Bio A – Molecular Biology
Name__________________
Study Guide Molecular Genetics
General information:
1. Some important molecules are made by linking together small molecules into large chains. The
individual molecules are called _______________ while the chains are called __________________.
2. The chemical reaction that links these molecules together is called ________________ __ while the
chemical reaction that breaks them apart is called ________________________
3. Enzymes are proteins. that _______________ (speed up/slow down) reactions in the cell. This means
that you __________________( increase/decrease) the chance that a reaction will occur.
DNA Structure:
4. What is the structure (made of coiled or folded DNA) was initially identified as the part of the cell
responsible for giving us our traits?
5. The two components of chromosomes are __________________ and _________________
6. Experiments done by several scientists showed that ____ _________ (which component of
chromosomes) was the hereditary molecule.
7. The two scientists who are credited with discovering the shape of DNA and describing it are
_________ and _____________ (even though Rosalind Franklin actually discovered the shape of
DNA).
8. The name they gave to the shape of the molecule in question 7 was a ___________________________,
which means that the DNA looks like a spiral staircase.
9. DNA consists of two long chains of ____________________ (what monomer) twisted together.
10. Draw and label the three parts of a DNA nucleotide. Identify the name of the sugar (be specific) and
the four possible nitrogen bases. Use your notes (or text book) if you need to.
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Bio A – Molecular Biology
Name__________________
11. Now draw ONE chain of 4 connected nucleotides (on the left) and a DNA molecule (two stranded)
showing the phosphate –sugar backbone, the bases, the hydrogen bonds and the covalent bonds.
SINGLE CHAIN
DOUBLE STRANDED CHAIN
12. The two chains of DNA must be _________________________(how are they paired) to each other
meaning:
a. All Adenines pair with ______________________
b. All Guanines pair with __ ____________________
There are no Uracil’s in DNA!!!
Replication:
13. DNA is located in the _ _______________________ so it must be copied there
What is replication? When does it happen?
a. Process by which we copy the DNA
b. Happens when the cell needs to divide. DNA is replicated only when cell division is going
to occur (mitosis or meiosis.
STEPS OF REPLICATION and the ENZYMES
14. What enzyme
a. Untwists and separates the two strands of DNA ______________________________
b. Builds the complementary chain of DNA on each original chain ____________________
15. How is Replication different from Transcription?
Transcription
RNA , RNA polymerase
RNA single, go to cytoplasm
RNA is used to creat proteins
Replication
DNA, helicase, DNA polymerase, ligase
DNA double,nucleus, make more cells
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Bio A – Molecular Biology
Name__________________
TRANSCRIPTION AND TRANSLATION
OVERVIEW
All RNA is created through transcription of DNA. HOWEVER, all RNA is not translated into amino acids.
Both ribosomal RNA (rRNA and transfer RNA (t-RNA) are RNA molecules that are transcribed but NOT
translated.
When mRNA is transcribed, and then translated into amino acids the processes are called PROTEIN
SYNTHESIS
RNA structure:
16. RNA is a single chain of __________ (WHAT MONOMER)
17. Identify the three components of an RNA nucleotide (name the specific of sugar, and identify the
specific bases the :
a. A sugar called ________________
b. A nitrogen base (name the 4 bases) _______________________
c. A phosphate
18. Draw a pictures of four RNA molecules in a single strand. Label the covalent bonds, P, S, B
19. There are three types of RNA. BE SURE you know the role each one plays in making protein.
a. mRNA: has the instructions for how to make the protein
b. tRNA: carries the correct amino acids to the ribosome to use to build the protein
c. rRNA: is part of the ribosome
20. In the mRNA, every group of ____________ (how many ) nucleotides is called a ________________.
a. AUG is the ____________ and is where the ribosome starts reading the directions. It will also
set up the reading frame.
b. UAG, UAA and UGA are the _____________ and are where the ribosome stops linking amino
acids to the polypeptide________
c. UAG, UAA and UGA do NOT have amino acids, but AUG does (met)
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Bio A – Molecular Biology
Name__________________
Making Protein: Transcription and Translation
To make the three types of RNA we have to go through __transcription_ which reads the DNA and builds RNA
21. Transcribe the following piece of DNA into RNA and underline the start codon (that means you need to
find the three DNA “letters” that will transcribe into AUG
Ste p 1 AUG = what are the complementary DNA bases for AUG? ___________ find the first
occurance of this DNA sequence and underline it in the strand below
Step 2. Now transcribe the rest of the strand until you get to a stop codon (or finish the strand)
DNA:
CTGGTACGGCCTCATATCAATCCAT
Bases that come
Before the start codon
mRNA:
GACC
Start
AUG CCG GAG UAU AGU
Stop
UAG ( GUA)
MET-PRO-GLU-TYR-SER
22. Since the DNA needs to be read to build the RNA , transcription must take place in the
__________________.
23. BUT we only need to build RNA one “recipe” at a time. The scientific word for a single recipe in the
DNA is ___ _________________.
24. These “recipes” are copied from the DNA and are used to identify the sequence of
____________________ (what monomer) required to make a specific __________________(polymer)
25. Where is the information encoded into the mRNA read and translated (at what organelle)? __________
26. The ribosome will read the mRNA one _________ (what is the 3-base sequence called) at a time
beginning with the start codon. Circle the start codon in the mRNA you transcribed above.
27. The ribosome provides a location for tRNA molecules with complementary ____________ (the
complement of the codon) on one end and an_____________ on the other to “match” with the mRNA
codon. The ribosome will continue to “read” the mRNA code and amino acids will join together one at
a time until end until it reaches a stop codon. Put a box around the stop codon above
28. The ____________ __ (the name of the translation table) is the “translation dictionary” that tells the
ribosome what amino acid each codon means.
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Bio A – Molecular Biology
Name__________________
29. Draw the sequence of tRNA molecules that will be brought in to your piece of mRNA shown above.
Be sure to show both the anticodon and amino acid. YES this means you need your chart. Remember
you are writing the anticodon of the tRNA…BUT….you look up the CODON of the mRNA not the
ANTICODON
TRNA UAC GGC CUC AUA UCA
MRNA AUG CCG GAG UAU AGU
Amino acids:
Anticodons: (tRNA)
Codons (mRNA)
30. Proteins are made by linking together ________________ . This process of producing a defined
sequence of amino acids is called _______________________ This occurs at the ________________
of the cell.
Mutations: (choose one or all words in parenthenses)
31. What is a mutation?
a. A ________________ (permanent/temporary) change in the DNA that can be _____________
(good, bad or have no effect) Mutagens are environmental things that cause mutations. They
include:_UV light, radiation, chemicals_.
32. Mutations also occur when ___________ ______ (what enzyme makes a strand of DNA) makes a
mistake during DNA replication.
33. _________________mutations affect a single nucleotide.
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Bio A – Molecular Biology
Name__________________
GO TO NEXT PAGE!
34. Describe each of the following and provide a two codon example that shows this. Substitutions is
completed as an example
Type of point
Description
Point mutation
a. Substitutions one nucleotide is swapped with another
b. Insertions:
Example
GAC – CCT becomes GAA – CCT
one nucleotide is _______, this causes a frame shift; - GAC- CCT becomes GAT-CCC-T
c. Deletions:____ONE NUCLEOTIDE IS DELETED, FRAMESHIFT
GAC-CCT  GCC -CT__
WHAT CAN RESULT FROM ONE OF THE THREE TYPES OF POINT MUTATIONS?
35. Frameshifts: Occur due to ______________(insertions , deletions, substitutions).
______ (one, some,
all) groups of three nucleotides are changed after the insertion or deletion A word example would be
– THE CAT ATE becomes HEC ATA TE
36. Provide a three codon example (in DNA) of a frameshift mutation:
GGG-CCC-TTT GGG ACC CTT T
37. Nonsense: A ____________ codon is created early, causing an shortened polypeptide (short nonworking protein
a. What is an example of an mRNA sequence that codes for an amino acid, but if you changed one
base it would become a stop codon?
UUG  UAG
b. What would the original 3 bases for DNA have been for the amino acid? For the stop codon?
AAC ATC
38. Silent: A codon is changed, but the amino acid stays the same – GGG becomes GGC but both code for
Glycine
What is the ONLY type of point mutation that can cause this? ________________
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Bio A – Molecular Biology
Name__________________
Genetic Engineering and testing:
45. What is genetic engineering?
a. Changing the DNA of an organism through laboratory techniques
39. What is cloning? How do we do it? What is the important molecule?
a. Creating an organism identical to its ONLY parent; Must move ALL the DNA from THE parent
into the baby. No mixing of DNA from two parents
b. Take DNA from the body cell of parent
Remove nucleus from egg cell
Inject nucleus from body cell into empty egg cell
Grow baby
c. The important molecule is DNA
40. What is a transgenic organism? Give three examples that help us in terms of either food or medicine.
(glow in the dark mice do not count)
a. An organism with a gene that came from another organism
b. Examples: plants with insecticide genes, cows with growth hormone, insulin making bacteria
41. Briefly, how are transgenics made? (this is the lab we did…and now we make it “more general”
a. Find the gene you are interested in, cut it out of its original nucleus, and incorporate it into the
DNA of the organism you WANT to have the gene.
b. New organism will read the gene and make the protein
c. Protein gives new organism new trait
GENETIC TESTING
42. What is genetic testing? Is this a type of genetic engineering?
a. Examining cells for gene mutations, chromosomal mutations or abnormal protein levels. No it is
not genetic engineering because the DNA is not being changed.
DNA FINGERPRINTS
43. What is a DNA fingerprint?
a. A gel displaying fragments of DNA sorted by size
44. What are they used for?
a. To compare DNA from two samples
b. Paternity cases
c. Crime scenes
d. Evolutionary relationships
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Bio A – Molecular Biology
Name__________________
45. How is a DNA fingerprint made done?
a. Cut each sample of DNA with a restriction enzyme (to make different fragments of DNA
b. Inject each sample into gel block
c. Perform electrophoresis (small pieces travel further than long pieces)
d. Compare bands and look for bands (fragments) that are the same size. (to show similarity)
BE ABLE TO READ A DNA FINGER PRINT!!!!
GENE THERAPY
46. What is Gene Therapy?
a. Technique used to correct genes or add corrected genes to individuals with genetic diseases.
47. What are the big limitations?
a. We have many cells, difficult to deliver gene to all those cells (we haven’t successfully done this
in humans)
48. Three diseases we’re working on?
a. Cystic fibrosis – lungs
b. Cancer – depend on type
c. Hemophilia – blood cells
49. How can we do it?
a. Modify a virus to deliver corrected gene (take out viral DNA and put in the gene we want).
B. Viruses can do this because they already know how to inject DNA into cells (infection)
C. Viruses are already specific to certain cells (each type of virus is specific for a certain
type of cell, so we match the virus to the cell). This solves problem of delivering only
to desired cells
Vocabulary:
Nucleotide
Transcription
Replication
Mutation
Amino Acid
Transgenic
Amniocentesis
Mutagen
rRNA
Ribosome
Nucleus
mutation
Translation
chromosome tRNA
codon
mRNA
Helix
Restriction enzyme
Electrophoresis
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