Genetics 3.1 Genes 3.2 Chromosomes

Genes vs Chromosome In your notes, list what you know about Genes and Chromosomes GENESCHROMOSOMES

Genes vs Chromosome Check your answers GENESCHROMOSOMES Heritable factor Consists of a length of DNA Influences a specific characteristic Occupies a specific location on a choromosome Various different forms of a gene (called alleles) Alleles differ by only 1 or a few bases Prokaryotes have one circular chromosome Some prokaryotes have plasmids Eukaryotes have linear DNA Eukaryotic DNA is associated with histone proteins In eukaryotes, different chromosomes carry different genes The number of chromosomes is a characteristic of members of a species

Homologous Chromosomes Homologous chromosomes carry the same sequence of genes but not necessarily the same alleles

Autosomes and Sex Chromosomes Autosomes are chromosomes that do not determine the sex of an individual. The sex of an individual is determined by the sex chromosomes:  Females have 2 X-chromosomes  Males have 1 X and 1 Y

Diploid vs Haploid Diploid nuclei have pairs of homologous chromosomes. Haploid nuclei have one chromosome of each pair.

Karyograms A karyogram shows the chromosomes of an organism in homologous pairs of decreasing length

Karyograms Karyograms can be used to determine the sex of an individual as well as the presence of a number of syndromes and chromosome abnormalities ▫Down syndrome:  Trisomy 21 ▫Edwards syndrome:  Trisomy 18 ▫Patau syndrome:  Trisomy 13 ▫Klinefelter syndrome:  XXY ▫Turner syndrome:  XO

Karyotype vs Karyogram Karyotype is the number and type of chromosomes present in the nucleus Karyogram is a photograph or diagram of the karyotype.

Karyograms Complete the Karyogram practical activity