Genetics and DNA Flashcards
Grade 8 · Science · Flashcards
Essential vocabulary for understanding DNA structure, genetic inheritance, and how traits are passed from parent to offspring.
Flashcards
- DNA (Deoxyribonucleic acid)
- The double-helix molecule containing the genetic instructions for the development and function of all known living organisms.
- Nucleotide
- The building block of DNA, consisting of a sugar (deoxyribose), a phosphate group, and one of four nitrogen bases.
- Complementary base pairing
- The rule that A pairs with T and C pairs with G in DNA, holding the two strands of the double helix together.
- Gene
- A segment of DNA on a chromosome that codes for a specific protein and influences a specific trait.
- Chromosome
- A tightly coiled structure of DNA and protein; humans have 46 in most body cells (23 pairs).
- Allele
- An alternate form of a gene; individuals inherit one allele from each parent for each gene.
- Dominant allele
- An allele that is expressed in the phenotype whenever it is present, masking the recessive allele.
- Recessive allele
- An allele expressed in the phenotype only when two copies are present (homozygous recessive).
- Genotype
- The genetic composition of an organism, written using letter symbols for alleles (e.g., Aa, BB).
- Phenotype
- The observable traits of an organism resulting from the expression of its genotype.
- Punnett square
- A grid used to predict the probability of different genotype combinations in offspring from a genetic cross.
- Mutation
- A permanent change in the DNA sequence; can be caused by replication errors, radiation, or chemicals.
- Heredity
- The passing of genetic traits from parents to their offspring through genes.
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