Genetic Structure Part 1.1 Flashcards
Explain genotype, phenotype and environmental influences
Genotype: DNA patterns, genes
Environmental influences: Changes made after birth
Phenotype: The physical attributes that are observed.
Describe genetic structures
-> In every cell, there is a nucleus (except for red blood cells) -> in every nucleus, there are 23 pairs of chromosomes (each from a parent) -> each chromosome contains DNA, and each segment of the DNA is called the gene.
-> The mitochondria also contains DNA, but only from the mother.
Characteristics of chromosomes in a cell and the structure of the chromosomes
-> There are 46 chromosomes (23 pairs) in a nucleus, apart from gametes (sex cell; only contains 23 chromosomes; male = sperm; female = ova)
-> Location of the genes with the same function is the same across the human species.
-> Three parts of the chromosome: short arm (p), centromere and long arm (q)
-> Chromosomes are made up of chromatin (a string). The chromatin is made up of proteins (histones and non-histones) and nucleic acids (DNA and RNA)
Explain Karyotype and characteristics
-> Karyotype is the genetic arrangement/content in a cell.
-> 1-22: Arranged in their sizes (1 as the largest pair)
-> 23: Sex chromosome: XX = female; XY = male
-> The Y chromosome is smaller than the X chromosome, which means it contains fewer information and some content is repetitive and inactive.
-> One of the advantages of having an extra X chromosome: some disease (e.g., fragile X chromosome) is related to the abnormalities of the X chromosome. With an extra X chromosome, it makes up the lacking proteins, which eases/lower the possibility of having the disease.
-> With female having an extra X, most of the time one of the X chromosome is inactive
Diseases related to abnormal karyotypes
Downs Syndrome: 47, XX/Y, 21
Klinefelter Syndrome: 47, XXY (only for men with an extra X chromosome)
XYY Syndrome: 47, XYY
Turner Syndrome: 45, X (only for females that have a lacking X chromosome in the sex chromosome)
