rRNAs). Other DNA portions are sometimes called “junk” because
they do not code for proteins or RNAs

(
these sections are repeats of the same short
sequence of bases over and over again
)
. Detectable differences in the noncoding
porti
ons of the genome comprise an individual’s
DNA fingerprint.
DNA fingerprinting
has many uses.


DNA fingerprinting is used by (1) police and courts to identify a person who has
committed a crime; (2) genetic counselors to determine if an individual has or w
ill
develop a genetic disorder; (3) lawyers to determine relatedness between individuals;
(4) scientists to determine the identity of individuals based on minimal remains after
death. DNA fingerprinting is also used by (1) conservation biologists to determ
ine the
genetic dissimilarity of males versus females for breeding purposes; (2) evolutionary
biologists to construct evolutionary trees; and (3) taxonomist to distinguish species.


DNA fingerprinting requires three steps (Figure 1):

1. Fragmentation of
a

selected portion of the genome. The DNA is digested with
restriction enzymes,
which results in variable
sized fragments unique to the individual.

2. Gel electrophoresis. The DNA fragments are separated according to their length, and
the result is a DNA pa
ttern unique to the individual.

3. Analysis of the DNA pattern. The pattern is revealed by using radioactive probes or
by staining. If you are dealing with just a small portion of the genome, staining of the gel
is sufficient to reveal the fragment pa
ttern.


Figure 1. DNA Fingerprinting.


During DNA fingerprinting, DNA samples are digested to fragments. The fragments are separated by
gel electrophoresis, and then the resulting fragment length pattern is observed. In this example, the
sample in well I

could be from the crime scene, making the DNA in well II from the criminal; or the
DNA from well I could be from a parent , making the donor of the sample en well II his child; or
sample I could be from a body part, making sample II the deceased individua
l. In the last case,
sample II would have been taken from some object known to belong to the individual in question.


2. Analyzing the DNA pattern:

Figure 2 shows the fragment patterns of 4 samples: one collected from a crime
scene (CS) and three suspects
(S1, S2, S3). Which of the suspect’s DNA matches
the DNA sample collected from the crime scene? _________.






Figure 2. DNA Fingerprints

These are the DNA fingerprints for the crime scene DNA sample and the three suspects’ s
amples. In this
case, comparing the DNA fragments patterns allows you to determine who committed the crime. In other
instances, DNA fragment patterns allow you to determine who is the parent of a child, whether a person has
a genetic disorder, or the ident
ity of the remains following death.


Task 5: Patterns of Genetic Inheritance

1. Read
“I
ntroduction


(pg 201
)
.

2. Read
“Autosomal Dominant and Recessive Traits


and familiarize yourself with
F
igure 1
5
.2

“Commonly
inherited t
raits

in human beings


(pg 202
) N
ote:
Don’t answer the questions.



3. Read section
15
.2

“Determining Inheritance”

(pg. 204). C
omplete
“Inheritance
of Genetic Disorders”

(pg 204
)

and
“Autosomal
Disorders


(pg. 205
-
206)
.

4. Read and complete
“X
-
linked Disorders”

(pg. 206
).

5. Read
“X
-
l
inked Genetic Problems”

and answer q
uestions 1
-
2 (pg 207
).

6. Read section
15
.3

“Determining the Pedigree”

(pg 208
). Complete
“Pedigree
Analysis”

(pgs 208
-
209
).

7. Answer


Laboratory

Review


Questions 1
-
9 (pg 211
).



Do not leave the class until your TA c
hecks your progress.

WRAP UP