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BIO 210 GENETICS FINAL EXAM
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What is mitosis? Correct Answer cell division of one cell into 2 exact duplicates What are the six stages of Mitosis in order? Correct Answer interphase, prophase, prometaphase, metaphase, anaphase, telophase and cytokinesis What happens during mitosis interphase? Correct Answer mitosis stage that the cell is primarily in chromosomes are uncondensed, so they are just hanging out in the nucleus 1 centrosome < 2 centrioles What happens during interphase s-phase? Correct Answer Centrosome replication ( 2 centrosomes < 4 centrioles) occurs and chromosome replication occurs (still uncondensed) What happens during mitosis prophase? Correct Answer centrioles move to opposite ends of the cell using spindle fibers nuclear membrane breaks down
chromatin (DNA) condenses into chromosomes (the "x"'s); bound by a kinetochore that attracts mitotic spindle fibers What happens during mitosis prometaphase? Correct Answer centrioles have reached polar regions and mitotic spindle fibers have connected to the kinetochore What happens during mitosis metaphase Correct Answer all chromosomes are lined up on the metaphase plate What happens during mitosis Anaphase? Correct Answer mitotic spindle fibers pull chromosomes apart into chromatids (4n) What happens during mitosis telophase? Correct Answer nuclear envelope reforms plasmo-membrane is pinched; sister chromatids are still condensed at this point What happens during cytokinesis? Correct Answer cells split off; genetic material becomes uncondensed What happens during Meiosis? Correct Answer Division of one diploid cell to yield 4 haploid cells that are completely different What happens during Meiosis 1? Correct Answer 1. Homologous chromosomes pair to form tetrads.
What are the 8 ingredients needed for DNA replication? Correct Answer Template DNA, Single-Strand Binding and Initiator Proteins, Helicase, Gyrase, nucelotide precursor, Primase and Primer, DNA Polymerase I, II, III, and DNA Ligase What end of a DNA strand are new base pairs added? Correct Answer 3'; bases added at the 3' end What are the three stages of DNA Replication? Correct Answer 1. Initiation
- Elongation
- Termination What happens during the initiation stage of DNA replication in prokaryotes? Correct Answer initiator proteins are added, helicase attaches to the strand, helicase unwinds DNA strand to form replication fork, DNA primase adds RNA primers, Single-stranded binding proteins bind onto the unwound strands to prevent the strands from rejoining What happens during the elongation stage of DNA replication in prokaryotes? Correct Answer DNA Polymerase 3 adds new nucleotides (DNTPs) to the 3' end of both strands What are the differences between the leading and lagging strands during DNA replication in prokaryotes? Correct Answer The leading strand undergoes continuous synthesis while the lagging strand undergoes
discontinuous synthesis (Synthesis of the lagging strand has to be discontinuous because DNA polymerase cannot make a new strand in the 3' to 5' direction. Therefore, a series of Okazaki fragments, each with their own RNA primer, must be made as to the fork advances) What are Okazaki fragments? Correct Answer Relatively short fragment of DNA synthesized on the lagging strand during DNA replication What enzyme relieves the tension caused by the discontinuous synthesis of the lagging strand? Correct Answer Topoisomerase What happens during the termination stage of DNA replication in prokaryotes? Correct Answer DNA Polymerase 3 dissociates, DNA Polymerase 1 removes RNA primers in a 5'-3' direction and replace the primers with DNA, DNA Ligase seals the strand and repairs any nicks left by the RNA primers What is the difference between prokaryotic and eukaryotic DNA Correct Answer prokaryotic DNA is small and circular eukaryotic DNA is long and linear What enables DNA Replication to occur as quickly as it does in eukaryotes (the entire human genome can be replicated in 8 hours)? Correct Answer Eukaryotes have multiple replicons (replication forks)
the transformed strain used in Griffith's experiment, if the mouse would still die. They concluded that DNA was the transforming principle observed by Griffith Explain what the Hershey-Chase experiment was and how it cemented DNA as the hereditary material responsible for the transforming principle Correct Answer Hershey and Chase used bacteriophages injected with radioactive sulfur (to test proteins) or radioactive phosphorus (to test nucleotides) to see, after infection, whether the infected cells would be radioactive. They used a centrifuge to isolate the protein shells from the nucleic acids. The pellet at the bottom for the test ran with radioactive sulfure showed the supernatant the pellet was in to be more radioactive and the test with the phosphorus showed the pellet to be more radioactive. This suggested that DNA was the transforming principle A nucleotide is made up of what 3 components? Correct Answer phosphate group, pentose sugar (deoxyribose in DNA and ribose in RNA), and a nitrogenous base What nitrogenous bases are purines Correct Answer Adenine and Guanine What nitrogenous bases are pyrimidines? Correct Answer cytosine, thymine, uracil How can you differentiate between purines and pyrimidines? Correct Answer purines are double-ringed while pyrimidines are single-ringed
What are the differences between DNA and RNA? Correct Answer DNA: double stranded, has deoxyribose sugar(hydroxyl group at 2' carbon), bases: A, T, G, C RNA: single stranded, has ribose sugar(one oxygen is removed from the 2' Carbon), bases: A, U, G, C Nucleoside vs Nucleotide Correct Answer nucleoside: pentose sugar + nitrogenous base nucleotide: pentose sugar + nitrogenous base + phosphate group What type of bonds bind nucleotide chains? Correct Answer Phosphodiester bonds What are the 4 requirements for a molecule to be genetic material? Correct Answer 1.) Must contain important info to encode hereditary traits 2.) Must be capable of replication 3.) Must be capable of variation by mutation 4.) Must be able to express information Where are chromosomes located? Correct Answer cell's nucleus what is a centrosome? Correct Answer location in the cell that contains centrioles What are centrioles? Correct Answer microtubules that produce mitotic spindle fibers, aids in cell division, and make up the cytoskeleton of the cell
meiosis in females makes one egg and three polar bodies. This is so the extra chromosomes have a place to go. Polar bodies eventually disenegrate. What are histones? Correct Answer Proteins that pack DNA into condensed formed; Because eukaryotic DNA is so long, histones help provide structural support by compacting the DNA How does acetylation/deacetylation help package and unpackage DNA along nucleosomes? Correct Answer When acetyl groups are added to cytosine, this makes the chromatin more compact (heterochromatin) When deacetylase removes these acetyl groups, this makes the chromatin less compact (euchromatin) Why are heterochromatin inaccessible for transcription? Correct Answer heterochromatin are densely packed so they are too compact for DNA Polymerase 3 to access the DNA. Thus, the template strand can not be accessed for transcription What is the Central Dogma? Correct Answer DNA (replication) - > RNA (transcription) - > Protein (translation) What are the names and function of the three basic elements of a gene? Correct Answer promoter- where initiation begins; the sigma factor binds to a strand of DNA and clips and untwists to make a transcription bubble)
RNA-coding sequence- the sequence that actually gets transcribed; 3'-5' strand terminator- marks the end of a gene What ingredients are necessary for RNA transcription in prokaryotes? Correct Answer RNA Polymerase (A holoenzyme the binds and unwinds DNA via its sigma factor), initiation factors, Where does transcription occur? Correct Answer the endoplasmic reticulum via ribosomes What direction is RNA polymerized? Correct Answer RNA is polymerized in a 5' to 3' direction Describe the differences between the template strand and the non-coding strand in transcription for prokaryotes (including the 5' and 3' orientation of both) Correct Answer The non-coding template strand is in a 5'-3' direction and is ignored during transcription The template strand is in the 3'-5' direction and is used to synthesize the transcript What are the two types of terminators used in prokaryotic transcription? Correct Answer Rho-dependent : Rho helicase gets added to the transcript and clips the RNA Rho-independent : no helicase added; C-G regions loop such that the RNA polymerase can no longer fit on the strand, causing it to dissociate
Capping: 5' methylguanine cap is added to the 5' end to prevent degradation Addition of polyadenylation site How do intronic sequences (introns) differ from exonic sequences (exons)? Which are more important for making a mature mRNA in Eukaryotes? Correct Answer Introns are removed because they do not code for the proteins the mature mRNA will yield after undergoing translation. Exons, however, do code for these proteins. Thus, exons are more important for making a mature mRNA What three things must a mature mRNA possess? Correct Answer 5'- 7 - methylguanine cap, exons spliced together, and polyadenylation tail What are the characteristics of the genetic code? Correct Answer 1. Linear mRNA sequence derived from the template DNA strand
- Triplet Code = Tree ribonucleotides --> One amino acid
- Unambiguous - Each triplet specifies only a single amino acid
- Degenerate - A single amino acid can be coded for by multiple triplet codes (18/20 amino acids
- No internal punctuation; therefore, comma less
- Non-overlapping - A single ribonucleotide can only be in one triplet code
- Universal with only minor exceptions
What is the triplet representing the START codon? Correct Answer AUG (met) Describe the structure and function of tRNA Correct Answer 1. Transfer RNA- a single polynucleotide strand that's folded into a clover shape.
- H bonds between specific base pairs hold the molecule in this shape.
- Every tRNA molecule has a specific sequence of 3 bases at one end called an anticodon.
- They also have an amino acid binding site at the other end.
- It is found in the cytoplasm and carries amino acids that are used to make proteins (translation) to the ribosome. What is an anticodon? Correct Answer An anticodon is the three unpaired bases on a tRNA that is complementary to one mRNA. What is the orientation of the codon to the anticodon? Correct Answer They are antiparallel to one another What is the difference between degeneracy and wobble in the genetic code? Correct Answer Wobbly says that the codon's third nucleotide can be changed while still yielding the same amino acid (the same tRNA can bind to different codons) Degeneracy says that different codons can code for the same amino acid
What is the role of the acceptor site? Correct Answer Located on the ribosome, the acceptor site accepts the tRNA and binds to anticodon site What are the small and large subunits within translation? Correct Answer Small subunit decoded the genetic message Large subunit catalyzes polypeptide formation What occurs at the A-site in translation? Correct Answer accepts a tRNA w/ amino acid What occurs at the P site of the ribosome during translation? Correct Answer holds the tRNA which is linked to the growing polypeptide chain. When a stop codon is reached, the peptidyl-tRNA bond of the tRNA located in the P-site is cleaved releasing the newly synthesized protein What occurs at the E-site during translation? Correct Answer tRNA that has released their amino acid is released from the ribosome In what direction is the mRNA read by the ribosome? Correct Answer 5'-3' direction In what direction is protein sequence synthesized during translation? Correct Answer Synthesized from N-terminal to C-terminal
What happens during the initiation stage of translation? Correct Answer Initiation factors bind to small subunit; causes small subunit to bind to mRNA Start codon for MET moved into P-site; a charged tRNA comes into the ribosome to bind to MET Initiation factors dissociate and the Large subunit binds (forms the translation complex) What happens during the elongation stage of translation? Correct Answer polypeptide chain is synthesized; 1 codon progression until stop codon is reached What happens during the termination stage of translation? Correct Answer The Release factor binds to the A-site, hydrolizing the ribosome and causing the translation complex to dissociate How does prokaryotic translation differ from eukaryotic translation? Correct Answer Eukaryotic translation utilizes a larger ribosome, IFs bind to the Kozak sequence rather than the Shine-Dalgarno sequence, and eukaryotic IFs bind to cap and poly-A tail to create a closed-loop structure (more effective translation) What is the genotypic ratio of the P1, F1, and F generations before/after a monohybrid cross? Correct Answer P1: 1:1 (parental genotype: parental genotype)
What genotypic ratios will the P1, F1, and F2 generations have if a dihybrid/trihybrid cross is performed? Correct Answer For a dihybrid cross, we anticipate a 1/16:2/16:1/16:2/16:4/16:2/16:1/16:2/16:1/16 genotypic ratio For a tri-hybrid cross, we anticipate a 27:9:9:9:3:3:3: genotypic ratio What phenotypic ratios will the P1, F1, and F2 generations have if a dihybrid/trihybrid cross is performed? Correct Answer For a dihybrid cross, we anticipate a 9:3:3: phenotypic ratio For a trihybrid cross, we anticipate a 27:9:9:9:3:3:3: phenotypic ratio What is Mendel's principle of segregation? Correct Answer The members of each pair of genes (alleles) separate (segregate) during gamete formation. What is Mendel's principle of independent assortment? Correct Answer genes/alleles assort independently from one another when forming gametes; these alleles combine at random in hybrids to form new combinations What phase of meiosis is responsible for the principle of segregation? Correct Answer Anaphase- 1
Which phase of meiosis is responsible for the principle of independent assortment? Correct Answer Metaphase 1 bc tetrads don't have to line up identically What is the product law in Mendelian genetics? Correct Answer The product law states that the product of the ratios derived from the monohybrid cross of parents will yield offspring of the genotypic ratio 9:3:3: What is the sum law as it applies to independent assortment Correct Answer The sum law is used whenever two events are independent of one another but produce the same result; genotypic ratios that express the same phenotype are added together What four assumptions underlie the predictable ratios in a Mendelian cross? Correct Answer 1.) Each allele is dominant or recessive 2.) Segregation normally occurs 3.) Independent assortment normally occurs 4.) Fertilization is random What is the formula for a chi-squared test? Correct Answer x^2= sum of ((observed - expected)^2)/expected What is pedigree analysis? Correct Answer a family tree that describes the interrelationships of parents and children across generations What is complementation? Correct Answer the phenomenon by which the effects of two different
