23 Study Guide-Genetics

Genetics

The study of how characteristics are transmitted from parents to offspring.

Gregor Mendel

Known as the father of genetics, he conducted extensive work with garden peas and discovered the principles of heredity.

Heredity

The passing on of traits from parents to offspring.

Probability

The likelihood of a particular outcome occurring, used by Mendel to interpret his results in genetics.

True-breeding strains

Plants that are pure or true breeding for a trait and always produce offspring with that trait.

P1 strain

The parental generation, consisting of pure-breeding strains used by Mendel in his experiments.

F1 generation

The first generation of offspring produced by crossing the P1 strains.

F2 generation

The second generation of offspring produced by allowing the F1 generation to breed.

Hybrid

Offspring produced by crossing two different pure-breeding parents, showing only the dominant trait.

Law of Segregation

Mendel's conclusion that paired factors separate during the formation of reproductive cells, resulting in each gamete receiving only one factor of each pair.

Principle of Dominance

The idea that in a hybrid, one factor may completely hide the presence of the partner factor.

Law of Independent Assortment

Mendel's observation that traits produced by dominant factors do not necessarily appear together, indicating that the factors for different characteristics are not connected.

Genotype

A description of the specific alleles carried by an organism with respect to the particular genes being considered.

Phenotype

The actual description of the characteristics observed in an organism.

Pure Breeding

A term referring to individuals that, when paired with an appropriate partner, always produce offspring with the same characteristics.

Hybrid

An individual produced by crossing two different pure-breeding parents.

Wild Type

The version of a trait that is overwhelmingly most common in nature.

Homozygous

An individual whose two alleles for a specific trait are identical.

Heterozygous

An individual who has two different alleles for a specific trait.

Homogametic Gender

The gender with two identical sex chromosomes.

Heterogametic Gender

The gender with two different sex chromosomes.

Dominance

The relationship between two alleles where the phenotype of the heterozygote is indistinguishable from the phenotype of one of the homozygotes.

Complete Dominance

A type of dominance where the phenotype of the heterozygote is indistinguishable from the phenotype of one of the homozygotes.

Recessive

The allele that is hidden in the heterozygote and is not expressed in the phenotype.

Incomplete Dominance

A type of dominance where the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes.

Co-dominance

A type of dominance where the heterozygote expresses both allelic traits simultaneously.

Pseudo Dominance

A situation where a particular combination of alleles produces a lethal effect, initially resembling complete dominance.

Locus

The location of a gene on the chromosomes of a species.

Pedigree

A charted family history used in genetics to determine the inheritance patterns of genetic factors.

Linked Genes

Genes that have their loci on the same chromosome and are inherited together unless separated by crossing over.

Chromosomes

Structures in the nucleus of a cell that contain genes and are made up of protein and DNA.

Nucleus

The part of a cell that contains the genetic material, including genes.

DNA

Deoxyribonucleic acid, a molecule that carries genetic information and is found in chromosomes.

Protein

A macromolecule made up of long chains of amino acids, used by biochemists as a candidate for carrying genetic information.

DNA

Deoxyribonucleic acid, a molecule made up of nucleotides that carries genetic information and determines the characteristics of living organisms.

Nucleotides

Smaller molecules that make up DNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Protein

A large biomolecule made up of amino acids that plays a crucial role in the structure and function of cells.

Chromosome

A thread-like structure made up of DNA that carries genetic information in the form of genes.

X-ray crystallography

A technique used to determine the three-dimensional structure of molecules by analyzing the pattern of X-ray diffraction.

Double-stranded helix

The structure of DNA, consisting of two strands that are twisted around each other in a spiral shape.

Rosalind Franklin

A scientist who made significant contributions to the discovery of the structure of DNA through her work on X-ray crystallography.

Maurice H

A scientist who worked with Rosalind Franklin and shared her X-ray photographs of DNA with James Watson, contributing to the discovery of its structure.

James Watson and Francis Crick

Scientists who, along with Maurice Wilkins, were awarded the Nobel Prize for their discovery of the structure of DNA as a double-stranded helix.

RNA

Ribonucleic acid, a molecule similar to DNA that plays a role in protein synthesis.

Base pairing

The specific pairing of nucleotides in DNA, where adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C).

Complementary base pairing

The strict pairing of nucleotides in DNA, where the bases on one strand pair with their complementary bases on the other strand.

Self-replication

The ability of DNA to make copies of itself by separating the two strands and assembling new partner strands based on complementary base pairing.

Transfer RNA

Small RNA molecules that act as adapters between the nucleotide language of DNA and RNA and the amino acid language of proteins.

Transcription

The process of creating messenger RNA (mRNA) from a segment of DNA, using complementary base pairing between ribonucleotides and one side of the DNA.

Translation

The process of converting the information coded in mRNA into a string of amino acids by ribosomes, according to the genetic code.

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