Starter:Using the family tree below, answer the questions on

your worksheet

Task Put the following in size order, smallest to

largest:1. Chromosome2. DNA3. Gene4. Nucleus

B1.7.1b Genes and Genetics

Sort the parts of the cell into order of size (E)

Describe how characteristics are inherited (C)

Compare inherited and environmental variation (B)

CharacteristicAlleleGeneDNAChromosomeGametesNucleusVariation

B1.7.1b Genes and Genetics

Sort the parts of the cell into order of size (E)

Describe how characteristics are inherited (C)

Compare inherited and environmental variation (B)

CharacteristicAlleleGeneDNAChromosomeGametesNucleusVariation

Chromosomes

Found in the nucleus of cells.

Chromosomes are formed from DNA molecules.

The nucleus of most human cells contains 23 different sorts of chromosomes.

There are usually two copies of each chromosome.

GenesGenes store

information as a type of code – the genetic code.

The genetic code organises amino acids to make specific proteins e.g. enzymes, hormones.

The DNA codeA DNA molecule is made of two strands joined together

by compounds called bases.The two strands are twisted around to form a double

helix.There are 4 different bases A, T, C and G in a molecule

of DNA.A gene is a sequence of bases along a strand of DNA.

The triplet codeProteins are made up

of amino acids linked together in a chain.

Different proteins contain different sequences of amino acids.

A set of three bases in a DNA strand carries the code for one amino acid.

Inherited variation – differences between living things that are caused by genes.

Environmental variation – features that depend on our surroundings or on things that happen to us

Inherited, environmental or both?

List as many characteristics of humans as you can and put them in the correct part of the Venn diagram.

Inherited EnvironmentalBoth