Questions and Answers
What is genetics?
The study of heredity, or how the characteristics of living organisms are transmitted from one generation to the next via DNA.
What does the Central Dogma describe?
The process of transcription and translation in gene expression.
Which of the following structures contains the genetic material in eukaryotic cells?
The smallest unit of a living organism is a ______.
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What are chromosomes composed of?
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Eukaryotes have non-membrane organelles.
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Which process describes the conversion of DNA to RNA?
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What is the function of ribosomes?
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Match the following terms to their definitions:
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Which of the following is not a component of the cell?
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What is the role of histones in the cell?
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Study Notes
Basic Genetic Concepts & Terms
- Genetics studies heredity and how traits are passed through generations via DNA.
- Key figures in DNA discovery: Rosalind Franklin, Maurice Wilkins, James Watson, and Francis Crick.
- DNA's double helix structure was first described in 1953.
The Central Dogma of Molecular Biology
- Central Dogma established by Francis Crick: DNA > RNA (Transcription) > Protein (Translation).
- Proteins are composed of 20 different amino acids, resulting in diverse structures across organisms.
Cell and Organelles
- Cells are the smallest living units, comprising 70% water and 30% chemicals.
- Size range: Mycoplasma gallicepticum (0.2 μm) to ostrich egg (15-18 cm).
- Two cell types: Prokaryotes (no membrane-bound organelles) and Eukaryotes (contain membrane-bound organelles).
Organelles and their Functions
- Nucleus: Contains genetic material (DNA) and nucleolus for rRNA production.
- Ribosomes: Synthesize proteins, made of 65% rRNA and 35% proteins, exist as free or membrane-bound.
- Mitochondria: Crucial for ATP production, contain their own mtDNA, and around 1,000-2,000 per cell.
Chromosomes and Chromatin
- Chromosomes are condensed DNA structures visible during cell division. Chromatin is the decondensed form.
- Chromosome number varies by species:
- Human: 46
- Dog: 78
- Cat: 38
- Chromosomes consist of sister chromatids held together by a centromere, with arms labeled p (short) and q (long).
Chromosomal Structure
- Telomeres protect chromosome ends, composed of repeated sequences (5’-TTAGGG-3’).
- Chromosome shapes classified by arm ratio: Metacentric, Submetacentric, Acrocentric, and Telocentric.
Karyotyping and Chromatin Types
- Heterochromatin: Densely packed, low gene expression.
- Euchromatin: Loosely packed, high gene expression.
- Packing levels progress from nucleosomes (DNA + histone) to chromatin fibers.
Genetic Terminology
- Genotype: Genetic makeup; Phenotype: Observable traits.
- Autosomes (non-sex chromosomes) vs. Sex chromosomes.
- Hemizygous: One allele present (e.g., male X and Y chromosomes).
- Nullizygous: Complete loss of gene/function.
Environmental and Genetic Sex Determination
- Temperature-dependent sex determination (TSD) observed in some reptiles and turtles, impacting sex outcomes based on incubation temperature.
- Genetic sex determination (GSD) primarily based on genetic makeup but can be influenced by environmental factors.
Phenotype and Genotype Examples
- Labrador coat color influenced by two genes:
- TYRP1 for eumelanin (black or brown).
- MC1R for eumelanin distribution (eumelanin vs. no eumelanin).
- Examples demonstrate how combinations of alleles (genotype) produce varying physical traits (phenotype).
Miscellaneous Organelles
- Other organelles include the Endoplasmic Reticulum, Golgi body, Centrioles, and Lysosomes, each with specific functions related to cellular processes.
Study Notes Consideration
- Focus on understanding the relationships and functions of DNA, genes, and chromosomal structures.
- Emphasize the importance of organelles and their roles in genetic expression and cellular metabolism.
- Engage with genetic terminology to clarify concepts for understanding inheritance patterns and phenotypic expressions.
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Description
This quiz covers fundamental genetic concepts and terms essential for understanding veterinary genetics. It includes topics on cell divisions such as mitosis and meiosis, Mendelian and extended Mendelian genetics. Test your knowledge and grasp of these critical principles in veterinary science.
