Comprehensive Biology Review: Meiosis, Genetics, Molecular Biology, and Evolution

These vocabulary flashcards cover cell division, heredity laws, molecular processes of DNA, and the mechanisms and evidence for evolution based on lecture notes.

Meiosis

The type of cell division that produces gametes, involving two cell divisions and resulting in four haploid cells.

Chromosome

A coiled structure made of DNA and protein that carries genetic information and is visible during cell division.

Homologous chromosomes

Pairs of chromosomes that are similar in size, shape, and genetic content, with one coming from each parent.

Diploid ($2n$)

A cell that contains two sets of chromosomes, one from each parent; in humans, the number is $46$.

Haploid ($n$)

A cell that contains only one set of chromosomes, such as sperm and egg cells; in humans, the number is $23$.

Crossing over

A process occurring during Prophase I where sections of DNA are exchanged between homologous chromosomes to create new gene combinations.

Tetrads

Structures formed in Prophase I when homologous chromosomes pair up.

Reduction division

Another name for Meiosis I because the chromosome number is reduced from diploid to haploid.

Sister chromatids

The duplicated parts of a chromosome that remain attached during Meiosis I and are separated during Meiosis II.

Genetics

The study of heredity and how traits are passed from parents to offspring.

Gregor Mendel

An Austrian monk known as the "Father of Genetics" who discovered basic principles of heredity through experiments with pea plants.

Law of Segregation

Determines that the two alleles for a trait separate during gamete formation so each gamete receives only one allele.

Law of Independent Assortment

States that alleles for different traits separate independently during gamete formation, increasing genetic variation.

Genotype

The combination of alleles an organism possesses for a specific trait, such as $PP$ or $Pp$.

Phenotype

The physical appearance or observable characteristic resulting from a genotype, such as purple flowers.

Dominant Allele

An allele that masks the effect of a recessive allele and is expressed whenever it is present.

Recessive Allele

An allele that is hidden when a dominant allele is present and is only expressed when two recessive alleles are inherited.

Homozygous Dominant

An organism that possesses two dominant alleles for a trait, such as $PP$.

Heterozygous

An organism that possesses one dominant allele and one recessive allele, such as $Pp$, resulting in a dominant phenotype.

Homozygous Recessive

An organism that possesses two recessive alleles for a trait, such as $pp$.

Punnett Square

A chart used to predict the possible genotypes and phenotypes of offspring.

Monohybrid Cross

A genetic cross that studies one trait at a time, often resulting in a $3:1$ phenotype ratio.

Dihybrid Cross

A genetic cross that examines the inheritance of two traits simultaneously, typically resulting in a $9:3:3:1$ phenotype ratio.

Pedigree

A chart used to track how a specific trait is passed through multiple generations of a family.

Sex-linked trait

A trait controlled by a gene located on a sex chromosome, most commonly the X chromosome.

Autosomes

The $22$ pairs of human chromosomes that are not sex chromosomes.

Karyotype

The number and visual appearance of the chromosomes in the nucleus of a cell.

Central Dogma

The explanation of how genetic information flows: $DNA \rightarrow RNA \rightarrow Protein$.

Double Helix

The twisted ladder shape of the DNA molecule.

Nucleotide

The building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogen base.

DNA Base Pair Rules

The rule that Adenine ($A$) always pairs with Thymine ($T$) and Guanine ($G$) always pairs with Cytosine ($C$).

Chargaff's Rules

States that in DNA, the amount of $A = T$ and the amount of $G = C$.

Helicase

The enzyme responsible for unwinding and opening the DNA double helix by breaking hydrogen bonds.

mRNA (Messenger RNA)

RNA that copies genetic instructions from DNA and carries them from the nucleus to the ribosome.

rRNA (Ribosomal RNA)

RNA that helps form ribosomes and assists in protein synthesis.

tRNA (Transfer RNA)

RNA that matches amino acids with mRNA codons during protein assembly.

Protein

An organic compound made of amino acids that builds tissues and acts as enzymes.

Transcription

The process occurring in the nucleus where DNA serves as a template to create mRNA.

Translation

The process occurring at the ribosome where the genetic code in mRNA is read to build a protein.

Codon

A sequence of three nitrogen bases on mRNA that codes for a specific amino acid or a start/stop signal.

Anticodon

A three-base sequence on tRNA that is complementary to an mRNA codon.

Evolution

The change in inherited traits within a population over many generations.

Population

A group of organisms of the same species living in the same area; it is the entity that evolves, not the individual.

Mutation

A random change in DNA that creates genetic variation and introduces new traits.

Gene Flow

The movement of genes between populations due to migration and reproduction.

Genetic Drift

A random change in allele frequencies within a population, most significant in small populations, driven by chance.

Natural Selection

The process where organisms with advantageous traits survive and reproduce more successfully, making those traits more common.

Adaptation

An inherited characteristic or trait that increases an organism's chance of survival and reproductive success.

Fitness

An organism's ability to successfully survive and pass its genes to the next generation.

Homologous Structures

Physical structures that share a similar anatomy because they were inherited from a common ancestor.

Vestigial Structures

Structures inherited from ancestors that no longer serve their original function, such as the human tailbone.

Fossil Record

The collection of preserved remains or traces of ancient organisms that provide a timeline of evolutionary history.

Biogeography

The study of the geographic distribution of organisms across the world.

Antibiotic Resistance

A real-world example of natural selection where bacteria with mutations survive medicine and reproduce, spreading the resistance.