MBB 446 Lecture Glossary Flashcards
diploid
organism with 2 copies per gene
allele
different version of a gene
Dominant
Version of allele that expresses its phenotype when heterozygous
recessive
Unexpressed allele when heterozygous–only expressed when homozygous
phenotype
expression of the genotype
homozygous
alleles within an organism are identical
heterozygous
an organism carries two different alleles of a gene
hemizygous
only one copy of the gene the second one being deleted as in X chromosomes in males
SNP single nucleotide polymorphism
DNA sequence variant in a single nucleotide position. Must occure in > 1% of the population to be considered an SNP.
Mutation
DNA sequence variant occurring in less than one percent of the population.
Euploid karyotype
normal configuration of chromosomes; 22 autosome pairs + sex chromosomes in mammals
Aneuploidy
deviation from the euploid karyotype
Spectral Karyotype (SKY)
karyotype stained with different colours to aid identification of chromosomes
Homogeneously Staining Region (HSR)
repeated rounds of reduplication of a chromosome segment fused head to tail in a long array
Double Minute chromosomes (DMs)
chromosomal segments that have broken loose from their original sites and replicate autonomously to many copies per nucleus
Gene amplification
The process whereby more copies of a gene are available for expression than should be ie HSR and DMs
Germ line
The nucleic material of the sperm and egg
Somatic mutations
Mutations affecting the genomes of cells everywhere else in the body
constitutional DNA
The DNA in germ cells
Histology; Histopahtology
microscopic examination of tissue sections
neoplasia
new growth
parenchyma
chyma = poured in; para = beside; the tissue of the tumour
stroma
the extracellular matrix ECM in which other cells (connective; adipocytes; blood vessels; immune system cells) are embedded
desmoplasia
the growth of fibrous or connective tissue ie scar tissue around surgery; the formation of abundant collagenous stroma stimulated by parenchymal cells
Primary tumour
site where cancer begins
metastases
the spread of cancer to secondary sites throughout the body; often can be traced back to the primary tumor
benign
local growth; no invasion of adjacent tissues
malignant
invasion of nearby tissues; also metastases
Ectoderm
The outermost (distal) of the three germ layers in the embryonic stage (skin)
Endoderm
The innermost (proximal) of the three germ layers in the embryonic stage (becomes internal organs; lung liver gallbladder pancreas esophagus stomach intestines)
Mesoderm
The middle layer of the three germ layers in the embryonic stage (ovaries)
basement membrane
specialized type of ECM providing structural support for the epithelial cells; barrier between epithelial cells and the underlying stroma (supporting connective tissue) aka basil lamina
Carcinoma
malignancy of the epithelial cells (derive from all three germ layers) 90%
Sarcoma
malignancy of the connective tissues (derive from the mesenchymal cell types; fibroblasts secrete collagen adipocytes store fat osteoblasts form bone myocytes form muscle) 2%
Leukemia
malignancy of the blood forming (hematopoietic) cells 8% w Lymphoma
Squamous cell carcinomas
Originating from epithelial cells that from protective cell layers
Adenocarcinomas
Originating from specialized epithelial cells that secrete substances into ducts or cavities that they line
leiomyosarcoma
arises from cells that form smooth muscle
Lymphoma
tumor of the lymphoid lineages (B & T lymphocytes); aggregate toform solid tumor masses found in lymph nodes
Neuroectodermal tumors
arise from cells that form components of the central and peripheral nervous system; from the ectodermal layer 1.3%
transdifferentiation
switching of tissue lineage and resulting acquisition of an entirely new set of differentiated characteristics
epithelial-mesenchymal transition EMT
epithelial cells often change shape and gene expression programs and take on attributes of nearby stromal cells of mesenchymal origin
anaplastic tumors
tumors have losta ll tissue-specific differentiated traits of their normal precursor tissues. Cells have dedifferentiated; no longer possible to use histopathology to id tissue of origin
