IB Biology Sub-topic D2.1 Definitions

This page contains our IB Biology definitions for sub-topic D2.1. By learning each one of these definitions, you will fully cover the content for IB Biology 'Cell division'.
carcinogen

Cancer-causing mutagens

chiasma

The location of crossing over that is completely random

crossing over

The exchange of DNA sequences of non-sister chromatids of homologous chromosomes

cytokinesis

Post-mitosis, a contractile ring of protein contracts to pull the plasma membrane inward, splitting the cell into two genetically identical daugther cells

diploid

A cell that contains both chromosomes in a homologous pair

haploid

A cell that contains one chromosome of the homologous pair

homologous chromosomes

Paired chromosomes with the same gene sequence but potentially different alleles

interphase

The cell's active period wherein it grows, lives, and prepares for mitosis

meiosis

The process by which one diploid nucleus divides to form four haploid nuclei

metastasis

A process where primary tumor cells detach and travel to another body site via the bloodstream

mitosis

The division of the nucleus into two genetically identical daughter nuclei

mitotic index

The ratio of the number of cells undergoing mitosis to the total number of visible cells

mutagen

A substance capable of causing a mutation

mutation

A random change to the base sequence of a gene

non-disjunction

The improper detachment of chromosomes during anaphase I or II

random orientation

The random lining up of homologous pairs at the equator during metaphase I

synapsis

The tight pairing up of homologous chromosomes

trisomy

An individual that has three homologous chromosomes instead of a pair

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