Flashcards in chromosome abnormalities, mutations and analysis Deck (37)
types of chromosome abnormalities
the presence of an abnormal number of chromosomes in a cell
disorder characterised by the presence of the three homologous chromosomes instead of two
down syndrome cause
3 copies of chomosome 21 (trisomy 21)
down syndrome characteristics
characteristic facial features (flattened, upward slanting eyes)
IQ less than 50
patau syndrome cause
3 copies of chromosome 13 (trisomy 13)
Patau syndrome characteristics
multiple dysmorphic features (eg. cleft lip and palate)
very few survive beyond first year
Edwards syndrome cause
3 copies of chromosome 18 (trisomy 18)
edwards syndrome characteristics
severe developmental problems such as small head, heart, kidney and breathing problems.
Many don't live past first birthday.
turner syndrome cause
one X chromosome
turner syndrome characteristics
females of short stature and infertile, neck webbing and widely spaced nipples.
flinefelter syndrome cause
sex chromosomes XXY
klinefelter syndrome characteristics
tall statue and long limbs.
male but infertile, small testes and half exibit gynaecomastia
mild learning difficulties.
balanced chromosome rearrangements
structural chromosome abnormalities that don't lead to the loss of genetic information
unbalanced chromosome rearrangements
structural chromosome abnormalities that lead to the loss of genetic information
chromosome in which the centromere is located near to the end of the chromosome
chromosomes with their centromere in the middle of the chromosome
a section of a chromosome breaks off from two non-homologous chromosome and they are swapped.
occurs when one parent has normal chromosomes and one has chromosomes that have undergone a balanced translocation. This causes the loss of genetic information.
chromosome breaks in two place and the section in between is removed. Then the two sections join back together
the chromosome breaks in two places then the section cut out inverts and is reinserted into chromosome
inversion that occurs with centromere in the inverted section
inversion that occurs when the section of the chromosome that inverts does not contain the centromere
A gene change in a body's reproductive cell (egg or sperm) that becomes incorporated into the DNA of every cell in the body of the offspring
An alteration in DNA that occurs after conception. Somatic mutations can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children
natural variation in the genome of organisms of the same species
types of mutation
Frameshift – deletion / insertion
point mutation in which the substitution of a base pair has no effect on the amino acid the codon it is part of codes for
point mutation in which the substitution of a base pair causes the coding of a different amino acid in a protein