In this topic we are learning to: z Distinguish the difference between inherited and acquired characteristics. z Recognise that a gene is the basic unit of inheritance.
z Appreciate the role of Gregor Mendel in developing our understanding of inheritance and consider a simple genetic cross.
Genetics is the study of how characteristics are passed on from one generation to another.
There are two types of characteristics:
1. Inherited characteristics are passed on from parents to their children by genes. For example, eye colour, blood type and curly or straight hair.
2. Acquired characteristics are not inherited from our parents. They are learned throughout our life. For example, the accent we speak in or being able to ride a bike.
Characteristics are also known as traits.
Fig. 4.1.1 Curly hair is an inherited characteristic
Key Words
Genetics Inherited
characteristics Acquired
characteristics Traits
Chromosomes DNA Gene
Gametes Sperm Egg
Zygote
Fertilisation Dominant Recessive Genetic cross
Fig. 4.1.2
Being able to ride a bike is an acquired characteristic
4.1
Chromosomes and Genes
Chromosomes are thread-like structures found in the nucleus of an animal or plant cell. They are made up of protein and a chemical called DNA (deoxyribonucleic acid).
A gene is a short section of the DNA in a chromosome. Each gene contains the information needed to make a different protein in a cell. Proteins make up everything in our bodies, such as enzymes, muscles, bones, hair and teeth.
There are approximately 20,500 genes in each cell in the human body. Nucleus
