T5M3 Flashcards
How many pairs of chromosomes in a human cell?
23
The pairs of chromosomes in a human cell consists of how many base pairs of DNA?
over 3 billion
How many protein coding genes in human genome?
estimated over 20 000
More than one gene per chromosome: yes or no?
yes
Alleles are linked on a single chromosome meaning they must
unlink and recombine in different ways
How many types of sex chromosomes? What are they?
2, X and Y
How many genes on Y chromosome? Code for how many proteins?
78, code for 25 proteins (half sex)
Non Homologous
almost none of the genes in the X chromosome have counterparts in Y chromosome
Sex linked gene
a gene on either sex chromosome, expression of phenotype depends on sex of individual
Do Mendel’s principles of inheritance apply to genes on X an Y?
no, did not observe in pea plants they have no sex
Ishihara colour test
red-green colorblindness, circle filled with dots
Women that are colour blind genotype
homozygous for the color blind allele
Male colour blind genotype
receives recessive colour blind allele from mother
Hemizygous individual
only have one locus for this allele, rule of dominance and recessiveness no longer apply
Hemizygous individual
only have one locus for this allele, rules of dominance and recessiveness no longer apply
Will a male show phenotype associated with the one allele they carry on X chromosome?
yes
Chances of passing on allele that determines colour blindness
50%
Haemophillia
blood clotting disorder, X linked recessive trait
Mendel’s second law of inheritance tells us that
two genes sort independently during gamete formation
Chromosome size
155 megabases/155m base pairs
Dystrophin codes for
protein muscle development
HPRT1 gene mutation can lead to
arthritis, hemophilia, colour blindness
Linked genes
Genes that are positioned close together on same chromosome
Will linked genes always be inherited together?
no
Recombination of alleles
position of gene does not change, relative association of allele does
Less recombination frequency in genes distance
genes that are closer together
Recombination frequency tool
used to determine distance between genes along the same chromosome
High density linkage maps
identify genetic loci that are merely a few thousand base pairs apart
GWAS
genome wide association study, look across entire SNP-linkage map for association between a phenotype and a mapped SNP
