MIDTERMS: Mendel’s Law Flashcards
Born in_____ (now Czech Republic) in 1822
Brunn, Austria
Studied_____ and was ordained priest in the Order St. Augustine
Theology
Went to the university of_____, where he studied botany and learned the Scientific Method
Vienna
Worked with pure lines of common garden pea plant,_____, for eight years
Pisum sativum
Prior to Mendel, heredity was regarded as a “blending” process and the offspring were essentially a “_____“ of the different parental characteristics.
Dilution
Man of Science, Man of God
Mendel
THREE REASONS WHY MENDEL CHOSE GARDEN PEA PLANT
It was easy to cultivate and had relatively short life cycle
It had discontinuous characteristics such as flower color and pea texture
Pollination was easy to control
7 CHARACTERISTICS:
Seed shape
Seed color
Pod shape
Pod color
Pod/ flower location
Stem length
Flower color
In 1866 he published________ (Versuche über Pflanzen-Hybriden) in which he established his_________
Experiments in Plant Hybridization
three Principles of Inheritance
He tried to repeat his work in another plant, but didn’t work because other plants reproduced______
asexually
Mendel was the first biologist to use________ – to explain his results quantitatively.
Mathematics
Mendel predicted the concept of_____ that it occur in pairs and that one gene of each pair is present in the gametes
genes
PHYSICAL TRAITS = AFFECTED BY PROTEINS
Skin color =_____
Height =_____
Characteristic of hair: Curly =_____ in proteins
Melanin
Growth
Cysteine
Proteins are composed of specific sequence of_____. Change one _____; the protein becomes altered.
amino acids
Central dogma
DNA - transcription
RNA - translation
Amino acid chain - folding
Protein
– a unit of heredity; a section of DNA sequence encoding a single protein
Gene
– the entire set of genes in an organism
Genome
– two genes that occupy the same position on homologous chromosomes and that cover the same trait (like ‘flavors’ of a trait).
Alleles
– a fixed location on a strand of DNA where a gene or one of its alleles is located.
Locus
– having identical genes (one from each parent) for a particular characteristic.
Homozygous
– having two different genes for a particular characteristic.
Heterozygous
2 terms are used to describe the relationship of ALLELES and the TRAITS they control
Dominant
Recessive
– the allele of a gene that masks or suppresses the expression of an alternate allele; the trait appears in the heterozygous condition
Dominant
– an allele that is masked by a dominant allele; does not appear in the heterozygous condition, only in homozygous
Recessive
– the genetic makeup of an organisms
Genotype
– the physical appearance or observable attributes of an organism (Genotype + environment)
Phenotype
: a genetic cross involving a single pair of genes (one trait); parents differ by a single trait.
Monohybrid cross
= Parental generation
P
= First filial generation; offspring from a genetic cross of P1 individuals
F1
= Second filial generation of a genetic cross
F2
Parents differ by a single trait.
Monohybrid
Crossing two pea plants that differ in stem size, one tall one short
Monohybrid
A useful tool to do genetic crosses
Punnett square
For a monohybrid cross, you need a square divided by______…
four
We use the ______ to predict the genotypes and phenotypes of the offspring.
Punnett square
Matings that involve parents that differ in two genes (two independent traits)
DIHYBRID CROSSES
For example, flower color:
P = purple (dominant)
p = white (recessive
DIHYBRID CROSSES
MENDEL’S PRINCIPLES
Dominance
Segregation
Independent assortment
One allele masks another, one allele is dominant over the other in the F 1 generation
Principle of Dominance
Mendel called the observed trait_____ and the trait that disappeared_____
dominant
recessive.
Mendel concluded that the allele for tall plants is_____ to the allele for short plants.
dominant
When recording the results of crosses, it is customary to use the same______ for different alleles of the same gene.
letter
An uppercase letter is used for the_____ allele and a lowercase letter for the_____ allele
dominant
recessive
The_____ allele is always written first.
dominant
(also called_______) occurs when the phenotype of the heterozygous phenotype is distinct from and often intermediate to the phenotypes of the homozygous phenotypes.
Incomplete dominance
partial dominance
RR (red)
rr (white)
Rr (pink)
Incomplete dominance
Genes show_______ dominance when the heterozygous phenotype is intermediate.
incomplete dominance
When F1 generation (all pink flowers) is_______, the F2 generation is 1:2:1 red, pink, white
self pollinated
- occurs when the phenotypes of both parents are simultaneously expressed in the same offspring organism.
Co-dominance
When gametes are formed, the pairs of genes become separated, so that each sex cell (egg/sperm) receives only one kind of gene.
Principle of Segregation
During gamete formation the segregation of the alleles of one allelic pair is independent of the segregation of the alleles of another allelic pair
Principle of Independent Assortment
When two distinct individuals with different characteristics are bred, or crossed, to each other–a process called a ____experiment–their offspring are referred to as____.
hybridization
hybrids
____experiment could involve a cross between a purple-flowered plant and a white-flowered plant.
hybridization
Mendel chose the garden pea,____, to investigate the natural laws that govern plant hybrids.
Pisum sativum
In plants, male gametes (sperm) are produced within___ grains formed in the___.
pollen
anthers
The female gametes (eggs) are contained within___ that form in the____
ovules
ovaries.
Mendel allowed plants to reproduce by_____, which means that the pollen and eggs are derived from the same plant.
self-fertilization
crosses between two particular plants and study their outcomes.
This process, known as_____, requires that the pollen from one plant be placed on the stigma of another plant
cross-fertilization
General characteristics of an organism are called_____.
For example, seed color is a ___ of peas and eye color is a____ of humans.
characters
The term____, is typically used to describe the specific properties of a character.
For example, yellow color is a __ (or variant) of peas and blue eye color is a __ (or variant) found in some people.
trait, or variant
______means that a trait does not vary in appearance from generation to generation.
For example, if the seeds from a pea plant were yellow, the next generation would also produce yellow seeds.
Likewise, if these offspring were allowed to self-fertilize, all of their offspring would also produce yellow seeds, and so on.
Breeding true
variety that continues to p roduce the same characteristic after several generations of self-fertilization is called a
truebreedin g line, or strain.
other. A cross in which an experimenter is observing only one character is called a_____
single-factor cross.
When the two parents are different variants for a given character, this type of cross produces…
single-character hybrids, also known as monohybrids
enables you to predict the types of offspring the parents are expected to produce and in what proportions.
Punnett square
Mendel conducted____ in which he followed the variants for a single character
single-factor crosses
Based on the results of his single-factor crosses, Mendel proposed three key ideas regarding inheritance:
(1) Traits may be dominant or recessive.
(2) Genes are passed unaltered from generation to generation.
(3) The two copies of a given gene segregate (or separate) from each other during transmission from parent to offspring.
he carried out two-factor crosses in which he followed the inheritance of two different characters within the same groups of individuals.
These experiments led to the formulation of a second law called the…
law of independent assortment.
_____ states:
Two different genes randomly assort their alleles during the formation of haploid cells.
In other words, the allele for one gene is found within a resulting gamete independently of whether the allele for a different gene is found in the same gamete.
Mendel’s law of inde pendent assortment
When an offspring receives a combination of alleles that differs from those in its parents, this phenomenon is termed…
genetic recombination
is explained by the random alignment of different chromosomes during metaphase of meiosis I
Mendel’s law of independent assortment
____is explained by the separation of homologs during meiosis
Mendel’s law of segregation
