Living things inherit traits in patterns Chapter 4

Parents and Offspring are similar Acquired trait – learned behavior Inherited trait – traits that resemble those of your parents

Genes are on chromosome pairs Long strands of DNA wrap around proteins to make up a cell’s chromosomes Gene is a segment of DNA Heredity is the passing of genes from parents to offspring

What are alleles? Alleles are different forms of the same gene. Example is a chromosome from one parent can be represented as: H – for tall height h – for short height

Number of chromosomes Chimpanzees – 48 chromosomes; 24 pairs Fruit flies – 8 chromosomes; 4 pairs Humans – 46 chromosomes; 23 pairs Human Sex chromosomes – XX – for female XY – for males

GREGOR MENDEL During the middle of Mendel's life, Mendel did groundbreaking work into the theories of heredity.theories of heredity Using simple pea pod plants, Mendel studied seven basic characteristics of the pea pod plants.

By tracing these characteristics, Mendel discovered three basic laws which governed the passage of a trait from one member of a species to another member of the same species.

Law of Genetics 1.The first law states that the sex cells of a plant may contain two different traits, but not both of those traits. 2. The second law stated that characteristics are inherited independent from one another (the basis for recessive and dominant gene composition).

3. The third theory states that each inherited characteristic is determined by two hereditary factors one from each parents, which decides whether a gene is dominant or recessive. In other words, if a seed gene is recessive, it will not show up within the plant, however, the dominant trait will.

Alleles interact to produce traits Genotype ▫the organism’s actual genetic make-up: for example, is it BB, Bb, of bb? Phenotype ▫the organism’s expressed traits, what it looks like, how the genes are expressed: for example, does it have brown or blue eyes?

Dominant Allele ▫the one that’s fully expressed; symbolized by a capital letter, often the first letter of the word for which it stands Recessive Allele ▫the one that’s completely masked; symbolized by the SAME letter, but lower case

Using a Punnet Square