Biology Lab || Blood and Blood Typing
Summary
TLDRIn this intriguing video, crime scene investigators collaborate with a forensic scientist to solve the mystery of a missing sandwich. After a mishap with a water glass, the sandwich vanishes, leaving behind a smudged fingerprint and blood drops. The blood type A negative matches the rarest type, guiding the investigation towards four suspects with bandaged hands. Through meticulous blood typing, the forensic scientist identifies suspect three as the likely culprit, whose blood type aligns with the crime scene, leading to a confession and the resolution of the case.
Takeaways
- 🔍 The video script describes a crime scene investigation process where a sandwich goes missing and evidence is collected to solve the mystery.
- 👮♂️ Crime scene investigators search for evidence like fingerprints, hair, or blood to prove the innocence or guilt of suspects.
- 🧬 Forensic scientists analyze the evidence, such as blood samples, to determine blood types which can help identify the culprit.
- 🍞 The case involves a missing sandwich where a suspect cut themselves on broken glass, leaving behind blood evidence.
- 🔎 The blood evidence collected is Type A, Rh-negative, which is rare and could be a significant clue in identifying the suspect.
- 🧬 Blood types are determined by the presence of antigens A, B, or neither, and can be further classified by the Rh factor.
- 🧪 Blood typing is done by mixing blood samples with serums containing specific antibodies to see how they react.
- 👤 There are four suspects with bandages on their hands, implying they might have a cut from the broken glass.
- 🧪 Each suspect's blood sample is tested against serums to determine their blood type and compared with the crime scene blood.
- 🔑 Suspect 3's blood type matches the crime scene blood, making them the prime suspect in the sandwich theft.
- 🤔 The matching blood type is not conclusive proof but, combined with the elimination of other suspects, it points to Suspect 3.
- 🎓 The script also educates about blood typing and the role of antigens and antibodies in the process.
Q & A
What is the main objective of the crime scene investigators in the script?
-The main objective of the crime scene investigators is to search for evidence that may prove the innocence or guilt of suspects, specifically focusing on the case of the missing sandwich.
What evidence was found at the scene of the missing sandwich incident?
-The evidence found at the scene included a smudged fingerprint and a few drops of blood on the broken water glass and on the table.
Why was the fingerprint evidence considered inconclusive?
-The fingerprint was smudged, which made it difficult to obtain clear and usable information for identification purposes.
What type of blood was found at the crime scene and how is this significant?
-Type A, Rh-negative blood was found at the crime scene. This is significant because it is rare, occurring in less than 1% of the world's population, which could help narrow down the suspects.
What is the role of forensic scientists in this investigation?
-The forensic scientists are responsible for analyzing the blood samples to determine the blood type, which can then be matched with a suspect to potentially solve the case.
How many possible suspects were identified in the script, and what common characteristic did they share?
-Four possible suspects were identified, and they all shared the common characteristic of having a bandage on their hand, which could be covering a cut made by the broken water glass.
What is the basis for blood typing and how is it performed?
-Blood typing is based on the presence of certain antigens and the Rh factor in the blood. It is performed by mixing small samples of blood with serums containing anti-A, anti-B, and anti-RH antibodies to see how they react.
How did the forensic scientist determine the blood type of the suspects?
-The forensic scientist used special slides with wells containing drops of blood and serum. By observing the reactions of the blood cells with the different serums, they were able to determine the blood type of each suspect.
What blood type did suspect 3 have and why was this significant in solving the case?
-Suspect 3 had AB blood type, which matched the blood type found at the crime scene. This was significant as it pointed towards suspect 3 being the likely culprit who took the sandwich.
How did the other three suspects' blood types not match the crime scene evidence?
-The blood types of the other three suspects were Type A positive, Type B positive, and Type O positive, none of which matched the Type A, Rh-negative blood found at the scene.
What was the final outcome of the investigation after testing the blood of all suspects?
-After testing the blood of all suspects, it was determined that only suspect 3 had the matching blood type to the crime scene. Upon confrontation with the blood test results, suspect 3 confessed to taking the sandwich.
Outlines
🔎 Crime Scene Investigation of the Missing Sandwich
The script introduces a crime scene investigation scenario where a sandwich goes missing after an investigator accidentally spills water, breaking a glass. The scene is examined for evidence, resulting in the discovery of a smudged fingerprint and drops of blood on the broken glass and table. The fingerprint is inconclusive, but the blood is sent to a forensic scientist for typing. Four suspects, each with a bandaged hand, are identified. The blood from the scene is determined to be rare Type A negative, which is a significant clue in narrowing down the suspects.
🧬 Blood Typing Analysis to Solve the Sandwich Mystery
This paragraph delves into the process of blood typing to identify the culprit behind the missing sandwich. It explains the basics of blood antigens and antibodies, the different blood types (A, B, AB, O), and the Rh factor. The forensic scientist uses special serums to test blood samples from the suspects against anti-A, anti-B, and anti-RH antibodies. The results of these tests are used to determine the blood type of each suspect and compare it with the blood found at the crime scene. Suspect 3's blood matches the crime scene's Type A negative, leading to the conclusion that they are likely the thief.
🎬 Conclusion of the Sandwich Investigation and Next Lab Preview
The final paragraph wraps up the investigation by confirming that Suspect 3's confession aligns with the blood typing results, solving the mystery of the missing sandwich. It also provides a brief preview of the next lab session, which will involve a demonstration of lung function, suggesting a continuation of the educational content in a different scientific context.
Mindmap
Keywords
💡crime-scene investigators
💡forensic scientist
💡evidence
💡blood type
💡antigens
💡antibodies
💡Rh factor
💡serums
💡suspects
💡blood typing
💡mystery
Highlights
Crime scene investigators search for evidence like fingerprints, hair, or blood to prove innocence or guilt of suspects.
The case of the missing sandwich is being investigated, with evidence found at the scene including a smudged fingerprint and blood drops.
The blood evidence is sent to a forensic scientist for analysis to determine the blood type.
Four possible suspects with bandaged hands are identified, and their blood samples are collected for testing.
Blood type A negative is rare, making it a significant clue in solving the case.
Blood types are determined by the presence of antigens A, B, or neither, and the Rh factor.
Special serums containing antibodies are used to detect the presence of antigens in blood typing.
Blood typing involves mixing blood samples with serums to observe reactions and determine blood type.
Suspect one's blood type is determined to be A positive, which does not match the crime scene blood.
Suspect two's blood type is B positive, also not matching the blood found at the scene.
Suspect three's blood type is AB, which matches the blood type found at the crime scene.
Suspect four's blood type is O positive, not matching the crime scene blood.
The matching blood type of suspect three makes him the probable culprit of the missing sandwich case.
Blood typing is a crucial forensic method used to solve crimes by matching blood evidence to suspects.
The forensic scientist's analysis of blood samples helps narrow down and identify the suspect in the case.
The mystery of the missing sandwich is solved using blood typing, demonstrating the practical application of forensic science.
The case illustrates the importance of careful evidence collection and analysis in criminal investigations.
Transcripts
[Music]
crime-scene investigators search the
scene of a crime looking for evidence
that may prove the innocence or guilt of
suspects they search for fingerprints
hair or a trace of blood that can be
matched to a suspect the evidence
gathered by crime scene investigators is
analyzed by forensic scientists in this
lab we are the crime scene investigators
and we will be working with a forensic
scientist to solve a mystery today we
are investigating the case of the
missing sandwich here are the facts
we've already established concerning
this case one of our investigators was
about to enjoy a delicious sandwich for
lunch when she accidentally knocked over
her glass of water the glass broke and
water spilled on the table and floor
she left the lunchroom to get some
towels to mop up the water when she
returned her sandwich was missing upon
examination of the scene we discovered
some evidence a smudged fingerprint and
a few drops of blood on the broken water
glass and on the table apparently the
person who took the sandwich cut himself
on the broken glass when he was reaching
for the sandwich the smudged fingerprint
provided inconclusive evidence so we
focused our attention on the drops of
blood we requested that samples of the
blood be sent to our forensic scientist
if she can determine the blood type and
we can match that blood type with a
suspect we may be able to solve this
case we found four possible suspects who
were seen near the lunch room late
yesterday afternoon each suspect had a
bandage on his hand
we knew the bandage could be covering a
cut made by the broken water glass a
sample of blood from each of the four
suspects was attained and delivered to
our forensic scientist let's go into the
lab to check on the progress of the
analysis our forensic scientist has
already determined that the blood
collected at the crime scene is Type A
beam
negative less than 1% of the world's
population has type a B negative blood
if any of the suspects has this blood
type we may have solved the mystery
what do we mean when we say blood type
all people have type a B a B or o blood
each blood type is determined by the
presence of certain antigens an antigen
is any substance that stimulates the
body to produce antibodies antibodies
are proteins that attack substances that
might cause disease or harm to the body
type A blood contains antigen a type B
blood contains antigen B type a B blood
contains both antigens a and B type O
blood contains neither antigen a nor B
blood may also contain another antigen
called the rhesus factor or Rh factor
any blood type that contains the Rh
factor is called Rh positive if blood
does not contain the Rh factor it is
called Rh negative this table will give
you a better understanding of the eight
different blood types we can detect the
presence of these antigens by using
special serums containing antibodies
blood typing is accomplished by mixing
small samples of blood with serums
containing anti a anti B and anti RH
antibodies to see how they react the
samples are mixed in the laboratory on
slides or cards if a serum containing a
specific antibody comes in contact with
its corresponding antigen the red blood
cells react by sticking together anti a
antibodies react to antigen a and type A
blood
if type A blood is added to a serum
containing anti a antibodies the red
blood cells stick together
however when type A blood is added to a
serum containing anti-b antibodies no
reaction occurs anti-b antibodies react
to antigen B and type B blood
if type B blood is added to a serum
containing anti a antibodies no reaction
occurs however when type B blood is
added to a serum containing anti-b
antibodies the red blood cells stick
together the red blood cells and type a
B blood will stick together with both
anti a and anti B serums because both
antigens a and B are present in its red
blood cells when Type O blood is tested
no reaction occurs in either serum
because Type O blood has neither antigen
a nor antigen B to determine if blood is
Rh negative or positive a sample of the
blood is added to a serum containing
anti RH antibodies the red blood cells
of Rh negative blood will not react to a
serum containing anti RH antibodies the
red blood cells of Rh positive blood
will stick together in a serum
containing anti RH antibodies now that
we have a better understanding of blood
types it is time to test the blood
samples of our suspects we use special
sides with Wells to contain the drops of
blood and serum we have a separate slide
for each suspect and have labelled the
slides s 1 s 2 s 3 and s 4 on each side
we have also labeled the wells a B and
Rh for the serums we will use to type
the blood a few drops of each serum have
been placed in each of the respective
wells next we carefully place a drop of
blood from the suspect one bottle and to
each well on the slide
labeled s whoa
to prevent contaminating our samples we
use a different stick to mix the
contents of each well let's examine the
results and compiled them in a table the
blood cells in well a are sticking
together so we write YES on our table
for anti a antibodies the cells and well
be show no reaction so we write no on
our table for anti-b antibodies the
blood cells in the RH well are also
sticking together so we write yes as
well for RH antibodies based on this
information what blood type is suspect
one blood that reacts to anti a
antibodies but not anti-b antibodies is
type A blood since the blood also
reacted to RH antibodies it is type a
positive because his blood does not
match the blood found at the scene of
the crime suspect one is probably not
the one who took the sandwich now we
follow the same procedure to test the
blood of suspect to the cells in well a
show no reaction but the cells and well
B are sticking together as are the cells
in the RH well what blood type is
suspect 2 we conclude that this blood
type is b-positive
since the blood of suspect 2 does not
match the blood found at the crime scene
suspect 2 is probably not the one who
took the sandwich now we test the blood
of suspect 3 the cells in well a and
well B are sticking together but the
cells and the RH well are not reacting
what blood type is suspect 3 we conclude
that this blood type is a b- the blood
of suspect 3 matches the blood found at
the crime scene so it is probable that
suspect 3 took the sandwich
however we should test the blood of
suspect
for just to be sure neither the cells in
well a nor the cells in well be show a
reaction however the cells in the RH
well are sticking together what blood
type is suspect for we conclude that the
blood type for suspect for is o+ which
does not match the blood found at the
crime scene the fact that the blood type
of suspect 3 matches the blood found at
the scene is not conclusive proof that
he took the sandwich however the fact
that the blood of the other three
suspects does not match the blood found
in the lunchroom is evidence that they
are not the ones who cut themselves on
the broken water glass when confronted
with the results of the blood test
suspect 3 confessed to taking the
sandwich by using blood typing we were
able to solve the mystery of the missing
sandwich in our next lab we will look at
a demonstration of how our lungs work at
this time proceed with the corresponding
activities
[Music]
you
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