genetics and inheritance Flashcards
locus
the exact position (location) of a gene on a chromosome
filial generation (F1)
offspring of parent organisms
gene
a segment of DNA in
a chromosome that codes for
a particular
characteristic
alleles
2 alternative forms of a gene at the same locus
genotype
The total genetic composition of an organism.
It’s the info present in the gene alleles
Eg, BB, Bb, or bb
phenotype
the physical
appearance of an
organism based on
the genotype, e.g. tall,
short
dominant
allele
An allele that masks or suppresses the expression of the allele partner on the chromosome pair and the dominant characteristic is seen in the homozygous (eg, TT) and heterozygous state (eg, Tt) in the phenotype
recessive
allele
An allele that is suppressed when the allele partner is dominant. The recessive trait will only be expressed/seen if both alleles for the trait are homozygous recessive e.g.: tt
heterozygous
An individual having two non-identical alleles for a characteristic
homozygous
When two alleles that control a single trait (on the same locus) are identical.
monohybrid
cross
a genetic cross involving one characteristic eg colour of seeds
dihybrid cross
a genetic cross involving 2 diff characteristics eg shape and colour of seeds
complete
dominance
a type of inheritance
where the
dominant allele
masks the
expression of a
recessive allele
in the heterozygous condition
incomplete
dominance
the type of inheritance where both alleles express themselves in such a way that an intermediate phenotype is formed
eg, a white flowering plant crossed with a red flowering plant will produce a pink flowering plant
co-dominance
the type of inheritance where both alleles are equally dom and both express themselves equally in the phenotype
eg, a white cow crossed with a red bull will produce a calf with red and white patches
multiple
alleles
when there are more than 2 possible alleles for one gene locus
eg, blood groups
karyotype
the number,
shape and
arrangement of
the
chromosomes
in the nucleus
of a somatic
cell
cloning
process by which
genetically identical
organisms are formed
using biotechnology
genetic
modification
manipulation of the
genetic material of
an organism to get
desired changes
human
genome
mapping of the exact
position of all the
genes in all the
chromosomes of a
human
homologous
pair of
chromosomes
a set of one maternal and one paternal chromosome that pair up
with each other inside a cell during meiosis – homologous
chromosomes are the same size and shape, and carry the same
or similar alleles
Mendel’s First Law of Inheritance: Law (principle) of Segregation
the 2 alleles for each gene are placed in diff gametes
Mendel’s Second Law of Inheritance: Law of Dominance
when 2 alleles of an inherited pair is heterozygous, then the allele that is expressed in the phenotype is dominant whereas the allele not expressed is recessive
Mendel’s Third Law of Inheritance: Law (principle) of Independent
Assortment
the alleles of 2 (or more) different genes get sorted into gametes independently of one another
albinism
the condition that results from the absence of skin pigmentation
artificial selection/ selective breading
the breading of organisms over many generations to achieve a desirable phenotype
biotechnology
the use of biological processes, organisms or systems to improve the quality of human life
clone
a copy of an organism that is genetically identical to the original organism
chromatin network
visible as thread-like structures in the nucleus of an inactive cell
chromosome
a structure made up of 2 chromatids joined by a centromere that carries the hereditary characteristics within the DNA
gene mutation
a change of one or more Nitrogen bases in the DNA of an organism
genetic variation
this includes a variety of diff genes that may differ from maternal and paternal genes resulting in new genotypes and phenotypes
haemophilia
a sex linked disorder characterised by the absence of a blood clotting factor
mutation
a sudden change in the sequence/order of nitrogenous bases of a nucleic acid
pedigree diagram
a diagram showing the inheritance of genetic disorders over many generation
population
a group of organisms of the same species living in the same habitat at the same time
stem cells/ meristematic cells
undifferentiated cells that can develop into any cell type
