Genetics and Inheritance
Genetics is the study of how characteristics are inherited from parents to offspring. DNA carries the instructions for building and running living organisms, and genes are passed from parent to child, explaining family resemblances and inherited conditions.
What You Need to Know
Key Concept Diagram
DNA (deoxyribonucleic acid) is the molecule that carries genetic information in almost all living things
Genes are sections of DNA that code for specific characteristics (traits)
Chromosomes are thread-like structures in the cell nucleus that carry genes; humans have 46 (23 pairs)
Dominant traits are expressed when at least one dominant allele is present; recessive traits require two recessive alleles
Sexual reproduction produces genetic variation; asexual reproduction produces genetically identical offspring
Key Vocabulary
DNA
Deoxyribonucleic acid; the molecule that contains the genetic instructions for all living organisms
Gene
A section of DNA that codes for a specific protein, determining a particular characteristic
Chromosome
A thread-like structure of DNA and protein in the cell nucleus; humans have 46 chromosomes
Allele
A version of a gene; for each gene we inherit two alleles, one from each parent
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
Where is DNA found in a human cell?
Question 2
A gene for eye colour has two alleles: Brown (B, dominant) and blue (b, recessive). A person with alleles Bb will have:
Question 3
Why does sexual reproduction produce more genetic variation than asexual reproduction?
Key Concepts Summary
- ●DNA (deoxyribonucleic acid) is the molecule that carries genetic information in almost all living things
- ●Genes are sections of DNA that code for specific characteristics (traits)
- ●Chromosomes are thread-like structures in the cell nucleus that carry genes; humans have 46 (23 pairs)
- ●Dominant traits are expressed when at least one dominant allele is present; recessive traits require two recessive alleles
- ●Sexual reproduction produces genetic variation; asexual reproduction produces genetically identical offspring