Genetics and Probability Lecture Review

Flashcards covering key vocabulary from the lecture notes on genetics, heredity, probability, and mutations.

Mendel's Experiments

Experiments with pea plants that revealed fundamental principles of heredity, showing traits are inherited as discrete units following predictable patterns.

Genes

Segments of DNA that fundamentally control the inheritance of traits in organisms by carrying instructions for building and maintaining an organism.

DNA (deoxyribonucleic acid)

The blueprint of life, a double helix structure composed of nucleotides, whose specific sequence forms the genetic code.

Chromosomes

Larger structures found in the nucleus of eukaryotic cells, composed of a long DNA molecule tightly coiled around histones, where genes are organized.

Alleles

Different versions of a gene, arising due to slight variations in the DNA sequence, dictating variations in traits (e.g., tall vs. dwarf).

Dominant-Recessive Interaction

A type of allele interaction where one allele (dominant) masks the effect of the other (recessive) when both are present.

Co-dominant Interaction

A type of allele interaction where both alleles are expressed equally and distinctly.

Incomplete Dominance

A type of allele interaction where a blend of the two alleles is expressed.

Gametes

Specialized cells (sperm and egg) formed through meiosis, containing only one copy of each chromosome and thus one allele for each gene.

Meiosis

The process during sexual reproduction that reduces the number of chromosomes by half to form gametes.

Probability

A mathematical measure quantifying the likelihood that an event will occur, expressed as a number between 0 and 1.

Event

A specific outcome or a set of outcomes in a random experiment.

Experiment (Probability)

A process that leads to well-defined outcomes, where the result cannot be predicted with certainty.

Outcome (Probability)

A single result of an experiment.

Sample Space

The set of all possible outcomes of an experiment.

Theoretical Probability

Probability based on logical reasoning and the assumed equal likelihood of outcomes, determined before any experiment takes place.

Experimental (Empirical) Probability

Probability based on the results of actual experiments or observations, calculated by dividing the number of times an event occurs by the total number of trials.

Subjective Probability

Probability based on personal judgment, experience, or intuition, often used when objective data is unavailable.

Independent Assortment

During meiosis, the random distribution of homologous chromosomes, where each division is an independent probabilistic event.

Punnett Squares

A tool used to visualize probabilities in genetic crosses by mapping out all possible combinations of alleles from the gametes of two parents.

Genotype

The specific set of alleles an organism possesses for a particular gene or set of genes, representing its genetic makeup.

Phenotype

The observable characteristic resulting from an organism's genotype.

Locus (Loci)

The specific location of a gene on a chromosome.

Genetic Code

Formed by the specific sequence of nitrogenous bases within the DNA molecule, where groups of three bases determine amino acid sequences in proteins.

Nucleotides

Repeating units that make up DNA, each consisting of a deoxyribose sugar, a phosphate group, and a nitrogenous base.

Nitrogenous Bases (DNA)

The four distinct components (Adenine, Guanine, Cytosine, Thymine) in DNA that carry genetic information and form the 'letters' of the genetic alphabet.

Base Pairing Rule (DNA)

Specific pairings that connect the two strands of the DNA double helix: Adenine (A) always pairs with Thymine (T), and Guanine (G) always pairs with Cytosine (C).

Codon

A sequence of three consecutive nitrogenous bases on a messenger RNA (mRNA) molecule that specifies a particular amino acid or a stop signal for protein synthesis.

Degenerate (Redundant) Genetic Code

Refers to the fact that most amino acids are specified by more than one codon.

Universality of the Genetic Code

The principle that a specific codon typically codes for the same amino acid across almost all known organisms.

Protein Synthesis

A highly regulated process involving transcription and translation, by which a cell produces proteins from genetic information encoded in DNA.

Transcription

The first stage of protein synthesis where genetic information from a gene in the DNA is copied into a messenger RNA (mRNA) molecule.

RNA Polymerase

An enzyme that binds to a promoter region on DNA and synthesizes a complementary mRNA molecule during transcription.

mRNA Processing (Eukaryotes)

In eukaryotic cells, the modification of newly synthesized mRNA (pre-mRNA) involving intron removal, exon splicing, and the addition of a 5' cap and poly-A tail.

Translation

The second stage of protein synthesis where the information carried by the mRNA molecule is used to synthesize a polypeptide chain (a protein) on ribosomes.

Ribosomes

Cellular structures in the cytoplasm where translation occurs, synthesizing polypeptide chains based on mRNA instructions.

Start Codon

The codon (typically AUG) that signals the beginning of protein synthesis and codes for the amino acid Methionine.

tRNA (transfer RNA)

Molecules that carry specific amino acids to the ribosome during translation and have anticodons that complement mRNA codons.

Anticodon

A three-nucleotide sequence on a tRNA molecule that base-pairs with a complementary mRNA codon during translation.

Stop Codon

Codons (UAA, UAG, or UGA) on the mRNA that signal the termination of protein synthesis, as there are no corresponding tRNAs.

Post-Translational Modification

Further changes to a newly synthesized polypeptide chain after translation, such as folding, cleavage, or chemical additions, to become a functional protein.

Central Dogma of Molecular Biology

Describes the fundamental flow of genetic information in cells: DNA
RNA
Protein.

Mutations

Changes in the DNA sequence that can have a wide range of effects on an organism.

Gene Mutations (Point Mutations)

Small-scale changes affecting one or a few nucleotides within a gene.

Substitution Mutation

A type of gene mutation where one base is replaced by another.

Silent Mutation

A substitution mutation where the new codon still codes for the same amino acid, resulting in no change in the protein.

Missense Mutation

A substitution mutation where the new codon codes for a different amino acid, which can alter protein function.

Nonsense Mutation

A substitution mutation where the new codon becomes a stop codon, resulting in a prematurely truncated, often non-functional protein.

Insertion/Deletion (Frameshift Mutations)

Gene mutations where one or more bases are added or removed, shifting the reading frame of the genetic code and drastically altering downstream codons.

Chromosome Mutations

Large-scale changes affecting entire chromosomes or significant parts of them.

Deletion (Chromosome)

A chromosome mutation where a segment of a chromosome is lost.

Duplication (Chromosome)

A chromosome mutation where a segment of a chromosome is repeated.

Inversion (Chromosome)

A chromosome mutation where a segment of a chromosome is reversed end to end.

Translocation (Chromosome)

A chromosome mutation where a segment of one chromosome breaks off and attaches to a different chromosome.

Aneuploidy

A chromosome mutation characterized by an abnormal number of chromosomes (e.g., Down syndrome due to an extra copy of chromosome 21).

Neutral Mutations

Mutations that have no discernible effect on the organism's phenotype.

Harmful Effects (Mutations)

Consequences of mutations such as loss of function, reduced survival rates, or genetic disorders.

Beneficial Effects (Mutations)

Consequences of mutations that provide an advantage, increase fitness, or introduce novel traits, driving evolution.

Lethal Effects (Mutations)

Mutations that are so detrimental they cause the death of the organism, often before birth or during early development.

Somatic Cells

Body cells; mutations in these cells affect only the individual and are not passed to offspring.

Germline Cells

Sperm or egg cells; mutations in these cells are heritable and can be passed to subsequent generations.