Lecture 5: Mendel and Basic Genetics Flashcards
blending inheritance
-gametes contained genes that blended when the gamet fused
why did Mendel work with peas?
- small, easy to grow, very short generation time
- therefore easy to get a lot of data on them very quickly
true breeding
- a plant that when they reproduce, all the offspring look like the parents
- he focused on flower color trait
monohybrid cross
-causes btwn 2 individuals that only differ in terms of a single trait
trait
- a specific form of a character
- ex: eye color is a character, brown eyes are a trait)
hybrid
-the offspring of crosses btwn organisms differing in one or more characters
p generation
- parental generation
- the first two individuals that mate in a genetic cross
F1 generation
-the first generation of offspring obtained from an experimental cross of two organisms
F2 generation
-offspring of the F1 generation
cross fertilization
- aka pollination
- process by which sperm from one flower’s pollen fertilizes the eggs in a flower’s pollen fertilzes the eggs in a flower of a different plant
self crossing
-pollen with fertilize an egg from the same plant
latent trait
-present but unseen traits (like carriers)
gene
-the unit of genetiv function which carries the information which carries the information for a polypeptife of RNA
allele
-the alternate form of a genetic character found at locus of a chromosome
homozygous
-an organism that has two alleles that are the same
heterozygous
-an organism that has two different alleles
phenotype
-the physical appearance of an organism resulting from both genetic and environmental factors
genotype
-the genetic constitution og an individual, either with respect to a single trait or with respect to a larger set of traits
law of segregation
- two alleles segregate during gamete formation to be rejoined at random during formation
- allows for the expression of latent traits in heterozygous parents
what is the phenotype and genotype ratios in a one gene punnett square?
- phenotype: 3:1
- genotype: 1:2:1
what is the phenotype ratio in a dihybrid cross?
- 9:3:3:1
- in F2 generations
the principle of independent assortment
-in a dihybrid cross the alleles of each gene assort independently
do genes always assort independently?
- no, they’re sometimes linked
- sometimes certain traits that belong to a given alleles almost always appear together
what does it mean to “cross” something?
-to breed
the meaning of the five element model: what conclusions does Mendel draw from each of his elements?
- parents give information to offspring
- each offspring gets 2 copies of each factor
- not all factors are the same and different combinations lead to different traits
- alleles don’t blend
- presence of a factor doesn’t guarantee it’ll be expressed
dihybrid crosses
-double heterozygous trait
two state cases vs. multi-state cases
- two state: cases of either/or
- multi-state: more than one thing affects genes; addictively affect inheritance (ex: some alleles add height, some don’t)
polygenic inheritance
-the heredity of complex characters that are determined by a large number of genes, each one usually having a realitvely small effect
epistasis
- an allele of one gene modifies or prevents the expression of alleles at another gene
- ->ex: one locus determines the color of the flower, however, the other locus determines the color of the flower
how is epistasis different from polygenic inheritance?
- epistasis is when an allele of one gene modifies or prevents the expression of alleles at another gene
- polygenic inheritance is when multiple genes affect a phenotype
given a genotype, would you know what color a labrador was?
- yes if given what alleles were dominant and recessive
- ee = yellow lab
- E_bb = brown lab
- E_B_ = black lab
pleiotropy
- aka multiple effect
- 1 gene = many traits/trait outcomes
why is sickle cell still around?
- sickle cell anemia > malaria > immune
- malaria = immune
incomplete domniance
-the heterozygous phenotype is intermediate btwn the two homozygous phenotypes; neither of the 2 alleles is dominant
codominance
-a condition in which two alleles at a locus produce different phenotypic effects and both effects appear in heterozygotes
how does incomplete dominance differ from codominance? could you tell them apart?
- in incomplete dominance, the phenotype resembles a sort of bleding of the two alleles (red and white pedals blended make pink petals)
- codominance is when both alleles are expressed separately(red and white pedals blended make a flower with white and red splotches)
environmental effects on gene expression
- huge impact on genes
- darker fur on extremeties and head due to the less blood flow/lower temperature, but white fur close to body
how are blood types determined?
-based on what parent’s blood types are and what results of codominance
the importance of quantification of results
-mathematical to see traits would show in ratios
gregor mendel and his work
- focused on how traits were passed down
- wanted all offspring to look alike
- crossed 1 true bred & created a hybrid, then crossed hybrids
gamete
- sex cells that contain sets of chromosomes
- 2 come together to form new life
