unit 11

Question 1

1) Proteins found on the surface of red blood cells are called .

Answer 1

Anti-gens

Question 2

Phenolphthalein is used to determine the presence of_____by its reaction with ____

Answer 2

Blood, hemoglobin and hydrogen peroxide

Question 3

CODIS stands for______.

Answer 3

Combined DNA Index System- developed by the FBI and it maintains local, state and national databases of DNA profiles

Question 4

What is the correct set of antigen/antibody found in the blood types A, B, AB, and O?

Answer 4

Type AB has A and B antigens, but no antibodies
Type O has no antigens but A and B antibodies
Type A has A antigens and B antibodies
Type B has B antigens and A antibodies

Question 5

How is luminol used to detect blood?

Answer 5

Reacts with blood and iron present in hemoglobin( red blood cell protien). It emits light which is a blue luminescence only seen in the dark

Question 6

What procedures and materials are used in the forensic analysis of semen?

Answer 6

Presumptive test where you look for semen with UV light and it turns purple in prescence of acid phosphatase
Or the confirmatory test where microscopes reveal spermatozoa which dna is also taken

Question 7

What are the problems with mitochondrial DNA (mtDNA) analysis in identifying a specific individual?

Answer 7

The problems with it is that it is more costlier and not as useful as STR

Question 8

Define the area of convergence and area of origin and explain what each reveal to an investigator.

Answer 8

convergence-The area on a two-dimensional plane where lines traced through the long axis of
several individual bloodstains meet. This approximates the two-Dimensional Place from which the
bloodstains were projected.

Origin- The location in three-dimensional space that blood
that produced a bloodstain originated from. The location of the
area of convergence and the angle of impact for each bloodstain is
used to approximate this arterial spray—A characteristic
bloodstain pattern containing spurts that resulted from blood
exiting under pressure from an arterial injury.

Question 9

A destructive protein found in the blood serum is called .

Answer 9

Antibody, fibrin, albumin

Question 10

Describe the droplet satellites.

Answer 10

The satellites are droplets that spar away from the main splatter in result of it hitting the ground. They provide additional information about the force and direction of the impact.

Question 11

What are the possible reasons for the difference?

Answer 11

Dropped at different angles, Velocity

Question 12

Compare a Polymerase Chain Reaction to a Short Tandem Repeat.

Answer 12

PCR is a technique used to amplify a specific DNA sequence, STR is a type of DNA polymorphism that is used in DNA profiling.

Question 13

What are the possible concerns with DNA evidence collection?

Answer 13

Contamination, degradation, mixtures of DNA from multiple sources and potential mishandling or tampering.

Question 14

How can pools of blood aid in reconstructing a crime scene?

Answer 14

They can be analyzed because the drying time of blood can give an estimation of time since the blood was dropped

Question 15

What are the steps needed for DNA extraction?

Answer 15

Cell lysis: breaking open cells to release the DNA DNA Precipitation: Separating the DNA from other cellular components DNA Purification: removing impurities to obtain pure DNA.

Question 16

Give a description of the shape of blood droplets on porous and nonporous surfaces.

Answer 16

On porous surfaces, blood droplets may appear more spread out but on NON porous surfaces they maintain a more circular shape with less absorption to the material its on—–> dropping blood on paper vs lab table.

Question 17

the three most distinctive patterns we discussed are gunshot, stabbing, and blunt object impact.

Answer 17

gunshot = <1mm
stabbing = 1-4mm
blunt object = 4-6mm

Question 18

define the area of convergence and area of origin an explain what each reveal to an investigator

Answer 18

AOC = the area 2D plane where lines traced through the long axis of several indiv bloodstains meet apprx from which bloodstains were projected
AOO= 3D space where a bloodstain originated from. location of AOC and AOI for each bloodstain is apprx this arterial spray
A characteristic bloodstain pattern containing spurts that resulted from blood exiting under pressure from an arterial injury

Question 19

What factors are considered evidence?

Answer 19

1. location
2. distribution
3. appearance
4. direction
5. dropping distance
6. angle of impact

Question 20

compare a polymerase chain reaction to a short tandem repeat

Answer 20

PCR = copy DNA strands, amplify minute quantities, shorter strands
STR = latest method of DNA typing, region of DNA molecule containing short segments of 3 to 7 repeating base pairs

Question 21

The width of the
bloodstain was measured at 2.3mm, with the length of the blood stain being measured at 2.9mm. What is the
angle of impact?

Answer 21

Width/Length and use tan-1, then multiply by180

tan-1(2.3/2.9) =x

x(180)= answer in degrees