Variation Among Individuals in Biology

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Questions and Answers

Which type of variation is primarily influenced by genetic inheritance?

  • Genotype-by-environment interaction
  • Environmental variation
  • Genetic variation (correct)
  • Phenotypic variation

What do TAS2R genes primarily influence?

  • Growth rate
  • Immune response
  • Visual perception
  • Taste perception (correct)

Which of the following codon variations is related to the TAS2R38 gene?

  • 49th codon – proline or alanine (correct)
  • 150th codon – leucine or methionine
  • 300th codon – serine or threonine
  • 262nd codon – alanine or valine (correct)

Which variation combines both genetic and environmental factors?

<p>Genotype-by-environment interaction (D)</p> Signup and view all the answers

The study conducted by Newcomb and colleagues in 2012 focused on which aspect of variation?

<p>Taste intensity ratings of individuals with different genotypes (C)</p> Signup and view all the answers

How many kinds of variation are outlined in the content?

<p>Three (D)</p> Signup and view all the answers

Which amino acid is found at the 262nd codon of the TAS2R38 gene?

<p>Alanine (D)</p> Signup and view all the answers

What role does the hemoglobin structure play in genetic variation?

<p>It affects oxygen transport in the body. (C)</p> Signup and view all the answers

What does 'reaction norm' refer to in the context of genotype-by-environment interaction?

<p>The range of phenotypes that a genotype can exhibit in various environments. (A)</p> Signup and view all the answers

Which statement about phenotypic plasticity is true?

<p>It enables a genotype to develop multiple phenotypes depending on environmental conditions. (C)</p> Signup and view all the answers

What role does genetic-by-environment interaction play in evolution?

<p>It provides the necessary variation for species to evolve in response to environmental changes. (B)</p> Signup and view all the answers

What is the primary focus of Caspi et al. in their study of genotype-by-environment interaction?

<p>Human genetic variations and their reactions to environmental conditions. (B)</p> Signup and view all the answers

In the context of Tobacco hornworm studies, what does the finding by Suzuki and Nijhout primarily emphasize?

<p>The significance of genotype-by-environment interactions in determining phenotypic outcomes. (D)</p> Signup and view all the answers

What role does the Sox9 gene play during embryonic development?

<p>It provides instructions for making a protein essential for sex determination. (A)</p> Signup and view all the answers

What is meant by the term 'reaction norm' in the context of phenotypic variation?

<p>It signifies the pattern of phenotypes developed based on varying environmental conditions. (A)</p> Signup and view all the answers

Which factor contributes to the variation in offspring sex ratios in leopard geckos?

<p>The incubation temperature experienced by fertilized eggs. (A)</p> Signup and view all the answers

Which of the following statements about Daphnia is most accurate?

<p>They show variations when exposed to diverse environmental factors. (D)</p> Signup and view all the answers

Which mechanism describes the interaction between genetic predispositions and environmental factors influencing phenotypic traits?

<p>Genotype-by-environment interaction. (A)</p> Signup and view all the answers

Which experiment results suggest a significant impact of temperature on offspring gender in reptiles?

<p>Temperature-dependent sex determination in Eublepharis macularius. (C)</p> Signup and view all the answers

What significant outcome is observed when individuals of certain species are incubated at intermediate temperatures?

<p>A higher likelihood of male offspring. (A)</p> Signup and view all the answers

Which of the following factors does NOT affect the phenotypic variation in Daphnia?

<p>The color of the Daphnia body. (D)</p> Signup and view all the answers

Flashcards

Genetic Variation

Differences in the genetic makeup of individuals within a population. This can be due to variations in DNA sequences, leading to different traits.

Environmental Variation

Variations in traits caused by environmental factors, such as diet, climate, or stress. This variation does not involve changes in the genetic code.

Genotype-by-Environment Interaction

Variation in traits that arises from the interaction between an individual's genotype (genetic makeup) and their environment. Some genes are more sensitive to environmental changes than others.

Hemoglobin

A protein responsible for carrying oxygen in the blood. It consists of four polypeptide chains and a heme group that binds to oxygen.

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TAS2R Genes

Genes that encode for taste receptors, responsible for detecting bitterness. These genes help us sense potentially harmful substances.

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TAS2R38

A specific gene within the TAS2R family that encodes for a receptor that detects phenylthiocarbamide (PTC), a bitter compound.

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Alleles

Different versions of a gene. For example, AVI and PAV are alleles of the TAS2R38 gene, leading to different sensitivities to PTC.

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PTC Tasting Ability

The ability to taste certain bitter compounds, like PTC, is influenced by the combination of alleles you inherit. Different combinations of alleles create different levels of bitterness perception.

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Sox9 gene

A gene that plays a critical role in sex determination during embryonic development. In some organisms, it can influence the sex of offspring based on environmental factors.

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Daphnia pulex

A species of water flea that exhibits phenotypic plasticity, meaning its traits can change in response to environmental conditions.

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Phantom Midge Larva

A type of midge larva that is sometimes found in freshwater habitats.

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Phantom Midge Fly

The adult stage of the phantom midge larva, a small, delicate fly.

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Reaction Norm

A graphical representation of the relationship between an organism's genotype and its phenotype across different environmental conditions.

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Phenotypic Plasticity

The ability of a single genetic makeup to produce a range of traits depending on the environment. Like a chameleon changing colors to blend in.

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Tobacco Hornworm Experiment

In the study by Suzuki and Nijhout, they studied how the size of tobacco hornworms was affected by both genetics (genes) and the type of food (environment). This is an example of how genes and environment work together to shape traits.

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Evolutionary Importance

Genetic variations and genotype-by-environment interaction are key to how species evolve. They provide the raw materials for change. It's like having a toolbox of parts and instructions to build something new.

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Study Notes

Variation Among Individuals

  • Variation is studied in real populations, examining specific examples like Linanthus ciliates (whiskerbrush), Asterina miniate (starfish), and Sonora semiannulata (ground snakes).

Three Kinds of Variation

  • Genetic variation: Differences in traits due to genes. Examples include variations in skin color and mixed twins with mixed parents.
  • Environmental variation: Variations in traits due to environmental factors.
  • Genotype-by-environment interaction: The combined effect of genes and the environment on traits.

Body Composition

  • A breakdown of how fats, proteins, water, skin, and other components of the body are made of amino acids, and peptides.
  • Proteins are chains of amino acids exceeding 10,000 molecular weight.
  • 80% of muscle is composed of amino acids.

Cellular Components

  • Red blood cells: Contain hemoglobin.
  • Goblet cells: Contain mucigen/mucin.
  • Rod cells: Contain rhodopsin.

3D Model of Hemoglobin

  • A 3D image shows the structure of hemoglobin.

Amino Acid Sequence of Hemoglobin

  • A detailed list of the amino acid sequence in hemoglobin is provided.

DNA Double Helix

  • The structure of the DNA double helix is depicted, highlighting the complementary chains of A, T, C, and G.
  • Examples of genes are shown on a diagram of human chromosome 7.

Genetic Variation: Phenylthiocarbamide (PTC)

  • PTC is a chemical accidentally discovered in 1931 by Arthur Fox.
  • The taste varies from extremely bitter to undetectable, based on genetics.
  • Its chemical structure resembles toxins found in plants.

Taste Receptors

  • Taste receptor cells in taste buds detect chemicals in food, sending signals to the brain.
  • Different chemical compounds are detected by various taste receptors.

TAS2R Genes in Individuals

  • Research examined TAS2R genes in various individuals to determine genetic variations.
  • Results showed different versions of codons that affect traits like the bitterness of PTC.
  • The study explored variations in codon 49 (proline or alanine), codon 262 (alanine or valine), and codon 296 (valine or isoleucine). This resulted in AVI and PAV alleles.

Intensity of PTC Sensation

  • Studies (Newcomb et al., 2012) measured how individuals with different genotypes perceived the intensity of PTC solutions.

Genotype-by-Environment and Evolution

  • The interaction of genotypes and environments affects the evolution of traits.

Environmental Variation

  • Variations occur in organisms like Daphnia exposed to different environmental conditions (Miyakawa, et al. 2010).
  • Examples include the impact of altitude training on endurance athletes, which has seen varying levels of benefit in studies.

Genotype-by-Environment Interaction: Sox9

  • Sox9 (or Sex-determining Region Y-box 9) plays a crucial role in embryonic development.
  • Variations in Sox9 can affect development based on environmental conditions.

Reaction Norm

  • An individual's reaction to different environments.

Phenotypic Plasticity

  • The ability of one genotype to produce various phenotypes under differing environmental factors.

Tobacco Hornworm

  • The color variations of tobacco hornworms as a result of heat shock.
  • Variations in color and heat shock based on lineage.

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Lesson 7: Variation Among Individuals (Evolution in Real Populations) PDF

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