Questions and Answers
What are codons?
Triplets of nucleotides that code for amino acids.
The genetic code is degenerate.
True
What does the Wobble Hypothesis refer to?
The third position of the codon is less specific and binds more loosely.
What is the function of tRNA?
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What are the start and stop codons?
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What is needed for the initiation of translation in bacteria?
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What is required for the elongation step of translation?
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Eukaryotic translation is simpler than bacterial translation.
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What is the role of post-translational modifications?
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How many phosphate equivalents are needed to make each peptide bond?
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The Breeder's Equation is represented as R = h^2 x ______.
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What is the difference between benign and malignant tumors?
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Heritability indicates the degree of a characteristic's influence within individuals.
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What are oncogenes?
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Which of the following conditions is associated with the CFTR gene?
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Cancer is considered a specific disease.
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What type of nutrition includes minerals and vitamins?
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What is the basal metabolic rate (BMR)?
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BMI is calculated using which two measurements?
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What is the main site of carbohydrate digestion?
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Which nutrient is responsible for providing 9 calories per gram?
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What are the two main types of oxidative stress?
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Which vitamins are known to neutralize free radicals?
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What does SOD stand for?
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What are macrominerals needed in large amounts?
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Which nutrient is essential for immune function and T cell development?
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Minerals are organic nutrients.
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What is the primary role of Vitamin A?
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Vitamin C is essential for __________ synthesis.
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What are the two categories of vitamins?
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What is the main function of potassium in the body?
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Match the following vitamins with their primary function:
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What is puromycin?
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What do tetracyclines inhibit?
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Chloramphenicol affects eukaryotes.
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What does cycloheximide block?
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How does streptomycin affect protein synthesis?
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Describe the SRP cycle.
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What does ubiquitin do?
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What does an A1c level of 5.7-6.4 indicate?
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What is Turner syndrome characterized by?
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Klinefelter syndrome (XXY) is defined by what?
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What is the definition of epistasis?
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State the Hardy-Weinberg equilibrium conditions.
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What does the coefficient of coincidence (CoC) measure?
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What is the significance of mutations in evolution?
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Describe gene flow.
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What does phenotypic plasticity mean?
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Define polygenic inheritance.
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Study Notes
Genetic Code and Translation
- Genetic code consists of codons, which are triplets of nucleotides coding for specific amino acids.
- Error rate in translation is higher than in DNA replication; however, proteins do not require perfect fidelity due to their transient nature.
- The genetic code is degenerate; multiple codons can specify the same amino acid due to the Wobble Hypothesis, where the third nucleotide in a codon is less specific.
- Each codon defines a reading frame, and a frameshift mutation can shift this frame, drastically altering the resulting protein.
- An open reading frame contains a start codon (AUG), internal codons, and a stop codon, while introns do not code for proteins and are spliced out.
- AUG functions as an initiation codon and also codes for fMet (formylmethionine); subsequent AUGs code for regular Methionine.
- Termination codons include UAA, UGA, and UAG, which do not code for any amino acid.
tRNA and Ribosomes
- Transfer RNA (tRNA) carries amino acids and has an anticodon arm that aligns antiparallel to mRNA codons, facilitating translation.
- The CCA sequence at the amino acid arm is critical for binding amino acids.
- Conservative substitutions in the anticodon can result in amino acids with similar properties.
- ATP is required during the tRNA charging process.
- Ribozymes are RNA molecules capable of catalyzing specific biochemical reactions, including their own protein synthesis.
- Bacterial ribosomes are composed of 30S and 50S subunits, forming a 70S ribosome, whereas eukaryotic ribosomes comprise 60S and 40S subunits, totalizing 80S.
- Ribosomes contain A (aminoacyl), P (peptidyl), and E (exit) sites and possess proofreading abilities to ensure fidelity during protein synthesis.
Mechanisms of Protein Synthesis
- Translation occurs in three stages: initiation, elongation, and termination, with mRNA read in the 5’ to 3’ direction.
- In bacteria, the initiation complex is guided by the Shine-Dalgarno sequence, which positions the start codon (AUG) at the P site, facilitated by initiation factor IF3.
- Eukaryotic initiation is more complex, using a Poly(A) binding protein (PABP) at the 3' end and a cap at the 5' end to circularize mRNA for efficient translation.
- During elongation, elongation factor EF-Tu brings aminoacyl-tRNA into the A site, and peptidyl transferase catalyzes the formation of peptide bonds, moving the growing polypeptide chain.
- Termination occurs when a stop codon is reached; termination factors dissociate tRNA from the ribosome, with eukaryotic termination factor eRF and bacterial RF1-3 facilitating this process.
- The synthesis of each peptide bond costs four phosphate equivalents.
Additional Concepts
- Polysomes are assemblies of multiple ribosomes on a single mRNA strand, enhancing the efficiency of protein production, particularly in bacteria where transcription and translation occur simultaneously.
- Posttranslational modifications are essential for the proper functioning and conformation of certain proteins, including processes like acetylation and methylation.
- Some proteins are synthesized from precursor polypeptides, with insulin being a notable example.### Pharmacology
- Puromycin: Inhibitory agent that terminates polypeptide synthesis; derived from mold.
- Tetracyclines: Antibiotics that inhibit bacteria by blocking the A site and aminoacyl-tRNA binding.
- Chloramphenicol: Blocks peptidyl transfer during protein synthesis; does not affect eukaryotic cells.
- Cycloheximide: Inhibits 80S ribosomes in eukaryotes; no effect on bacteria.
- Streptomycin: Causes misreading of mRNA at low concentrations; inhibits initiation of translation at high concentrations.
Protein Targeting and Degradation
- Endoplasmic Reticulum: Site for synthesis, folding, and transport of proteins and lipids; employs the SRP cycle to halt protein chain elongation.
- Golgi Apparatus: Processes and packages molecules; proteins enter on the cis side and exit on the trans side.
Gene Targeting and Proteins
- Nuclear Localization Signal (NLS): Directs proteins to the nucleus.
- Ubiquitin: Tags proteins for destruction via the 26S proteasome.
HbA1c
- Glucose binds to hemoglobin in a concentration-dependent manner.
- HbA1c levels:
- 5.7-6.4% indicates pre-diabetes.
- Over 6.5% shows diabetes presence.
Genetic Principles
- Codominance: Heterozygote exhibits a mixture of both phenotypes, e.g., red with white patches.
- Penetrance: Percentage of individuals with a genotype that express the associated phenotype.
- Expressivity: Degree to which a trait is expressed.
Genetic Pathological Conditions
- Turner Syndrome: Monosomy (XO); characterized by webbing of the neck, short stature, and a coarcted aorta.
- Klinefelter Syndrome: Trisomy (XXY); affects males who exhibit female characteristics due to nondisjunction.
- Poly-X Females: Often tall and thin; may experience learning challenges but usually have a normal lifespan.
- XYY Males: Generally tall; Y chromosome lacks significant genetic information.
Chromosomal Variation
- Principle of Segregation: Alleles separate and recombine during meiosis; proximity of genes affects inheritance likelihood.
- Recombination Frequency: Likely percentage of crossovers; used to create genetic maps (0-50%).
- 3-Point Testcross: Technique to determine gene order and locations of crossovers.
Types of Chromosomal Mutations
- Aneuploidy: Abnormal chromosome number due to nondisjunction; includes nullisomy, monosomy, trisomy, and tetrasomy.
- Polyploidy: Complete sets of chromosomes present; can be autopolyploidy or allopolyploidy.
- Chromosomal Rearrangements: Can result in duplications, deletions, inversions, or translocations.
- Fragile Chromosomes: Specific sequences more likely to break; linked to cancers.
Population and Evolutionary Genetics
- Evolution: Species change over time via descent with modification and natural selection.
- Hardy-Weinberg Law: Describes allele/genotype stability under specific conditions (random mating, no migration, etc.); utilizes equations to assess frequencies.
- Gene Flow: Transfer of genes within populations, promoting genetic diversity but hampered by barriers.
Quantitative Genetics
- Quantitative Traits: Influenced by multiple genes and environmental factors; exhibit continuous variation.
- Polygenic Inheritance: Controlled by many genes; distinct versus overlapping phenotypes.
- Quantitative Trait Loci (QTL): Regions associated with quantitative traits (e.g., height, weight).
Statistical Methods in Genetics
- Normal Distribution: Described by the 68-95-99.7% rule (standard deviations).
- Measures of Central Tendency: Mean, median, and mode reflect datasets in different ways.
- Variance and Standard Deviation: Assess variability within datasets; standard deviation calculation involves mean deviations and their squares.
This summary captures essential details on pharmacology, genetics, population dynamics, and quantitative traits, focusing on key concepts and their implications in biology.### Genetics Concepts
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Variance: Influenced by multiple factors affecting phenotypic expression.
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Heritability:
- Broad-sense: Includes all genetic variation sources; calculated as ( H = \frac{\text{Genetic variance}}{\text{Total phenotypic variance}} ).
- Narrow-sense: Focuses on additive genetic variance; represented by ( h = \frac{\text{Additive variance}}{\text{Total phenotypic variance}} ).
- Limitations include its population scope, individual relevance, and lack of universal application.
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Selection Types:
- Artificial selection: Deliberately selecting specific traits.
- Natural selection: Occurs without human intervention.
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Response to Selection:
- Defined as the change in a characteristic subject to selection from one generation to the next.
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Breeder’s Equation: ( R = h^2 \times S )
- ( R ): Response to selection; ( S ): Selection differential; ( h^2 ): Narrow-sense heritability, ranges from 0 to 1.
- Response tends to plateau over time.
Cancer Pathogenesis
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Cancer: Characterized by uncontrolled cell growth; classified into benign (non-spreading) and malignant (spreading).
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Associated Factors: Environmental causes like tobacco use.
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Common Cancers:
- Prostate and breast (#1)
- Lung (#2)
- Colon and rectum (#3)
- Bladder and uterine (#4)
- Melanoma (#5)
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Mutations: Necessary for normal cells to evolve into malignant cells.
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Genetic Factors:
- Germline mutations: Inherited mutations increasing cancer risk.
- Somatic mutations: Acquired mutations.
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Key Genes:
- Oncogenes: Mutated genes promoting cancer; e.g., RAS.
- Tumor-suppressor genes: Require both alleles to mutate for cancer to develop; e.g., BRCA1, P53 (guardian of the genome).
Ocular Pathologies
- Retinoblastoma: Mutation in the RB gene affecting G1/S checkpoint.
- Down Syndrome: Associated with congenital cataracts.
- Marfan Syndrome: Mutation in FBN1 gene leads to lens dislocation.
- Glaucoma: Linked to MYOC, OPTN genes.
- AMD: Related to complement genes on chromosome 1 and ARMS2/HTRA on chromosome 10.
Nutrition Basics
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Macronutrients:
- Carbohydrates: 4 cal/g.
- Proteins: 4 cal/g.
- Lipids: 9 cal/g.
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Balanced Diet: Emphasizes vegetables, limits dairy; portion control is critical.
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Basal Metabolic Rate (BMR): Determined by age and activity level; caloric needs vary by gender and age group.
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BMI Calculation:
- Convert pounds to kilograms and feet to meters; ( \text{BMI} = \frac{\text{kg}}{(\text{m}^2)} ).
- Categories: 30+ (obese), >40 (severe obesity).
Consequences of Poor Nutrition
- Leads to a range of health problems, including:
- Vision issues.
- Type 2 Diabetes (insulin resistance and metabolic syndrome).
- Malnutrition, heart disease, osteoporosis, dental issues, and impaired immune function.
Digestion Overview
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Protein Digestion:
- Begins in mouth with mechanical breakdown.
- Stomach releases gastric juices (HCl + pepsin) to denature proteins.
- Small intestine is the primary site for absorption; pancreatic enzymes assist in breakdown.
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Carbohydrate Digestion:
- Starts in mouth via amylase; continues in the small intestine with pancreatic amylase converting starches to sugars.
- Monosaccharides are absorbed into the bloodstream.
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Lipid Digestion:
- Initiated by lingual lipase in the mouth; bile emulsifies fats in the small intestine.
- Pancreatic enzymes break down fats into fatty acids for absorption through the lymphatic system.
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Hormonal Regulation:
- Insulin and glucagon orchestrate blood sugar levels; insulin promotes glucose uptake while glucagon triggers glycogen breakdown.
Lactose Intolerance
- Caused by a deficiency in lactase; leads to fermentation of undigested lactose resulting in gas and bloating.
- Lactase production diminishes with age, compounding the issue.
Biochemical Pathways
- Involves crucial metabolic processes such as glycolysis and Krebs cycle which generate ATP and are dependent on vitamin B cofactors.
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Description
This quiz covers the details of protein metabolism, focusing on the genetic code and the translation process. Explore concepts such as codons, the degeneracy of the genetic code, and the implications of errors in protein synthesis. Test your understanding of how proteins are made from mRNA and the significance of tRNA.
