Chapter 1 Flashcards
genotype
your DNA sequence, both nuclear and mitochondrial
phenotype
collection of your observable traits other than your DNA sequence
phenotype = genotype + environment + life history + epigenetics
epigenetic factors
inheritable and acquired gene regulation patterns that alter gene function (phenotype) without changing gene structure (genotype)
Most of your cells have the same DNA sequence except for …
- egg and sperm cells
- erythrocytes (red blood cells)
- cells of the immune system
CRISPR-Associated (Cas) system
powerful technique for genome editing
The most general classification of cells according to their structure and molecular biology is …
- prokaryotes (cells without a nucleus)
- eukaryotes (cells with a nuclei)
What are the two problems cells face when structuring their DNA?
- packaging to fit (eukaryotes have an even harder challenge because they also have a nucleus to account for)
- what to do during cell division, after DNA replication, to ensure each daughter cell gets one copy of the DNA
proteins
polymers of amino acids (20 amino acids which proteins are constructed from)
ORF
- Open Reading Frame
- found in protein-coding regions of a DNA sequence
- starts with a start codon and ends with a stop codon
exons and introns
- found in eukaryotes only
- exons are the coding region
- introns are the non-coding region that needs to be removed to form mRNA
Why do genes for tRNA have a cloverleaf pattern?
some regions are expressed as non-protein-coding RNA which may show regions of local self-complementarity corresponding to hairpin loops
What are the two basic approaches to identifying genes in genomes?
- priori method: which seeks to recognize sequence patterns within expressed genes
- ‘been there seen that’ method: which recognizes regions corresponding to previously known genes
- combined approaches are also possible
metagenomic data
sequences determined from environmental samples without isolating individual organisms
How much does any two person’s genomic sequence differ from one another?
0.1% (except for identical siblings)
Which changes in a DNA sequence count as a mutation?
Any change including substitutions, insertions, translocations, and deletions
Many of the differences between individuals take which form?
- single-nucleotide polymorphisms (SNPs)
- short deletions
- variations in number of replicates of repetitive sequences
Mutations in different DNA molecules of diploid chromosomes become separated by … while mutations in the same DNA molecules become separated by …
- assortment
- recombination (except for most of the Y chromosome and mitochondrial DNA)
What effect does “loss of function” mutations being recessive have?
homozygosity for the mutant allele generally has more more severe consequences than heterozygosity
Many diseases are associated with the formation of insoluble aggregates which are usually what?
misfolded proteins
How will mutations in the same DNA molecule in diploid chromosomes become unlinked?
recombination events that occur between their loci (the greater the separation distance, the more recombination)
The MHC region contains over 120 expressed genes, coding for proteins that do what?
- provide the mechanism by which the immune system distinguishes “self molecules from “non-self” molecules
- determine individual profiles for competence for resistance to diseases
- useful markers for determining relationships (among humans and animals)
What are two basic approaches to reversing extinction?
- selective breeding
- using CRISPR/Cas system to modify the genome of a living relative to approach that of the extinct species
Gene Drive
applies CRISPR/Cas technology to accelerate the dispersal of a chosen gene throughout a population (much faster than selective breeding)
De novo sequencing
sequencing a novel genome where there is no reference sequence available for alignment and sequence reads are assembled as contigs
Resequencing
once a reference genome is available, fragment sequences are mapped on the reference genome
What is exome sequencing used for?
- most inherited diseases result from the loss of activity of particular proteins which frequently arises from a specific mutation in the sequence coding for the protein (exon)
- to identify such a mutation we only need to sequence the exons
Central Dogma
DNA makes RNA makes Protein
proteome
amino acid sequences of the proteins expressed
Which RNAs are involved in the control of gene expression?
most non-coding RNAs except for RNAs involved in the machinery of protein synthesis, such as tRNAs an the ribosome
pseudogenes
degenerate genes that have mutated so far from their original sequences that the polypeptide sequence they encode will not be functional
Variable Splicing
possibility of omitting one or more exon
