Biology — Genetics

Gregor Mendel established the fundamental laws of inheritance through his studies on pea plants.

RNA contains Uracil, while DNA contains Thymine instead.

Replication is the biological process of producing two identical replicas of DNA from one original DNA molecule.

Humans have 23 pairs of chromosomes, consisting of 22 pairs of autosomes and one pair of sex chromosomes.

Messenger RNA (mRNA) carries the genetic blueprint from DNA to the ribosome to guide protein assembly.

The backbone of DNA consists of alternating deoxyribose sugar and phosphate groups.

Down syndrome, also known as Trisomy 21, is caused by the presence of all or part of a third copy of chromosome 21.

The Central Dogma describes the flow of genetic information from DNA to RNA to protein.

James Watson and Francis Crick proposed the double-helix structure of DNA in 1953.

A mutation is an alteration in the nucleotide sequence of the genome of an organism.

The Law of Segregation states that the two alleles for a trait separate during gamete formation.

Homozygous individuals have two identical alleles for a trait, whereas heterozygous individuals have different alleles.

Color blindness is an X-linked recessive disorder, making it more common in males.

PCR is a laboratory technique used to make multiple copies of a specific DNA segment.

The phenotype (observable traits) is a result of the interaction between the genetic makeup (genotype) and the environment.

A gene is the basic physical and functional unit of heredity.

According to Chargaff's rules, Adenine pairs with Thymine, and Guanine pairs with Cytosine.

The Punnett square is a tabular summary of every possible combination of one maternal allele with one paternal allele.

Turner syndrome occurs when one of the X chromosomes is missing or partially missing in females (45, X).

Helicase enzymes 'unzip' the double-stranded DNA by breaking the hydrogen bonds between base pairs.

The centromere is the specialized DNA sequence of a chromosome that links a pair of sister chromatids together.

Phenotype refers to the observable physical or biochemical characteristics of an organism, determined by both genetic makeup and environmental influences.

William Bateson first used the term 'genetics' in a letter to Adam Sedgwick, and later used it publicly at a conference in 1906.

tRNA acts as an adapter molecule that brings specific amino acids to the ribosome, matching them to the mRNA codon sequence.

A heterozygous organism has two different alleles at a particular gene locus.

Thymine is found exclusively in DNA, while Uracil replaces it in RNA molecules.

Epistasis is a genetic interaction where one gene masks or interferes with the phenotypic expression of another gene.

Mendel's Law of Independent Assortment states that different pairs of alleles segregate independently during gamete formation, observed in dihybrid crosses.

DNA Helicase breaks the hydrogen bonds between the nitrogenous bases, separating the two strands of the DNA helix.

A normal human somatic cell contains 46 chromosomes, arranged in 23 pairs (22 pairs of autosomes and 1 pair of sex chromosomes).

Klinefelter syndrome is a condition in males who have an extra X chromosome, leading to hypogonadism and reduced fertility.

DNA Ligase acts as molecular 'glue' by forming phosphodiester bonds between DNA segments, commonly used in joining Okazaki fragments.

Polygenic traits are controlled by two or more genes, leading to a continuous variation; skin color and height are classic examples.

A gene is the basic physical and functional unit of heredity, consisting of a sequence of DNA that encodes for the synthesis of a protein or RNA molecule.

According to the Law of Dominance, the dominant allele masks the expression of the recessive allele in the F1 generation.

Deoxyribonucleic acid (DNA) is the primary molecule that stores and transmits genetic information in most living organisms.

PCR is a laboratory technique used to amplify a single or a few copies of a piece of DNA across several orders of magnitude.

Incomplete dominance happens when one allele does not completely mask the other, resulting in a 'blending' (e.g., pink flowers from red and white parents).

A codon is a sequence of three nucleotides on mRNA that corresponds to a specific amino acid during protein synthesis.

Mitochondria (and chloroplasts in plants) contain their own unique DNA, often referred to as extranuclear or cytoplasmic DNA.

A locus is the fixed position on a chromosome where a particular gene or genetic marker is located.

The Law of Independent Assortment is observed during a dihybrid cross, where two pairs of traits are tracked simultaneously.

mRNA carries the genetic 'blueprint' from the DNA in the nucleus to the ribosomes, where it serves as a template for assembling amino acids.

Non-disjunction is the failure of chromosomes to separate properly during cell division, often leading to aneuploidy (e.g., Down syndrome).

In RNA, Uracil pairs with Adenine. In DNA, Uracil is replaced by Thymine.

Pleiotropy occurs when one gene affects two or more distinct phenotypic traits.

DNA Ligase acts as a molecular glue by sealing the nicks or gaps between DNA fragments during replication or repair.

Reverse transcription is a process observed in certain viruses (retroviruses) where RNA is used as a template to synthesize DNA.

Polygenic inheritance involves multiple genes working together to produce a single trait, resulting in a continuous range of phenotypes like skin color.

Crossing over, or the exchange of genetic material between homologous chromosomes, occurs during Prophase I of meiosis.