Eukaryotic Development and Genetic Mutations

A comprehensive set of flashcards covering vocabulary from eukaryotic development, genetics, mutations, and biotechnology.

Morphogens

Signaling molecules that diffuse through embryonic tissues to form concentration gradients, directing cell fate.

Example of Morphogen

Sonic hedgehog (Shh) in limb development.

Segmentation genes

Establish body segmentation in the embryo.

Gap genes

Define broad regions in segmentation (e.g., hunchback in Drosophila).

Pair-rule genes

Refine segmentation (e.g., even-skipped and fushi tarazu).

Segment polarity genes

Define segment boundaries (e.g., engrailed and wingless).

Hox genes

Encode transcription factors that regulate body patterning.

Homeotic transformations

Mutations in Hox genes that lead to changes in body organization (e.g., antenna-to-leg transformation in Drosophila).

Hormones

Regulate gene expression via receptor binding.

Example of Hormone Action

Estrogen binds to estrogen receptors to activate transcription.

Growth factors

Trigger intracellular signaling cascades.

Example of Growth Factor

Epidermal growth factor (EGF) activates cell division.

Promoters

Control where and when a gene is expressed.

Alternative Promoters

Promoters that allow different expression patterns depending on the tissue.

Microsatellites

Repeated DNA sequences in vasopressin receptor promoters affect gene expression.

Genetic Variation and Behavior

Variation in gene expression correlates with monogamous vs. polygamous behaviors in voles.

Reporter Genes

Used for studying gene regulation.

Common Reporter Genes

GFP (Green Fluorescent Protein), luciferase assays.

MyoD

Master regulator of muscle differentiation.

Myostatin

Inhibits muscle growth; mutations can lead to increased muscle mass.

Human Evolution and Enhancers

Loss of regulatory elements contributed to unique human traits.

Histone Acetylation

Modification that leads to gene activation.

Histone code

Combination of modifications that dictate transcriptional outcomes.

Epigenetics

Heritable changes in gene expression without DNA sequence alteration.

DNA Methylation

Suppresses gene expression, often associated with gene silencing.

HATs

Histone Acetyltransferases, enzymes that activate genes.

HDACs

Histone Deacetylases, enzymes that repress gene expression.

Polycomb complexes

Maintain long-term gene repression.

Intergenerational Inheritance

Direct exposure effects that influence offspring.

Transgenerational Inheritance

Effects that persist beyond directly exposed generations.

Nutrigenomics

Interaction between diet and gene expression.

Dutch Hunger Winter

Period of malnutrition that led to epigenetic changes affecting later generations.

Thrifty Phenotype Hypothesis

Fetal adaptations to scarcity increase disease risk in abundance.

Glucocorticoid receptor expression

Affected by maternal care and influences stress resilience.

Genomic Imprinting

Certain genes expressed from only one parent.

Genetic Conflict Hypothesis

Paternal genes favor growth, while maternal genes restrict growth.

Imprinting defects

Lead to disorders such as Prader-Willi and Angelman syndromes.

lncRNA

Long non-coding RNA that regulates gene expression via chromatin remodeling.

Antisense RNA

Blocks translation of complementary mRNA.

piRNA

Silences transposons in germ cells.

siRNA & miRNA

Mediates RNA interference, degrading mRNA or blocking translation.

Dicer

Cuts double-stranded RNA into siRNA or miRNA.

RISC

RNA-Induced Silencing Complex that targets complementary mRNA for degradation.

Germ-Line Mutations

Occur in reproductive cells and can be passed to offspring.

Somatic Mutations

Occur in body cells and are not inherited.

BRCA1 Mutation

In germ cells increases risk of hereditary breast cancer.

Observation Methods of Mutation Rates

Phenotypic observation, molecular sequencing.

Average Human Mutation Rate

About 1 mutation per 100 million base pairs per generation.

Spontaneous errors in DNA replication

One of the factors affecting mutation rates.

Environmental Mutagens

Chemicals, radiation, UV light that can cause mutations.

Repair Mechanisms

If defective, can lead to accumulation of mutations.

Xeroderma Pigmentosum

Lack of proper UV-induced damage repair leading to skin cancer.

Aneuploidy

Gain or loss of individual chromosomes (e.g., Trisomy 21).

Polyploidy

Extra sets of chromosomes, common in plants.

Structural rearrangements

Deletions, duplications, inversions, translocations in chromosomes.

Deletions

Loss of a chromosome segment (e.g., Cri-du-chat syndrome).

Duplications

Extra copies of a chromosome segment (e.g., Charcot-Marie-Tooth disease).

Inversions

A segment is flipped within the same chromosome.

Translocations

Exchange of chromosome parts (e.g., Philadelphia chromosome in CML).

Base substitutions

Change a single nucleotide in DNA.

Insertions & deletions

Can cause frameshift mutations.

Expanding nucleotide repeats

Increase in repeat sequences (e.g., Huntington’s disease).

Transition mutations

Purine ↔ Purine or Pyrimidine ↔ Pyrimidine.

Transversion mutations

Purine ↔ Pyrimidine changes.

Cystic fibrosis mutation

ΔF508: a 3-base-pair deletion that preserves the reading frame.

Point Mutations

Can be silent, missense, or nonsense.

Silent Mutation

No change in the amino acid sequence.

Missense Mutation

Changes one amino acid in the sequence.

Nonsense Mutation

Creates a premature stop codon.

Gene Dosage

Extra gene copies can disrupt regulation.

Fragile X Syndrome

Expanded CGG repeats cause chromosomal fragility.

Pseudodominance

If a dominant allele is deleted, the recessive allele is expressed.

Reciprocal Translocations

Equal exchange between two chromosomes.

Nonreciprocal Translocations

Unequal exchange between chromosomes.

Robertsonian Translocation

Fusion of two acrocentric chromosomes.

Consequences of Monosomy

Turner Syndrome (XO).

Consequences of Trisomy

Down Syndrome.

Polyploidy in Plants

Common occurrence of extra chromosome sets.

Autopolyploidy

Duplication within one species.

Allopolyploidy

Hybridization between species.

DNA Mutagens

Agents that cause DNA damage, such as depurination and oxidative radicals.

Proofreading in DNA Repair

Correction of errors by DNA polymerase.

Mismatch Repair

Fixes errors in the newly synthesized DNA strand.

Nucleotide Excision Repair

Removes damaged DNA including UV-induced thymine dimers.

Forward Mutations

Wild type → Mutant.

Reverse Mutations

Mutant → Wild type.

Suppressor Mutations

A second mutation compensates for the first.

Cancer

Not a single disease but a family of diseases characterized by uncontrolled cell division.

Lung Cancer Mutations

Typical lung cancer has ~22,000 mutations.

HeLa Cells

Cervical cancer cells from Henrietta Lacks, used widely in research.

Characteristics of Cancer Cells

Ignore signals to stop dividing, evade apoptosis, express telomerase.

Aneuploidy in Cancer

Cancer cells often exhibit abnormal chromosome numbers.

Clonal Evolution of Tumors

Tumors develop through a multistep process leading to aggressive clones.

Steps of Metastasis

Detachment, invasion, intravasation, travel, extravasation, angiogenesis.

Proto-Oncogenes

Normal genes regulating cell growth that can become oncogenes.

Oncogenes

Mutated proto-oncogenes that promote uncontrolled growth.

Tumor Suppressor Genes

Inhibit cell division and promote apoptosis.

p53

Key tumor suppressor gene linked to growth control.

Signal Transduction Pathways

Transmit signals from outside to inside the cell, often hijacked by oncogenes.

Cyclins

Proteins that regulate the cell cycle by binding to CDKs.