cellular and molecular Flashcards
DNA is made up of 4 deoxyribonucleotides containing the purine bases _______ and ________, and the pyrimidine bases _________ and ________.
The bond between the bases is a ________ bond.
adenine and guanine
cytosine and thiamine
Adenine binds to thymine and cytosine binds to guanine.
hydrogen
- The central dogma of molecular biology is that DNA can be copied to DNA and to messenger RNA (process is called _________), and that proteins can be synthesized using the information in mRNA as a template (called _______), but that the information can’t be transferred back from protein to nucleic acid, or from RNA to DNA.
transcription, translation
- How is the structure of RNA different from DNA?
- Thymine is replaced with uracil
- The base pairs are linked by ribose rather than 2’ deoxyribose
- RNA is usually single stranded
- RNA is much more susceptible than DNA to degradation by nucleases
- What are/were the benefits of sequencing the genome?
- The expectation that knowledge of the sequence of position of all genes would produce tangible improvements in medical care
- Tools could be developed for storing and analyzing the large amount of information produced
- The work would produce a biotechnology industry to stimulate the development of new medical applications from the data
- A Boxer was chosen for the canine genome sequencing project because this breed was described as having the lowest rate of _________, in other words, the lowest rate of variation in sequence, when compared to other breeds.
heterozygosity
- The feline genome has also been sequenced. What is of particular interest?
-The large numbers of endogenous retrovirus-like sequences identified, accounting for about 4% of the feline genome.
- Only approximately __% of the genome codes for mRNA, rRNA, tRNA, small nuclear RNA, and small nucleolar RNA.
10
- Transcription is mediated by a DNA-directed what? Where in the cell does it occur?
- RNA polymerase
- Primarily in the nucleus, but also in the mitochondria
- The length of genes is often many times greater than that of the transcribed mRNA molecule due to the presence of _______ which are noncoding nucleic acids, that separate the exons, or the coding sequence. The base triplets of three nucleotides are termed codons and code for individual amino acids.
introns
- Translation of mRNA molecules to a polypeptide occurs in the _________.
ribosomes
The presence of intronic sequence permits alternative splicing of the exons and thus variation in the sequence, which is translated to protein from a single gene and is called a ____ ______. An important example is the increased expression of a splice variant in breast cancer causing a reduced survival time due to shorter time to tumor mets.
splice varient
- The majority of genomic DNA present within mammalian cells is not _______, with less than 2% of the haploid human genome coding for genes.
transcribed
- Areas of noncoding elements, which are highly conserved between mammalian species, are often associated with genes that code for ____________________
regulation of development.
- The one way flow of genetic information is not always the case. What is the enzyme that can generate a DNA sequence from and RNA template? What is the best described reverse transcriptase in mammalian cells and why is it thought to be important?
- Reverse transcriptase
- Telomerase, implicated in aging and oncogenesis b/c it is responsible for preventing the shortening of the telomere length and its expression is a near universal marker of malignancy
- Segments of DNA sequence that are transcribed into mRNA are termed _______. Its position and the start of the gene are identified by a sequence upstream termed the _______.
transcription units
promoter
- Genes such as ribosomal proteins and histones have a common function between different cells and thus are constitutively expressed between different cell types and are called ______ genes.
housekeeper
- What is epigenetics? What are some of the mechanisms by which it occurs? Give an example in dogs.
- Methods other than DNA sequence that control differential expression in different cell types within an individual
- Via DNA methylation and histone acetylation
- Hypomethylation is associated with transcriptional activity and has been implicated in the neoplastic transformation of cells and has been identified in canine neoplasia such as lymphoma
- What are mutations called that don’t affect the fitness of an individual?
-Neutral mutations
- What is a haplotype?
-When a set of alleles that are closely linked at a particular locus and they are inherited together, each different set is termed a haplotype
- What is the most common type of mutation? What are other examples.
-Most common is a single nucleotide polymorphism, or a point mutation
If it changes a protein sequence or length it is called a nonsynonymous mutation
-A missense mutation results in a change to an amino acid codon, which may alter the protein structure
-A nonsense mutation is when the mutation may replace the normal amino acid codon with a stop codon leading to termination of the protein sequence
-A synonymous mutation changes the sequence but not the amino acid
-The deletion or addition of a single or multiple base pair sequence will change the frame in which the sequence is read by RNA polymerase and is termed a frame shift mutation
