Genes, Chromosomes, and Alleles Flashcards
What is a gene?
A heritable factor that controls a specific characteristic.
How many genes does a typical plant or animal cell nucleus contain?
Thousands: humans have between 30,000 and 40,000
What is the genome?
It represents the whole genetic information of an organism.
About how many genes does a typical animal or plant chromosome contain?
1,000
Within a chromosome, how are genes organized?
In a linear sequence
What is the gene locus?
The position of a gene on a chromosome.
What’s an allele?
A form of a gene.
How do alleles differ from each other?
A few bases at most differ from other alleles, but they occupy the same locus (position) as the other alleles of that gene.
What are the two chromatids connected by?
A centromere.
What is gene mutation?
A change to the base sequence of a gene.
What is base-substitution?
When one base in a gene is replaced by another base. This is the smallest possible change.
What is an example of a base-substitution mutation?
Sickle cell anemia.
What do replicated and unreplicated forms of chromosomes mean?
Replicated: before division, but ready to divide. Unreplicated: after division, not ready to divide.
What are somatic cells?
Body cells, such as muscle cells, skin cells, a fertilized egg. Also, a diploid.
What is 2n?
A diploid cell.
