Genome & Gene Structure Flashcards
Define genome.
The genome is the full set of chromosomes or genes in a gamete. In modern molecular biology, the genome of an organism is its hereditary information encoded in DNA. The genome includes both the genes and the non-coding sequences of the DNA.
What is the difference between genetics and genomics?
Genetics is on a single-gene level while genomics is genetics on the genome level.
What is the C-value enigma? (C-value refers to the genome size)
The number of base pairs and the number of genes are very variable. While it is largely true for prokaryotic and viral genomes that genome size corresponds to the number of genes, this is definitely not true for most eukaryotic genomes. It is not a linear relationship.
What is the genome melting point?
This refers to the temperature at which 50% of the genome goes from double-stranded to single-stranded.
What is melting in reference to DNA?
Melting is the process by which the hydrogen bonds between the nucleotide base pairs come apart.
How is UV light used to measure DNA melting?
Melting corresponds to a dramatic increase in UV absorption. Double-stranded DNA does not absorb much light, so as DNA melts, it is able to absorb more light.
What is the relationship between the percentage of G-C bonds in a genome and the temperature required to melt it?
The more G-C bonds in a genome, the higher the temperature required to melt it. This is because G-C bonds are composed of three hydrogen bonds vs the two in A-T bonds. So as G-C% rises, the melting point rises.
How do re-association kinetics studies work?
These studies examine the rate at which genomes reassemble after melting to single strands. The sample is allowed to cool and the DNA that reassembles is measured using UV light absorption.
What is the relationship between annealing rate and genome size in re-association kinetics studies?
In these studies, size matters. The smaller the genome, the faster it will re-anneal.
Name the three distinct phases of eukaryotic re-association kinetics and where they re-anneal in the reaction.
- Highly repeated fraction: re-anneals early in the reaction because there are many more partners for which the parts can bind.
- Moderately repetitive fraction: re-anneals in the middle of the reaction.
- Non-repeated fraction: re-anneals at the end of the reaction.
What percent of the human genome is non-coding?
98%.
What is the transcriptome?
The transcriptome represents the collection of all the mRNAs in an organism/tissue/cell (at a given time point).
Define proteomics.
Proteomics reveals the proteome, which represents the collection of all the proteins in an organism/tissue/cell (at a given time point).
How are prokaryotic genes linked together?
They are linked together in groups called operons. Operons allow several genes with a linked function to share common upstream regulator sequences known as promoters to generate multi-cistronic mRNA.
