Genetics and Molecular Biology Review - DNA, Replication, Inheritance

Vocabulary flashcards covering DNA structure, replication, mutation, gene expression, cell cycle, meiosis, and inheritance concepts from the lecture notes.

Chargaff's rules

In double-stranded DNA, %A = %T and %C = %G; A pairs with T, C pairs with G.

DNA nucleotide composition calculation

Determine base percentages (e.g., A%, T%, C%, G%); A% + T% = 100% − (C% + G%).

DNA double helix model

The right-handed double-helix structure of DNA described by Watson and Crick.

Rosalind Franklin X-ray crystallography

X-ray diffraction data that helped reveal DNA’s helical shape.

Hershey-Chase experiment

Demonstrated that DNA, not protein, is the genetic material in bacteriophages.

Sister chromatids

Two identical copies of a chromosome held together at the centromere.

Centromere

Chromosome region where sister chromatids are held together and where spindle fibers attach.

Histones

Proteins around which DNA wraps to form nucleosomes (spools of protein).

Hydrogen bonds in DNA

Weak bonds that hold A–T and C–G base pairs together.

Autosomes vs sex chromosomes

Autosomes are the same in males and females; sex chromosomes determine sex.

Karyotype

A chart showing an individual’s chromosomes, used to detect abnormalities and determine sex.

DNA Polymerase

Enzyme that adds nucleotides to a growing DNA strand and proofreads.

Primer

Short RNA sequence providing a starting point for DNA synthesis.

Semiconservative replication

Each new DNA molecule consists of one old strand and one new strand.

DNA replication steps

Helicase unwinds; primase lays primers; DNA polymerase adds nucleotides; ligase seals gaps.

Mutation

A change in the DNA sequence.

Nucleotide dimers

UV-induced covalent bonds between adjacent pyrimidines (e.g., thymine dimers).

Gene

A DNA sequence that codes for an RNA or protein product.

Gene expression

Process by which a gene’s information is used to synthesize RNA or protein (transcription and translation).

DNA vs RNA differences

DNA is double-stranded, uses A, T, C, G; RNA is single-stranded, uses A, U, C, G.

Transcription components

Enzymes such as helicase, primase, and RNA polymerase; introns and exons are parts of genes.

Introns vs Exons

Introns are non-coding sequences removed during processing; exons code for amino acids.

Translation

Ribosome reads mRNA codons and assembles the corresponding amino acids into a protein.

tRNA

Transfer RNA carries amino acids to the ribosome and has an anticodon that pairs with codons.

Codons

Three-nucleotide sequences in mRNA that specify amino acids.

Substitution

A DNA base is replaced by a different base.

Insertion

A nucleotide is added into the sequence.

Deletion

A nucleotide is removed from the sequence.

HeLa cells

A famous immortal human cancer cell line used in research.

Interphase

Cell grows and DNA replicates; the majority of the cell cycle occurs here.

Prophase

Chromosomes condense; nuclear envelope breaks down; spindle apparatus forms.

Metaphase

Chromosomes align at the cell’s equator.

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

Nuclear envelope forms around separated chromatids; chromosomes de-condense.

Cleavage furrow

In animals, contractile ring pinches the cell membrane to divide the cell.

Meiosis vs Mitosis

Meiosis produces four haploid cells for sexual reproduction; mitosis produces two diploid, identical daughter cells.

Crossing over

Exchange of genetic material between homologous chromosomes, increasing diversity.

Homologous chromosomes

Pairs of chromosomes of the same length and gene order, one from each parent.

Tumor

A mass of abnormal cells due to uncontrolled growth.

Neoplasm

An abnormal growth of tissue forming a lump; can be benign or malignant.

Oncogenes

Genes that promote cancer development when mutated or overexpressed.

Homozygous

Having two identical alleles for a gene.

Heterozygous

Having two different alleles for a gene.

Genotype

An organism’s genetic makeup (the alleles it carries).

Phenotype

The observable physical traits of an organism.

Monohybrid cross

Cross involving one gene with two alleles to study dominance relationships.

25% recessive offspring

With Aa x Aa, there is a 25% chance of aa offspring in the Punnett square.

Nondisjunction

Failure of chromosome pairs to separate during meiosis, leading to abnormal chromosome numbers.

Turner syndrome

Females with only one X chromosome (monosomy X).

Down syndrome

Trisomy 21; three copies of chromosome 21.