DNA Profiling

Question 1

How can DNA be important in criminal investigations?

Answer 1

DNA sequences are unique to everyone (except twins)
Variation within non-coding parts for the DNA molecule is the basis for forensic I.D.

Question 2

Besides in criminal and other forensic cases, what are three other types of cases
that may utilize DNA profiling?

Answer 2

-Parentage
-Identification of disasters and war victims
-Resolution of historical and recent missing persons cases

Question 3

what is the long name for DNA?

Answer 3

Deoxyribonucleic acid (DNA)

Question 4

What is the purpose for DNA?

Answer 4

Contains genetic code for the production of proteins that enable a cell to replicate its DNA and carry on life functions.

Question 5

Nucleotides consist of three parts. What are they?

Answer 5

-nitrogenous bases
-phosphate group
-pentose sugar molecule

Question 6

What are the four nitrogenous bases that make up the helix ladder?

Answer 6

-adenine
-thymine
-cytosine
-guanine

Question 7

What is the difference between exons and introns?

Answer 7

exons:
-will be expressed
-part of the coding regions

Introns:
-will be deleted
-not part of the coding region

Question 8

What are autosomes? What are karyotypes?

Answer 8

Autosomes:The other 44 chromosomes that aren’t sex chromosomes, appear in homologous pairs

Karyotype: picture of the paired homologous chromosomes and sex chromosomes in a cell.

Question 9

How are polymerase chain reactions (PCR) related to collecting DNA evidence?

Answer 9

A method of amplifying (duplicating) minute amounts of DNA evidence for
the use of investigations.

Question 10

What is the downside to PCR?

Answer 10

Amplifying will also copy cross contamination as well as the DNA sample.

Question 11

What are three ways to limit cross contamination when handling DNA?

Answer 11

-wear and change disposable gloves.
-Avoid touching areas where DNA may exist.
-Avoid talking, sneezing, and coughing around evidence.

Question 12

What are three conditions that will damage DNA?

Answer 12

-humid
-warm
-bright

Question 13

What are restriction enzymes?

Answer 13

“Molecular scissors”
-a molecule that cuts a DNA molecule at a specific
base sequence.

Question 14

What are short tandem repeats (STRs)?

Answer 14

Sequence of repeating bases in noncoding regions of DNA that are used in DNA profiling

Question 14

how are restriction fragments created?

Answer 14

in preparation for gel
electrophoresis

Question 15

What happens during gel electrophoresis?

Answer 15

Restriction fragments are separated by size on a gel when an electric field is applied. Radioactive probes bond to the highly variable regions, creating a unique band pattern.

Question 16

How could a STR pattern be different between two people?

Answer 16

For example, one person could have a repeat of GAAT that occurs 6 times:(GAAT), (GAAT), (GAAT), (GAAT), (GAAT), (GAAT).A different form of that STR could be four repeats in a different person: (GAAT), (GAAT), (GAAT), (GAAT)

Question 17

why do forensic scientists use the 13 core STRs for identification?

Answer 17

Some chromosomes have more than 1 core STR locus, while others do not have any of the core STR loci. Some are easier to identify because of its number of repeats. It simplified a way of coding region of high variability.

Question 18

What is an allele?

Answer 18

an alternative form of a gene

Question 19

What happens when several core STR loci are used when comparing two DNA
profiles?

Answer 19

it provides greater probability of knowing that the DNA profile came from one individual and not someone else.

Question 20

How are STR markers identified during STR analysis?

Answer 20

adding fluorescent dyes to the PCR reaction, it is possible to identify different STR markers
STR alleles are id by size and color on the graphic display

Question 21

What is an allele frequency?

Answer 21

a calculation of how often a particular allele appears within
a given population.

Question 22

Why are Y STRs unique?

Answer 22

only males carry a Y chromosome.

Question 23

Why is mtDNA important for establishing familial connections?

Answer 23

Ancestry traced through the maternal line uses mtDNA because only mothers pass on mitochondrial DNA

Question 24

Why do forensic scientists only look at the regions of high variability while
comparing two DNA profiles?

Answer 24

-low variability means that there’s little difference between 2 profiles
-99% of all human DNA is the same, so scientists only need to examine that 1% region of variability

Question 25

How were forensic scientists able to confirm the remains of Saddam Hussein?

Answer 25

scientists compared samples of DNA from his sons.Saddam’s identity was confirmed using a rapid DNA test that compared his Y
STRs to his sons

Question 25

Why does DNA profiling raise civil liberty concerns?

Answer 25

this is a violation of the Fourth Amendment right that
protects the individual from improper search and seizure.

Question 26

Why did STR analysis replace gel electrophoresis?

Answer 26

has fewer bases that can retrieve degraded or limited samples of DNA.

Question 27

What are the coding regions called and what are the noncoding regions called?

Answer 27

exon coding regions
introns non coding regions

Question 28

What is NDIS?

Answer 28

-National DNA Index System (NDIS)
-Database of DNA profiles of individuals who were involved of a serious
crime.

Question 29

What is CODIS?

Answer 29

-Combined DNA Index System (CODIS)
-Collects, analyzes, and communicates criminal information.
-NDIS is a part of CODIS