Biology Notes: Heredity, Genetic Code, Cell Division, Mutation, Genetic Cross, Blood Type & Paternity

A set of vocabulary-style flashcards covering heredity, genetic code, cell division, mutation, genetic crosses, and blood type/paternity concepts.

Heredity

Transmission of traits from parents to offspring.

Genetics

The study of heredity and variation.

Genes

Segments of DNA that code for traits (e.g., eye colour, blood type).

Alleles

Alternative forms of a gene (e.g., A and a).

Genotype

Genetic makeup; the combination of alleles (e.g., AA, Aa, aa).

Phenotype

Physical appearance or trait (e.g., brown eyes).

Dominant

An allele that shows in the phenotype if at least one copy is present.

Recessive

An allele that shows in the phenotype only when two copies are present.

DNA

Deoxyribonucleic acid; the molecule that stores genetic information; double helix.

Double helix

The two intertwined strands that make up the DNA molecule.

Nucleotides

Building blocks of DNA: phosphate + deoxyribose sugar + nitrogen base.

Bases

A, T, G, C; pair via A–T and G–C.

Base-pairing rule

A pairs with T; G pairs with C.

Coding DNA

DNA regions that code for proteins; a gene is part of coding DNA.

RNA

Ribonucleic acid; single-stranded molecule made during transcription; bases A, U, G, C; U replaces T.

mRNA

Messenger RNA; carries code from DNA to the ribosome.

tRNA

Transfer RNA; brings amino acids to the ribosome.

rRNA

Ribosomal RNA; makes up ribosomes.

Codon

A group of three RNA bases that codes for one amino acid.

Codon table

Chart that translates mRNA codons into amino acids.

Start codon

AUG; codes for Methionine and signals the start of translation.

Methionine

Amino acid encoded by the start codon AUG.

Proline

Amino acid encoded by certain codons (e.g., CCU).

Lysine

Amino acid encoded by codons such as AAG.

Amino acids

Building blocks of proteins; amino acids are coded by codons.

Mitosis

Cell division for growth, repair, and asexual reproduction; results in 2 identical diploid cells.

Meiosis

Cell division for sexual reproduction; produces 4 non-identical haploid cells; increases genetic variation.

PMAT

Stages of mitosis: Prophase, Metaphase, Anaphase, Telophase.

Crossing over

Exchange of chromosome segments during meiosis; increases genetic variation.

Independent assortment

Random orientation of homologous chromosomes during meiosis; increases variation.

Mutation

A change in the DNA sequence.

Point mutation

One base changes.

Insertion

A base added to the DNA sequence.

Deletion

A base removed from the DNA sequence.

Frameshift

Insertion or deletion that shifts the reading frame of a gene.

Spontaneous

Mutations caused by natural replication errors.

Induced

Mutations caused by radiation, chemicals, UV light.

Neutral

Mutation that has no effect on organism fitness.

Harmful

Mutation that negatively affects the organism (e.g., disease).

Beneficial

Mutation that provides a selective advantage (e.g., antibiotic resistance).

Genetic cross

Breeding experiment to study inheritance patterns.

Punnett square

Diagram used to predict offspring genotypes and phenotypes from parental genotypes.

Monohybrid cross

A cross involving one trait (e.g., height with dominant and recessive alleles).

Trait

A characteristic such as height or eye colour.

Dominant trait

Trait expressed when at least one dominant allele is present (e.g., tall).

Recessive trait

Trait expressed only when two recessive alleles are present (e.g., short).

ABO system

Blood group system controlled by one gene with three alleles: A, B, O.

Genotypes (ABO)

A = AA or AO; B = BB or BO; AB = AB; O = OO.

Codominant

A and B alleles are codominant; O is recessive.

Paternity testing

Process used to exclude possible fathers before DNA testing.

Exclude

Rule out a potential father based on evidence (e.g., blood type incompatibility).