W2: Genetics & Heredity Flashcards
Name and explain the types of mutations
- Silent muations - DNA change does not alter the amino acid sequence of polypeptide chain
- Nonsense - DNA change creates a premature STOP codon
- Missense - DNA change alters a single amino acid in the polypeptide chain
- Frameshift - Addition (insertion) or removal (deletion) of a base alters the reading frame of a gene; affects every codon beyond the point of mutation (domino effect)
Why is chromatin a dynamic structure?
Most of the time chromatin is diffuse, however it can condense to form chromosomes in preparation for cell division
What type of bonds form the sugar-phosphate backbone of DNA
phosphodiester bonds
stronger than hydrogen bonds
What bonds are between base pairs
Hydrogen bonds
* G-C uses 3 hydrogen bonds
* A-T uses 2 hydrogen bonds
Therefore, G-C stronger
If ‘T’ replaces ‘U’, do the codons encode for an amino acid?
No, only Uracil encodes for amino acids (Thymine = DNA)
Discontinuous variation - examples
Eye colour (blue vs brown)
Blood type
Continuous variation - examples
height, skin colour
* continuous range/sprectrum
How many number of possible chromosome arrangements do humans (haploid pairs = 23) have?
2^(23)
* Formula = 2^n, where n = no. haploid chromosomes
No. daughter cells in mitosis vs meiosis
- Mitosis - 2 diploid daughter cells, genetically identical to parent
- Meiosis - 4 haploid daughter cells, genetically different from parent and each other
When does crossing over occur? and where?
During prophase I
Occurs at the chiasma(ta)
What is pleiotropy?
one single gene affects 2+ phenotypes
What is epistasis?
When more than 1 allele is essential to a phenotype
* alleles influence eachother - one can’t do its job w/o the other
What is polygenic inheritance?
One phenotype is the result of 2+ genes having an ADDITIVE effect
