Nucleic Acids & Genetics Review

Flashcards covering key vocabulary terms from lectures on Nucleic Acids and Genetics, including DNA, RNA structure, inheritance patterns, Mendelian genetics, and the Central Dogma.

Nucleic acids

Polymers of nucleotides.

Nucleotide

A repeating monomer made of a phosphate group, a 5-carbon sugar, and a nitrogenous base.

Nucleoside

A 5-carbon sugar combined with a nitrogenous base.

Ribose

The 5-carbon sugar found in RNA, characterized by a hydroxyl group (-OH) on its 2' carbon.

Deoxyribose

The 5-carbon sugar found in DNA, which lacks a hydroxyl group (has only hydrogen) on its 2' carbon.

Nitrogenous base

A component of nucleotides, containing nitrogen atoms in its ring structure; categorized into pyrimidines and purines.

Pyrimidine

A category of nitrogenous base with a single 6-atom ring structure containing two nitrogens. Includes Cytosine (C), Uracil (U), and Thymine (T).

Purine

A category of nitrogenous base with a double-ring (a 6-member and a 5-member ring) structure containing four nitrogens. Includes Adenine (A) and Guanine (G).

Cytosine (C)

A pyrimidine nitrogenous base characterized by an amino group.

Uracil (U)

A pyrimidine nitrogenous base with a carbonyl group; found in RNA, replacing thymine.

Thymine (T)

A pyrimidine nitrogenous base with carbonyl and methyl groups; found in DNA.

Adenine (A)

A purine nitrogenous base characterized by an amino group; also found in ATP.

Guanine (G)

A purine nitrogenous base with both a carbonyl and an amino group.

Phosphodiester linkage

A covalent bond that joins the 3' carbon of one nucleotide to the 5' carbon of the next nucleotide via a phosphate group, forming the backbone of nucleic acids.

Nucleotide polymerization

The process of forming phosphodiester bonds between nucleotides, often driven by energy from nucleoside triphosphates.

DNA (Deoxyribonucleic acid)

A nucleic acid polymer of deoxyribonucleotides, containing deoxyribose sugar and nitrogenous bases Adenine, Guanine, Cytosine, and Thymine.

RNA (Ribonucleic acid)

A nucleic acid polymer of ribonucleotides, containing ribose sugar and nitrogenous bases Adenine, Guanine, Cytosine, and Uracil (instead of Thymine).

5' end

The end of a nucleic acid strand with an unlinked 5' phosphate group.

3' end

The end of a nucleic acid strand with an unlinked 3' hydroxyl group, where new nucleotides are added during polymerization.

Chargaff's Rules

Rules stating that in DNA, the total number of purines equals pyrimidines (A+G=T+C), and the amount of adenine equals thymine (A=T), while cytosine equals guanine (C=G).

Double helix

The secondary structure of DNA, consisting of two antiparallel strands coiled around a central axis.

Antiparallel (DNA strands)

Describes the orientation of the two strands in a DNA double helix, where one strand runs in the 5'->3' direction and the other runs in the 3'->5' direction.

Hydrogen bonds (in DNA)

Weak bonds that stabilize the complementary base pairs (G-C and A-T) in the interior of the DNA double helix.

Major groove

A wider, deeper indentation on the surface of the DNA double helix, providing a site for protein binding.

Minor groove

A narrower, shallower indentation on the surface of the DNA double helix.

Complementary base pairing

The specific pairing of nitrogenous bases through hydrogen bonds (A with T/U, G with C), which is fundamental to DNA replication and RNA structure.

DNA replication

The process by which two identical copies of a DNA molecule are made, with each original strand serving as a template for a new complementary strand.

Ribozymes

RNA molecules that possess catalytic activity, functioning as enzymes to accelerate specific biochemical reactions.

Messenger RNA (mRNA)

An RNA molecule transcribed from a DNA template that carries genetic information from the DNA to the ribosomes for protein synthesis.

Transcription

The process of synthesizing RNA from a DNA template, where the genetic information is copied from DNA to mRNA.

Translation

The process by which the information encoded in mRNA is used to synthesize a polypeptide chain (protein) on ribosomes.

Genetics

The branch of biology focused on inheritance and the mechanisms by which traits are passed from parents to offspring.

Heredity

The transmission of traits from parents to their offspring.

Character (genetic)

An observable physical feature of an organism (e.g., flower color).

Trait

A specific form of a character (e.g., purple flowers or white flowers).

Blending inheritance

An outdated hypothesis suggesting that hereditary determinants blend in the zygote, resulting in offspring with intermediate traits.

Particulate inheritance

Mendel's hypothesis proposing that hereditary determinants are distinct particles that remain intact and discrete in the zygote.

Zygote

A diploid cell formed by the fusion of two haploid gametes (e.g., sperm and egg).

Model organism

A species studied in research that can be easily manipulated and whose findings are often applicable to other organisms.

Self-fertilization

A form of sexual reproduction in which an organism's own sperm (pollen) fertilizes its own eggs (ovules).

Cross-pollination

A controlled Mating process where pollen from one plant is manually transferred to the stigma of another plant to achieve fertilization.

Pure breeding varieties (True-breeding lines)

Organisms that, when self-fertilized, produce offspring identical to themselves generation after generation for specific traits.

Parental generation (P)

The initial generation of individuals chosen for a cross in a genetic experiment.

F1 (first filial) generation

The first generation of offspring resulting from a cross between two parental (P) individuals.

F2 (second filial) generation

The second generation of offspring, typically produced by self-pollinating or intercrossing individuals from the F1 generation.

Dominant trait

A trait that is expressed phenotypically in individuals who are heterozygous for that gene.

Recessive trait

A trait that is only expressed phenotypically in individuals who are homozygous for the recessive allele.

Hybrids

Offspring resulting from a genetic cross between two true-breeding parents with different traits.

Alleles

Different versions or forms of a particular gene.

Phenotype

The observable physical or biochemical characteristics of an organism, determined by its genotype and environmental interactions.

Genotype

The genetic makeup of an organism, specifically the combination of alleles it possesses for a particular gene or genes.

Law of Segregation

Mendel's law stating that the two alleles for each gene separate (segregate) during gamete formation, so each gamete receives only one allele.

Homozygous

Having two identical alleles for a particular gene (e.g., RR or rr).

Heterozygous

Having two different alleles for a particular gene (e.g., Rr).

Monohybrid cross

A genetic cross between parents that are heterozygous for a single trait (e.g., Rr x Rr).

Test Cross

A genetic cross used to determine the unknown genotype of an individual displaying a dominant phenotype by mating it with a homozygous recessive individual.

Punnett Square

A diagram used to predict all possible genotypic and phenotypic outcomes of a genetic cross between two individuals.

Gamete

A haploid reproductive cell (sperm or egg) that carries only one allele for each gene.

Dihybrid Cross

A genetic cross between parents that are both heterozygous for two different traits (e.g., RrYy x RrYy).

Law of Independent Assortment

Mendel's law stating that alleles for different genes assort independently of one another during gamete formation.

Probability (in genetics)

Mathematical calculations used to predict the expected frequencies of genotypes and phenotypes in genetic crosses.

Multiplication Rule

A probability rule stating that the probability of two or more independent events occurring together is the product of their individual probabilities.

Addition (Sum) Rule

A probability rule stating that the probability of an event that can occur in two or more mutually exclusive ways is the sum of their individual probabilities.

Pedigree

A chart representing the genetic relationships within a family, used to track the inheritance of a particular trait across generations.

Carrier

An individual who is heterozygous for a recessive allele, meaning they possess the allele but do not express the associated phenotype.

Autosomes

Any chromosome that is not a sex chromosome.

Autosomal inheritance

The pattern of inheritance for genes located on autosomes.

Consanguineous relationships

Relationships between individuals who are closely related by blood, which increases the likelihood of offspring inheriting rare recessive traits.

Chromosome Theory of Inheritance

The theory proposing that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for Mendel's laws of inheritance.

Histones

Proteins around which DNA is wrapped to form nucleosomes, facilitating the compact packaging of DNA within eukaryotic cells.

Nucleosomes

The basic repeating unit of chromatin, consisting of a segment of DNA wound around a core of histone proteins.

Chromatin

The complex of DNA and proteins (histones) that forms chromosomes within the nucleus of eukaryotic cells.

Sex chromosomes

Chromosomes that determine the sex of an individual (e.g., X and Y chromosomes).

Karyotype

A visual display of the complete set of chromosomes of an individual, arranged by number, shape, and size.

Diploid (2n)

A cell or organism containing two complete sets of chromosomes, one from each parent.

Homologous chromosomes

A pair of chromosomes (one maternal, one paternal) that are similar in size, centromere position, and carry the same genes at the same loci, but may have different alleles.

Haploid (n)

A cell or organism containing a single set of chromosomes, such as gametes.

Ploidy

The number of complete sets of chromosomes in a cell.

Haploid number (n)

The number of distinct types of chromosomes in a given species.

Gene expression

The process by which information encoded in a gene is used to synthesize a functional gene product, such as a protein or RNA molecule.

One-gene, one-enzyme hypothesis

The hypothesis, proposed by Beadle and Tatum, suggesting that each gene codes for a single enzyme.

Metabolic pathway

A series of sequential biochemical reactions within a cell, each catalyzed by a specific enzyme, that converts a starting molecule into a final product.

One-gene, one-polypeptide hypothesis

A refined version of the one-gene, one-enzyme hypothesis, stating that each gene codes for a single polypeptide chain.

RNA polymerase

An enzyme that synthesizes RNA by reading a DNA template strand and building a complementary RNA strand.

Central Dogma

The fundamental concept that genetic information flows from DNA to RNA to protein.

Genetic code

The set of rules that specifies the correspondence between nucleotide triplets (codons) in DNA or RNA and specific amino acids in proteins.

Codon

A sequence of three nucleotides in mRNA that specifies a particular amino acid during protein synthesis.

Start codon (AUG)

The specific codon (AUG) in mRNA that signals the initiation of protein synthesis and typically codes for methionine.

Stop codons

Three specific codons (UAA, UAG, UGA) in mRNA that signal the termination of protein synthesis.

Redundant (genetic code)

A characteristic of the genetic code where most amino acids are specified by more than one codon.

Unambiguous (genetic code)

A characteristic of the genetic code where each codon specifies only one particular amino acid.

Universal (genetic code)

A characteristic of the genetic code meaning that, with minor exceptions, the same codons specify the same amino acids in all living organisms.

Conservative (genetic code)

A characteristic of the genetic code where, when multiple codons specify the same amino acid, the first two bases of those codons are often identical.

Template strand (DNA)

The specific strand of a DNA double helix (running 3' to 5') that serves as the pattern for synthesizing a complementary RNA molecule during transcription.