Card Set Information
Define haploid cell
Cell containing only 1 set of chromosomes
Define diploid cell
Cell containing two sets of chromosomes
ie somatic cells
Incorrect number of a specific chromosome in a cell. Can affect multiple chromosomes
ie Down syndrome
Define a monosomic cell
Cell resulting from a gamete without a specific chromosome. Resulting cell has only one of a specific chromosome
Define trisomic cell
Cell with 3 of a certain chromosome.
i.e Down syndrome
Where homologous chromosomes fail to separate during meiosis I OR
Sister chromatids fail to separate during meiosis II resulting in aneuploid gametes
What is Klinefelter syndrome? Symptoms?
Where somatic cells contain an extra X chromosome - XXY.
Males who are taller, feminine, sterile, may see breast development
What is Turner syndrome? Symptoms?
Where somatic cells contain only an X chromosome - XO.
Females who are shorter, sterile, may exhibit brown spots on skin
What is a Barr body? How does it arise?
Barr body is a region of hetero-chromatin close to the nuclear envelope found in females following X inactivation.
List n, number of cells and number of chromosomes at each step of meiosis.
Prophase I - 2n=46, duplicated, 1 diploid cell
Telophase I - n=23, duplicated, 2 haploid cells
Telophase II n=23, unduplicated, 4 haploid cells
Removal/loss of a chromosomal segment
Repeat of a chromosomal segment on a chromosome
Reversal of a chromosomal segment on a chromosome
Segment transferred from one chromosome to another.
Define reciprocal translocation.
Exchange of chromosomal segments between two chromosomes
Possession of multiple ENTIRE sets of of chromosomes.
i.e a tetraploid has 4 sets of chromosomes
Define incomplete dominance.
Where both alleles in a heterozygous sample are shown in phenotype AT REDUCED LEVELS
ie Snap dragon flower shows reduced red pigment in RW heterozygote
Where phenotypes of both alleles are seen in a heterozygous sample
Gene at one locus affects another.
i.e Labradors can have black or brown hair pigment - only if gene for hair pigment is present at another locus
Where there are multiple alleles for a gene.
i.e eye colour - blue, brown, green - however, each human only has two alleles.
Ability of a gene to have multiple effects
i.e sickle cell anemia
Describe how environmental factors can contribute to variation in ratios predicted by Mendelian genetics.
Environment can cause phenotypic variation in individuals with same genotype
i.e, hydrangea flowers with same genotype are different colours depending on soil pH