Intro to human genetics

models of disability

medical, social, human rights

medical model of disability

• a problem that needs to be fixed

• focus on what individuals can’t do compared to ‘normal’ function

• negative light

• basis for determining access to services

social model of disability

• recognises barriers in society create disability

• looks at individual and their social context

• emphasizes social and environmental factors

• remove barriers for equality

human rights model

• disability is natural oart of human diversity

• equal rights

• eliminating societal barriers is not enough

• specialised and individual support

genotype

inherited genetic info that influecnes observable properties

phenotype

observable properties produced by genotype and environmental influences

chromosomes

• somatic cells - 46 in 23 pairs (1 from each parent)

• gametes = 23 chromosomes

• each pair carries genes of same type and match in size and function

karyotype

visual representation of the chromosomes in a cell

• Autosomes numbered 1–22

• Sex chromosomes X and Y

• Used to detect chromosomal abnormalities

down syndrome

extra 21 chromosome (3 in total) = physical and developmental differences

klinefelter syndrome

in males - extra X chromosome (XXY). 3 ways affects development

• physical - weak muscles and lagging development

• language

• social - tends to be quieter and undemanding

chromosome structure

before replication chromosome is single. after rep 2 chromatids are joined at centromere forming X (sister chromatids) - only visible during mitosis and meiosis otherwise are uncoilded

• short arm = p arm

• long arm = q arm

what are chromosomes made of

chromatin which contains nucleic acid and proteins (histone and nonhistones)

deoxyribonucleic acid

antiparallel double helix made of nucleotides hydrogen bonded together

• nucleotide = phosphate group + pentose sugar + nitrogenous base

• backbone = sugar and phosphate

• runs 5’ to 3’ direction

locus

sequence of DNA situated on specific region on chromosome

gene

a segment of DNA that contains the building instructions

• influences phenotype

• triplet of bases codes for specific amino acid

transcription

the process by which DNA is copied into mRNA

translation

mRNA is converted into amino acid chain for protein synthesis

• codon - 3 base sequence in mRNA for specific amino acid

allele

a variant form of a gene that can produce different traits

• dominant - always expressed

• recessive - only when both recessive

single nucleotide polymorphism

variation at a single position in DNA sequence among individuals

mutation

process of change in DNA sequence

types of mutations

• base substitution

• deletion of DNA

• insertion of DNA

• whole or partial chromosomal abnormalities