Science Test – Genetics:
Terms and definitions:
DNA
The unique characteristics and qualities of someone or something
Gene
Unique traits that makes us what we are (how we look like)
Chromosome
A thread like structure that carries traits
Allele
A section where the genes are the same on a chromosome
Heterozygous
Gene/trait aspect
Homozygous
Homozygous is a word that refers to a particular gene that has identical alleles on both homologous
chromosomes
Homologous
When the same trait from the mother and the father are in the same location
Recessive
Characterises from genes which only occur when they come from both parents
Dominant
A gene/trait which is dominant
Genotype
A coding for a particular trait (genes)
Phenotype
The physical aspect of a trait
Mutation
Mutation is the term used when a certain gene/trait has gone through incorrect coding during the
process of being made.
Autosomes
Any chromosome that isn't a sex chromosome
Autosomal
The 22 pairs of chromosomes (the 23 being x and y, mother and father is a sex chromosome, therefore
meaning that it isn't autosomal)
Sex chromosomes
The 23 pair (x and y - from mother and father) of chromosome
Codon
A sequence of three nucleotides (ATT, CGG, GCC, TAA) which together form a unit of genetic code in a
DNA or RNA molecule.
Nucleotide
A nucleotide is a nitrogen base with a sugar phosphate at the end - ATG
Natural Selection
The process in which adaptation occurs in animals allowing their children to carry certain traits to
survive in a particular environment.
Punnet Squares:
Science Test – Genetics:
Sickle cell anemia:
With sickle cell disease, an inherited group of disorders, red blood cells contort into a sickle
shape. The cells die early, leaving a shortage of healthy red blood cells (sickle cell anaemia)
and can block blood flow causing pain (sickle cell crisis).
Infections, pain and fatigue are symptoms of sickle cell disease.
Treatments include medication, blood transfusions and rarely a bone-marrow transplant.
Remember:
Mitosis produces diploid cells (46 chromosomes) whereas meiosis produces haploid cells (23
chromosomes). Mitosis produces two identical daughter cells whereas meiosis produces
four genetically different daughter cells.