Biology: DNA, Genetics, and Evolution Concepts

A collection of flashcards covering key concepts in Biology related to DNA, genetics, cellular processes, and evolution.

Griffith's Experiment

Showed that the 'transforming principle' in bacteria could make harmless bacteria virulent.

Avery, MacLeod, McCarty Experiment

Determined that DNA was the transforming substance.

Hershey & Chase Experiment

Showed that DNA, not protein, carries genetic information using radioactive labeling.

Chargaff's Rules

Found base-pair ratios: A=T and G=C.

Watson & Crick Model

Proposed the double helix structure of DNA with complementary base pairing.

Rosalind Franklin

Used X-ray crystallography to show that DNA was helical.

Histones

Proteins that DNA wraps around to form nucleosomes.

Nucleosome

A structure made of DNA wrapped around histones.

Chromatin

Loose DNA found during interphase.

Chromosomes

Highly condensed chromatin visible during cell division.

Gene

A segment of DNA that codes for a protein or RNA.

DNA Complementarity

DNA bases pair A-T and G-C.

Semi-Conservative Replication

New DNA molecules have one old strand and one new strand.

Karyotype Analysis

Counting chromosomes and checking for abnormalities in size and number.

Central Dogma of Biology

Describes the flow of genetic information from DNA to RNA to protein.

Transcription

Process of synthesizing pre-mRNA from DNA in the nucleus.

RNA Processing

Introns removed and exons spliced to form mature mRNA.

Translation

Process of synthesizing proteins at ribosomes using mRNA.

Alternative Splicing

Combines exons in different ways to increase protein diversity.

Nucleic Acids

Molecules that store and transmit genetic information.

Role of Proteins

Perform cellular functions such as catalysis, structure, signaling, and transport.

Genetic Code Redundancy

Multiple codons can code for the same amino acid.

Gene Expression Regulation

Mechanisms controlling which genes are transcribed and translated.

Point Mutation

Single base change that can result in various effects on proteins.

Lytic Cycle

Viral replication process resulting in cell lysis.

Lysogenic Cycle

Viral DNA integrates into the host genome and can later enter a lytic phase.

Steps of Viral Infection

Attachment, entry, replication, transcription/translation, assembly, release.

Apoptosis

Programmed cell death to remove unnecessary or damaged cells.

Binary Fission

A method of asexual reproduction in prokaryotes producing two identical daughter cells.

Transformation

Uptake of free DNA by a prokaryotic cell from its environment.

Conjugation

Direct transfer of DNA between prokaryotic cells via pili.

Transduction

Transfer of DNA by bacteriophages between prokaryotic cells.

Chromatin vs Chromosomes

Chromatin: loose DNA. Chromosomes: condensed DNA during cell division.

Homologous Chromosomes

Chromosome pairs inherited from each parent that have the same size and shape.

Cell Cycle

The series of stages a cell goes through prior to division.

G1 Phase

Cell growth and normal functions occur.

S Phase

The synthesis phase where DNA replication occurs.

G2 Phase

Prepares the cell for division; checks for errors.

M Phase

The phase of mitosis and cytokinesis.

G0 Phase

Resting phase for cells that no longer divide.

Mutation Accumulation and Apoptosis

Cells detect severe DNA damage and undergo apoptosis to prevent cancer.

Regulated Cell Division

Functional checkpoints and controlled growth in normal cells.

Unregulated Cell Division

Cancerous growth due to mutated/tumor suppressor genes.

Haploid Cells

Cells with one set of chromosomes (N), e.g. gametes.

Diploid Cells

Cells with two sets of chromosomes (2N), e.g. somatic cells.

Asexual Reproduction

Reproduction involving a single parent producing genetically identical offspring.

Sexual Reproduction

Reproduction involving two parents, resulting in genetically diverse offspring.

Mitosis

Cell division resulting in two diploid daughter cells.

Meiosis

Cell division resulting in four haploid gametes.

Genetic Diversity Sources

Independent assortment, crossing over, and fertilization increase variation.

Identical Twins

Formed when one zygote splits, resulting in genetically identical individuals.

Fraternal Twins

Result from two eggs fertilized by two different sperm, genetically unique.

Nondisjunction

Failure of chromosomes to separate, leading to abnormal chromosome numbers.

Aneuploidy

Abnormal number of chromosomes (e.g., Down syndrome).

Polyploidy

Organisms having extra complete sets of chromosomes.

Evolution Definition

Change in allele frequencies in a population over time.

Evidence for Evolution

Fossils, comparative anatomy, embryology, biogeography, molecular biology.

Natural Selection Definition

Process where individuals with favorable traits reproduce more successfully.

Hardy-Weinberg Equilibrium

Allele frequencies remain constant if no evolution occurs.

Modes of Natural Selection

Includes directional, stabilizing, and disruptive selection.

Sexual Dimorphism

Differences in appearance between males and females of the same species.

Mutation as an Evolution Agent

Introduces new alleles to the gene pool.

Gene Flow

Movement of alleles into or out of a population through migration.

Genetic Drift

Random changes in allele frequency, especially in small populations.

Non-random Mating

Mating individuals based on preferences affecting allele distribution.

Evolutionary Agents Comparison

Natural selection vs. artificial selection in trait modification.

Allele Frequency Calculation

Calculated as the number of specific alleles divided by total alleles in a population.

Predation as Selective Pressure

Influences survival rates based on individual traits.

Embryology Evidence

Similar early development across different species supports evolutionary theory.

Comparative Anatomy

Comparison of homologous versus analogous structures to infer evolutionary relationships.

Environmental Effects on Phenotype

Phenotypes influenced by both genotype and environmental factors.

Genotype vs Phenotype

Genotype is the genetic makeup; phenotype is the observable trait.

Test Cross

Determining an unknown genotype by crossing with a homozygous recessive.

Law of Segregation

Alleles segregate during meiosis ensuring gametes get one allele per gene.

Dihybrid Cross

Tracks two traits and requires a 16-square Punnett square.

Polygenic Traits

Traits influenced by multiple genes resulting in continuous variation.

Codominance

Both alleles in a heterozygote are expressed equally.

Incomplete Dominance

Heterozygote displays a blended phenotype.

X-Inactivation

Random inactivation of one X chromosome in female mammals.