Download DNA Questions #1

DNA Questions #1
Fo Sci
Name ________Key__________________________
Use PPT slides 1-11 to answer the following questions.
1) Who are these gentlemen and what did they discover?
__James Watson and Frances Crick discovered the
structure of DNA. Won the Nobel Prize in 1953.
_____________________________________________
What year did they make their discovery? __1953____
2) DNA is composed of nucleotides. A nucleotide is a unit of a
nucleic acid. Many nucleotides make a strand of DNA and two
strands make the double helix of a DNA molecule. There are 4
different types of nucleotides. What are their names and what
letter symbols are used to identify them?
_Adenine nucleotide A_________________________________
__Guanine nucleotide G________________________________
___Cytosine nucleotide C_______________________________
__Thymine nucleotide T________________________________
3) DNA is considered a double helix. That means that it is made of two strands of nucleotides that sit opposite of
each other joined by hydrogen bonds. If one side of a strand of DNA has the following code, what is the
complimentary strand sequence of nucleotides? (Your strand will look a lot like the strand below but it will have
complimentary nucleotides opposite the nucleotides listed—A-T and C-G).
A - G - C - T - T - G - A - C - T - C -C - T - G - A - T - A
T
C
G A
A
C
T
G
A G G
A C
T
A
T
4) What type of bonds hold the two strands of DNA together? Are they strong or weak bonds?
____Hydrogen bonds that are very weak bonds____________________________________________________
5) What is a gene? What do coding genes carry the code for? What is the value of non-coding genes?
_____Segment of the DNA. Coding genes carry the code for a protein. _________________________________
______Non-coding genes can be used to make a DNA profile! _________________________________________
6) Why is it important for most coding genes in humans to be identical in nucleotide sequence? For example, why
is it necessary for all humans to have the same nucleotide sequence for their hemoglobin molecules?
__Because they code for proteins that are necessary to survive. Any variations or mutations would form a nonfunctional protein and the person would die._____________________________
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7) Fill in. There are two types of DNA found in your cells. The first type, ___nDNA__________ is found in the
nucleus of your cells. It is in the form called ___chromosomes________, which are linear structures that are
made of DNA and proteins. Each of your cells has ____46______(number) pieces of these linear structures in
the nucleus. The linear structures are paired. One of the pairs is inherited from your mother (maternal) and the
other is inherited from your ___father_______(paternal). The nucleotide sequences in your
____chromosomes______(linear pieces) is an important type of forensic evidence even though it is
____class_______(individual/class) evidence. The strength of this evidence makes it as important as the
individualized evidence you worked with in the last unit: _fingerprinting_____.
Unfortunately, nDNA is fairly fragile and breaks down easily. The second type of DNA is smaller, and is circular in
shape. It does not break down as easily and can be obtained from very old or dried samples. This second type
of DNA is _______mt DNA_______________. This DNA is found in the organelle in your cells called the
____Mitochondria_______________________. You have hundreds of these organelles in one of your cells.
Therefore, you have ___1,000’s_________ (a number) copies of this type of DNA in one cell. The function of the
organelle is ____to be the site of cellular respiration to produce_____ ATP___________. The DNA in this
organelle is inherited from your ___mother__________. As such, the nucleotide sequence you inherit from your
mother will be identical to the sequence any of your siblings inherits. Your aunts and cousins on your mom’s
side of the family will also have the same sequence of nucleotides in their mtDNA because they all inherited the
sequence from your grandmother! This type of evidence is helpful but it is only ___class_______(individual/
class) evidence and it is not as valuable as a nDNA profile.
Word Bank:
23
46
ATP
chromosomes
class
entomology
father
fingerprinting
individualized
mitochondria
mother
mtDNA
n DNA/ chromosomes
nuclear DNA
one
ten
thousands (1,000’s)
8) Are coding genes used in DNA fingerprinting? Why or why not?__No. Coding genes code for important proteins.
These proteins do not have much variation in the nucleotide sequence from person to person because any variations or
mutations would cause the protein to be non-functional and the person would die. If the coding genes do not differ
from person to person, you cannot use them to identify a specific person. All people would have the same sequence!__
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Match the following types of DNA to the statements below:
a. nDNA
b.mtDNA
c. both types of DNA
9) Used to identify the source of evidence.___c______
10) The best type of class evidence.__a________
11) Fragile and easily broken down.___a___
12) Can be isolated from degraded skeletal remains.__b____
13) Is only inherited from the maternal side.___b_____
14) Is identical in identical twins.___c______
15) Thousands of copies are found in each cell.___b______
16) Contains approximately 20,000 coding genes.___a______
17) Composed of a circular piece of DNA.____b______
18) Some genes code for proteins.____c_______
19) Contains 3 billion base pairs.____a______
20) Contains alleles.___c______
21) Composed of A, T, G and C nucleotides.___c______
22) Represented by picture to upper right. ___a________
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DNA Questions #2
Fo Sci
Name _______Key________________________
Use slides 11-21- to answer the following questions: (some questions may be answered using previous slides)
23) Which of the following is true about your nuclear-nDNA? ( 2 answers)
a. It is identical to your mother’s DNA.
b. It is similar to your both of your parents DNA.
c. It is part of your paired chromosomes. One of each pair is inherited from
your mother (maternal) the other is from your father (paternal).
d. It contains genes that code for carbohydrates and fats.
e. Some chromosomes are linear while the smaller ones are circular in shape.
24) A gene is located at a specific spot (or loci) on a chromosome. The allele at that loci is the nucleotide sequence
for the gene found at that location. If a gene found on the paternal #20 chromosome has the following allele
sequence: A_T_G_C_C_A_T_A, and the alleles between the maternal and paternal homologs are heterozygous,
which of the following alleles could be on the maternal #20 chromosome at the same gene loci? (circle two
possible answers)
a. A_T_C_C_C_A_T_A
b. A_T_G_C_C_A_T_T
c. A_T_G_C_C_A_T_A
25) What percent of your DNA codes for proteins (coding DNA)?
a. 97%
b. 50%
c. 25%
d. only 2-3%
26) You can find non-coding DNA
a. In between genes
c. Within genes
b. In nDNA
d. All of these
27) How is non-coding DNA different from coding DNA? Which type of DNA is best for DNA profiling? Why? (This
question is redundant—it WILL be on the test!)
_____“Non-coding DNA does not code for important proteins. Your coding genes code for important proteins
that are necessary for survival. Coding genes do not have much variability in the nucleotide sequences from
person to person because mutations would create non-functioning proteins and the person would die.
Everyone needs to make the same protein in order to survive. Non-coding DNA does not code for proteins so
mutations that take place in those genes will not affect the person. The different, unique nucleotide sequences
that result from these variations can be used in DNA profiling to distinguish between different people.”______
28) A tool used to determine the identity of, or verify the identification of and individual based on DNA is
called a _____DNA fingerprint or DNA profile___________. Do not confuse it with a regular fingerprint!
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29) DNA profiling uses ___non-coding_________(coding, non-coding) regions of the DNA to compare body fluids at
a crime scene to an individual.
30) What does S-T-R stand for? __short tandem repeat_____________________ Is it a length polymorphism?
__YES! Some alleles have only 3 repeats while others may have 5. The two repeats will be different in size.___
31) How do tandem repeats like STR’s differ from person to person? ___ The differences are in the number of
repeats. Some repeats are the same in number between people, but others can be different. ______________
32) A person has 5 tandem repeats for an STR with the sequence: TATC. Write the sequence for the allele below:
____TATC TATC TATC TATC TATC ________________________________________________________________
The 5 repeats are on the paternal homolog for chromosome 15. If the person is heterozygous for the
polymorphism, what number of repeats might you find on the maternal homolog?
______(answers can be various but will not be 5 repeats) __________________________________
Write out a possible (there are many different answers here) sequence for the maternal homolog:
___________________ TATC TATC TATC TATC TATC TATC TATC _______________________________________
33) How many nucleotides are in a single repeat of a typical Short Tandem Repeat (STR)? __3-7________________
34) What does purification do to DNA? __separates DNA from other parts of the cell__________________________
35) What is amplification? What is the process called that can amplify segments of the DNA? _____Amplification
means to copy segments of the DNA. PCR can amplify target sequences of DNA up to billions of copies.______
___________________________________________________________________________________________
36) Which of the following might be a source of DNA? __all but RBC’s____________________________________
a.
saliva
b. buccal cells
c. urine
e. red blood cells
g. feces
d. skin cells
f. white blood cells
h. semen
Note: Red blood (erythrocytes) cells are formed from stem cells in your bone marrow.
Shortly after they are formed, they dump their nucleus and organelles. They contain
thousands of hemoglobin molecules which function to carry oxygen throughout your
body. They only live about 100 days after which they are broken down in the spleen
by white blood cells. Approximately ¼ of your cells are red blood cells!
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DNA Questions #3
Fo Sci
Name _______Key________________________
Use slides 20-27 to answer the following questions: (some questions may be answered using previous slides)
37) What does PCR stand for? What is the function of the PCR process? ___polymerase chain reaction___________
__PCR amplifies or copies the DNA to form billions of copies of the target sequences of interest._____________
38) What process that normally takes place in a cell is most similar to PCR amplification?
__DNA replication______________
39) Which of the following is a significant difference between amplification of DNA in a cell (DNA Replication) and
amplification of DNA by PCR for a DNA profile?
a. replication takes place in the cytoplasm while amplification takes place in the nucleus of the cell
b. replication copies all of the DNA in the nucleus but amplification only copies shorter, target sequences
c. replication makes thousands of copies of the nuclear DNA while PCR amplification makes only one copy of
each target sequence.
d. replication occurs in a thermocycler while PCR can take place inside of a living cell.
40) Place the following in order of how the process of PCR takes place:
a. weak hydrogen bonds between complimentary nucleotides break
b. Begin again
c. DNA polymerase helps to add nucleotides to the single strands of DNA
d. Primers attach to ends of the target sequences
e. Cool down stabilizes new strands
f. Heat up DNA
answer: ___F-A-D-C-E-B_____
41) What is the correct order of the following processes in DNA profiling?
a. Gel electrophoresis to visualize the DNA
b. Purification of sample to eliminate all cellular material from the D
c. PCR to amplify the DNA to produce billions of copies
d. Extraction of DNA from the cells
answer: ___ D-B-C-A____________________
42) Visualize means to “see” something. Do you think you could visualize a few strands of DNA?__NO!______
How many strands of DNA are produced during PCR? __billions______ (10’s, 100’s, 1000’s, billions)
Why do you have to run a PCR on the DNA before you can visualize the results in gel electrophoresis?
___If you don’t amplify the target sequences to a billion copies, you will not be able to see them on the gel.___
43) Which of the following are true? (Correct any false statements.)
a. When PCR is used, all of the DNA is amplified. __no, only the target sequences___________________
b. The product of the PCR process is several copies of the target sequence. _no, billions_____________
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