Genetic Variation Flashcards
Stages of meiosis 1
interphase, prophase 1, metapahse 1, and anashase 1
what happens in interphase
chromosomes duplicate
what happens in prophase 1
Homologous chromosomes pair and exchange segments
what happens in metaphase 1
tetrads line up
what happens in anaphase 1
pairs of homologous chromosomes split up
what is the Independent assortment of chromosomes
-The orientation of the chromosomes is random like a flip of coin: Heads or Tail
-Each gamete has 50:50 chance of having paternal or
maternal chromosomes or of having both
-Each gamete represents one of many possible
combination of maternal and paternal chromosomes
What is the number of possible combinations for the gametes
2^n= where n is the number of chromosomes in the genome
What is the independent assortment of chromosomes for humans
A human gamete contains 1 or 8 million possible assortments of the chromosomes inherited from the mother and father
What is random fertilization
the random chance of any one sperm and egg coming together is a product of these two probabilities
Egg->1/8million x 1/8 million
What are contributors to genetic variation
Each gamete has a unique genetic identity therefore the zygote will have a unique genetic identity therefore each human being is genetically unique (exemption- identical twins)
What are human Karyotypes
contain 22 pairs of autosomal chromosomes and one pair of sex chromosomes
The display of the chromosome paid off a cell arranged by size, shape and staining patterns
What is the methodology to obtain a karyotype
Obtain sample from the individual being studied
- culture the cells in synchrony and when they are dividing vigorously, stop the cell division in metaphase by treatment with colchicine
- chromosomes are stained with special staining
- chromosomes are then examined with the microscope for their length, size shape and position of the centromere and pattern of staining
How do scientists identify the sec of a baby or abnormalities that indicate genetic diseases or tumor cells
Using combination of dyes, shapes and number
what is the condition Polyploidy
A chromosomal alteration in which the organism has more than two complete sets of chromosomes
What’s an aneuploidy
A chromosomal alteration in which certain chromosomes are present in extra copies or are deficient in number
What is Down syndrome
An aneuploid condition that results from three copies of chromosome 21
- trisomy 21
How do aberrations form
Non- disjunction
What is non - disjunction
An error in meiosis 1 in which members of a pair of homologous chromosomes fail to separate properly from each other or an error in meiosis 2 in which a pair of sister chromatids fail to separate properly from each other
2n-1
Mono sonic turners syndrome
Short sterile, do not develop secondary sex characteristics normal intellectually
Breakage if a chromosome can lead to how many types of changes in chromosome structure
Deletion- removed a chromosomal segment
Duplication- repeats a segment
Inversion- reverses a segment within a chromosome
Translocation- moves a segment from a non homologous chromosome to another
