Basic Genetics and Biochemistry of Inheritance

Chromosomes

Consists of a long DNA molecule that is folded around proteins. Each unit of _ consists of two rod-like structures joined together at a constricted point.

chromatin

DNA and chromosome proteins are called _.

Centromere

is the region of the chromosome where chromatids are held together.

Karyotype

An arrangement that provides a picture of the complete set of chromosomes. It shows the differences in size and banding pattern of the chromosomes. It is useful in determining the chromosome number of a species.

Loci

The position or location on a chromosome where a particular gene is found.

Allele

• Different forms of the gene that can be found on the same loci. 

• Genes are different 

• Occupies same position in the chromosome 

• Have effects on same trait

Mitosis

Increase in the number of cells from a single-celled zygote that contains the exact same set of chromosomes as the original single-celled zygote

Meiosis

• Produces four haploid cells after the process, each with its own genetic composition which is different from the diploid mother cell.

• Haploid reproduction cells (gametes, spores) are the product of this division.

Y CHROMOSOME

contains the SRY gene (sex-determining region of the Y chromosome) located on the short arm of the Y chromosome. Its presence provides the initial signal for the differentiation of the gonads in the embryo to develop into a testis rather than an ovary.

Chromosomal Aberrations

variations in the number of individual chromosomes as well as rearrangements of the genetic material either within or among the chromosome. (Trisomy, Monosomy, Euploidy, Aneuploidy)

Trisomy

with extra chromosome

Monosomy

 lacks one chromosome

Euploidy

contains a complete diploid set of chromosomes.

Aneuploidy

occurs when an organism loses or gains one or more chromosomes.

DNA

Consists of two strands that wrap around each other to resemble a twisted ladder 

nucleotides

Each strand of the DNA is a linear arrangement of repeating similar units called _

spatial arrangements

Because of the angled _ between the sugars, phosphates, and bases, the DNA actually spirals around itself.

Purines,Pyrimidines

• _: Adenine, Guanine 

• _: Thymine, Cytosine

structural gene

A segment of DNA including all the nucleotides that are transcribed into mRNA is called a _.

Replication

_ begins with separation of the double helix. As the strands unwind, nucleotides in the cell pair up with the complementary bases. Synthesis is catalyzed by the enzyme DNA polymerase.

Transcription

the DNA sequence in one of the strands acts as a template for the synthesis of RNA. Synthesis is catalyzed by the enzyme RNA polymerase

Transcription

Synthesis of new proteins begins with _ as DNA is undergo this process to RNA to produce mRNA, rRNA or tRNA

Translation

After transcription, RNA is further transported outside the nucleus to the cytoplasm where it becomes active in _ (actual synthesis of proteins)

Hugo Deveries, Carl Carrens, Erich Von Tschermak.

Mendel first reported results from his experiments on garden peas in 1866, which was largely unnoticed until 1900, when Mendel’s laws of inheritance were independently rediscovered by three scientists: _, _, and _.

Breeding

a branch of genetics, which is concerned with the proper selection. Use of the parents' traits to produce offspring with predictable and desirable traits for the improvement of animals in general.

Genes

carry the genetic information that is passed from parent cell to offspring /daughter cell one generation to the next, via meiosis, for gametogenesis, a situation where genes are segregated and can assort resulting in new individuals.

monohybrid

An individual heterozygous for one pair of genes (Aa) is called a _.

dominant allele

A _ is one of the genes/alleles of a specific locus on homologous chromosomes, overpowering the expression of the other allele.

recessive allele

A _ is one of the genes whose expression is prevented/overpowered by the dominant allele.

Phenotype

 a physical expression of trait

Genes

unit factors representing units of inheritance

Alleles

 alternative forms of a single gene

Genotype

the genetic makeup of an individual

Homozygote

 identical alleles constituting the genotype

Heterozygote

different alleles constituting the genotype

Monohybrid Cross

The simplest cross involving one pair of contrasting traits.

Punnet Squares

shows the genotypes and phenotypes from the recombination of gametes during fertilization.

Test Cross

The organism of the dominant phenotype, but unknown genotype, is crossed to a homozygous recessive individual.

Dihybrid Cross

A cross involving two pairs of contrasting traits. It is also known as the two-factor cross.

Unit Factors in Pairs

Mendel’s Postulates in which Genetic characters are controlled by unit factors that exist in pairs in individual organisms.

Dominance/Recessiveness

Mendel’s Postulates stating that when two unlike factors responsible for a single character are present in a single individual, one unit factor is dominant to the other, which is said to be recessive. Mixing one trait always results in a 3:1 ratio

Segregation

Mendel’s Postulates stating that during the formation of gametes, the paired unit factors separate or segregate randomly so that each gamete receives one or the other.

Independent Assortment

The emergence of one trait will not affect the emergence of the other. During gamete formation, segregating pairs of unit factors assort independently of each other. Mixing two traits showed 9:3:3:1 ratios