Gene expression - Yr 2 Flashcards
Totipotent (or omnipotent)
Cells which can mature into any type of body cell
Pluripotent
Cells which can differentiate into almost all types of cells eg in a blastocyst
Multipotent
Cells which can differentiate into a related family of cells eg blood or muscle cells. Used by body to repair and replace damaged tissue
Induced pluripotent stem cells
iPSCs
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.
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
Adult stem cells
Multipotent cells still existing in adult animals. Difficult to find and culture as usually only multipotent
Embryonic stem cells
Pluripotent cells existing in embryos ie before they have differentiated. From ‘spare’ IVF embryos- therefore ethically debatable
Transcriptional factors
Specific molecules which move from cytoplasm to nucleus to stimulate transcription
siRNA
Small interfering RNA- small double-stranded sections of RNA which prevent gene expression by bonding to complementary base pairs to ‘block’ transcription
Epigenetics
Epigenetics is the study of cellular and physiological traits (and their underlying mechanisms) that are heritable by daughter cells and which result from changes in gene expression that are not due to an alteration in the DNA nucleotide sequence).
Methylation
Methyl groups are added to the DNA which represses transcription as it leads to the DNA becoming more tightly packed.
Acetylation
Acetyl groups are added to histones which allows transcription as it leads to the DNA becoming more loosely packed.
Heterochromatin
Tightly packed DNA – strong association between histones and DNA.
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.
Benign tumour
Tumour which grows slowly, remains encased in a capsule and does not spread far eg wart. Removable by surgery or chemotherapy
Metastasis
Tumours which spread to the bloodstream or lymphatic system and can spread to other body parts, causing secondary tumours there-the most difficult to treat.
Proto-oncogene
Gene which controls a cell’s division, by stimulating it
Tumour suppressor gene
Gene which controls a cell’s division, by slowing it down
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’)
Genome
All of the genetic material in an organism.
Complete proteome
The full range of proteins coded for by the genome. (Identified by gel electrophoresis and mass spectrometry).
Cellular proteome
refers to the proteins produced by a given type of cell under a certain set of conditions.
Epigenome
The sum of all the epigenetic changes in a cell.
Sanger Sequencing
Initial method of sequencing genomes that requires terminator nucleotides, free nucleotides, primers, DNA polymerase and result in multiple fragments of varying length, which allows the DNA sequence to be determined.
Human Genome Project
International scientific research project to determine the nitrogenous base pair sequence which make up human DNA, identifying and mapping all the genes of the human genome
Next Generation Sequencing (NGS)
Faster, more recent sequencing methods that are continually developing and becoming more efficient, powerful and cost effective.
Whole-genome (shotgun) sequencing
Focuses on sequencing all of the DNA in an organism’s genome by cutting the DNA into many small, easily sequenced sections then uses computer algorithms to align overlapping segments to assemble the entire genome.
DNA electrophoresis
Method of separating out negatively charged DNA fragments by applying a current. The smaller fragments will move quicker towards the positive anode.
