BIOL 104

Gene Expression

Process by which genetic instructions are used to synthesize proteins.

Transcription

Process of copying DNA into mRNA.

Translation

Conversion of mRNA into a polypeptide (protein).

RNA Polymerase

Enzyme responsible for transcribing DNA into RNA.

Promoter Region

DNA sequence that initiates transcription.

Enhancers

DNA sequences that increase the efficiency of transcription.

Silencers

DNA sequences that inhibit gene transcription.

Epigenetics

Study of heritable gene expression changes without altering DNA sequence.

DNA Methylation

Addition of methyl groups that can silence gene expression.

Histone Modification

Chemical changes to histones affecting DNA accessibility.

Chromatin Remodeling

Structural changes in chromatin that affect gene expression.

Operon Model

Gene regulation system in prokaryotes.

Lac Operon

Classic example of gene regulation in bacteria.

Repressor Proteins

Proteins that inhibit gene transcription.

Transcription Factors

Proteins that bind to DNA and regulate gene expression.

Alternative Splicing

Process allowing a single gene to code for multiple proteins.

MicroRNAs (miRNAs)

Small RNAs that regulate gene expression post-transcriptionally.

RNA Interference (RNAi)

Mechanism that inhibits gene expression via miRNAs or siRNAs.

Codon

Three-nucleotide sequence in mRNA specifying an amino acid.

Start Codon

AUG sequence signaling the start of translation.

Stop Codon

UAA, UAG, or UGA sequence signaling the end of translation.

Exons

Coding sequences in a gene.

Introns

Non-coding sequences removed during RNA processing.

Gene Mutation

Permanent alteration in DNA sequence.

Point Mutation

A single nucleotide change in DNA.

Frameshift Mutation

Insertion or deletion of nucleotides disrupting the reading frame.

Nonsense Mutation

A mutation that introduces a premature stop codon.

Missense Mutation

A mutation that changes an amino acid in a protein.

Silent Mutation

A mutation that does not change the amino acid sequence.

Genetic Code

Universal set of codons mapping to amino acids.

tRNA (Transfer RNA)

Brings amino acids to ribosomes during translation.

rRNA (Ribosomal RNA)

Structural RNA forming ribosomes.

Polyribosome

Multiple ribosomes translating a single mRNA.

Operon

Cluster of genes under a single promoter (common in prokaryotes).

Housekeeping Genes

Genes that are always active for basic cell functions.

Mendelian Inheritance

Classical genetic inheritance following Gregor Mendel's laws.

Law of Segregation

Each gamete carries only one allele per gene.

Law of Independent Assortment

Genes for different traits assort independently.

Dominant Allele

An allele that expresses its trait even when heterozygous.

Recessive Allele

An allele that only expresses when homozygous.

Homozygous

Two identical alleles for a trait.

Heterozygous

Two different alleles for a trait.

Genotype

Genetic makeup of an organism.

Phenotype

Observable traits of an organism.

Punnett Square

Diagram predicting offspring genotype probabilities.

Monohybrid Cross

Genetic cross involving one trait.

Dihybrid Cross

Genetic cross involving two traits.

Incomplete Dominance

A blending of traits in heterozygous individuals.

Codominance

Both alleles are fully expressed in heterozygotes.

Polygenic Inheritance

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

Fertilization

Union of sperm and egg to form a zygote.

Embryonic Development

Process of growth and differentiation post-fertilization.

Gastrulation

Formation of three germ layers in the embryo.

Differentiation

Process where cells become specialized in function.

Human Sperm

Streamlined shape aids swimming through reproductive fluids.

Acrosome

Membrane-enclosed sac containing enzymes for egg penetration.

Haploid Nucleus

Contains one set of chromosomes from the sperm.

Mitochondria in Sperm

Provide energy from fructose for flagellum movement.

Oviduct

Tube connecting ovary to uterus, site of fertilization.

Follicular Cells

Layer surrounding the egg, first barrier to sperm.

Jelly Coat

Outer layer of the egg, second barrier to sperm.

Acrosomal Enzymes

Digest jelly coat, allowing sperm to penetrate egg.

Zygote

Single diploid cell formed after sperm and egg fusion.

Meiosis II Completion

Final stage of egg division triggered by sperm entry.

Impenetrable Plasma Membrane

Prevents additional sperm from entering the egg.

Dormant Metabolic Machinery

Awakens post-fertilization for growth and development.

Cleavage

Rapid cell divisions producing a multicellular ball.

Blastocyst

Fluid-filled ball of about 100 cells.

Inner Cell Mass

Cluster of cells forming the future fetus.

Ectopic Pregnancy

Embryo develops outside the uterus.

Miscarriage

Spontaneous abortion of an embryo.

Endoderm

Innermost layer developing into digestive organs.

Mesoderm

Middle layer forming muscles and organs.

Ectoderm

Outer layer developing into the nervous system.

Programmed Cell Death

Selective cell death shaping body structures.

Amnion

Fluid-filled sac protecting the embryo.

Umbilical Cord

Lifeline connecting embryo to placenta.

Chorionic Villi

Fingerlike structures absorbing nutrients from mother.

Placenta

Organ providing nourishment and waste disposal.

First Trimester

Period of greatest changes in embryo.

Second Trimester

Development refinement and size increase.

Third Trimester

Rapid growth and preparation for birth.

Stem Cells

Cells with potential to become any cell type.

Cell Division

Process where one cell splits into two.

Chromosomal Abnormalities

Genetic defects causing developmental issues.

Fluid-Filled Cavity

Central space in the blastocyst.

Facial Features Development

Fetus develops human-like facial characteristics.

Temperature Regulation

Fetus learns to control body temperature.

Organ Formation

Development of essential body organs.

Nervous System Development

Growth of the brain and neural pathways.

Heart Development

Formation of the fetal heart and circulatory system.

Limb Formation

Development of arms and legs.

Neural Tube Closure

Critical process in forming the spinal cord.

Yolk Sac

Temporary structure that provides early nutrients.

Gene Expression

Regulation of genetic information for development.

Sex Determination

Process that leads to male or female characteristics.

Hormonal Regulation

Influence of hormones in fetal growth.

Neural Crest Cells

Cells that contribute to the nervous system and other structures.

Bone Development

Formation of skeletal structures.

Muscle Differentiation

Specialization of muscle cells for movement.