A gene is a section of DNA that holds the genetic code for a protein.

A genetic variant is produced when a mutation causes a change in the genetic sequence of a gene or non-coding DNA.

A genetic variant in a gene creates an allele (a different version of the gene), which produces a different phenotype.

The triplet code is carried by genes. Each three nucleotide bases codes for a specific amino acid.

The phenotype is the physical characteristics of an organism.

Genetic variants in genes can influence phenotype

Biology

Pupils will learn about dominant and recessive alleles, and how to use models of single gene inheritance to make predictions about the genotypes and phenotypes of offspring.

Pupils learned about flower structure, wind and insect pollination, fertilisation, seed and fruit formation and dispersal.

This unit covers the structure and function of eukaryotic and prokaryotic cells, DNA as the genetic material, and key genetic terms. It also explains protein synthesis, genetic variants, and how DNA structure affects proteins. The emphasis is on using models to explain scientific concepts.

DNA and the genome

Which word means the physical characteristics of an organism?

A different version of a gene, created by a mutation, is called an {{}}.

a section of DNA that holds the genetic code for a protein

a section of DNA in which a mutation has changed the base sequence

a different version of a gene, created by a mutation

a set of three nucleotide bases that codes for one amino acid

Match each word to its correct definition.

Match each mutation to the change it would cause in the amino acid sequence of the protein coded for by a gene.

A mutation changes the sequence of bases in a gene.

Translation takes place at a ribosome, when tRNA joins amino acids together.

The amino acid chain folds to make a protein.

The protein folds differently because one or more amino acids has been changed.

The protein structure is changed, so it might not work properly.

Put the steps in the correct order to describe how a mutation in a gene can change an organism’s phenotype.

Izzy: “A substitution mutation in a gene.”

Jun: “A deletion mutation in a gene.”

Sam: “A substitution mutation in non-coding DNA.”

Who identifies a mutation that is the **most** likely to result in a non-functional protein?

the number of amino acids coded for by each triplet of bases

the number of nucleic acid strands in a DNA molecule

the number of nucleotide bases in one triplet code

the number of different nucleotide bases found in DNA

Match each of the following to the correct number.

If a single nucleotide base in DNA is swapped for another one, this is called a substitution {{}}.

What is the cause of **most** mutations in DNA?

This is part of a genetic code: **TAC CAG TCA CAG**. A mutation changes the code to **TAC CAG TCC AG**. What kind of mutation has taken place?

Insertion mutations remove a base from a triplet code.

Insertion mutations add a base to a triplet code.

Insertion mutations change every triplet code before the mutation.

Insertion mutations change every triplet code after the mutation.

Insertion mutations swap one base for another in a triplet code.

Insertion mutations have a greater effect on the genetic code than substitution mutations. Why?

In which type of cell would a mutation have to happen if the mutation was to be inherited by a person’s offspring?

Exit Quiz