Gregor Mendel

Quiz and photos

Gregor Mendel was:

a) an English scientist who carried out research with Charles Darwin

b) a little known Central European monk

c) an early 20th century Dutch biologist who carried out genetics research

B is CORRECT

He worked in virtual obscurity during the mid

19th century.

Unfortunately, Charles Darwin did not know of

Mendel`s work. He was one of the few

scientists of that time who might have

understood and appreciated Mendel`s huge

contribution to science.

Which statement is true about him?

a) His discoveries concerning genetic inheritance were generally accepted by the scientific community when he published them during the mid 19th century.

b) He believed that genetic traits of parents will usually blend in their children.

c) His ideas about genetics apply equally to plants and animals.

C is CORRECT

He gave us the basis for understanding genetic inheritance in all living things, including humans. His realization that we inherit units or genes was the key to it all.

Mendel believed that the characteristics of pea plants are determined by the:

a) inheritance of units or factors from both parents

b) inheritance of units or factors from one parent

c) relative health of the parent plants at the time of pollination

A is CORRECT

We now call these units genes. Each inherited trait is determined by at least one gene from each parent.

An allele is:

a) another word for a gene

b) a homozygous genotype

c) a heterozygous genotype

d) one of several possible forms of a gene

D is CORRECT

An allele is one of two or more alternate forms of a gene. If an individual is homozygous (YY or GG) for a trait, it has inherited the same allele from both parents. If it is heterozygous (YG), it has inherited different alleles for the trait.

Phenotype refers to the

______________________ of an individual.

a) genetic makeup

b) actual physical appearance

c) recessive alleles

B is CORRECT

Phenotype is the observable characteristics, including physical appearance. It results from the genotype and environmental influences. A phenotype includes not only easily measured traits like hair color but also less apparent ones such as blood type.

When the genotype consists of a dominant and a recessive allele,

the phenotype will be like the dominant allele.

the phenotype will be like the recessive allele.

the phenotype will be neither like the dominant nor the recessive allele.

A is Correct

The dominant allele masks the appearance of the recessive one. However, there are some traits for which this simple rule of dominance does not apply.

Assuming that both parent plants in the diagram below are homozygous, why would all of the f1 generation have yellow phenotypes?  

a) because the f1 genotypes are homozygous

b) because yellow is dominant over green

c) because both parents passed on yellow alleles

B is correct

When there is a genotype that consists of a dominant and a recessive allele, the phenotype generally looks like the dominant one. In this case, yellow is dominant.

The idea that different pairs of alleles are passed to offspring independently is

a) Mendel's principle of unit inheritance

b) Mendel's principle of segregation

c) Mendel's principle of independent assortment

C is Correct

This is a definition of his principle of independent assortment. Stated in other words, the genes that determine a trait assort independently of the genes for other traits. As a result, new combinations of genes, present in neither parent, are possible.

The idea that the pair of alleles of each parent separate and only one allele from each parent passes to an offspring

a) is Mendel's principle of independent assortment

b) is Mendel's principle of hybridization

c) is Mendel's principle of segregation

C is correct

This is the definition of the principle of segregation. Stated in other words, genes occur in pairs and during the process of sex cell production, the members of each pair separate so that each sperm and ovum cell receives one member of each pair.

Task: Definition of terms

PollinationUnit genesHomozygous genotypesHeterozygous genotypesAllele (dominant and recessive)PhenotypeIndependent AssortmentSegregationHybridization

Pollination

the process that transfers pollen grains, which contain the male gametes (sperm) to where the female gamete(s) are contained within the carpel

Unit Gene

A gene is a unit of Heredity

Allele

(from the Greek αλληλος allelos, meaning each other) is one member of a pair or series of different forms of a gene. Usually alleles are coding sequences. An individual's genotype for that gene is the set of alleles it happens to possess. In a diploid organism, one that has two copies of each chromosome, two alleles make up the individual's genotype.

Zygosity

It refers to the genetic condition of a zygote. In genetics,it describes the similarity or dissimilarity of DNA between homologous chromosomes at a specific allelic position.

Zygosity is also used to describe the genetic condition of the zygote(s) from which twins emerge, where it refers to the similarity or dissimilarity of the twins' DNA. Identical twins are monozygotic - Fraternal twins are dizygotic.

Zygosity

The terms homozygous, heterozygous and hemizygous are used to simplify the description of the genotype of a diploid organism at a single genetic locus.

Diploid organisms generally have two alleles at each locus, one allele for each of the two homologous chromosomes.

Homozygous describes two identical alleles or DNA sequences at one locus, heterozygous describes two different alleles at one locus, and hemizygous describes the presence of only a single copy of the gene in an otherwise diploid organism.

Homozygous genotypes

Occurs when both alleles at a particular gene locus are the same.

Heterozygous Genotype

Occurs when the two alleles at a particular gene locus are different. A heterozygous genotype may include one normal allele and one mutation, or two different mutations. The latter is called a compound heterozygote.

Phenotype

Any observable characteristic of an organism, such as its morphology, development, biochemical or physiological properties, or behavior. Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and possible interactions between the two.

Independent assortment*

Mendel's law of independent assortment, states that allele pairs separate independently during the formation of gametes. This means that traits are transmitted to offspring independently of one another.

*Assortment : separation into classes

Segregation*

allele pairs separate or segregate during gamete formation, and randomly unite at fertilization

* To segregate: to separate or isolate from the main body or group

hybridization

Production of a hybrid by pairing complementary ribonucleic acid and deoxyribonucleic acid (DNA) strands. Production of a hybrid by pairing complementary DNA single strands