Th2L03 Modes of genetic inheritance


Medicine Y1 (Theme 2 | Genetics) Flashcards on Th2L03 Modes of genetic inheritance , created by Emma Allde on 22/08/2016.
Emma Allde
Flashcards by Emma Allde, updated more than 1 year ago
Emma Allde
Created by Emma Allde over 7 years ago

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Question Answer
What occurs during meiosis I One round of DNA replication; 46 > 92 chromosomes
What occurs during meiosis II Two rounds of cell division the second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two (4 haploid gametes)
What are gametes haploids cells (23 chromosomes) such as an egg or sperm
Gametes unite during sexual reproduction to produce what a diploid zygote
What is monogenic inheritance The manner in which a particular genetic trait or disorder is passed from one generation to the next
Autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, multifactorial, and mitochondrial inheritance are examples of what monogenic inheritance
What are the characteristics of sperm production (@) Maintained throughout lifetime From puberty onwards
What are the characteristics of oogenesis (4) Largely complete at birth Suspended in meiosis I Resumes once a follicle releases its oocyte into the fallopian tube Then arrests at meiosis II
Human non-disjunction rate up to 3 in 100 (if fertilised most are miscarried)
What is the concept of Mendelian inheritance Basic principles associated with the transmission of genetic material, forming the basis of genetics
What are Mendel's laws the law of segregation and the law of independent assortment
What is the law of segregation Genes segregate at meiosis so each gamete gets 1 of the 2 genes from the parent
What is the law of independent assortment Alleles of different genes assort independently during gamete formation
What is an allele a variant of gene
What is a dominant allele an allele that has the same effect on the phenotype whether it is present in the homozygous or heterozygous state
What is a recessive allele A hidden allele whenever the dominant allele is present
What are the 3 examples of Non-Medelian inheritance Mitochondrial inheritance Cytoplasmic Extranuclear inheritance
What makes mitochondrial inheritance non-Mendelian (2) • Mitochondria contain their own circular genome which encodes 13 polypeptides plus rRNA and tRNA • Mitochondria are inherited exclusively from the mother (sperm cell mitochondria are excluded from the zygote)
Mutations in mtDNA affects organs that: Use high amounts of energy (ATP) e.g. muscle and nerve
What are the 3 general characteristics of mitochondrial cytopathy Can affect both sexes but can only be passed on by the mother Matrileneal Does not follow any of the autosomal or sex-linked inheritance patterns
What are the two types of mitochondrial cytopathy MELAS and LHON
What is MELAS a mitochondrial cytopathy resulting in myopathy (disease of muscle tissue), encephalopathy (disease in which the functioning of the brain), lactic acidosis, stroke-like symptoms
What is Leber's hereditary optic neuropathy (LHON) a mitochondrial cytopathy resulting in rapid loss of vision in both eyes typically occurs in adulthood but can occur any time after adolescence
What is pathogenic presentation of Leber's hereditary optic neuropathy (LHON) dependent on enough cells w/ a predominant amount of mutant mitochondria in the eye
What is Cytoplasmic transfer Healthy and unhealthy cytoplasm (good + bad mitochondria) then fertilised by IVF
What is the drawback to Cytoplasmic transfer Can still pass on unhealthy mitochondria to child
Is Cytoplasmic transfer available Yes but not in the US, banned by FDA in 2001
What are complex disorders Most human characters are not Mendelian but are controlled by genes at more than one locus (polygenic)
What kinds of polygenic traits exist Discontinuous or continuous
What is the feature of discontinuous polygenetic traits Either is there or it isn't (e.g. type II diabetes mellitus)
What is an example of continuous polygenic trait height
What are multifactorial traits Polygenic and influenced environment
What are the four most common disorders showing multifactorial inheritance that currently are the leading causes of death in the developed world CVD, diabetes mellitus, obesity, mental illness
What is indicated by the term concordance rate the percentage of twin pairs or other pairs of relatives who exhibit the same disorder; used to assess the contribution made by genetics
What is the threshold zone liability of an individual to develop a given disorder depends on a combination of the number of predisposing genes and exposure to environmental factors (e.g. diet)
How is the threshold zone for a given disorder determined Based on a combination of genetic and environmental contributions
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