IB BIO TOPIC 4.1 CHROMOSOMES, GENES, ALLELES

Question 1

What are Eukaryotic chromosomes made of ?

Answer 1

Eukaryotic chromosome is made of DNA and protein.

Question 2

Define a gene

Answer 2

gene = a heritable factor that controls a specific characteristic

Question 3

Define an allele

Answer 3

allele = one specific form of a gene, differing from other alleles by one or a few bases only and occupying the same gene locus as other alleles of the gene

Question 4

Define a genome

Answer 4

genome = the whole of the genetic information of an organism

Question 5

Define: a gene mutation

Answer 5

a gene mutation is a change in the base sequence of a gene.

Question 6

Explain the consequence of a base substitution mutation in relation to the process of transcription and translation, using the example of sickle cell anemia.

Answer 6

substitution: the replacement of one (or more) base with another
because of the redundancy of the genetic code, some substitutions will have no effect on the amino acid sequence coded for by the gene
where the substitution does have an effect, it may produce either missense, altering a single amino acid, or nonsense, introducing a new stop codon

Sickle cell anemia: substitution in gene for ß chain of hemoglobin