Unit 3- Basic Principles of Heredity Flashcards
gene
an inherited factor (encoded in DNA) that determines characterstics
allele
1 of 2 or more alternate form of gene
locus
specific place on chromosome occupied by allele
genotype
set of alleles possessed by indiv
heterozygous
indiv with 2 diff alleles at locus
homozygous
indiv with same 2 alleles at locus
phenotype/trait
appearance of characteristic
characteristic/character
attribute or feature possessed by organism
monohybrid cross
cross between 2 parents that differ in a single characteristic
Mendel conclusions from monohybrid cross
- a character is encoded by 2 genetic factors
- 2 genetic factors (alleles) seperate when gametes are formed
- dom and recessive traits
- 2 alleles sep with equal probability into gametes
Principle of Segregation
each indiv diploid organism possesses 2 alleles for any trait. These 2 alleles separate when gametes form (1 in each gamete)
Sutton
chromosomal theory of heredity
probability
the likelihood of the occurrence of a particular event
Multiplication Rule
aka “AND” rule
Addition Rule
aka “OR” rule
dihybrid crosses
- examine 2 traits at a time
- principle of Independent Assortment
(foil out traits so RrYy = RY, Ry, rY, ry and multiply or do two seperate punnett squares and multiply.)
(*9:3:3:1)
Chi-square goodness of fit
the probability that the diff between the observed and expected value is due to chance
sum of (O-E)^2 / E
hermaphroditism
both sexes in same organism
monoecious
BOTH male and female reproductive structures in same organism
diaecious
EITHER male or female reproductive structures in 1 organism
XX-XO system
XX: female
XO: male
- ex: grasshoppers
XX-XY system
XX: female
XY: male
- ex: mammals
ZZ-ZW system
ZZ: male
ZX: female
- ex: birds, snakes, butterflies, some amphibian, and fish
Haplodiploidy System
haploid set: male
diploid set: female
- ex: bees, wasps, and ants
genic sex-determining system
no sex chromosomes, only the sex-determining genes
- ex: some plants, fungi, protozoans, and fish
examples of environmental sex determination
Limper’s position in the stack and temperature in turtles
sex determination in fruit fly
- genic balance system
- X:A ratio (x= # of x chromosomes; A= # of haploid sets of autosomes)
0-0.5: metamale
0.5: male
0.5-1: intersex
1: female
1-1.5: metamale
1.5: metafemale
what determines maleness?
SRY gene of y chromosome
- y chromosome lost DNA over time
Turner Syndrome
XO, 1/3000 females
Klinefelter syndrome
XXY or XXXY or XXXXY or XXYY; 1/1000 males
poly-x females
1/1000 females
dosage compensation
the amount of protein produced by x-linked genes and randomly inactivated in 2 sexes
barr body
the inactivated x chromosomes (any after the first one)
