Gene Expression Flashcards
Cells which can mature into any type of body cell
Totipotent (or omnipotent)
Cells which can differentiate into almost all types of cells eg in a blastocyst
Pluripotent
Cells which can differentiate into a related family of cells eg blood or muscle cells. Used by body to repair and replace damaged tissue
Multipotent
normal, specialised adult cells that have been genetically reprogrammed to become undifferentiated, pluripotent stem cells. iPSCs are a new development, still at the research stage, but they may solve some of the problems of both adult and embryo stem cells.
Induced pluripotent stem cells
(iPSCs)
Explant
Small samples of plant used for tissue culture/micro-propagation.
Callus
A mass of undifferentiated plant cells grown from individual cells from a plant. A callus can be stimulated to form a plantlet
PGRs
Plant Growth Regulators- added to callus to allow them to grow into plantlets for propagation
Multipotent cells still existing in adult animals. Difficult to find and culture as usually only multipotent
Adult stem cells
Embryonic stem cells
Pluripotent cells existing in embryos ie before they have differentiated. From ‘spare’ IVF (In vitro fertilisation) embryos- therefore ethically debatable
Transcriptional factors
Specific molecules which move from cytoplasm to nucleus to stimulate transcription
Small interfering RNA- small double-stranded sections of RNA which prevent gene expression by bonding to complementary base pairs to ‘block’ transcription
siRNA
Heritable changes in gene function without changing the base sequence of DNA, caused by changes in the environment
Epigenetics
Methyl groups are added to the DNA which represses transcription as it leads to the DNA becoming more tightly packed.
Methylation
Acetylation
Acetyl groups are added to histones which allows transcription as it leads to the DNA becoming more loosely packed.
Tightly packed DNA – strong association between histones and DNA.
Heterochromatin
Euchromatin
Loosely packed DNA – weak association between histones and DNA.
Tumour
A tumour is mass of identical cells (clones) formed by uncontrolled cell division.
Malignant tumour
Tumour which grows quickly and spreads throughout the surrounding tissue, affecting its normal function and so causing harm (e.g. lung cancer reduces elasticity of alveoli). More difficult to treat without damaging the whole tissue.
Tumour which grows slowly, remains encased in a capsule and does not spread far eg wart. Removable by surgery or chemotherapy
Benign tumour
The spread of tumours to the bloodstream or lymphatic system and can spread to other body parts, causing secondary tumours there-the most difficult to treat.
Metastasis
Proto-oncogene
Gene which controls a cell’s division, by stimulating it
Gene which controls a cell’s division, by slowing it down
Tumour suppressor gene
Two-hit hypothesis
Mutation of both alleles necessary to inactivate tumour suppressor genes ie the reason cancers are often associated with old age (mutation rates are slow so over a longer time, increased chance of two ‘hits’)
