B11 Inheritance Flashcards
inheritance
the transmission of genetic information from generation to generation
Chromosome
a thread like structure of DNA, carrying genetic information in the form of genes
Gene
a length of DNA that codes for a protein
XX and XY
XX=girl and XY=boy
Haploid nucleus
a nucleus containing a single set of unpaired chromosomes e.g. sperm and egg cells
Diploid nucleus
a nucleus containing two sets of chromosomes e.g. body cells
mitosis
a nuclear division giving rise to genetically identical cells (two of them with 46 chromosomes each) their role is repair tissue, growth, asexual reproduction and replacement of cells
meiosis
reduction division in which the chromosomes number is halved (4 different ones with 23 chromosomes each) from diploid to haploid resulting in genetically different cells
genotype
the genetic make-up of an organism in terms of alleles present
phenotype
the observable feature of an organism
homozygous
having two identical alleles of a particular gene
heterozygous
having two different alleles of a particular gene
dominant allele
an allele that is expressed if it is present
recessive allele
an allele that is only expressed when there is no dominant allele of the gene present
Punnett squares
diagram to show what the possible genotypes are with the parents genotypes
variation
difference between individuals of the same species
continuous variation
results in a range of phenotypes between to extremes e.g. height
discontinuous variation
results in limited number of phenotypes with no intermediated e.g. tongue rolling
phenotypic variation
it’s caused by both genetic and environmental factors
mutation
a change in a gene or chromosome
natural selection
when organism struggle for survival because of the environment or competition for resources and a certain characteristics helps them survive and then it gets passed onto multiple generations
selective breeding
when humans select 2 organisms with desirable characteristics and breed them throughout a few generations
