chapter 9 Flashcards
Achromatopsia
an inherited form of total colour blindness
Albinism
an inherited inability to produce pigment in hair, skin and eyes.
Allele frequency
how often each allele of a gene occurs in a population
anaemia
a condition in which there is a reduced amount of haemoglobin in the blood, or reduced number of red blood cells.
Aneuploidy
a change in the chromosome number as a result of non-disjunction
Bottleneck effect
an extreme form of genetic drift that occurs when the size of a population is severely reduced due to a sudden event such as a national disaster. The allele frequency of survivors may not reflect that of the original population.
Chromosomal mutation
a change to the structure and/or number of chromosomes in an organism
Cri-du-chat syndrome
a rare genetic disorder caused by a missing part of chromosome 5.
Cystic fibrosis
a disorder controlled by a recessive allele carried on an autosome that is incurable but can be detected during foetal development ; mucus-secreting glands, particularly in the lungs and pancreas, become fibrous and produce abnormally thick mucus, resulting in chest infections
Down syndrome
trisomy 21
a genetic disorder resulting from an extra copy of chromosome 21 or an extra part of chromosome 21.
Duchenne muscular dystrophy
a genetic disease resulting in wasting of leg muscles and then arms, shoulders and chest.
Evolution
the gradual change in the characteristics of a species
Evolved
having gone through the process of evolution
Founder effect
a type of genetic drift where a new population is formed by a small number of individuals; the small sample size can cause marked deviations in allele frequencies from the original population.
frameshift
a mutation involving an insertion of a deletion that results in a change in the way that the sequence is read.
Gene flow
the transfer of alleles from one population to another through migrations.
Gene mutation
an alteration to a single gene.
Gene pool
the sum of all the alleles carried by the members of a population.
Genetic drift
also random genetic drift
the occurrence of characteristics in a population as a result of chance rather than natural selection;
occurs only in small populations; also called genetic drift or Sewall Wright effect.
Geneticist
a scientist who specialises in the study of genetics
Genotype
The combination of allele for a gene
Geographical barrier
a feature of the landscape that prevents populations from interbreeding; includes oceans, mountain ranges, large lake systems, deserts and extensive ice sheets.
germinal or germline mutation
a change in the hereditary material in the egg or sperm that becomes incorporated into the DNA of every cell in the body of the offspring.
Heterozygote advantage
a situation where heterozygous genotype has a higher chance of survival that either homozygous geneotype.
Induced mutation
a mutation caused by a mutagenic agent
Klinefelter syndrome
A genetic disorder resulting from inheritance of two X chromosomes and one Y chromosome.
Lethal recessive
a recessive allele that inherited in the homozygous condition results in the death of the embryo, foetus or child.
Migration
the movement of people from one area to another with the intention of settling permanently.
Missense mutation
a mutation that causes a change in an amino acid resulting in a different protein l=being produced.
Monosomy
where an individual has only one copy of a chromosome instead of two.
Mutagen, mutagenic agent
an environment agent that increases the rate of mutations
Mutant
an organism with a characteristic resulting from a mutation
Mutation
a change in a gene or chromosome leading to new characteristics in an organism.
Natural Selection
the process by which a species becomes better adapted to its environment.
Those individuals with favourable characteristics have a survival advantage and so pass those characteristics on to subsequent generations
Neutral mutation
a mutation that causes a change in an amino acid, however it does not cause an overall change in the protein.
Nonsense mutation
a mutation that results in a STOP cpdon, producing a shortened peptide chain.
Partial monosomy
where part of a pair of chromosomes is missing
Patau syndrome
a genetic disorder resulting from an extra copy of chromosome 13.
Phenotype
the observable characteristic due to the genotype.
Phenylketonuria PKU
an inherited disease resulting in damage to the growing brain and, thus, extreme intellectual deficiency. Also a tendency for epilepsy and a failure to produce skin pigmentation.
Point mutation
a change in just one of the bases in a DNA molecule.
Population
a group of organisms of the same species living together in a particular place at a particular time.
Selective agent
any factor that causes the death of organisms with certain characteristics, but which has no effect on individuals withour those characteristics.
Sickle cell anemia
an inherited disease causing early death.
results from the inheritance of two alleles for sickle-cell anemia.
Silent mutation
a mutation that does not change the sequence of amino acids.
Sociocultural barrier
barrier to interbreeding that is due to social or cultural factors.
Somatic mutation
a change occurring in a gene in a body cell. (not a gamete- ova or sperm)
Special creation
the belief that a god created all species.
Speciation
the process of new species developing
Species
the basic unit of biological classification; members of a species are capable of interbreeding and producing fertile offspring.
Spontaneous mutation
a mutation that occurs due to an error in a natural biological process.
Struggle for existence
a principle where the number of organisms is greater than the resources in the environment can support.
Therefore there is competition between the organisms for resources
Survival of the fittest
a principle whereby organisms with favourable characteristics survive.
Organisms with unfavourable characteristics die before they have a chance to reproduce
Tay-Sachs disease tsd
a genetic disorder caused by a missing enzyme that results in fatty substances accumulating in the nervous system.
Turner syndrome
a genetic disorder resulting from inheritance of one X chromosome and no other sex chromosome
variation
the difference that exist between individuals or populations of a species.
