Chapter 9 Glossary terms Flashcards
Gonads
Organs that produce gametes
Ovaries
Organ in females that produce eggs, ova
Testes
Organ in males that produces sperm
Gametes
Egg, sperm - haploid cells which fuse during fertilisation in organisms that reproduce sexually
Zygote
first diploid cell formed after the fusion of two gametes
Fertilisation
Fusion of a male and female gamete
Germline cells
Specialised diploid cells found in the gonads that can undergo meiosis
Somatic cells
Diploid body cells. All body cells except gametes
Diploid cells
Cells with two sets of chromosomes (2n), one set derived from each parent. In humans the diploid number is 46
Haploid cells
Cells with one set of chromosomes (n). These cells are produced by meiosis. In humans the haploid number is 23
Gene
A section of DNA that codes for a protein, basic unit of heredity.
Allele
Alternative form of a gene
Genome
Al of the genes in a cell. Not all genes are switched on in any cell, but all genes are present. Every cell has the same genome.
Chromosome
Threadlike structures made up of DNA and protein. Only visible during cell division.
Chromatin
Chromosomes when not in mitosis or meiosis. Chromatin are made up of DNA and protein
Autosome
Any chromosome other than sex chromosomes. Humans have 44 autosomes
Sex chromosomes
Chromosomes that determine gender. In humans there are 2 sex chromosomes. Female: XX Male: XY
Homologous pairs of chromosomes
Chromosomes that are matched, one set derived from the mother and the other from the father. Important for successful meiosis producing viable gametes. Each pair carry genes controlling the same trait.
Chromatid
A copy of a duplicated chromosome, joined to the other copy by the centromere. Required for cell division and is produced in the S phase of the cell cycle.