Human Chromosomes

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Genome Noun

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[jee-nohm]

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Genome

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The complete set of genetic information, encoded in DNA, that an organism carries in its cells.

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Example: An individual's genome is their complete set of DNA, with half inherited from the father and half from the mother, determining their unique traits.

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Chromosome Noun

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[kroh-muh-sohm]

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Chromosome

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A thread-like structure of nucleic acids and protein found in the nucleus, carrying genetic information in genes.

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Example: This diagram shows a chromosome is a structure found inside a cell's nucleus, made of tightly coiled DNA, and has key parts like a centromere.

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Karyotype Noun

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[kar-ee-uh-tahyp]

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Karyotype

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A visual profile of an individual's chromosomes, arranged in homologous pairs and ordered by decreasing size.

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Example: A karyotype is an organized picture of all the chromosomes from one cell, arranged in pairs from largest to smallest, with the sex chromosomes (XX or XY) at the end.

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Diploid Adjective

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[dip-loid]

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Diploid

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Describes a cell or organism containing two complete sets of chromosomes, one inherited from each parent.

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Example: This diagram shows that diploid (2n) cells have two copies of each chromosome, shown as pairs, unlike haploid (n) cells which have one.

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Haploid Adjective

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[hap-loid]

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Haploid

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Describes a cell or organism having a single set of unpaired chromosomes, which is typical of gametes.

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Example: This image compares diploid cells, with two copies of each chromosome, to haploid cells, which have only one copy of each chromosome.

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Sex Chromosome Noun

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[seks kroh-muh-sohm]

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Sex Chromosome

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A type of chromosome involved in determining the sex of an organism, such as the X and Y chromosomes.

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Example: This image shows that humans have two types of sex chromosomes, X and Y. A female has two X chromosomes (XX), and a male has one X and one Y chromosome (XY).

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Autosome Noun

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[aw-tuh-sohm]

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Autosome

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Any chromosome that is not a sex chromosome and appears in pairs within somatic cells.

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Example: This diagram shows a human karyotype, visually separating the 22 pairs of autosomes (numbered 1-22) from the sex chromosomes (X and Y).

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Allele Noun

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[uh-leel]

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Allele

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One of two or more alternative forms of a gene that are found at the same place on a chromosome.

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Example: This diagram shows that alleles are versions of a gene located at the same position (locus) on a pair of homologous chromosomes.

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Dominant Allele Noun

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[dom-uh-nuhnt uh-leel]

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Dominant Allele

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An allele that expresses its phenotypic effect even when heterozygous with a recessive allele.

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Example: This diagram shows that when a dominant allele (A) is present on one chromosome, it is expressed, masking the effect of the recessive allele (a).

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Recessive Allele Noun

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[ri-ses-iv uh-leel]

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Recessive Allele

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An allele whose phenotypic effect is masked in a heterozygote by the presence of a dominant allele.

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Example: This diagram shows a recessive allele (labeled 'b' in yellow) on a chromosome, contrasting it with a dominant allele ('B') in different genetic pairs.