Intro to Genetics Flashcards
what is FAP
familial adenomas polyposis - autosomal dominant inherited condition
numerous polyps form in the epithelium of the large intestine - start benign but can lead to colon cancer
what ways can you diagnose a genetic disorder
family trees, physical exams, non-genetic and genetic tests
what types of non-genetic tests are there and what can they identify
blood tests - enzyme assays, inborn errors of metabolism
haematology - thalassaemia
x rays - skeletal dysplasia, achondroplasia
what types of genetics tests are there
genomic architecture - cytogenetics, array-based techniques
gene faults - sequencing, OLA assays, MLPA tests
in genome anatomy how many nucleotides is 750 megabytes of uncompressed data
3x10 ^9
what is DNA stable and RNA unstable
because of the OH on 2’ carbon which attacks the phosphodiester bond between RNA molecules causing the RNA to fall apart
what is a karyotype
combination of chromosomes in a cell
describe the anatomy of a chromosome
two arms - attach at mitotic spindle (p - short, q - long)
telomeres - on each arm - labelled ptel and qtel
q banding splits the arms into further division eg 7q5 which allows chromosomes to be coordinated as they are linear
what is the role of telomerase
which cells is it active and inactive in
TERT - replaces telomere lost in replication - inactive in somatic cells ie a finite number of divisions
active in cancer cells
what is our DNA content
n = 23
2n = 46
3x10^9 from paternal and maternal so 6x10^9 in total
why do we need two alleles
haploinsufficency occurs if single copy of allele at the locus so can’t produce standard phenotype
which chromosome do we only need one
X chromosome - the other is inactivated
what are pseudoautosomal regions
homologous (shared/same) regions between X and Y
what is the SRY gene
in males, present on the Y gene which leads to development of testes and determination of male traits
what percentage of the genome is non-coding
more than 90%
how many protein coding genes are there
20,000
what is the genome made up of
genes, repetitive sequences and satellite DNA
what are genes made out of
UTR’s, introns and exons
what is the result of alternative splicing
removes different introns so different proteins can be coded from the same gene
where are UTRs located and what are they replaced by in transcription
within the coding region and replaced by cap and polyA tail
what is the definition of gene families
structurally related genes which have differentiated over time due to divergence and duplication
what is pseudogene
genes that no longer work
what is a processed gene
intronless copies of genes which are caused by reverse transcription and reintegration (eg HIV) - most of the time non-functional
what are two examples of repetitive sequences
satellite DNA
interspaced repeats
what is satellite DNA
give an example
large blocks of repetitive DNA mainly near centromeres
alphoid DNA - 171 repeat - they allows identification of chromosome
required for assembly of centromere
what are interspaced repeats and give an example
scattered around the genome
eg Alu repeat (a SINE) - short interspaced nuclear element (300 bp) which makes up 5% of the genome
it has a role in molecular pathology
what is mitochondria derived from
evolutionary remnants of endosymbiotic bacteria
describe the structure of mitochondrial genome
circular genome which is reduced over time
16,569 bp
37 genes
cytoplasmic inheritance through oocyte
what is a nucleosome
around 200 bp of DNA wrapped around a histone protein
