Which of these is NOT a nucleotide found in DNA? |
uracil (U) |
If the sequence of one strand of DNA is AGTCTAGC, what is the sequence of the complementary strand? |
TCAGATCG |
In addition to the base, what are the other components of a nucleotide? |
phosphate and sugar |
The _____ chromosomes in a human cell from inside the cheek are found in the _____. |
46; nucleus |
Each chromosome contains _____. |
DNA and proteins |
You can detect DNA that is specifically from the X chromosome in a DNA sample from a person. Why can't you definitively determine the sex of that person (male or female) from the presence of the X chromosome? |
Both males and females have an X chromosome and you would have to check for the presence of a Y chromosome. |
Human red blood cells are enucleated (i.e., they do not have nuclei). Is it possible to isolate DNA from red blood cells? Why or why not? |
No, the genomic DNA is found only in nucleated cells. |
DNA replication is said to be semiconservative because a newly replicated, double-stranded DNA molecules consists of _____. |
one old strand and one new strand |
Which statement about PCR is true? |
DNA polymerase is the enzyme that copies DNA in PCR. |
What naturally occurring process does PCR mimic in a test tube? |
DNA replication |
If you start with one copy of a DNA fragment, how many rounds of PCR will it take to end up with a total of 32 copies? |
5 |
Complete the following statements regarding the steps necessary to copy a DNA sequence during PCR: |
1) heat, 2) DNA polymerase; complementary nucleotides |
What is the purpose of careful primer design before PCR? |
Primers indicate the section of DNA that will be amplified and mark where DNA polymerase begins replication |
An individual's STR may vary from the same STR of another individual by the _____. |
number of times a particular sequence is repeated. |
Which phrase represents genetic variation between individuals? |
the number of STRs in their genomes |
Gel electrophoresis separates DNA for profiling based on the _____. |
size (length) |
The entire sequence of DNA in a cell used for DNA profiling is called the _____. |
genome |
Which STR will have migrated farthest through an electrophoresis gel? |
GAAG repeated twice |
You are studying the DNA profile of an individual, and you are looking at the results for a chromosome with just one STR site. How many bands will you see? |
either 1 or 2 |
Which person would have DNA that is least similar to yours? |
your mother's brother |
DNA evidence can give an investigator information regarding which of the following? |
family relationships between suspects and the identity of an individual based on a profile |
How many STRs are typically used to create a profile in forensic investigations? |
15 |
You are investigating a crime. The DNA profile database has no perfect matches to the DNA collected at the crime scene. However, one profile in the database has at least one band in common with the crime scene DNA at every STR site. Which statement is the most likely conclusion can you draw? |
A parent-child relationship exists between the DNA collected at the crime scene and the DNA in the database. |
From the STRs used in a forensic investigation, which STRs on which chromosomes would be particularly useful in determining whether crime scene evidence was left by a female or a male? |
Y chromosome STR |
DNA testing became a _______ part of court cases. |
standard |
DNA is found where? |
in the nucleus |
What is a chromosome and where is it found? |
a single, large DNA molecule wound around proteins. |
Human cells have how many chromosomes? |
23 |
We inherit ____ chromosome of each pair from our mother and the other from our father for a total of ____ chromosomes. |
1; 46 |
Which chromosome determines a person's sex? |
the 23rd |
Men have an __ and a ___, and pass on one or the other and women have ___ x's ad therefore can only pass on an x. |
x & y; 2 |
Children who inherit a y from dad and an x from mom are what? |
males |
Children who inherit 2 x's from each parent are what |
females |
Is hair analysis reliable? |
not always |
If the DNA of a single chromosome was stretched out it would be how many meters long? |
1-3 meters |
A DNA molecule is made up of two strands of _____ linked together in long chains. |
subunits |
Each subunit of DNA is called a ________. |
nucleotide |
Each nucleotide consists of? |
a sugar, phosphate group, and a base |
What forms the "backbone" of the helix? |
the sugars and phosphates |
What type of bond holds the DNA double helix together? |
hydrogen bond |
What are the 4 different type of nucleotide bases? |
adenine (A), thymine (T), guanine (G), and cytosine (C). |
How many hydrogen bonds do A's and T's have between them? |
2 |
How many hydrogen bonds do G's and C's have between them? |
3 |
The 2 strands forming a double helix are considered to be what |
complementary |
What happens in the 1st step of replication? |
an enzyme called helicase unwinds the helix, and the 2 strands "unzip" from each other. |
What happens after the 2 strands "unzip" from each other during replication? |
then the enzyme DNA polymerase builds a new strand of DNA along each unzipped strand Then free nucleotides floating inside the cell's nucleus are added to each new strand in a sequence that is complimentary to the nucleotide sequence on the original template strand. The end result is 2 complete double-stranded molecules of DNA. |
DNA replication is considered to be what? |
semi-conservative, just meaning that each newly made DNA molecule has one original DNA strand and one new DNA strand. |
Polymerase Chain Reaction (PCR) takes place where? |
in a test tube |
How does PCR work? |
scientists add nucleotides to a small sample of DNA, the DNA polymerase enzyme , and primers (short segments of DNA). The DNA is first heated to separate strands, and then cooled to allow the primers to associate with the DNA and new nucleotides to be added by DNA polymerase. |
Genome is generally what? |
one complete strand of genetic instructions encoded in the DNA of an organism. |
What varies among person to person in STR's? |
the exact length of str's |
Every person has ___ copies of STR's? |
2 |
Which of the following is NOT a nucleotide found in DNA? |
uracil (U) |
If the sequence of one strand of DNA is AGTCTAGC, what is the sequence of the complementary strand? |
TCAGATCG |
In addition to the base, what are the other components of a nucleotide? |
phosphate group and sugars |
The ______ chromosomes in a typical human cell are found in the ________. |
23; nucleus |
Each chromosome contains? |
DNA and proteins |
DNA replication is said to be semiconservative because a newly replicated, double-stranded DNA molecule consists of? |
one old strand and one new strand |
Which of the following statements about PCR is true? |
DNA polymerase is the enzyme that copies DNA in PCR. |
Which STR will have migrated farthest through an electrophoresis gel? |
GAAG repeated twice? |
An individual's STR may vary from the same STR of another individual by? |
the number of times the sequence is repeated |
Which of the following represents genetic variation between the individuals? |
the sequence of nucleotides along the length of each chromosome. |