Genetic Innovations Flashcards
Factors similar to all cells
-Chromosomes
-RNA polymerases
-DNA repair enzymes
-Ribsiomal proteins
-enzymes involved in metabolism
-proteins in cytoskeleton
How to differentiate between specialized cells
Some proteins are abundant in specialized cells and cannot be detected elsewhere even by sensitive tests. Example is haemoglobin
How many genes does a cell express at a time
10,000-20,000 of their 30,000 genes
Gene expression changes in response to external signals
-Liver exposed to glucocorticoid hormone will dramatically increase the production of specific proteins
-Glucocorticoids are released during starvation or exercise and signal the liver to increase glucose production and increase the production of tyrosine aminotransferase to convert tyrosine to glucose
-protein levels drop when hormone is no longer present
-Other cells will respond differently to glucocorticoids as fat cells reduce tyrosine amniotransferase production and other cell types don’t even respond
-There are also features of the gene expression pattern that do not change and give each cell type its permanently distinctive character
Where can gene expression be regulated I’m the pathway from FNA to RNA
-Controlling when and how often a gene is transcribed
-control how the RNA transcript is spliced or otherwise processed
-selecting which completed mRNAs in the cell nucleus are exported to the cytoskeleton and determining where in the cytoskeleton they are localized
-selecting which mRNAs in the cytoplasm are translated by ribosome
-selectively destabilizing certain mRNA
-selectively activating, inactivating, degrading, or compartmentalising specific protein molecules after they have been made
Summarized gene expression in pathway
-Transcription control
-RNA processing control
-RNA transport and localized control
-Translation control
-mRNA degradation control
-Protein activity control
G banding
It is uses Giemsa-staining that sticks to regions in chromosomes rich in A-T causing them to be bands while areas rich in G-C have inter bands.
-Each chromosome has a specific pattern like a bar code and so this techniques allows each chromosome to be identified by their patterns
Limitation of G-banding
The smallest fragment it can analyze is 5000kb
FISH
Fluorescence in Situ Hybridization
-It works by adding specific probes which contain specific DNA sequences that bind to matching sequences in chromosomes in order to analyze chromosomal abberations as the probes will bind to it. Diffent probes have different colors which allows you to say where and what chromosomal abberations are present as well as locate where specific genes in a chromosomes or detect how many copies of a genes are present in a genome
G-Banding vs FISH
G-banding is better than FISH as it is cheaper and less labor intensive. FISH can analyze fragments in the 1000s
Microarray-based karyotyping
It is a genetic test that measures dna gains and losses throughout the genome
It can only detect unbalanced chromosomal abnormalities and it cannot detect balanced abnormalities such as:
-reciprocal translocations
-inversions,
-ring chromosomes
as these abnormalities do not affect copy number which is what is detected by this technology
Array-based workflow
• DNA labelling: DNA is extracted from the samples) and labelled with a fluorescent dye.
• Hybridization: Mix and hybridise to an array printed with thousands of oligonucleotide probes and wash.
• Fluorescence visualisation and imaging: Detect signals with a fluorescence scanner and compute and report gains and losses by comparing them to a reference genome.
PCR Origin
• Kary Mullis - was awarded a Nobel Prize in Chemistry in the year 1993 for inventing the PCR technique
• PCR is a method of DNA cloning
• It is a rapid method that does not require host cells for DNA replication
• Can amplify target DNA sequence from tiny amounts of DNA
- Used to determine how changes in sequence lead to downstream changes in gene expression and protein structure
