Genetics Study Important Point
Subject:- Genetics & Plant Breeding
Genetics Study Important Table
1.Difference between Additive Variance & Dominance Variance
| Additive Variance | Dominance Variance |
| Difference between homozygotes | Deviation of Aa from the mean of AA and aa |
| Genes show lack of dominance | Genes show incomplete, complete or over dominance. |
| Associated with homozygosity | Associated with heterozygosity |
| It is fixable | Non-fixable |
| Selection is very effective | Selection is ineffective. |
| It is the cause of transgressive segregation | Cause of heterosis. |
2.Difference between Polygenic Traits and Oligogenic Traits
| Polygenic Traits | Oligogenic Traits |
| Governed by several genes | Governed by few genes |
| Effect of each gene is not detectable | Effect of each gene is detectable |
| Variation is continuous | Variation is discontinuous |
| Usually governed by additive genes | Governed by non additive genes |
| Highly influenced by environmental factors | Not influenced by environmental factors. |
3.Difference between Mendelian Inheritance and Cytoplasmic Inheritance
| Mendelian Inheritance | Cytoplasmic Inheritance |
| Governed by nuclear genes | Governed by plasma genes |
| Exhibits distinct segregation pattern | Does not exhibit distinct segregation |
| Reciprocal differences are not observed | Reciprocal differences are observed |
| Does not show maternal effects | Exhibits maternal effects |
| Genes can be easily mapped on chromosomes | Mapping of plasma genes is very difficult |
| Nuclear genes are associated with chromosomes | Plasma genes are associated with either chloroplast DNA or mitochondrial DNA |
4.A Comparison of DNA and RNA
| DNA | RNA |
| Localization | |
| Primarily in nucleus also in mitochondria and chloroplasts | Primarily in cytoplasm, nucleolus and chromosomes |
| Pyrmidine bases | |
| Cytosine(C), Thymine (T) | Cytosine (C), Uracil (U) |
| Purine bases | |
| Adenine(A), Guanine(G) | Adenine(A), Guanine(G) |
| Pentose sugar | |
| Deoxyribose | Ribose |
| Strands | |
| Mostly double stranded | Mostly single stranded |
| Cytochemical reactions | |
| Feulgen | Basophilic dyes with Ribonuclease treatment |
| Hydrolysing enzyme | |
| Deoxyribonuclease (DNase) | Ribonuclease (RNase) |
| Role in cell | |
| Always genetic information | Synthesis of proteins, sometimes genetic(mostly virus) |
5.Differences between Mitosis and Meiosis
| MITOSIS | MEIOSIS |
| Mitosis occurs in almost all organisms | Occurs only in sexually reproducing organisms. |
| Mitosis takes place in all somatic cells whether haploid, diploid or polyploids. | Takes place in diploid cells such as zygote, Spore mother cells, and gamete mother cells, also occurs in polyploid cells but never in haploid cells. |
| It completes in one sequence formation of two diploid from a diploid mother nucleus | It completes in two successive nuclear divisions and results in the formation of four haploid nuclei. |
| Prophase -shorter duration no subphase | Prophase- longer duration and five subphases. |
| Synopsis does not take place. | Synopsis in zygotene stage. |
| Crossing over, chiasmata formation absent. | Crossing over occurs during pachytene and chiasmata are formed. |
| Each chromosomes consists of two chromatids. | Each bivalent consists of four chromatids |
| Metaphase- the chromosome are arranged at the equatorial plane The centromers lies on the equatorial plane and arms remain free. | Bivalents are arranged at the equatorial plane during metaphase-1. Arms of chromatids lie on the equatorial plane and centromers are away from it. |
| During Anaphase the chromatids separate and move to opposite poles. | Anaphase-1 homologous chromosome of each bivalent separate and move to opposite poles (dis-junction) |
| Telophase → daughter nuclei are organized. | Telophase → two daughter nuclei may be organised they are haploid. |
| The number of the chromosome in daughter nuclei is same as in the parent nucleus. | Daughter nuclei are haploid and contains half of the number of chromosome of the parent nucleus |
| Chromosome of daughter nuclei are quantitatively and qualitatively similar. | Chromosome of daughter nuclei are qualitatively dissimilar due to crossing over. |
Genetics Study Important Table
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Please provide more one liners related to breeding aspects
Sir humble request plz provide more material related to plant science
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