Inheritance, Genes & Cell Division Flashcards

Vocabulary flashcards covering core definitions for chromosomes, genes, protein synthesis, cell division (mitosis and meiosis), monohybrid inheritance, codominance, and sex linkage based on IGCSE Biology notes.

Inheritance

The transmission of genetic information from generation to generation.

Chromosome

A thread-like structure of DNA located in the nucleus of cells, carrying genetic information in the form of genes.

Gene

A short length of DNA found on a chromosome that codes for a specific protein.

Alleles

Variations or different versions of the same gene.

Sex Chromosomes

The chromosome pair that determines the sex of an organism, present as XX in females and XY in males.

Transcription

The stage of protein synthesis in which the base code of a gene in DNA is rewritten onto a messenger RNA (mRNA) molecule.

Translation

The stage of protein synthesis where the ribosome reads mRNA base triplets and attaches amino acids together in a specific sequence to form a protein.

Messenger RNA (mRNA)

An RNA molecule onto which the base code of a gene is transcribed, carrying the code out of the nucleus to a ribosome.

Gene Expression

Whether a particular gene is transcribed and translated in a specific cell or not.

Diploid Nucleus

A nucleus containing two sets of chromosomes, giving a total of 46 chromosomes in human body cells.

Haploid Nucleus

A nucleus containing one set of unpaired chromosomes, giving a total of 23 chromosomes in human gametes.

Mitosis

Nuclear division giving rise to genetically identical cells.

Stem Cells

Unspecialised cells found in tissues that divide by mitosis to produce daughter cells that can differentiate and become specialised.

Meiosis

A reduction division in which the chromosome number is halved from diploid to haploid, resulting in genetically different gamete cells.

Phenotype

The observable characteristics of an organism.

Genotype

The combination of alleles that control each characteristic in an organism.

Dominant Allele

An allele that only needs to be inherited from one parent in order for the characteristic to show up in the phenotype.

Recessive Allele

An allele that needs to be inherited from both parents in order for the characteristic to show up in the phenotype.

Homozygous

Having two identical alleles of a particular gene.

Heterozygous

Having two different alleles of a particular gene.

Pure-Breeding

Organisms that are identically homozygous for a particular characteristic, producing offspring with the exact same genotype and phenotype when bred together.

Monohybrid Inheritance

The inheritance of characteristics controlled by a single gene.

Test Cross

A genetic cross between an individual showing a dominant phenotype and an individual with a homozygous recessive phenotype to determine the unknown genotype of the dominant parent.

Codominance

A condition in which both alleles in a heterozygous individual contribute to the phenotype.

Sex-Linked Characteristics

Characteristics controlled by alleles located on the sex chromosomes, almost always on the X chromosome.

Carrier

A female who has one recessive sex-linked allele masked by a dominant allele on her X chromosomes, showing no disease symptoms herself but possessing a 50% chance of passing the allele to offspring.

Cytokinesis

The process where the cell begins to divide after the chromatids have been separated during cell division.