Genes Flashcards
Gene
Unit of heredity, regions of chromosomal DNA encoding polypeptides and RNAs
Intron length
Short in unicellular/oligocellular euk, many kb in multicellular euk
Exon length
Usually short, encoding for fewer than 100 amino acids
Intron-early hypothesis
Interrupted genes that correspond to proteins or independently functioning noncoding RNA probably originated in interrupted form
Intron-late hypothesis
Earliest genes did not contain introns
Two parity rules
1) A=T, G=C 2) Equal amounts of A and T, and G and C, found on stretch of single-stranded RNA
Homologous genes
Share common features and common ancestor
Paralogous genes
Homologs within same species
Orthologous genes
Homologs that diverged after a speciation event but have a conserved function
Housekeeping gene
A gene that is (theoretically) expressed in all cells because it provides basic functions
Some ____ correspond to protein functional domains
Exons
What suggests that introns do not separate functional domains?
Varying intron positions in actin gene family
The use of _______ allows multiple variants of a polypeptide chain (3)
Alternative initiation or termination codons, alternative splicing, mRNA read in different reading frames
The number of genes in eukaryote genomes is ______ to genome size
Not proportional
Total amount of DNA in the genome
C-value
Lack of relationship between the DNA-content of organism and it’s coding potential
C-value paradox
Majority of repetitive DNA content
Transposons
Polypeptides are generally encoded by sequences in _____
Nonrepetitive DNA
Luxury genes
Gene encoding a specialized function (usually) in large amounts in certain cell types
In any particular cell, most genes are expressed at a ______
Low level
Not all genes are essential. In yeast and flies deletions of less than ___% have detectable effects
50
Repeated sequences account for more than ___% of the human genome
50
__% of human genome consists of exons
1
Human genome has about _____ genes
20,000
Mitochondria (mtDNA) and chloroplasts (cpDNA or ctDNA) have genomes that show ________
Non-Mendelian inheritance (typically maternal)
_____ between multiple copies allows the active genes to be maintained during evolution in Y chromosome
Gene conversion
Region of the animal mitochondrial DNA molecule that is variable in size and sequence and contains the origin of replication
D loop
Animal cell mtDNA encodes for?
13 proteins, 2 rRNAs, 22 tRNAs
Animal cell mtDNA encodes for?
Very compact: 13 proteins, 2 rRNAs, 22 tRNAs
