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General Biology: Meiosis, Genetics, DNA Replication, and Gene Expression

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Termini in questo insieme (36)

  • Gene

    A DNA sequence that affects a trait.

  • Allele

    A version of a gene, such as A or a.

  • Locus

    The gene's address on a chromosome.

  • Chromosome

    One long DNA molecule plus proteins.

  • Sister chromatids

    Identical copies of one chromosome made during S phase, stuck together.

  • Homologous chromosomes

    A pair (one from mom, one from dad) with the same genes in the same order, possibly different alleles.

  • Diploid (2n) vs Haploid (n)

    Diploid has two sets of chromosomes; haploid has one set.

  • Gamete

    A haploid sex cell, such as egg or sperm.

  • Crossing over

    DNA segments swap between homologous chromosomes during Prophase I of meiosis.

  • Synapsis

    When homologous chromosomes pair up tightly during meiosis.

  • Tetrad

    The paired homologs consisting of 4 chromatids total.

  • Chiasma

    The visible crossover point where homologous chromosomes exchange DNA.

  • Independent assortment

    Random orientation of homolog pairs in Metaphase I, creating genetic variation.

  • Genotype

    The allele combination an organism has (e.g., AA, Aa, aa).

  • Phenotype

    The observable trait resulting from the genotype.

  • Dominant vs Recessive allele

    Dominant allele shows in heterozygotes; recessive shows only if homozygous.

  • Homozygous vs Heterozygous

    Homozygous: same alleles (AA or aa); heterozygous: different alleles (Aa).

  • Carrier

    A heterozygote who does not show a recessive phenotype but can pass the allele.

  • Test cross

    Cross an unknown dominant-phenotype individual with a homozygous recessive to infer genotype.

  • Law of segregation

    Alleles separate into different gametes during meiosis.

  • Law of independent assortment

    Genes on different chromosomes assort independently during gamete formation.

  • Incomplete dominance

    Heterozygote shows an intermediate phenotype between the two alleles.

  • Codominance

    Both alleles are fully expressed in heterozygotes (e.g., AB blood type).

  • Epistasis

    One gene masks or modifies the effect of another gene.

  • Autosomal vs Sex-linked genes

    Autosomal genes are on chromosomes 1–22; sex-linked genes are often on the X chromosome.

  • Semiconservative replication

    Each new DNA molecule has one old strand and one new strand.

  • Replication fork

    Y-shaped region where DNA is unwound and copied during replication.

  • Leading vs Lagging strand

    Leading strand is made continuously toward the fork; lagging strand is made in Okazaki fragments away from the fork.

  • DNA ligase

    Enzyme that seals sugar-phosphate backbone between Okazaki fragments.

  • Central dogma

    Flow of genetic information: DNA → RNA → protein.

  • Transcription

    Process of making RNA from DNA template.

  • Translation

    Ribosome builds a polypeptide chain from mRNA codons.

  • Codon and Anticodon

    Codon: 3 mRNA bases coding an amino acid; anticodon: tRNA triplet matching the codon.

  • Introns and Exons

    Introns are removed; exons are kept during mRNA splicing in eukaryotes.

  • 5′ cap and poly-A tail

    mRNA modifications that aid stability, export, and translation in eukaryotes.

  • Mutation

    A change in DNA sequence that can alter the gene product.