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BIO 302 Exam 3
| Question | Answer |
|---|---|
| Who discovered "nuclein" based off of experiments with pus? What did the experiment find? | Miescher; found in nuclei of all cells |
| Who did the experiments with R and S strain pneumonia? What did the experiment conclude? | Griffith; unknown carrier of genetic information which is a transforming factor |
| Who discovered that the transforming factor is DNA expanding on Griffith's work? What was the experiment? | Avery, MacLeod, and McCarty; protease and deoxyribonuclease to determine DNA and not protein is transforming factor |
| Who did the experiment with bacteriophages and viruses? What did it conclude? | Hershey and Chase; DNA and not protein is genetic material |
| What are the purine bases? | Adenine and guanine |
| What are the pyrimidine bases? | Thymine, uracil, cytosine |
| What type of bond links the base to sugar and sugar to phosphate group? | Covalent |
| Phosphate group is on __' end and OH grou pis on __' end | 5; 3 |
| Polynucleotide chains are written __'-> __' | 5' to 3' |
| What is Chargaff's rule? | The amount of adenine = amount of thymine, and amount of guanine= amount of cytosine |
| How many hydrogen bonds link A and T? Link G and C? | Two; three |
| A DNA molecule n base pairs long has ___ combinations | 4^n |
| What does DNA polymerase do in DNA replication? | Reads nucleotide sequence and inserts complementary nucleotides in 5'-3' direction |
| What does DNA ligase do in DNA replication? | Seals Okazaki fragments together |
| Possible combinations of amino acids in a protein: | 20^n (n= number of amino acids) |
| A sequence of 3 nucleotides allows __ combinations to code for amino acids | 64 (4^3) |
| What are the three stop codons? | UAA, UAG, UGA |
| What is the start codon? | AUG (methionine) |
| In initiation of transcription, RNA _____ binds to a specific nucleotide sequence called the ___ that marks the beginning of a gene | polymerase; promoter |
| In elongation of transcription, RNA polymerase moves along the template strand to form ____ | pre-mRNA |
| Nucleotides called ______ mark the end of a gene at termination of transcription | 3' termination sequence |
| __ are removed from pre-mRNA and ___ are spliced together. AFter a ___ is added to 5' end and ___ is added to 3' end, the mRNA is mature. | Introns; exons; cap; poly-A tail |
| What is alternative splicing? | Exons can be retained or remove during splicing allowing mature mRNA to contain different combinations of exons |
| Each polypeptide has a free amino group at one end (___) and a free carboxyl group at other end (___); written in which direction? | N-terminus; C-terminus; N-C |
| In translation, initiation is complete when the ____ binds to the initation complex (made up of ___, ___, and ___) | Large subunit; mRNA; tRNA; small ribosome subunit |
| In translation, termination occurs when: | The ribosome reachs a stop codon (does not code for an amino acid) |
| What is a polysome? | mRNA loaded with multiple ribosomes |
| What is a prion? | A protein folded into an infectious conformation that is the cause of disease |
| At what level is the most important gene regulation? | Transcriptional |
| ___ is a main mechanism of gene regulation; it modifies the histones and making some site available for gene activation and some sites unavailable | Chromatin remodeling |
| In RNA interference, a single-stranded RNA called ____ folds back on itself, remaining single-stranded regions are removed by ____, one of the strands is degraded, and the RNA binds to _____ to block ribosome from loading on or ____ | micro RNA; enzyme called Dicer; cleaving mRNA |
| What are the two categories of mutations? | Somatic and germ-line |
| Geneticists usually assume that a mutation has taken place if the mutant allele is ___; fully ____ in everyone and appears in a family with __ ___ | Dominant; expressed; no history |
| What is mutation rate? | The number of events that produce mutated alleles per locus per generation |
| For a certain gene, 4 of 100,000 births have mutated phenotype; mutation rate is _ | 4/200,000 |
| To make sure mutation rate is accurate, a gene must (5): | Never be recessive; always be fully expressed; have clearly established paternity; never be produced by nongenetic agents; be produced by mutation of only one gee |
| What is considered the mutation rate in humans? | 1 mutation in every million copies of a gene |
| Factors that can influence mutation rate: (larger/smaller) genes are bigger targets; clusters of short nucleotide sequences called ____ _____; spontaneous chemical changes because ___ bases are susceptible to change | Larger; trinucleotide repeats; cytosine |
| What is the definition of radiation? | The process by which energy travels through space |
| Natural sources of radiation are called: | Background radiation |
| In the US, the average person is exposed to ___ mrem/year | 360 |
| Mutagenic chemicals that resemble nucleotides and are incorporated into DNA or RNA during synthesis are called: | Base analogs |
| 5'bromouracil takes the place of ___ and turns a ___ pair into a ___ pair | Thymine; A/T; G/C |
| Nitrates and nitrites used in preservation of meats modify bases to: | Turn one base into another |
| What are chemicals that resemble base pairs & distort DNA called? | Intercalating agnets |
| What is a missense mutation? | Mutations that causes the substitution of one amino acid for another in a protein |
| What is a sense mutation? | Change a stop codon to an amino acid |
| What is a nonsense mutation? | Change an amino acid to a stop codon |
| What mutations expand the number of repeats in a gene, it's called ___ ____ | Allelic expansion |
| Exposure of DNA to UV light causes thymine bases adjacent to each other to pair, forming ___ ___ | Thymine dimers |
| What is an epigenetic trait? | A stable phenotype that results from changes in gene expression |
| Epigenetics do not change the ___ ___ but they affect how genes behave | Nucleotide sequence |
| What is genetic imprinting? | Selective use of either the maternal or paternal copy of a gene |
| Cancer is characterized by two prope | Uncontrolled cell division and the ability to metastasize |
| Cancer begins in a ___ ___; a cell becomes cancerous after it accumulates _; once formed, cancer cells divide ____ and become ____ | single cell; mutations; continuously; invasive |
| What is Loss of Heterozygosity? | The loss of normal function in one allele of a gene where the other allele is already inactivated by mutation |
| Loss of heterozygosity is associated with (familiar/sporadic) cancers | familial |
| What are the 3 main checkpoints of the cell cycle? | G1/S; G2/M; late metaphase |
| External signals that tell the cell to divde are processed by the __ ___ | signal transduction |
| Genes that turn off/decrease rate of cell division are __ ___ __; genes that turn on or increase rate of cell division are __ ___ | tumor-suppressor genes; proto-oncogenes |
| Mutant forms of proto-oncogenes are called: | Oncogenes |
| The ras proto-oncogene family encodes ___ __ proteins; a single base change can lock it into the active state and cause it to become cancerous | signal transduction |
| Genomic instability is seen as ___ ___ __ as the cancer develops | progressive chromosomal changes |
| All forms of cancer share higher-than-normal rates of __, abnormalities of ____, and none or more forms of ___ ____ | mutation; chromosome structure/number; genomic instability |
| BRCA1 and BRCA2 are both involved in DNA ____; the normal alleles encode large proteins found only in the ____ | repair; nucleus |
| BRCA1 is activated when ___ in DNA strands are detected; its actions stops DNA replication | breaks |
| The genetic pathway from the mutant FAP allele to colon cancer has two important features: | 5-7 mutations in a single cell; specific sequence of mutational events |
| There are two paths to colon cancer: mutation in ___ genes or mutation in ___ ____ gene | APC; DNA repair |
Created by:
Emily017