Intro to human genetics Flashcards
Width of DNA?
2nm
Charge of phosphate group?
Negatively charged
How many H-bonds between Thymine and Adenine?
2
How many H-bonds between Guanine and Cytosine?
3
how does the sugar phosphate backbone bond?
5’ phosphate bonds to 3’ ribose Carbon
How many histones make up a nucleosome?
8
How wide is a nucleosome?
11nm
How many times does DNA wrap around histones?
1.65 times (210 base pairs)
How wide are nucleosomes once folded together into a fibre?
30nm
What are the length of the loops formed from nucleosome fibres?
300nm
What are the light areas of a nucleus called? What are some traits of this area?
Euchromatin.
DNA more accessible.
Where active genes are.
What are the dark areas of a nucleus called? What are some traits of this area?
Heterochromatin.
Less accessible DNA (More packaged).
Less gene transcription occurring.
What are karyotypes?
An individuals complete set of chromosomes.
How are karyotypes dyed to be visible?
G-banding.
Giesma is applied on a cell arrested in metaphase.
What is the purpose of G-banding?
Identify abnormalities.
Identify where chromosomal translocations occur.
What is a Mendelian trait?
A trait controlled by a single locus in an inheritance pattern
What is a gene?
Unit of inheritance transferred from parent to offspring.
Determines a characteristic of offspring.
What is the law of segregation?
During gamete formation.
Alleles from each gene segregate.
So gametes only carry one allele for each gene.
What is the law of independent assortment?
Genes from different traits can segregate independently during the formation of gametes.
What is the law of dominance?
Some alleles dominant, some recessive.
An organism with at least one dominant allele, will display the dominant phenotype.
What is meant by X-linked?
Gene only on X chromosome.
