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BIOL 205
Genetics Midterm 1
| Question | Answer |
|---|---|
| What is DNA? | Deoxyribonucleic acid is the genetic code of humans, It is a strand-like macromolecule of numerous nucleotides (nt), each composed of a deoxyribose sugar and a phosphate group (structural) and a base (carriers of genetic info ir. nitrogenous base) |
| What are the purine bases? | adenine and guanine |
| What are the pyrimidine bases? | thymine What and cytosine |
| What is the pyrimidine base used in RNA instead of thymine? | Uracil |
| What are some characteristics of DNA? (3) | 1. Double strand of TWO complementary nucleotide chains 2. The 5' to 3' strand complements the sequence of 3' to 5' strand 3. The 2 nucleotide chains run antiparallel (backbones run opposite directions) |
| How many hydrogen bonds are located between A and T bases? | 2 hydrogen bonds |
| How many hydrogen bonds are located between G and C bases? | 3 hydrogen bonds |
| What structure is a purine base? | double-ring structure |
| What structure is a pyrimidine base? | single-ring |
| What are the differences between the somatic cells and germ cells? | Somatic: 1. Mitosis -> development, gene expression, gene function Germ Cells: 1. Meiosis -> inheritance, evolution |
| What are the characteristics of the soma? | 1. muscle fibers 2. Nuclear DNA is DIPLOID 3. 2 chromosome sets that are different for each parent, can see boundaries between cells 4. Mitochondrial DNA: found in cytoplasm, small circular genome |
| What are the characteristics of a germline? | 1. Nuclear DNA is HAPLOID 2. 1 chromosome set, different from parent cells and each other i.e could have different allele and gene compared to sperm beside it 3. Mitochondrial DNA: inherited via egg only. Males do not contribute. |
| What did Watson and Crick discover in 1953? | They recognized the three-dimensional structure of DNA from which they could deduce the mechanism of its replication that allows the reliable transmission of genetic info from one generation to the next. |
| What aids the process of Replication? (4) | The multi-enzyme complex containing helicases, topoisomerases, various DNA polymerases and other protein. |
| What are Helicases? | Enzyme that start replication by unwinding the DNA bidirectionally, leading to the seperation of the hydrogen bonds and, in effect, the two chains. this creates two "replication forks" |
| What are Topiosomerases? | Enzymes that prevent a super coiling of the DNA helix during unwinding and separation because they are capable of cutting individual strands, permitting them to unwind |
| What are Ligases? | Enzymes that splice cut DNA pieces (during replication) |
| What are Polymerases? | Enzymes that synthesize DNA or RNA strands |
| Describe the process of Replication. | 1. Proceeds from starting point in both directions of the replicons. 2. begins with a complementary RNA primer formed by polymerase alpha and later cut out and replaced by DNA. 3. New DNA is synthesized in a 5' to 3' direction. |
| Why can new DNA only be synthesized in a 5' to 3' direction? | only the 3' end of the growing chain can the next nucleotide be attached. Therefore only 1 of the unwinding DNA parent strands (the leading strand) allows continuous synthesis in the 5' to 3' direction. |
| What do we call a lagging strand of DNA that is 5' to 3' replicated discontinuously (backwards) in small 200 bp fragments? | Okazaki fragments |
| What happens with Okazaki fragments during replication? | each fragment needs a new RNA primer, and after replication, adjacent fragments are linked by a DNA ligase. |
| What is the purpose of proofreading function of DNA polymerase? | 1. Identifies errors 2.cuts out faulty bases and replaces with correct bases |
| What is the result of replication? (the products) | 2 daughter DNA molecules |
| Why is a virus considered not alive? | does not have its own metabolism composed of 9 genes require a host to survive no meiosis |
| What is a genotype? | genetic make up of a cell ie. refers to basic sequence or copy number or alleles of gene present how many copies do we have? 2! (mom and dad) |
| What is a phenotype? | cells/individuals observable or measurable units/traits |
| Do 4 tissues/organelles have same genotype? | No, the genotypes are the same but the gene expression is different ex. genome from stomach and eye will have the same genome but with small mutations |
| What is gene expression? | turning on (alleles of) a gene to produce its product. |
| What two products do genes produce? | RNA and Proteins |
| Variation in genotype | 1. variation can lead to variation in phenotype or sometimes there is no change (ie. Dominant allele) 2.Environmental Input (ie. height growth due to nutrition) 3.genome sequence trial - not every genotype will change a phenotype |
| What is a gene? | a functional unit in the genome that contains the genetic info for one or more gene products |
| A protein coding gene is composed of what? | 1. the coding sequence 2. regulatory sequences 3. useless sequences |
| What is a pseudogene? | DNA sequences that have all the characteristics of a potential encoding transcription unit but which encode for no funtional product. |
| What is gene expression patterns? ` | the particular set of alleles/genes that is turned on or off in a given context. Environmental input may affect |
| Variation in gene expression patterns may lead to what? | variation in phenotype |
| What is the sense strand? | The DNA strand which (except Ts and Us) corresponds to the RNA sequence |
| The complement of the sense strand is what? | the antisense strand which is a template for RNA biosynthesis |
| What lies at the start of the gene? | the promoter region |
| what is the promoter region? | serves as a docking station for various specific transcription factors and an RNA polymerase that represents the transcription initiation complex. |
| Name a classic promoter sequence. | TATA box -> situated 25 nucleotides upstream of the transcription start site. |
| What is a transcriptome? | complete set of RNA molecules in a population of cells. |
| What do you call the sequence before the start codon and after the stop codon of a gene? | untranslated regions (UTR) |
| what is the coding region? | the part of the gene that is translated into protein |
| exons? | coding sequences in the pre-mRNA that are seperated by noncoding introns |
| introns? | non-coding sequences in a gene that are poitioned between coding sequences and are removed by splicing from the pre-mRNA transcript |
| UTRs? | the part of the gene that is transcribed and included in the matter mRNA but is not translated into a protein. |
| What is a telomere? | the ends of the chromosomes that consist of numerous tandem repeats of 5'-TTAGGG-3' sequence . protect end of chromosomes a countdown, tells cell when to stop dividing. |
| What are the 3 classes of Tandem Repeats? | 1. Short Tandem repeats (STRs): tandem repeats with a unit size of 2 to 6 nt. 2. Minisatellites (variable number tandem repeats): Tandem rep. with a unit size 10 to 60 nt. 3.Satellite DNA: 60 to 200 nt that create important structures like centromeres |
| What are copy number variants (CNV)? | segments (1 kb-1Mb) of chromosomes that repeat in different multiples among individuals. (variation in the # times that the variation appears) |
| What is the central dogma? | the info flow from nucleic acid to protein. |
| why are we so concerned with prions? | prions are misfolded proteins (mad cow disease) |
| What was Chargaff's Rules? | in any organism the amount of purines = the amount of pyrimidines AND the amount of T=A, amount of G=C |
| How do we determine Directionality? | determined by carbon position of phosphate attachment |
Created by:
courtneycameron
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