Ap Bio Unit 6 Questions
Why is redundancy in the genetic code important?
-universal to all life - multiple codons for one amino acid
List and describe the steps of transcription
1. DNA unzips the gene 2. complementary bases bond to make mRNA 3. mRNA is released 4. DNA zips back up
List 3 differences between DNA and RNA
1.) different sugars: deoxyribose for DNA, ribose for RNA 2.) double stranded (DNA) vs. single stranded (RNA) 3.) DNA contains thymine, RNA contains uracil; both pair with adenine
The DNA from a certain plant species is analyzed. The DNA contains 22% thyme. Determine the percent of the other bases.
22% adenine 78% guanine and cytosine
What does it mean that DNA strands are antiparallel?
3 to 5 and 5 to 3
A section of the template strand of DNA reads: 5-CAACACATAA-3 Determine the mRNA sequence and translate it
3'- GUUGUGAUU -5' and Valine, Valine, Isoleucine
If one DNA strand reads 3 ACTAG 5 what would the complementary look like?
5 TGATC 3
Describe the consequences of a chemical that prevents the 5 cap poly-a-tail from forming on eukaryotic mRNA
5cap: modified guanine added to 5 end
What does it mean if a gene/ trait is "evolutionarily conserved"
A gene that has remained essentially unchanged throughout evolution.
What does it mean that DNA strands are antiparallel and complementary? Draw a strand of DNA is strand with 6 nucleotides to support your answer
A term used to describe the opposite orientations of the two strands of a DNA double helix; the 5' end of one strand aligns with the 3' end of the other strand.
Mutations can be detrimental, beneficial, or neutral. Give an example where it is beneficial
An example is a mutation that confers antibiotic resistance in bacteria. Other mutations are harmful and decrease fitness, such as the mutations that cause genetic disorders or cancers
How can mutations lead to natural selection
Any time mutations occur, they are subject to natural selection. Genetic changes can sometimes enhance the survival and reproduction of an organism.
An mRNA sequence reads 5-CGUAGCAGA 3 translate the sequence
Arginine, Cysteine, Arginine
If one bacterial cell has a gene that is promoting its survival, explain how other bacterial cells can benefit from it
Conjugation is a process by which one bacterium transfers genetic material to another bacterium through direct contact. During conjugation, one of the bacterial cells serves as the donor of the genetic material, and the other serves as the recipient.
Create your own DNA sequence of 9 nucleotides. Determine the corresponding mRNA sequence and the three amino acids code for. Using the example you created now insert one nucleotide near the beginning of the DNA sequence and show what happens to the resulting mRNA sequence and the amino acids it code for
Create your own DNA sequence of 9 nucleotides. Determine the corresponding mRNA sequence and the three amino acids code for. Using the example you created now insert one nucleotide near the beginning of the DNA sequence and show what happens to the resulting mRNA sequence and the amino acids it code for
Draw a Venn diagram comparing prokaryotic and eukaryotic DNA
Draw a Venn diagram comparing prokaryotic and eukaryotic DNA
If the tRNA anticodon reads 3 CUU 5 then what does the mRNAQ codon read that it can bind to? knowing this what amino acid will the tRNA be carrying?
GAA; glutamic acid
Differentiate between histone acetylation and DNA methylation
Histone acetylation adds acetyl groups to histones, which loosens the DNA while DNA methylation adds methyl groups to DNA, which causes the chromatin to condense
Describe how it is possible for only one identical twin to express an inherited disease
Identical twins can be genetically different, which could explain why they do not always share disorders such as schizophrenia or autism, according to a study published in March in PLoS One. Identical twins develop from one fertilized egg, and so start out with the same genetic information from each parent.
When some people hear apoptosis they think that this is a bad thing that cells go through. Provide one example that illustrates the importance
If apoptosis did not occur during the development of human hands and feet then we would be born with webbed fingers and toes.
In reference to question 2 what would happen if you then add lactose to the medium
If we add lactose to the growth medium, the lac operon remains "off", with the cell continuing to utilize glucose. When the glucose is gone, however, the lac operon turns "on" and synthesizes the enzymes needed for the cell to use the lactose as a carbon source.
Errors in DNA replication can lead to natural selection. Why? Would natural selection still occur if all errors were corrected? Why or why not?
Once such mistakes are established, the cell no longer recognizes them as errors. Natural selection can occur without leading to evolution if differences among individuals are not genetically based.
Identify the major classes of macromolecules and then identify their monomers and polymers
Proteins (polymers of amino acids) Carbohydrates (polymers of sugars) Lipids (polymers of lipid monomers) Nucleic acids (DNA and RNA; polymers of nucleotides)
Differentiate between purines and pyrimidines.
Purines: Adenine and Guanine Pyrimidines: Cytosine and Thymine
What are restriction enzymes? Where do they come from
Restriction enzymes are proteins made by many bacterial species, to defend against viral infections.
Differentiate between silent, missense, and nonsense mutations
Silent mutations still code for the same amino acid, missense codes for a different amino acid, and nonsense results in a stop codon. The most detrimental would be nonsense because it would completely stop the production.
During gel electrophoresis, which size of DNA will move the furthest? Why?
Small DNA molecules move more quickly through the gel than larger DNA molecules.
If an error occurs in DNA replication, how is it fixed
Some of the mistakes are corrected immediately during replication through a process known as proofreading, and some are corrected after replication in a process called mismatch repair
Describe the mutation that causes cystic fibrosis
The F508del mutation is a small scale mutation because of the deletion of the three base pairs
How can PCR be used to produce copies of a gene
The denaturing of DNA separates the DNA into two single-stranded DNA, then the annealing allows for the DNA primers to attach to the template DNA, and the extending step allows for the Taq polymerase makes new strands of DNA and the three steps
Is the DNA positively or negatively charged? How could you tell just by looking at a strand of DNA
The phosphate backbone of DNA is negatively charged due to the bonds created between the phosphorous atoms and the oxygen atoms. Each phosphate group contains one negatively charged oxygen atom, therefore the entire strand of DNA is negatively charged due to repeated phosphate groups
Describe the Meselson and Stahl experiment that supported the semi-conservative model of DNA replication
The presence of one parental subunit for each daughter DNA double helix supported semi-conservative replication. The third conclusion made by Meselson and Stahl stated that for every parental DNA molecule, two new molecules were made. Therefore, the amount of DNA after each replication increased by a factor of two.
Describe transformation. Are all bacteria competent
Transformation is the uptaking of DNA from a nearby cell and not all bacteria are competent.
Summarize the purpose of translation in 1-2 sentences
Translation is the process by which a cell makes proteins using the genetic information carried in messenger RNA(mRNA). The mRNA is made by copying DNA, and the information it carries tells the cell how to link amino acids together to form proteins.
If a bacterial cell grown in a nutrient rich, lactose free medium, what would you expect to see at the lac operon
When lactose is absent the lac operon is switched off. This is becasue a repressor protein is produced which binds to the operator region. This prevetns RNA polymerase from binding to the operon and therefore prevents transcription of the structual genes.
Differentiate between a repressible and inducible operon
a repressible operon stops transcription while an inducible operon starts transcription
The very first tRNA will enter at which site on the ribosome (A, P, or E)
a site
Referring to question 3, which amino acid does this tRNA carry
aug
How does gel electrophoresis separate DNA fragments
by size
Fill in the blank: the mRNA nucleotide triplets are called __. These code for __ __
codons, amino acids
Why does DNA move during gel electrophoresis
gel elctrophoresis
Fill in the blank: tRNA has an __ region which is complementary and antiparallel to ___
mrna
Circle the correct option: substitutions are small/ large scale mutations
small
When does translation stop
stop codon enters a site
T or F: only the template strand of DNA is transcribed during transcription
t
Describe step-by- step how DNA is replicated
the opening of the double helix and separation of the DNA strands, the priming of the template strand, and the assembly of the new DNA segment. During separation, the two strands of the DNA double helix uncoil at a specific location called the origin.
Describe the process transduction
the process by which a virus transfers genetic material from one bacterium to another. Viruses called bacteriophages are able to infect bacterial cells and use them as hosts to make more viruses.
Describe the process of conjugation
the process by which one bacterium transfers genetic material to another through direct contact. During conjugation, one bacterium serves as the donor of the genetic material, and the other serves as the recipient. The donor bacterium carries a DNA sequence called the fertility factor, or F-factor.
After fertilization a zygote forms. The cells then go through mitosis. Explain how this bundle of cells eventually forms a human with specialized cells
the process of differentiation produces cells that are specialized to perform specific functions. For example, one cell may become a muscle cell whose function is to shorten or lengthen to allow movement.
What role do cytoplasm determinants play in early embryonic development
they are responsible for the regulation of gene expression in the early development of the embryo
In which direction does DNA move during gel electrophoresis
towards positive electrode
Fill in the blanks: protein synthesis occurs in two stages ___ and __
transcription and translation
How does transcription and translation differ between prokaryotes and eukaryotes
transcription and translation occurs simultaneously in prokaryotes and in eukaryotes the RNA is first transcribed in the nucleus and then translated in the cytoplasm
Circle the correct option: microRNAs and siRNAs block transcription/translation
translation
T or F: morphogenesis is the process that gives an organism its shape
true
True or False: plasmids replicate separately from chromosomal DNA
true
If a bacterial cell uses up its tryptophan storage, what would happen to the trp operon
turned off or repressed
Using a codon chart determine what UAU codes for?
tyrosine
If a bacterial cell does not need tryptophan and it builds up inside of the cell what would happen to trp operon
will no longer require transcription of the tryptophan operon. In the above case, the regulation of the tryptophan operon in cells which express a mutant form of the tryptophan repressor that cannot bind to DNA - the genes would be continuously activated
Can a transformed organism pass on its new traits to its offspring
The experimenters would be able to make immediate modifications to the lab procedure, in order to get the desired results. It would also enable one to move onto the next stages of the experiment, instead of wasting time waiting for the organism to reproduce. If an organism that reproduced slowly were used, it would take a greater amount of time to observe the results of the experiment.
Where does translation occur?
cytoplasm
T or F: the genetic code is read in groups of two nucleotides at a time called the doublet code
f, groups of 3
What would be the immediate effect to transcription if a region
hat would be the immediate effect to transcription if a region
What functional group defines 3 end of DNA?
hydroxyl group
What if you were preforming gel electrophoresis and the morlecule you were examinging moved towards the negative electrode? What does this mean about the change of the moelcule you are analyzing
if the electrodes were plugged into the wrong outlets the DNA would move in the opposite direction, causing it to go right off the gel.
Circle the correct item: the lac operon is repressible/ inducible
inducible
If a bacterial cell has a mutation to the trp repressor that changes shape of the active site, how would this affect the production or tryptophan
it would change the function
What are the two reproduction cycles of bacteriophages? Describe each
lytic (virulent) or lysogenic (temperate).
What is the center of DNA composed of?
nucleotide pairings
In eukaryotic cells where does transcription occur
nucleus
Fill in the blank: A change in an organism's genotype can cause a change in the organism's ___
phenotype
What is the backbone of DNA?
phosphate and sugar
What functional group defines 5 end of DNA?
phosphate group
What is a promoter region? Are promoter regions upstream or downstream of the gene?
promoter is a region of DNA where RNA polymerase begins to transcribe a gene, upstream
What are the three parts of an operon
promoter, operator, structural genes
Circle the correct item: the trp operon is repressible/ inducible
repressible
Fill in the blanks: the process of __ converts DNA to RNA. The process of ___ turns RNA into proteins
rna polymerase, transcription
Trace the path of a newly produced polypeptide that will leave the cell
rough ER → Golgi → secretory vesicles → cell exterior
In which stage of the cell cycle does DNA replicate
s phase
Referring to the question 3, what is the codon that ht e tRNA binds to
tac
