Chapter 8 Flashcards
Where in an animal cell is genetic information found? Plant? Bacteria?
Animal: Cell Nucleus
Plant: Cell Nucleus
Bacteria: Nucleoid
In what forms can viral genetic information be found?
CIRCULAR & LINEAR
(bacteriophages have circular DNA)
(ALSO: RNA Viruses, DNA Viruses, Reverse Transcribed DNA, Proviral DNA, mRNA)
What does (+) Positive Sense refer to? (ex: (+)ssDNA)
Positive-sense means that the genetic sequence of the viral genome can be directly translated into proteins, similar to cellular messenger RNA (mRNA)
How is (+)ssDNA turned into proteins?
DNA -> Transcription -> RNA -> Translation -> Protein
How does +ssRNA become protein and why does it return back to +ssRNA?
Why is this important?
RNA -> Translation -> Protein
To return back to +ssRNA:
Viral RNA is replicated into complementary negative-sense RNA (-ssRNA) in order to create new copies of the +ssRNA
- THIS ENSURES THE CONTINUITY OF THE VIRAL LIFE CYCLE
How do retroviruses create proteins and do viral replication?
Reverse Transcription!
The reverse transcriptase synthesizes a complementary DNA strand (cDNA) using the viral RNA as a template. This results in the formation of a double-stranded DNA molecule.
Why is it that if you swallow a rhinovirus you will not get sick? Why doesn’t the rhinovirus infect dogs?
The primary site of infection for rhinoviruses is the upper respiratory tract, particularly the nasal passages and throat. Rhinoviruses primarily target and replicate in the cells lining the nose and throat.
Rhinoviruses don’t infect dogs because viruses often show a high degree of HOST SPECIFICITY (they have evolved to infect humans), as well as RECEPTOR SPECIFICITY and the fact that viruses can’t survive long if they can’t replicate in certain types of cells (SPECIES BARRIER)
Characterize e. Coli’s genome.
Circular, double-stranded DNA genome
Relatively small (only 4.6 million base pairs)
Genes & Coding Regions
Operons
(Plasmids)
What is a BAC library and how are bacterial plasmids used in sequencing?
A collection of cloned DNA fragments from a particular organism’s genome that have been inserted into Bacterial Artificial Chromosomes (BACs). BACs are large plasmid vectors that can accommodate large DNA fragments, typically ranging from 100 to 300 kilobase pairs (kb).
BAC libraries are used for genome mapping, allowing researchers to create physical maps of an organism’s genome.
What are “Orthologs”?
Genes found in different organisms that have similar purpose and can be traced back to a gene present in their common ancestor.
What is the difference between Genomics, Transcriptomics, and Proteomics?
Genomics: DNA genome comparisons
Transcriptomics: mRNA comparisons (studying SPLICING!)
Proteomics: Protein Comparisons
What is splicing? Why is mRNA splicing necessary? Why might alternative splicing be beneficial?
Removing sections (introns) of mRNA transcript and ligating (fusing) together the remaining exons.
-> product is mRNA that is ready for translation
NECCESSARY for the formation of continuous coding sequences and the enhancement of mRNA stability and transport
Roughly how much of the human genome is made up of protein-coding genes?
~1.5%
What are SNPs? How are they useful?
Predictable locations for point mutations that allow us to only look at places where bases can vary between person to person. HELPS WITH DNA SEQUENCING. EVERY PERSON HAS THE SAME DNA EXCEPT FOR THE SNPs
(Single Nucleotide Polymorphisms)
What are some large-scale chromosomal alterations that can occur?
Inversions
Duplications
Transpositions
Can you define and explain inversions, duplications, and transpositions?
Inversions: flipped or inverted!! an inversion is a segment of DNA is reversed in orientation within a chromosome
Duplications: the presence of multiple copies of the same gene or genomic region within an organism’s genome.
- can be caused by unequal crossing-over and transposons
Transpositions: the movement of genetic elements, often specific DNA sequences called transposons or “jumping genes,” within a genome.
What are linked genes?
Linked genes are genes that are located close to each other on the same chromosome. They tend to be inherited together.
How do you connect genes with diseases/phenotypes?
Identify SNPs, Focus on specific potential genes in studies, Observe proteins formed
How do you distinguish between healthy and diseased individuals on a pedigree? How about living vs. deceased?
Healthy = empty box
Diseased = red box
Living = no line through
Deceased = line through
What is a dot plot in the context of genomics?
A graphical method for comparing two biological sequences and identifying regions of close similarity after sequence alignment
What is a “Genome Map” and what can it tell us?
Species-specific map of the genome. It can offer firm evidence that a disease transmitted from parent to child is linked to one or more genes. Mapping also provides clues about which chromosome contains the gene and precisely where the gene lies on that chromosome.
What is a sequencing “read”?
A shorter segment of DNA
- Used with A LOT of other reads to create contigs. Multiple reads create higher fold coverage.
What is a “sequencing assembly”?
Aligning and merging reads from a longer DNA sequence in order to reconstruct the original sequence.
What is a sequencing “contig”?
A set of DNA segments or sequences that overlap in a way that provides a contiguous representation of a genomic region.
