Life at Molecular, Cellular and Tissue Level: Genetics, Meiosis, and DNA Technology

Comprehensive vocabulary flashcards covering nucleic acids, DNA replication, protein synthesis, meiosis, Mendelian genetics, mutations, and DNA technology based on lecture notes.

Nucleic acids

Biological molecules that have the capacity to store information controlling cellular activity and organism development by controlling protein synthesis.

Chromatin

Chromosomal material made up of DNA, RNA, and histone proteins found in a non-dividing cell.

Extranuclear DNA

Small amounts of DNA found outside the nucleus in the mitochondria of plants and animals, and in the chloroplasts of plants.

Nucleotide

The monomer building block of a nucleic acid, composed of a sugar molecule (deoxyribose or ribose), a phosphate molecule, and a nitrogenous base.

Purines

A class of nitrogenous bases composed of two fused rings of nitrogen, carbon, and hydrogen atoms, including adenine and guanine.

Pyrimidines

A class of nitrogenous bases composed of one ring of atoms that are smaller than purines, including thymine, cytosine, and uracil.

Exons

Protein-coding regions of DNA, making up approximately $2\%$ of human DNA.

Introns

Non-coding regions of DNA that interrupt protein-coding regions and can form functional RNA molecules with regulatory functions.

DNA replication

The process taking place in the nucleus during interphase where a new DNA molecule is produced from an existing DNA molecule to make an identical copy.

Mitochondrial DNA (mtDNA)

A double-stranded, ring-shaped DNA molecule of $16500$ base pairs found in the mitochondria that is inherited exclusively from the mother via the egg cell.

Transcription

The process occurring in the nucleus where DNA makes and codes an mRNA strand, catalyzed by the enzyme RNA polymerase.

Codon

A sequence of three nitrogenous bases on an mRNA strand that functions as a code word for an amino acid or a stop signal.

Translation

The process occurring in the ribosome by which a specific protein is assembled from a chain of amino acids according to the mRNA codon sequence.

Anticodon

A triplet of bases found at one end of a tRNA molecule that binds to its complementary codon on the mRNA strand.

Ribosomal RNA (rRNA)

The most abundant type of RNA in the cell that combines with proteins to construct ribosomes and reads codons along the mRNA during translation.

Point mutation

A small, localized gene mutation in the structure of a DNA strand that involves a single nucleotide via substitution, insertion, or deletion.

Mutagens

Factors that increase the rate of mutations, such as ionizing radiation, mutagenic chemicals, viruses, or micro-organisms.

Short Tandem Repeats (STRs)

Highly variable repeating sequences of base pairs located in non-coding DNA that differ in number between individuals and are used in DNA profiling.

Homologous pair

A matching pair of maternal and paternal chromosomes of the same size and shape that carry the same genes at the same loci, though not necessarily the same alleles.

Meiosis

A reduction division occurring in reproductive organs that reduces chromosome number from diploid ($2n$) to haploid ($n$), creating four genetically unique daughter cells.

Synapsis

The pairing up of replicated homologous chromosomes during prophase I of meiosis to form bivalents or tetrads.

Crossing over

The mutual exchange of chromosome pieces between inner chromatids of paired maternal and paternal chromosomes during late prophase I.

Chiasmata

The specific points of crossing over where paired chromatids break and exchange genetic material.

Chromosome non-disjunction

The failure of chromosomes or chromatids to separate correctly during meiosis, resulting in gametes with extra or missing chromosomes.

Aneuploidy

A chromosomal condition resulting from non-disjunction where a zygote contains either an extra chromosome or a missing chromosome.

Klinefelter's syndrome

A genetic condition in males caused by an extra X chromosome ($XXY$), leading to characteristics such as sparse body hair, enlarged breasts, and reduced fertility.

Down syndrome (Trisomy-21)

An aneuploidy caused by an extra copy of chromosome $21$ ($2n+1$), resulting in $47$ total chromosomes, intellectual delays, flattened facial features, and heart defects.

Amniocentesis

A procedure in which a small sample of amniotic fluid is removed from the amniotic cavity in the uterus to extract foetal cells for diagnostic testing.

Karyotype

A visual representation showing the full set of chromosomes in a cell, displaying their number, size, and shape during metaphase of mitosis.

Gene

A section of DNA composed of a series of nucleotides that controls a specific hereditary characteristic.

Alleles

Different versions or forms of a gene that control the same trait and occupy the same locus on homologous chromosomes.

Gene pool

The complete set of all genes and genetic information present in a population of sexually reproducing organisms.

Hox genes

Master control genes that direct the developmental pattern of the body from a single zygote.

Epigenetics

The study of gene control mechanisms that determine how genes are switched on or off without changing the underlying DNA sequence.

Genotype

The complete genetic composition of all alleles an organism carries on its chromosomes, inherited from its parents.

Phenotype

The physical appearance and observable characteristics of an organism, programmed by the genotype and influenced by external factors.

Complete dominance

An inheritance pattern where the dominant allele completely masks the recessive allele in a heterozygous state, producing the dominant phenotype.

Mendel's law of segregation

A genetic principle stating that during meiosis, allele pairs separate so that each gamete carries only a single allele for each trait.

Mendel's law of independent assortment

A genetic principle stating that alleles of different genes segregate randomly and independently of one another during gamete formation.

Test cross

A breeding cross between an individual showing a dominant phenotype and a homozygous recessive individual to determine if the dominant individual is homozygous or heterozygous.

Autosomes

Non-sex chromosomes that share similar shape and size within homologous pairs, comprising $22$ pairs in humans.

Gonosomes

The sex chromosomes (X and Y in humans) that differ in shape and determine the biological sex of an organism.

Sex-linked alleles

Alleles located specifically on the non-homologous portion of the sex chromosomes (primarily the X chromosome).

Haemophilia

A rare, sex-linked recessive disorder carried on the X chromosome that impairs normal blood clotting, leading to excessive bleeding.

Polygenic inheritance

A pattern of inheritance where more than one pair of alleles controls a single trait, producing a continuous range of phenotypes.

Continuous variation

A range of slight graduations of a phenotypic characteristic forming a graduated series, typically controlled by polygenic inheritance.

Single Nucleotide Polymorphism (SNP)

A point variation in a DNA sequence where one nucleotide is substituted for another, occurring frequently in non-coding DNA across populations.

Genome

The complete set of genetic instructions (genes) required to create and maintain an organism.

Albinism

An autosomal recessive genetic condition characterized by a partial or complete lack of the pigment melanin in the skin, hair, and iris.