GAG WK1 Flashcards
What is a genome
all the genetic information of an organism
What are the 2 main human genomes
nuclear & mitochondrial
What are the features of nuclear genome
- found in the nucleus
- most of the organisms’ genes (larger genome)
- contains linear DNA organised into 23 pairs of chromosomes
What are the features of mitochondrial genome
- found in the mitochondria
- contains 37 genes & involved in energy production
- smaller genome
- contains circular DNA
DNA definition
a polymer of nucleotides that forms double helix
What are features of double helix structure
- they have major & minor grooves
- they can form different double helix structures that can affect its regulation
What is a feature of the major grooves of DNA
- they have more open space so they can allow proteins in
- (major/minor grooves affect protein binding)
How is the DNA Structure so stable
- base pairings with H bonding
- base stacking allows hydrophobic effect, and Van der Waals interaction maximises favourable interactions
What is DNA Packaging
DNA is wrapped around nucleosomes to help contain DNA in nucleus
What are histones
proteins associated with DNA that have tails which can influence gene expression via epigenetic modification
What are nucleosomes
they are made up of 4 pairs of histones and form an Octomer
What are the 2 main types of chromatin
- euchromatin
- heterochromatin
What are the features of euchromatin
- loosely packed + less condensed chromatin
- found in transcriptionally active regions (most chromosomes)
- accessible to transcription for active gene expression
What are the features of heterochromatin
- tightly packed + less condensed chromatin
- found in inactive genes or repetitive DNA sequences (ex: telomeres)
- non-accessible to transcription for silencing genes
What are karyograms
visual representation of chromosomes showing distinct banding patterns (organised in descending size order)
Why would karyograms be useful
- identify chromosomes
- detecting chromosomal abnormalities
What kind of genes does mitochondrial genome encode for
essential genes for mitochondrial functionn
What is DNA sequencing
determining the order of nucleotides in DNA
What is the purpose of DNA sequencing
- identify: mutations + structure + genes
What are the 3 main types of DNA sequencing
- Sanger Sequencing
- Next generation sequencing
- nanopore sequencing
What is Sanger sequencing
sequencing DNA by making DNA fragments different lengths
Outline the 5 main steps of sanger sequencing
- DNA denaturation
- Primer annealing
- Strand (DNA) Synthesis
- Chain termination
- separating DNA fragments via electrophoresis
What happens during Step 1 of Sanger sequencing
- DNA denaturation
- double strand is denatured into single strands
What happens during step 2 of Sanger sequencing
- primer annealing
- primer is added to start strand synthesis
What happens during step 3 of Sanger sequencing
- strand synthesis
- DNA polymerase extends strand w/ dNTPs
What happens during 4th step of Sanger sequencing
- Chain termination
- ddNTPs are randomly added to stop strand synthesis
- each ddNTP has a fluorescent dye
What happens during step 5 of Sanger sequencing
- separating DNA fragments via electrophoresis
- They are separated by size, and the detectors reconstruct the DNA
Why do ddNTP terminate DNA synthesis
- they lack 3-OH group and cannot make phosphodiester bonds
What are the benefits of Sanger sequencing
- they can sequence small pieces of DNA (small-scale sequencing)
What is Next Generation Sequencing
it allows millions of DNA fragments to be sequenced at once via parallel sequencing