B11 Inheritance Flashcards
define inheritance
transmission of generic information form generation to generation
define chromosomes
thread like structure of DNA, carrying generic information in the form of genes
define genes
length of DNA that codes for protein
define allele
versions of a gene
define haploid nucleus
nucleus containing a single set of unpaired chromosomes
define diploid nucleus
nucleus containing two sets of chromosomes
in diploid cells, chromosomes are arranged in pairs of ..
23
so haploid - 23
diploid - 46
define mitosis
nucleur division giving rise to genetically identical cells
exact duplication of chromosomes occurs before/after mitosis
before
state the role of mitosis (4)
- growth
- repair of tissues
- replacement of cells
- asexual reproduction
define meiosis
reduction of division in which the chromosomes number if halved from diploid to haploid resulting in genetically different cells
meiosis is involved in the production of …….
gametes, egg cells and sperm cells
define genotype
genetic make up of an organism in term of the alleles present
eg. bb Bb BB
define phenotype
observable features of an organism
eg. black hair blue eyes
define homozygous
having two identical alleles of a particular gene
eg. BB bb
define hetrozygous
having two different alleles of a particular gene
eg. Bb
not pure breeding
define dominant
allele that is expressed if it is present
define recessive
allele that is only expressed when there is no dominant allele of the gene present
define variation
differences between individuals of the same species
describe phenotype variation
the differences between features between individuals, cuased by both environment and genetic
describe genetic variation
differences in genes between individuals
eg. blood types, gender
define mutation
change in a gene or chromosome
examples of things causing mutation
ionizing radiation
chemicals
define evolution
change in adaptive features of a population overtime as the result of natural selection
describe natural selection
- genetic variation
- overpopulation
- competition due to the struggle for existence
- survival for the fittest
- advantageous characteristics passed on to generation
define adaptation
process, resulting from natural selection, by which populations become more suited to their environment over many generations
describe selective breeding
- selection by humans of individuals with desirable features
- crossing these individuals to produce offspring
- selection of offspring with the desirable features
example of selective breeding
improve crops and domesticated animals
example of natural selection
antibiotic-resistant bacteria
