This definitions covers Key Definitions within Sex Determination for GCSE Biology. Sex chromosomes and sex determination mechanisms It is section 5 of 11 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 5 of 11
Practice
26 questions
Recall
20 flashcards
Key Definitions
Sex chromosome: One of the 23rd pair of human chromosomes that determines the biological sex of an individual. Females have two X chromosomes (XX); males have one X and one Y chromosome (XY).
Autosome: Any chromosome that is not a sex chromosome. Humans have 22 pairs of autosomes (44 chromosomes), which carry genes for non-sex-related characteristics.
X chromosome: A sex chromosome present in both males and females. Females have two X chromosomes; males have one. The X chromosome is much larger than the Y chromosome and carries many genes unrelated to sex determination.
Y chromosome: A sex chromosome present only in males. It is much smaller than the X chromosome and carries fewer genes, including the SRY gene that triggers male sex development.
Sex-linked disorder: A genetic condition caused by an allele on a sex chromosome (usually the X chromosome). Because males have only one X chromosome, they are more likely to be affected by X-linked recessive conditions than females, who have two X chromosomes.
Carrier (sex-linked): A female who is heterozygous for an X-linked recessive allele (X^A X^a). She does not show the condition because her second X chromosome carries the dominant allele, but she can pass the recessive allele to her children.