IMMS Flashcards
Name drugs that target parts of mitosis to treat cancer
Mitotic spindle- taxol and Vinca alkaloids.
Anaphase-Colchicine-like drugs
Spindle poles-Ispinesib
Describe sperm production
Primordial germ cells undergo mitosis to produce spermatogonia.
Cytoplasm divides equally to form 4 equal gametes.
Describe egg production
Primordial germ cells undergo mitosis to produce oogonia.
Oogonia enters meiosis I by 8th month of intrauterine life
Cytoplasm divides unequally – 1 egg and 3 polar bodies (that apoptose)
What is Gonadal Mosaicism
Occurs when precursor germline cells to ova or spermatozoa are a mixture of two or more genetically different cell lines
Define Genotype
Genetic constitution of an individual
Define Phenotype
The appearance of an individual resulting from the interactions between the genotype and their environment
Define Polymorphism
Frequent hereditary variations at a locus
Define Penetrance
The proportion of individuals with a certain genotype who express the associated phenotype.
Define Hemizygous
only one allele refers to a locus on an X chromosome in a male
Define ACMG criteria
formal scoring system to decide if a gene variant is “pathogenic”
Define Consanguinity
reproductive union between two relatives
Define Recipricol Translocation
When part of one chromosome is exchanged with another.
Summarise multifactorial inheritance
Combination of genetic and environmental factors.
If the affected individual is female, males relatives will be more at risk and vice versa.
State 2 technologies used to identify chromosomal abnormalities
- FISH- fluorescence hybridisation
- Microarrays- investigate the genome at a higher resolution
What are oligosaccharides?
Carbohydrate which contains 3-12 monosaccharides.
What are phosphoacylglycerols?
Derived from phosphatidic acid.
Formed from fatty acids esterified to glycerol and phosphorylated at C 3.
Examples:
Phosphatidylcholine, Phosphatidylserine
Describe the key features of steroids
Formed from cholesterol
Derive our sex hormones from
Fat soluble
How are protein structures determined?
X-ray diffraction of protein crystals
-Crystalise pure proteins
-Rays bounce off electrons
-Creates diffraction patterns
-Carry out density calculations on spots
How is DNA damaged?
chemicals, UV, radiation, chance
How is DNA repaired?
- Base or nucleotide excision
- Mismatch repair
Give an example of a tumour suppressor gene and its function.
Pause cell cycle until repair is carried out
Halt cell cycle if DNA not repaired
Apoptosis
What are enhancers?
non-coding sequences in the genome that activate the expression of target genes
What does methylation of cytosine do?
Inhibits gene expressions
Summarise cystic fibrosis
Autosomal recessive condition
Carrier frequency- 1/25
Incidence- 1 in 2500
CTFR gene on chromosome 7q31.2
Summarise cystic fibrosis
Autosomal recessive condition
Carrier frequency- 1/25
Incidence- 1 in 2500
CTFR gene on chromosome 7q31.2
What is the probability of healthy siblings of someone affected being carriers of the same disease?
2/3
What is expressivity?
Refers to the range of phenotypes expressed by a specific genotype
What is anticipation?
Whereby genetic disorder affects successive generations earlier or more severely, usually due to expansion of unstable triplet repeat sequences
Somatic mosacism
Genetic fault present in only some tissues in body.
Gonadal (germline) Mosaicism
Genetic fault present in gonadal tissue. (generally more common in X-linked disorders)
Lyonization
X-inactivation
Generally only one of two X chromosomes is active in each female cell. Can be skewed so the number of cells with the X chromosome from their mother and father switched off isn’t 50%
What is (genomic) imprinting?
Non-mendelian inheritance
An epigenetic phenomenon that causes genes to be expressed in a parent-of-origin-specific manner
What is homoplasmy?
a eukaryotic cell whose copies of mitochondrial DNA are all identical
What is heteroplasmy?
there are multiple copies of mtDNA in each cell
Define Splice-Site Variant
Affects the accurate removal of an intron
Define Non-Sense Variant
A mutation that changes a codon to a stop codon
Define a Missense Variant
Single base substitution that changes the type of amino acid in the protein
Define Allelic Heterogeneity
Lots of different variants in one gene e.g. cystic fibrosis
Define Locus Heterogeneity
Variants in different genes give the same clinical condition e.g. hypertrophic cardiomyopathy
Define a loss of function variant
Only one allele of the pair is functioning.
Most loss of function variants are recessive.
Define a gain of function variant
A mutation that lead to:
-Increased gene dosage
-Increased protein activity
