Genetics & Inheritance Flashcards
(21 cards)
what is DNA
deoxyribonucleic acid, double stranded helix, made of 4 bases
what is a chromosome
a long DNA molecule containing genes
What are the componenets of a nucleotide
phosphate group, deoxyribose sugar, nitrogen-containing base
what is a gene
a unit of heredity that codes for a protein or enzyme
what is an allele
alternate version of a gene
how many autosomes do humans have
22 pairs
what are sex chromosomes
the 23rd pair (XX female, XY male)
what does homozygous mean
two identical alleles for a gene
what does heterozygous mean
two different alleles for a gene
what is a genotype
the genetic makeup (e.g., BB or Bb)
what is a phenotype
the physical expression of the genotype
what is a dominant allele
expressed even if only one copy is present
what is a recessive allele
expressed only if two copies are present
example of autosomal dominant disease
Neurofibromatosis Type I
Example of autosomal recessive disease
Cystic Fibrosis
what is co-dominance
both alleles are expressed (e.g., AB blood type)
What is a sex linked disorder
disorder carried on the X chromosome (eg. red-green colour blindness)
what are the 2 types of cell division
mitosis and meiosis
when does DNA replication occur
during the S phase of interphase
purpose of mitosis
replace somatic (body) cells
purpose of meiosis
Form gametes (egg/sperm)
