B6 - Inheritance, Variation And Evolution Flashcards
What is DNA?
A molecule that carries genetic information
Where is DNA found?
In the nucleus of cells, arranged into chromosomes
What is a gene?
A small section of DNA that codes for a specific protein
What is a chromosome?
A long molecule of DNA found in the nucleus
How many pairs of chromosomes do humans have?
23 pairs (46 total)
What is an allele?
Different forms of the same gene
What is the difference between dominant and recessive alleles?
Dominant alleles are always expressed; recessive alleles are only expressed if both copies are recessive
What does homozygous mean?
Having two identical alleles for a gene
What does heterozygous mean?
Having two different alleles for a gene
What is a genotype?
The combination of alleles an individual has
What is a phenotype?
The physical characteristics resulting from the genotype
What does inherited mean?
Passed from parents to offspring through genes
What is cystic fibrosis caused by?
A recessive allele
What is polydactyly caused by?
A dominant allele
What is variation?
Differences in characteristics between individuals of the same species
What causes genetic variation?
Differences in genes due to inheritance and mutations
What is evolution?
A gradual change in the characteristics of a species over time
What is natural selection?
The process where organisms with advantageous traits survive and reproduce
What is selective breeding?
Choosing organisms with desirable traits to breed and produce offspring with those traits
What is extinction?
When no individuals of a species remain alive
