Chapter 1: Mendel's Principles Of Heredity Flashcards
Genes
The basic units of biological information
A specific segment of DNA in a discrete region of a chromosome that serves as a unit of function by encoding a particular RNA or protein
Heredity
The way genes transmits traits from parents to offspring
Parental transmission of physiological, anatomical, and behavioral traits
Inherited genes determine individual traits
Genome
All the genes you possess
The sum total of genetic information in a particular cell or organism
Genetics
The science of heredity
The study of biological structures and mechanisms that determine inheritance
Self - fertilization
Fertilization in which both egg and sperm come from the same plant or animal
Cross- fertilization
Carry out a fertilization where the sperm and the egg come from two different organisms
Discrete trait
An inherited trait that exhibits an either/or status
Continuous trait
Inherited Trait that is controlled by many different genes, and sometimes environment factors
Pure-breed
True- breed
Organisms that produce offspring with parental traits that remain constant from generation to generation
Homozygote
Inbred
Individuals or a population of organisms produced by matings of close genetic relatives
Hybrid
Offspring with genetically dissimilar parents
Heterozygotes
Reciprocal Crosses
The characters of traits in the males and females reversed relative to the other, thereby controlling whether a particular character is transmitted by the male or female gamete
Alternate male and female parents
Parental generation
P1
Pure-breeding
Individuals whose offspring in subsequent generations will be studied for specific traits
Homozygote
First Filial generation
F1
Offspring of the P1 generation in a controlled series of crosses
First offspring
Heterozygotes
Expresses dominant phenotype
Monohybrid Cross
Crosses between parents that differ in only one trait
Second Filial Generation
F2
Offspring resulting from self- crosses or intercrosses between individuals of the F1 generation in a series of controlled matings
Second generation
Recessive form reappears at a 3:1 ratio
Dominant
The trait that appears in the F1 hybrids (heterozygotes) resulting from a mating between pure-breeding parental strains showing antagonistic phenotypes
Recessive
The trait that remains hidden in the F1 hybrids resulting from a mating between pure-breeding parental strains showing antagonistic phenotypes
Usually reappears in F2
Alleles
Alternative forms of a single gene
Monkhybrids
Individuals having two different alleles of a single gene
Gamete
Specialized cells (egg and sperm) that carry genes between generations
The Law of segregation
The two alleles of each gene separate during gamete formation, and then unite at random, one from each parent, at fertilization
The Punnett Square
Visualization of segregation and random union of alleles
Pisum Sativum
Garden pea plant
self- fertilizing producingabundant offspring
Mendel’s model
He created 7 pairs (14) true-breeding lines
Antagonistic Traits Examined
Pea color
Pea shape
Pod color
Pod shape
Flower color
Stem length
Flower position
Mendel’s Patterns
Pattern 1: If 2 true-breeders are observed, the offspring will look like one parent and not the other
Pattern 2: In monohybrid crosses one gene is dominant over the other; F1 will be all dominant and in F2 the Recessive shows up at a 3:1 ratio
Genotype
An individual’s set of alleles
Phenotype
Appearance
Manifestation of a trait
Product rule
The probability of two or more independent events occuring together is the product of the probabilities that each event will occur by itself
Probability of event 1 AND event 2 = probability of event 1 x probability of event 2
Independent events
Sum rule
The probability of either of two mutually exclusive events occuring is the sum of their individual probabilities
Mutually exclusive
Probability Of event 1 OR event 2 = Probability of event 1 + probability of event 2
Homozygous
Describes a genotype in which the two copies of the gene that determine a particular trait are the same allele
Heterozygous
Describes a genotype in which the two copies of a gene are different alleles
Homozygotes
An individual with identical alleles for a given gene or locus
Heterozygotes
An individual with two different alleles for a given gene or locus
Testcross
Across used to determine the genotype of an individual showing a dominant phenotype by mating with an individual showing the recessive Phenotype
A cross used to determine whether genes are linked and the distance between linked genes
Dihybrid
An individual that is heterozygous at I-wo different genes
Parental Type
Phenotypes that reflect a previously existing parental combination of alleles that is retained during gamete formation
Recombinant Types
Phenotypes reflecting a new combination of alleles that occured during gamete formation
Independent Assortment
The random distribution of alleles of different genes during gamete formation
The Law of Independent Assortment
During gamete formation, different pairs of alleles segregate independently of each other
Branched- Line Diagram
A System for I isting The expected results of multihybrid crosses
Thalassemia
Reduce amounts of hemoglobin; anemia, bone and spleen enlargement
Caused by a recessive allele
Sickle-cell Anemia
Abnormal hemoglobin; sickle- shaped red cells, anemia, blocked Circulation; increased resistance to malaria
Caused by recessive allele
Cystic fibrosis
Defective cell membrane protein; excessive mucus production; digestive and respiratory failure
Caused by a recessive allele
Cl- transport deficiency; 12 million American Carrier (10% survive into their 30s)
Horizontal inheritance
Unaffected Carriers can have affected offspring
Consanguineous matings concentrate recessive alleles
Tay- Sachs disease
Missing enzyme; buildup of fatty deposit in brain; buildup disrupts mental development
Caused by a recessive allele
Phenylketonuria
Missing enzyme; mental deficiency
Caused by a recessive allele
Hypercholesterolemia
Missing protein that removes cholesterol from the blood; heart attack by age 50
Caused by a dominant allele
Huntington Disease
Progressive mental and neurological damage; neurologic disorders by ages 40-70
Caused by a dominant allele
Late onset dominant trait; involuntary, uncoordinated movement, personality change, gradual intellectual decline, death
Vertical inheritance- affected individual has an affected parent
Pedigree
Orderly diagram Of a family’s relevant genetic features; often features2-3 generations
Probability can be used to determine mode of inheritance
Bombay Phenotype
there is not H on the RBC, which is a sugar polymer
Their genotype is homozygous recessive (hh) for the second gene and don’t make the H gene at all
They appear to have type O blood because there’s no way to add anything to it
Homozygosityfor the recessive h allele if the H - substance gene masks the effects of the ABO gene, making it epistatic
Recessive Epistasis
Gene at one locus masks the expression of a gene at a second locus, so its phenotype isn’t exposed
I.e. LabradorRetrievers
Labrader Retrievers - recessive epistasis
B_E_-Black
bbE_-Brown
_ ee - yellow
If it in herits the homozygous recessive genotype ofthe E gene, it will be yellow regardless of if it’s dominant or recessive
The recessive genotype at ee masks the phenotypic expression of the B gene
9/16 A_B
3/16 A_BB
3/16 aaB_
1/16 aabb
B allele determines pigment
E allele determines eumelinen production (Brown)
ee allele produces phomelanin (yellow)
Reciprocal recessive epistasis
The dominant alleles of two genes together (A_B_) produce color or some other trait, while the other three genotype classes (A_bb, aaB_, and aabb) don’t
9:7 ratio
i.e. Sweet peas
Dominant Epistasis
Epistasis can also be caused by a dominant allele
The presence of B hides the effects of either A_ or aa
Epistasis in which the dominant allele of one gene hides the effects of another gene
12:3:1 ratio
