DNA, Alleles, Chromosomes, Genes

Question 1

What is DNA?

Answer 1

a structure which contains the genetic instructions (used in the development and functioning of proteins).

Question 2

What is a gene?

Answer 2

a section of DNA that codes for a particular protein/

feature/characteristic.

Question 3

What is a chromosome?

Answer 3

An organised structure of DNA found in the
nucleus of a cell)

They come in pairs (humans have 23 pairs).

Question 4

What is the consequence of a chromosome coming in pairs?

Answer 4

Because chromosomes come in pairs for each trait, there will be two possible alleles.

Question 5

What is an allele?

Answer 5

The different versions of each gene e.g. the alleles for the gene of eye colour would be the allele for blue eyes and the allele for brown eyes

Question 6

What is a genotype?

Answer 6

This combination of alleles for each trait is called the
genotype; this can be any combination of two of the
available alleles.

e.g. Bb or BB or bb

Question 7

What is a phenotype?

Answer 7

The physical appearance of the organism which is dictated by the genotype.

Dominant alleles (B) will be expressed (is shown in the phenotype) over recessive alleles (b)

Question 8

What are the four bases that make up DNA?

Answer 8

• G, C, A, T

Guanine
Cytosine
Adenosine
Thymine

• G always binds with C
• A always binds with T