Unit 2 Part 2: Non-Mendelian Genetics Flashcards
Responsible for the traits that Mendel studied in pea plants were on different chromosomes.
Genes
T/F: When genes are close to each other on the same chromosome, they usually segregate at random during meiosis and therefore their expression does not support Mendel’s predictions.
F; do not segregate
Genes close on a chromosome are packaged into the same gametes and are said to be ______
linked
Refers to the transmission of genes on the same chromosome
Linkage
Who identified more than 50 genes on Drosophila’s 4 pairs of chromosomes?
Thomas Morgan
Do not assort independently and do not produce Mendelian ratios for crosses tracking two or more genes
Linked Genes
He discovered that many seemed to be linked together. They are almost always inherited together & only rarely become separated.
Thomas Morgan
Grouped genes into 4 linkage groups
Thomas Morgan
Linkage maps were first developed by?
Alfred Sturtevant
A map based on the frequencies of combination between markers during crossover of homologous chromosome
Linkage Map
A map of the genes on chromosome based on linkage analysis
Linkage Mapping
T/F: A linkage map does not show the physical distances between genes but rather their relative position, as determined by how Gene loci are inherited together.
T
Some DNA sequences are nearly always inherited together, like two inseparable friends. This nonrandom association between DNA sequences is called
Linkage Disequilibrium (LD)
The human genome consists of many LD blocks, where stretches of alleles stick together, interspersed with areas where crossing over is prevalent. LD blocks, called __________, could be used to track genes in populations.
haplotypes
Is a combination of alleles at multiple linked loci that are transmitted together
Haplotype
May refer to as few as 2 loci or to an entire chromosome depending on the number of recombination events that occurred between a given set of loci
Haplotype
The term haplotype is a portmantaeu of ________
Haploid Genotype
Is a set of single nucleotide polymorphisms (SNPs) on a single chromatid that are statistically associated
Haplotype
T/F: Sex is determined by genetic information in human
T
It extensively controls physical, psychological, and behavioral traits which are also influenced by genetic information
Sex-Linked Traits
may be categorized by how sex affects phenotypic traits, including sex itself as a trait (i.e., sex determination), sex-linked trait, sex-limited trait, and sex- influenced trait
Sex-related genetics
Genes on the Y chromosome
Y-linked
Genes on the X chromosome
X-linked
T/F: Y-linked traits are rare because the chromosome has few genes, and many of its genes have counterparts on the X chromosome.
T
T/F: X-linked traits are passed from male to male, because a female does not have a X chromosome.
F; Y-linked traits are passed from male to male, because a female does not have a Y chromosome.
T/F: No other Y-linked traits besides infertility (which obviously can’t be passed on) are yet clearly defined.
T
T/F: Some traits at first attributed to the Y chromosome are actually due to genes that have been inserted into that chromosome from other chromosomes, such as a deafness gene.
T
Part of Chromosome
Mutation = Infertility
SRY
Part of Chromosome
Controlled by multiple genes
Tooth Enamel Formation
Part of Chromosome
Mutation = Male can produce necessary fluids but no sperm; angospermia
AZF / Azoospermia Factor
Part of Chromosome
Pseudoautosomal regions - create homology between X & Y chromosomes
PAR2
T/F: A disproportionate number of X-linked genes cause illness when mutant. The chromosome includes 4 percent of all the genes in the human genome, but accounts for about 10 percent of Mendelian (single-gene) diseases.
T
T/F: X-linked diseases are more common in males
T
T/F: In males, X-linked traits are passed just like autosomal traits—that is, two copies are required for expression of a recessive allele and one copy for a dominant allele.
F; females
T/F: In males, however, a single copy of an X-linked allele causes expression of the trait or illness because there is no copy of the gene on a second X chromosome to mask the effect. A man inherits an X-linked trait only from his mother.
T
The human male is considered __________ for X-linked traits, because he has only one set of X- linked genes.
hemizygous