Genes and Chromosomes Flashcards
What is a gene and what does it determine
a sequence of DNA inherited from the parents, it determines a particular characteristis (eg hair/eye colour) and is the code for proteins that produce a variety of traits
each gene has a specific location on a pair of chromatids like an address.
What is an allele
an allele is a different form of a gene. For examples the gene for eye colour has serveral variations (allelles) such as an allele for blue eyes or an allele for brown eyes. It is a subcategory of the category given by genes.Most people have an allele from each parents
What is a chromosome
chromsomes consist of tighlty coiled up DNA
How many chromosome in an average person
there are 23 pairs (46 all together one from each parent)
what is pairs 1-22 and what is pair 23
pairs 1-22 are autosomes and are called homologous pairs
pair 23 looks different and is different because it determines sex.
What is homozygous
2 of the same allele, 2 recessive or 2 dominant (purebread)
what is heterozygous
1 recessive and 1 dominant allele. (hyrbid)
what is recessive allele
is masked or covered up when the dominant allele is present
what is a dominant allele
masks or covers up other alleles
what is a phenotype
the visible appearanceof the genetic factor (what the offspring looks like) e.g. tall or short
what is a genotype
the type and arrangment of the genes in the organism (tt, TT or Tt)
what is the parent generation
the generation of individuals of different genotypes that are mated to produce hybrids
What is teh F1 generation
first gen of offspring distinctly different to their parents
what is the F2 generation
second generation that consists of the offspring from F1
How do X and Y chromosomes determine sex
females specifically have two X chromsomes whereas males have an X and Y
