Genetics 3.1 Genes

Question 1

What is a genome?

Answer 1

Genome is the whole of the genetic information of an organism.

Question 2

What is a gene?

Answer 2

Gene is a heritable factor that controls a specific characteristic.

Question 3

What is an allele?

Answer 3

An allele is one of a number of different version of a gene

Question 4

What is the Human Genome Project?

Answer 4

The HGP is an international research effort to sequence , map and understand all the genes of members of species, homeosapiens. 18 different countries were involved. It began in 1990 and finished in 2003

Question 5

What importance does the Human Genome Project have? Why do we need the sequencing of the complete human genome?

Answer 5

By being able to read nature’s complete genetic blueprint of a human being:

• to learn about the causes of genetic diseases and thus find cures and treatments.
• to discover more about how different people are related to each other and to other species /evolutionary relationships
• to understand more about the aging process

Question 6

What is gene mutation?

Answer 6

Gene mutation is natural process that causes changes in the DNA sequence caused by a mutagen. The change in DNA sequence causes a change in mRNA, and amino acid sequence and thus produce new alleles.

Question 7

What is mutagen?

Answer 7

Mutagen is a physical or chemical factor that causes a change in DNA base sequence.

Question 8

What are the consequences of mutations?

Answer 8

There negative effects of mutations such as cancer. Positive effects of mutation are the creation of new alleles for adaption. Sometimes there are no consequences at all as the it codes for the same amino acid.

Question 9

What is a consequence of a base substitution mutation?

Answer 9

Base substitution mutation is a change of a single base in a sequence of DNA. Example: Sickle Cell Anemia
Base substitution mutation:
- the sequence of nucleotide bases in DNA codes for the sequence of amino acids in proteins
- DNA is transcribed into mRNA, which is translated into amino acids of protein
- normal (ß chain) hemoglobin gene / DNA produces - normal (ß chain) hemoglobin protein / amino acids
substitution= the replacement of one (or more) nucleotide base with another
- caused by a copying mistake during DNA replication
as a result of a mutagen / X-rays / chemical / UV radiation / other mutagen
- mutation in normal (ß chain) hemoglobin gene alters the sequence of nucleotide bases
- normal nucleotide sequence = CTC altered to CAC
resulting in altered mRNA (GAG to GUG) during transcription
- resulting in altered sequence of amino acids in (ß chain) hemoglobin protein (glutamic acid to valine) during translation
- causing red blood cells to change shape / sickle under low oxygen conditions
- causing sickle cells anemia when two copies of the mutated gene are inherited
- producing a sickle cell carrier when one copy of the mutated gene is inherited
- sickle cells anemia reduces oxygen flow to organs, leading to their deterioration