AP bio essays Unit 7

predict DNA point mutation that will result in a methionine to valine sub

A to G (AUG to GUG)

differences in transcription and translation (2005 B#3)

transcription occurs in nucleus; translation in cytoplasm/rough ER. product is RNA vs. polypeptide. Template is DNA vs. mRNA

Cells regulate both protein synthesis and protein activity. Discuss TWO specific mechanisms of protein regulation in eukaryotic cells. (4 points; 2009 #4)

Histone acetylation: brings in postively charged acetyl groups that promotes transcription by loosening the wrapping of histones. RNA poly has better access to DNA Methylation: induces transcription by bringing in methyl groups which causes tighter packing of DNA. Promoter: region at beginning of gene binding of polymerase and transcription factors to control speed of transcription. increases RNA poly. binding.

Predict length of mature gene of mRNA if the full length is expressed in prokaryotic cells (2pts; 2016 #4)

15kb long b/c the RNA processing does not occur in prokaryotic cells. no introns/exons

similarities btwn transcription and translation (2005 B#3)

Base pairing: transcription uses DNA strand as the base for complementary RNA strand. vs. mRNA and tRNA codon and anti-codon. Both use specific start sites. promoter/TATA box in transcription and initiation/start codon in translation.

If the cell is a secretory cell, how is the protein targeted, pkged, and secreted to exterior of cell? (3pts. 2007 B#3)

If ribosome is attached to the ER, the polypeptide will be folded by chaperonins into a protein. Then protein will be transported to Golgi apparatus where it is modified, stored, and packaged. enclosed in a Golgi membrane, protein moves to cell membrane where it fuses and exits the cell thru exocytosis.

draw an x on the plasmid to indicate where human DNA fragment was inserted. explain (2pts; 2016 #5)

Insert on KAN gene. b/c the DNA was disrupted on the kan gene/promoter

researchers found eDNA to silver carp, but it was a false positive and no silver carp had entered the lake. What reason could have resulted in this? (1pt; 2016 #6)

May have entered by other means than the fish such as by boat, river flow, or waste from predators.

describe structural changes that occur to protein after translation to function properly (2005 B#3)

Polypeptide is folded by chaperonin proteins to activate the protein. chemical modifications may be made by adding sugars, lipids, phosphates etc. also may be send to Golgi apparatus to be packaged into a glycoprotein

a molecule of mRNA has been synthesized. what modifications may occur before it leaves the nucleus? (2007 B #3; 3pts)

a guanine cap is added to the 5' end and a poly-A tail to the 3' end to protect the mRNA from damage to prevent degradation and to help pass through the nuclear membrane. Also, introns are removed and exons spliced together

why is eDNA an effective technique for detecting the presence of silver carp. propose an advantage of longer eDNA vs. short fragments. (2pts; 2016 #6)

allows fish to be identified without having to physically see or catch the fish. Long strand would be good b/c longer sequences increases the accuracy that the DNA is from a silver carp and not a related species

Explain how deoxycycline can be an effective treatment for an infection in humans (2016 #4 2pts)

apicoplasts have 30s/prokaryotic ribosomes, and deoxycycline inhibits the function of that. also, prokaryotic apicoplasts proteins aren't synthesized when deoxy. is present, so it prevents the reproduction of the infection

describe two characteristics of pedigree that would support the researchers claim saying the disorder is an autosomal dominant condition (2014 #2; 2pts)

autosomal b/c disorder inherited equally b/w males and females. dominant b/c there are no unaffected carriers of the gene and the phenotype is most likely to be observed

discuss how a specific GMO might provide a benefit for humans and also a treat to a population or ecosystem (3 pts. c; 2007 #4)

benefit: if a sheep was modified to produce thicker wool, economic benefit harmful: sheep could live longer in the cold, and overgraze fertile land

The wild-type allele encodes a GA3H enzyme with alanine (Ala), a nonpolar amino acid, at position 229. The mutant allele encodes a GA3H enzyme with a threonine (Thr), a polar amino acid, at position 229. Describe the effect of the mutation on the enzyme and provide reasoning to support how this mutation results in a short plant phenotype in homozygous recessive plants. (2 points; 2017 #3)

change from nonpolar amino acid to a polar amino acid disrupts shape and structure of protein (tertiary structure). since function changes with shape, the mutation will decrease or eliminate the giberellin production causing the plant to be short.

identify the control treatment in the original experiment and provide support for researcher's decision to not use a set of unsprayed plants as a control (2pts. 2016 #1)

control: water only treatment without insecticide. Did not use unsprayed plants as control b/c this would not distinguish b/w the effect of insecticide water vs. just water.

describe a mechanism that could lead to genetic variation in flies (1pt; 2014 #8)

crossing over and ind. assortment could produce new combos of alleles/traits.

give evidence that would indicate new genetic variation in flies (1pt; 2014 #8)

expression of a new phenotype

describe transcription (2005 B#3)

occurs in the nucleus; first step of protein synthesis. Initiation: RNA ply binds to DNA at the promoter region with help of TATA box to bind to correct spot. DNA strands unwind to begin transcription in 5' to 3' dir. complimentary RNA will form due to base pairing w/ template strand. translation continues until RNA poly reaches a terminator site. Then post transcription editing takes. place.

how individuals with one (heterozygous) or two (homozygous) copies of the wild-type GA3H allele can have the same phenotype. (1 point; 2017 #3)

people heterozygous for wild type allele can have same phenotype if enough of the active giberellin enzyme is produced from one dominant allele to show the dominant phenotype. ABLE TO CONVERT GIBBERELLINS TO PROMOTE STEM ELONGATION

Describe how recombinant bacteria could be identified (1 pt. b part 2; 2007 #4)

phenotypic selection may be utilized which is checking to see if a certain characteristic has been produced to identify the presence of recombinant genes such as GFP linked to plasmids with recombinant genes

describe 2 potential risks of large scale cultivation and use of GM plants (2pts; 2014 #5)

proteins produced to resist herbicides and pests may be harmful to humans; pesticides produced by the plant may destroy local insect populations which can disrupt the food chain

propose a practical approach to reducing the risks above (2pts; 2014 #5)

research and testing may be done to understand the effects of the proteins. to protect the ecosystem, safe, non gm plants should be planted along side gm plants to provide an alternative food source

calculate min. number of nucleotides required in a the coding region of the LDS2B mRNA to produce and terminate the 565 amino acid. provide 2 reasons that the number of nucleotides in the mature mRNA may differ from the number of base pairs in the gene (2014 #2; 2pts)

565 amino acids x 3nucleotides = 1695 nucleotides. 1695 + 3 + 3 = 1701. number of nucleotides in mature mRNA may differ from number of base pairs b/c introns are removed from the mRNA, but remain in the gene structure.

The central dogma does not apply to some viruses. Select a specific virus or type and explain how it deviates from the central dogma. (3 points; 2009 #4)

A retrovirus such as HIV or the flu virus deviates from the central dogma because it does not go from Dna to Rna to protein. it may go from RNA to DNA, RNA to protein etc. This deviates from the central dogma b/c it uses its host cell to create DNA from the viruses RNA.

cells are treated with a chemical mutagen that causes only nucleotide substitutions in DNA. Predict the likely results of a comet assay for this treatment. (1 point; 2017 #6)

All the DNA will remain in the head/nucleus and the head will be shorter

Explain the role of each of the following in protein synthesis in eukaryotic cells. (5 points; 2009 #4)

RNA polymerase: binds to DNA at promoter region and transcribes DNA to RNA splicesomes (snRNPs): removes introns and splices together pre mRNA exons Codons: mRNA is positioned into codons, subunit of mRNA in sequences of 3 that eventually code for amino acids. Ribosomes: attaches to mRNA and marks the site of protein synthesis. tRNA: transports amino acids by matching anticodons with codons until it reaches a stop codon.

the primary transcript in the figure is 15kb long, but the mature mRNA is 7kb in length. Describe the modification that most likely resulted in the 8kb difference in length of the mature mRNA molecule. Identify the location in the cell where the change occurs. (2pts; 2016 #4)

RNA processing - removal of introns from pre mRNA. occurs in nucleus

describe the role of three of the following in the regulation of protein synthesis (3pts; 2012 #3)

RNA splicing: occurs in nucleus; introns removed and exons are spliced together. aided by snRNPs/splicesomes. Repressor proteins: bind to promoter region and inhibit transcription/translation (inactivates genes). DNA methylation: DNA or histone methylation prevents transcription and Protects against restriction enzymes.

A student incorrectly plotted a value. identify the error and provide reasoning to support the use of a logarithmic scale on y axis. (2pts. 2016 #1)

error: seed formation stage/immature seeds data from water only treatment. Used logarithmic scale to display all the data on one graph. differences for small values would not be ale to be spotted on a linear scale

describe how genetic variation in a population contributes to evolution (1pt; 2014 #8)

genetic variation allows for phenotypic variation, allowing for natural selection and the strongest phenotypes will be reproduced

support the claim that says cells located in the tip of the plant shoot detect the light by comparing treatment group 1 with treatment group 2 and 3 (2pts; 2015 #5)

in treatment 2, where the tip was removed, the plant did not bend towards the light. group 3 did not bend towards the light b/c the cap blocked any light from reaching the tip

def. insecticide was used and number of seeds was reduced. describe the most likely interaction btwn affected insects and the plants in experiment. justify response (2pts. 2016 #1)

insects must be pollination flowers b/c when pollination is prevented, seeds do not develop.

construct labeled diagram of restriction map of plasmid and explain how the map was developed.

made by trial and error (E - 10 - H - 20 - E - 40 - H - 30). Trial and error was used to determine the length of the cuts

Describe how expression of the gene of interest could be ensured (1 pt. b part 3; 2007 #4)

to ensure expression, the gene of interest may be inserted downstream of a promoter that can be induced.

describe the pathway that secretory proteins take from theri synthesis to their release from the cell (1pt. 2015 #6)

moved from rough ER, to Golgi Apparatus, put in a vesicle, then to cell membrane where it was fused and exited cell through exocytosis

explain most likely genetic change that resulted in polypeptide in species 3 (2pts; 2013 #5)

mutation (substitution/insertion/deletion) which introduced a stop codon after val in position 8. led to the termination of polypeptide after val.

propose three features of a model to connect genetic mutaton with the activity of a signaling pathway involving LDS2B gene product

mutation may cause a structural change to the polypeptide activation a signal by changing sequence (gain function), or the model could lose a function due to a decrease of a signal pathway.

Describe how recombinant DNA technology could be used to insert a gene of interest into a bacterium (4pts. b part 1; 2007 #4)

(1) gene of interest needs to be cut from the source/from the plasmid using a restriction enzyme. (2)the same restriction enzyme should be used to cut the plasmid that the gene will be inserted to to ensure compatible ends. (3) the gene of interest and plasmid need to be combined so that complementary ends can math up and join together (sticky ends) (4) once inserted, gene of interest and plasmid need to be incubated with competent cells so they can take up plasmid.

describe 2 pieces of evidence to support the claim tat apicoplasts evolved from free living prokaryotic organisms (2016 #4 2pts)

(1)has a double membrane, similar to prokaryotes (2) consists of DNA in a ring structure like prokaryotes

Once in cytoplasm, how is mRNA translated to a protein? (6pts; 2007 B#3)

(1)mRNA bases determine the sequence of amino acids which eventually code for a protein. (2) Initiation: small ribosomal subunit attaches to 5' end of mRNA and the large ribosomal subunit binds containing p and A site. (3) tRNA carries in the firs start amino acid (methionine) to mRNA (4) energy from process comes from GTP (5) elongation occurs when ribosome moves along mRNA matching tRNA anticodons to codons, then the amino acid will attach at the A site. (6)tRNA moves from a, to p, to e site to grow chain and connect amino acids with peptide bonds. (7) termination occurs when ribosome encounters a stop codon

calculate the percent of plants remaining from one life stage to the next. identify the plant stage at which the insects have a greatest impact on the life cycle of the plant. describe the most likely interaction between insects and the plants (4pts. 2016 #1)

(1)see calculations in packet (2)greatest impact during seed maturation b/c (3)seed maturation is the only time with a big dif in percent remaining. (4) insects must be eating and hurting developing seeds

explain the movement of DNA fragments in the comet assay, identify one property of DNA and provide reasoning to support how the property contributes to the movement during the comet assay technique. (2 points; 2017 #6)

DNA phosphate bases have an overall negative charge, so when an electric current is applied, DNA will move towards the positive charge.

Using the codon chart provided, predict the change in the codon sequence that resulted in the substitution of alanine for threonine at amino acid position 229. (1 point; 2017 #3)

GCA to ACA (first base substitutes a G with an A)

predict what results would be if mRNA were radioactively labeled instead of polypeptides. (2pts. 2015 #6)

the RNA would be in the nucleus first, then to cytoplasm, ribosomes, and the ER. this is b/c mRNA is transcribed in the nucleus, then moved to cytoplasm for translation

predict outcome of culturing transformed E.coli in presence of tetracycline. justify prediction (2pts; 2016 #5)

the e-coli or bacteria population will increase in size b/c the expression of the tet resistance gene

predict effects of the mutation on the structure and function of the resulting protein in species 4 (2pts; 2013 #5)

the protein may have a different structure and function because the Change in amino acid sequence of the protein starting at position 5 could alter the overall structure or local structural regions, interfering with function of the protein.

in groups 4 and 5, the tips had a permeable or impermeable barrier. describe two additional characteristics of the phototropism response. (2015 #5; 2pts)

the tip of the plant produces a signal in response to the light that tells plants to bend. the signal diffuses from the tip to the rest of the plant. the signal was unable to pass through the impermeable barrier.

describe translation (2005 B#3)

translation begins with initiation: binding of a small ribosome subunit to mRNA and large ribosome subunit with P and A sites. Elongation: ribosome moves along mRNA matching codons with anticodons and amino acids are added to ape sites. amino acids moved using tRNA. continues until a stop codon is encountered