lab 1: mendelian genetics Flashcards
gene
-a hereditary factor that influences a particular trait
-portions of DNA that have the ability to code for a trait
allele
a version of a gene
locus
specific position on a chromosome where a particular gene is located
gametes
sex cells (sperm & egg)
genotype
a listing of the alleles in an individual (RR) (Rr) (rr)
phenotype
an individual’s observable traits
homozygous
having 2 of the same alleles (RR) (rr)
heterozygous
having 2 different alleles (Rr)
dominant allele
-an allele that is fully expressed in the phenotype of a heterozygote
-will always mask recessive alleles
recessive allele
-an allele that is masked when a dominant allele is present
-only expressed in homozygotes
pure line
individuals of the same phenotype that, when crossed, always produce offspring with the same phenotype
hybrid
offspring of crosses between parents with different traits
polygenetic traits
many genes coding for one trait
particulate theory of inheritance
-genes that govern traits are inherited as discrete units that remain unchanged as they are passed from parent to offspring
-asserted that genes are located on chromosomes
law of segregation (Mendel’s first law)
-the 2 alleles of a given gene segregates into separate gametes
-each gamete has an equal chance of possessing either member of a pair of homologous chromosomes
-when joined in fertilization they combine to produce a phenotype based on the rules of dominance
-gametes combine randomly
law of independent assortment (Mendel’s second law)
-genes on non-homologous or different chromosomes will be distributed randomly into gametes
-increases genetic variation
what is the difference between Mendel’s 1st & 2nd law?
the key difference is that the 1st law describes the segregation of the alleles of a given locus into separate gametes during gametogenesis while the 2nd law describes the independent transmission of alleles of genes into daughter cells without the influence of each other
what was Mendel’s experimental method?
-he removed the anther (male part) then dusted the stigma (female part) with pollen from the white plant
-the resulting seeds were planted & grew
what is the p generation?
original parent generation (true breeding parents)
what is the F1 generation?
generation after parents (all were purple heterozygotes in Mendel’s experiments)
what is the F2 generation?
generation after F1 (Mendel let them self fertilize & they had a 3:1 ratio)
what is the phenotypic ratio for a monohybrid cross?
3:1
what is the phenotypic ratio for a dihybrid cross?
9:3:3:1
simple dominance
-the dominant one masks recessive when present
-the recessive one only can be expressed when both copies present are recessive
incomplete dominance
-a pattern of inheritance in which 2 alleles, inherited from the parents, are neither dominant nor recessive
-the resulting offspring have a phenotype that is a blending of the parental traits
-ex: if a red & white flower are breed together then it creates a pink one
codominance
-a condition in which both alleles for a gene are fully expressed
-ex: if a pink & white flower was breed together, then the new flower is pink & white
codominance example in blood types
type AB is a popular example since both A & B are dominant while type O is recessive
what is the genotype of blood types?
-type A (I^A I^A) or (I^A i)
-type B (I^B I^B) or (I^B i)
-type AB (I^A I^B)
-type O (ii)
what determines your blood type?
-the proteins called antigens are on the surface of all the red blood cells (if you have type A you have A antigens, type B has B antigens, type AB has both A & B antigens, & type O wouldn’t have any antigens)
what antibodies would the blood types have?
-the antibody against the antigen it doesn’t carry
-type A: b antibodies
-type B: a antibodies
-type AB: none
-type O: a & B antibodies
which blood type is the universal donor? a universal acceptor?
-type O = universal donor
-type O can only receive type O
-type AB is the universal acceptor
how can we determine which blood type it is?
-to determine a person’s blood type, we add serums to blood samples & see if clumps form
-agglutination (clumping) occurs when blood cells stick & clumps together, when donor blood cells are incompatible with recipient serum
how to understand which blood type it is based on the serum?
-will react positively if their type is in the serum = no clumps
-will react negatively if their type is not in the serum = clumps
how do we know if a blood type is positive or negative?
-if you have positive, then you have the protein Rh on the surface of the blood cells
-if you have negative, then you do not have the Rh protein
pedigrees (won’t be tested on but cool to know ig)
-a consistent graphical presentation of matings & offspring over multiple generations for a particular trait
-family histories
-disease trait: dominant or recessive?
-symbols: male = square, female = circle, affected = full, carriers = half filled in
