Biology Chapter on Chromosomes and Genes
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Questions and Answers

What are chromosomes made of?

DNA molecules

What is DNA?

Genetic material found in every cell of your body. Pair of nucleotide bases.

What do genes contain?

Instructions for making protein that are building blocks for your body.

How many chromosomes are there in most human cells?

<p>46</p> Signup and view all the answers

What are the first 22 pairs of chromosomes called?

<p>Autosomes</p> Signup and view all the answers

What is the 23rd pair of chromosomes called?

<p>Sex chromosomes</p> Signup and view all the answers

What are gametes?

<p>Reproductive cells that have 23 chromosomes each</p> Signup and view all the answers

What is a zygote?

<p>A fertilized egg</p> Signup and view all the answers

What is a phenotype?

<p>An organism's physical appearance, or visible traits.</p> Signup and view all the answers

In-vitro fertilization (IVF) is a process where sperm and egg are mixed together in a lab dish and then placed in the woman's uterus.

<p>True (A)</p> Signup and view all the answers

Approximately how many genes are included in a child's chromosome?

<p>25,000</p> Signup and view all the answers

What was the Human Genome Project?

<p>An international collaborative effort to map and sequence the DNA of the entire human genome</p> Signup and view all the answers

What did the Human Genome Project contribute to?

<p>Personalized treatment, inherited diseases, and understanding human evolution.</p> Signup and view all the answers

What are homozygous alleles?

<p>Two identical alleles for a trait</p> Signup and view all the answers

What is a dominant allele?

<p>One whose trait always shows up in the organism when the allele is present</p> Signup and view all the answers

What is a recessive allele?

<p>An allele that is masked when a dominant allele is present</p> Signup and view all the answers

What is incomplete dominance?

<p>Situation in which one allele is not completely dominant over another allele</p> Signup and view all the answers

Which of the following are dominant phenotype traits?

<p>Dimples (B), Curly hair (E), Dark hair (G), Thick lips (H)</p> Signup and view all the answers

Which of the following are recessive phenotype traits?

<p>Thin lips (A), Straight hair (C), No dimples (D), Light hair (G)</p> Signup and view all the answers

A dominant allele will always show up, even if there is only one recessive allele.

<p>True (A)</p> Signup and view all the answers

A recessive allele only shows up if both copies of the gene are recessive.

<p>True (A)</p> Signup and view all the answers

Give an example of a recessive allele.

<p>The allele for blue eyes</p> Signup and view all the answers

What is hemophilia?

<p>A disorder where the blood does not clot easily and sufferers can bleed severely with minor injuries.</p> Signup and view all the answers

What causes Down syndrome?

<p>Extra 21 chromosome</p> Signup and view all the answers

What is behavioural genetics?

<p>The study of how genes and the environment influence behaviour</p> Signup and view all the answers

What is polygenic inheritance?

<p>The combined effect of two or more genes on a single character</p> Signup and view all the answers

Give an example of polygenic inheritance.

<p>Height</p> Signup and view all the answers

What type of twins come from one fertilized egg?

<p>Monozygotic (A)</p> Signup and view all the answers

What type of twins are fraternal twins?

<p>Dizygotic (B)</p> Signup and view all the answers

What is reaction range?

<p>The same genotype can produce a range of phenotypes in reaction to environment</p> Signup and view all the answers

What is epigenesis?

<p>The continuous interplay between genes and multiple levels of the environment that drives development</p> Signup and view all the answers

What do heritability coefficients estimate?

<p>The extent to which differences between people reflect heredity</p> Signup and view all the answers

What is heritability?

<p>The proportion of variation among individuals that we can attribute to genes</p> Signup and view all the answers

What does heritability apply to?

<p>Specific groups of people (not an individual) in specific environments</p> Signup and view all the answers

What is methylation?

<p>A chemical reaction in the body in which a small molecule called a methyl group gets added to DNA.</p> Signup and view all the answers

What is niche-picking?

<p>The deliberate seeking environments that fit one's heredity</p> Signup and view all the answers

What is a shared environment?

<p>Those environmental factors that are experienced by all relevant members of a household</p> Signup and view all the answers

Study Notes

Chromosomes and Genes

  • Chromosomes are threadlike structures of DNA containing genes.
  • DNA is the genetic material in every cell.
  • Genes contain instructions for making proteins, the building blocks of the body (e.g., eye color, hair color).
  • Most cells contain 46 chromosomes in 23 pairs.
  • Autosomes are the first 22 pairs of chromosomes; the 23rd pair is the sex chromosome.
  • Gametes are reproductive cells with 23 chromosomes each.
  • A zygote is a fertilized egg.
  • Genotype is the complete set of genes a person inherits.
  • Phenotype is the physical appearance determined by genotype and environment.

Inheritance Patterns

  • Alleles are different forms of a gene, typically occurring in pairs.
  • Homozygous alleles are identical.
  • Heterozygous alleles are different.
  • Dominant alleles always express their trait.
  • Recessive alleles only express their trait when homozygous.
  • Incomplete dominance occurs when one allele is not completely dominant over another.
  • Traits exhibiting dominant phenotypes include curly hair, dark hair, thick lips, and dimples.
  • Traits exhibiting recessive phenotypes include straight hair, light hair, thin lips, and no dimples.
  • Recessive traits require inheriting two recessive alleles, one from each parent.
  • Examples of sex-linked disorders include hemophilia, where blood clotting is impaired.
  • Down syndrome results from an extra 21st chromosome.

Genetic Concepts and Studies

  • Behavioral genetics studies the influence of genes and environment on behavior.
  • Polygenic inheritance involves multiple genes influencing a trait.
  • Monozygotic twins (identical) originate from one fertilized egg.
  • Dizygotic twins (fraternal) originate from two fertilized eggs.
  • Reaction range describes how the same genotype can yield different phenotypes based on the environment.
  • Epigenesis emphasizes the dynamic interplay between genes and the environment.
  • Heritability coefficients estimate the portion of variation linked to heredity.
  • Heritability applies to specific groups in specific environments, not individuals.
  • Methylation is a chemical reaction that controls gene expression.
  • Niche-picking involves individuals actively choosing environments fitting their heredity.
  • Shared environment affects all family members similarly.
  • Non-shared environment makes each individual unique.
  • The Human Genome Project was a large-scale effort to map and sequence the human genome, contributing to personalized treatments, understanding diseases, and human evolution.

Genetic Techniques

  • In vitro fertilization (IVF) mixes sperm and egg in a lab dish, placing selected fertilized eggs into the uterus.

Additional details

  • Human cells have approximately 25,000 genes. Chromosome 1 has the most genes; the Y chromosome has the least.

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Description

Explore the fundamental concepts of chromosomes and genes in this quiz. Learn about the structure of DNA, inheritance patterns, and how genetic traits are expressed in individuals. Test your knowledge on key terms such as genotype, phenotype, and allele types.

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