Cell Division, Genetics & Evolution Lecture Review

Vocabulary flashcards covering cell cycle, genetics, mutation, and evolutionary concepts from the lecture notes.

Chromosome

A DNA molecule that contains many genes; chromosomes contain genes.

Gene

Unit of inheritance that occupies a specific locus on a chromosome.

S phase (Interphase)

Part of the cell cycle when DNA replication occurs.

Semiconservative Replication

DNA replication mechanism producing one old strand and one new strand in each daughter molecule.

G1 phase

Portion of interphase in which the cell grows and performs normal functions.

Mitosis

Nuclear division producing two identical diploid nuclei; phases: Prophase, Metaphase, Anaphase, Telophase (PMAT).

Cytokinesis

Division of the cytoplasm; cleavage furrow in animals, cell plate in plants.

Binary Fission

Asexual reproduction in prokaryotes; chromosome duplication starts at the origin of replication.

Centrosome

Eukaryotic organelle that organizes the mitotic spindle; absent in binary fission.

Origin of Replication

Site where DNA replication begins; replaces centrosome role in bacterial cell division.

Diploid (2n)

Cell with two sets of chromosomes; produced by mitosis.

Haploid (n)

Cell with one set of chromosomes; gametes produced by meiosis are haploid.

Gamete

Haploid reproductive cell (sperm or egg) formed by meiosis.

Meiosis

Two-division process producing four genetically unique haploid cells.

Crossing Over

Exchange of DNA between homologous chromosomes during Prophase I of meiosis.

Independent Assortment

Random orientation of homologous chromosome pairs in Metaphase I, contributing to genetic diversity.

Homologous Chromosomes

Pair of chromosomes of the same type, one from each parent; separate in Meiosis I.

Sister Chromatids

Identical copies of a chromosome; separate in Meiosis II.

Heterozygous

Genotype with two different alleles (e.g., Jj).

Homozygous

Genotype with two identical alleles (e.g., JJ or jj).

True-breeder

Organism homozygous for a trait, consistently passing down the same phenotype.

Dominant Phenotype

Trait expressed with at least one dominant allele (e.g., JJ or Jj).

Recessive Phenotype

Trait expressed only when both alleles are recessive (e.g., jj).

Polyploidy

Condition of having more than two sets of chromosomes; more tolerated in plants.

Polygenic Inheritance

Trait controlled by multiple genes (e.g., skin color, height).

Color Blindness

X-linked recessive disorder; sons of carrier mothers have 50% chance of being affected.

Down Syndrome

Genetic disorder resulting from trisomy 21 (three copies of chromosome 21).

Mutation

Change in DNA sequence; can lead to cancer if it causes uncontrolled cell growth.

Point Mutation

Single-base change in DNA; causes disorders like Huntington’s or melanoma.

Somatic Mutation

DNA change in non-reproductive cells (e.g., melanoma); not inherited.

Germline Mutation

DNA change in gametes; heritable (e.g., Huntington’s disease).

Complementary Base Percentage

If DNA has 15% thymine, it has 35% cytosine (because A=T and G=C).

Jean-Baptiste Lamarck

Proposed (incorrectly) that acquired characteristics are inherited.

Alfred Russel Wallace

Co-discoverer of natural selection alongside Darwin.

Charles Darwin

Proposed evolution by natural selection; author of 'On the Origin of Species'.

Population (Evolutionary Unit)

Group of interbreeding individuals; basic unit of evolution.

Transcription

Process in which RNA polymerase copies DNA into mRNA.

RNA Polymerase

Enzyme that synthesizes RNA during transcription.

Antiparallel

Orientation of DNA strands running in opposite 5'→3' directions.

DNA Nucleotide Components

Composed of a deoxyribose sugar, phosphate group, and nitrogenous base.

mRNA Processing

Addition of 5' cap, poly-A tail, and removal of introns before translation.

Methionine (AUG)

Start codon; first amino acid incorporated in every protein.

Complementary mRNA Sequence

DNA 3'-TAGGCTC-5' transcribes to mRNA 5'-AUCCGAG-3'.

Prokaryote Evolution

Prokaryotes first evolved approximately 3.5 billion years ago.

Chemical Evolution Steps

Organic molecules → macromolecules → protocells → self-replicating molecules.