Genetics

the expected phenotype result of a monohybrid cross is A.1:1:1:1 B.3:1 C.9:3:3:1 D.2:1

B.3:1

In a monohybrid cross between two heterozygous parents,what would be the expected genotype and phenotype ratio?

H_|_ h H| --|---------- h| So there will be one homozygous Dom (HH) 2 heterozygous (Hh) and one homozygous recessive (hh) The Genotype would be 3/4 will have the dominant trait and 1/4 recessive. The Phenotype will be 3-1 Dominant.

What is the difference between genetics and heredity?

Heredity refers to the passing of characteristics from parents to offspring. Genetics is the study of heredity, genes and variations in organisms. Heredity occurs in plants, animals, bacteria and fungi.

Why do our chromosomes come in pairs?

Sexually reproducing species have somatic cells (body cells), which are diploid [2n] having two sets of chromosomes (23 pairs in humans with one set of 23 chromosomes from each parent), one set from the mother and one from the father. Gametes, reproductive cells, are haploid [n]: They have one set of chromosomes.

What is the relationship between the genotype and phenotype?

The Genotype codes for the Phenotype The "internally coded, inheritable information", or Genotype, carried by all living organisms, holds the critical instructions that are used and interpreted by the cellular machinary of the cells to produce the "outward, physical manifestation", or Phenotype of the organism.

homologous chromosomes

The cell has two sets of each chromosome; one of the pair is derived from the mother and the other from the father. The maternal and paternal chromosomes in a homologous pair have the same genes at the same loci, but possibly different alleles.

Difference between Monohybrid and Dihybrid

The main difference between monohybrid an dihybrid is, monohybrid involves one gene as a set of allele, for example color of a plant while dihybrid involves two set of genes for example color and height.

What is a heterozygous genotype?

heterozygous genotypes are those that feature non-identical alleles for a given pair of genes. The term is most often used to describe an organism that has one copy of a recessive gene and one copy of a dominant gene.

Dihybrid cross

involves a pair of gene. It means two characteristics are used to cross over. For example, pea color and shape. First step is to find all possible allele combinations. From the monohybrid cross we know that genotypically, one or two Y alleles will turn the pea yellow phenotypically while genotypically (yy) will lead to green colour of pea phenotypically. But there are also two alleles that determine the shape of the pea. They can be round or wrinkled. The genotypically dominant allele R can turn the pea in round shape. The recessive gene r will cause the pea to be wrinkled phenotypically. So if you cross a homozygous dominant round yellow plant, genotypically (RRYY), with a homozygous recessive, wrinkled green plant, genotypically (rryy) the gametes will be RY and ry. All the plants phenotypically will be round and yellow but they will all be heterozygous for both the characteristics genotypically (RrYy). So if then we cross two F1 plants the possible gametes will be RY, Ry, rY and ry genotypically. F2 generation will me more mixed, there will be 9:3:3:1 ratio of round yellow to wrinkled yellow to round green to wrinkled green respectively. Dihybrid crosses are used to predict two traits at the same time.

Difference between Law of Segregation vs Law of Independent Assortment

1) Mendel's law of Segregation states that two alleles for a particular gene segregate (or separate) from each other during gamete formation and end up in different gametes. 2) Mendel's law of Independent Assortment states that each pair of alleles segregates independently of other pairs of alleles during gamete formation. In other words, traits are transmitted to offspring independently of one another.

Monohybrid:

1. It is a cross between two pure organisms in order to study the inheritance of a single pair of alleles. 2. It produces a phenotypic monohybrid ratio of 3: 1 in F2 generation. 3. It produces genotypic ratio of 1: 2: 1 in F2.

Di-hybrid:

1. It is a cross between two pure organisms of a species in order to study the inheritance of two pairs of alleles. 2. It produces a phenotypic di-hybrid ratio of 9: 3: 3: 1 in F2 generation. . It produces genotypic ratio of 1 : 2 : 1 : 2 : 4: 2 : 1 : 2

Which of these is an example of heterozygous genotype? A. Rr B. RR C. wrinkled D. round

A. Rr. Heterozygous basically means not the same. RR is homozygous since it has 2 of the same alleles. Wrinkled and round are both phenotypes and not genotypes.

Key Differences between Monohybrid and Dihybrid

Cross between two perfect specie to study the inheritance of one gene involved is called monohybrid cross over while a cross between two pure organisms involving two pair of genes is called Dihybrid crossing. In monohybrid cross only one characteristic is focused phenotypically as well as genotypically while in Dihybrid cross two characters are crossed together to generate the result. Mendel focused on monohybrid crossing over first then he further assessed it by introducing Dihybrid model. Phenotypically in monohybrids cross over ratio of 3:1 is produced in second generation while in Dihybrid cross over ratio of 9:3:3:1 is produced in second generation. Monohybrid cross produces genotypic ratio of 1:2:1 in second generation while the Dihybrid cross over produce genotypic ratio of 1:2:1:2:4:2:1:2:1. The test cross ratio of monohybrids is -1:1 while Dihybrid is -1:1:1:1.

A procedure in which an individual of unknown genotype is crossed with a homozygous ....? A.monohybrid cross B.dihybrid cross C.hybrid cross D.test cross

D.test cross

monohybrid cross

In monohybrid allele one gene is required to cross over. For example, crossing of phenotypically yellow homozygous dominant plant color (YY) with phenotypically green homozygous recessive plant colour (yy), the gametes will be heterozygous dominant. The genotype will look like Yy and phenotypically it will be yellow. So if then we cross two F1 plants gene, the possible genotypes of F2 generation will be, one homozygous dominant specie (YY) which will be phenotypically yellow, two heterozygous dominant (Yy) which will also be yellow and one homozygous recessive (yy) which will be green phenotypically. The phenotypic ratio becomes 3:1. It tells the outcome of just one trait. This one character is responsible to bring about the change in specie.

What is the difference between Allele and Trait?

• Alleles are the alternative form of gene, whereas trait is the physical expression of the gene. • Allele is in a specific location, in the chromosome, whereas trait is a physical expression. • Alleles determine the different traits which carry different phenotype. • Allele may be in homozygous state or heterozygous state, whereas trait does not have such state. • Allele is a small segment of DNA, whereas trait is a product of biochemical reactions. • Alleles carry information which is accountable for a trait of an individual, whereas trait is a characteristic of an individual.