The Cellular Basis of Reproduction and Inheritance Review Flashcards
Structure of the eukaryotic chromosome
DNA plus protein = chromatin
How many chromosomes do we have?
46
Sister Chromatids
replicated chromosomes still attached at the centromere
Homologous chromosomes
chromosomes that carry similar genetic information. This is found in diploid cells.
Karyotype
is a picture of the 23 homologous pairs of chromosomes in humans. You receive one from each parent.
Why do cells divide by mitosis?
- Growth
- Repair
- Replacement
What is the end result of mitosis?
2 identical daughter cells
What is meiosis?
*Meiosis is cell division that produces gametes (egg & sperm)
*Meiosis results in ½ the original # of chromosomes (haploid)
*Meiosis results in new genetic combinations
Meiosis results in 4 haploid daughter cells that are genetically different
*2 separate cell divisions meiosis 1 and 2
*Meiosis 1 results in haploid cells with duplicated chromosomes
How do new genetic variations arise?
- Crossing over
- Independent assortment - during Metaphase I, homologous chromosomes align randomly at the cells equator. This process and crossing over leads to the genetic variation of the gametes
Alleles
alternative forms of gene
Maybe dominant or recessive
Letters are used to indicate the alleles; R - dominant, r - recessive
For each inherited characteristics an organism has 2 alleles one from each parent
Gene
a controller of an inherited trait
Dominant allele
a gene that hides or dominates the effect of another gene
Recessive allele
a gene whose effect is hidden by a dominant gene
Phenotype
outward expression of the genes (appearance)
Genotype
actual gene pairs (alleles) of an individual
