Traits, Heredity + Genes
Brought to you by Text Tuesday
Introduction to Heredity + Genetics
Heredity + Chromosomes
SPIRAL: Through sexual reproduction - specifically fertilization in which a sperm cell fuses with an egg cell - each parent contributes 50% of its genes to the offspring - allowing for greater genetic variation within a species.
Dominant or Recessive Traits? Which one will show?
So in summary - a dominant trait will show up if at least 1 dominant allele has been inherited; a recessive trait will only show up if 2 recessive alleles have been inherited.
Genotype vs. Phenotype
The gene combination an organism contains is known as it genotype. You cannot always know an organism’s genotype simply by looking at its phenotype. Typically, genotypes are represented with letters, for example Dd, rr, MM, etc.
Why are some letters in the genotype written in uppercase/capital letters and others written in lowercase? This is to show which gene is dominant and which gene is recessive. The dominant gene will always be written with an uppercase letter (i.e. D, M, P, Q, R, etc.) and the recessive gene will always be written with a lowercase letter (i.e. d, m, p, q, r, etc.).
Homozygous vs. Heterozygous + Dominant vs. Recessive
Homozygous refers to both alleles of a gene being the same (both dominant or both recessive). Heterozygous refers to the alleles of a gene being different (one dominant, one recessive).
First, just think of your prefixes ( homo = same, hetero = different) and then look at whether the trait/allele is dominant (CAPITAL LETTER) or recessive (lowercase letter).
Let's practice some by classifying the examples on your page.
Pedigree vs. Punnett Squares
Check out the video below to learn how to solve Punnett squares!