inheritance

• What is the genome of an organism?

  The genome is the entire DNA of an organism.
• What is a gene?

  A gene is a section of DNA that codes for a specific protein.
• Where are genes located in a cell?

  Genes are located on chromosomes within the nucleus of a cell.
• What is a chromosome?

  A chromosome is a threadlike structure made of coiled DNA found within the cell nucleus.
• Describe the structure of a DNA molecule.

  A DNA molecule consists of two strands coiled to form a double helix, linked by paired bases: adenine (A) with thymine (T), and cytosine (C) with guanine (G).
• What pairs with adenine (A) in DNA?

  Thymine (T) pairs with adenine (A) in DNA.
• What pairs with cytosine (C) in DNA?

  Guanine (G) pairs with cytosine (C) in DNA.
• How does RNA differ from DNA?

  RNA is single stranded and contains uracil (U) instead of thymine (T).
• What are the two steps in processing the instructions stored in DNA?

  The two steps are transcription and translation.
• What occurs during transcription?

  • A section of DNA serves as a template for creating mRNA.
  • The mRNA carries information from DNA to other parts of the cell.
  • This information is often used to manufacture proteins.
• What occurs during translation?

  • The mRNA is read by ribosomes.
  • The information in mRNA directs the creation of a protein molecule.
  • tRNA brings amino acids to the ribosome for protein synthesis.
• What is the sequence of events in protein synthesis?

  1. DNA is transcribed into mRNA.
  2. mRNA leaves the nucleus to the ribosomes.
  3. Codons in mRNA pair with tRNA anticodons.
  4. tRNA brings amino acids to the ribosome.
  5. mRNA is translated into a polypeptide chain.
• What are alleles?

  Alleles are different or alternative forms of a gene.
• What does homozygous mean?

  Homozygous means having the same allele, either both dominant or both recessive.
• What does heterozygous mean?

  Heterozygous means having different alleles, one dominant and one recessive.
• What is a dominant allele?

  A dominant allele is a form of a gene that is always expressed in the phenotype.
• What is a recessive allele?

  A recessive allele is only seen in the phenotype of a homozygote and not in a heterozygote.
• What is a genotype?

  A genotype is the specific combination of alleles in an organism.
• What is a phenotype?

  A phenotype is the observable characteristics or features associated with a specific genotype.
• How are alleles expressed in a heterozygote?

  Both alleles are always shown in the phenotype of a heterozygote.
• What is polygenic inheritance?

  Polygenic inheritance refers to traits controlled by multiple genes.
• Give an example of a polygenic trait.


  Examples of polygenic traits include skin color, height, and weight.
• How do polygenic traits differ from discontinuous traits?

  • Polygenic traits show continuous variation.
  • Represented using histograms.
  • Discontinuous traits can be grouped in discrete categories.
  • Represented using bar charts.
• What are the probabilities in monohybrid inheritance when the recessive allele causes disease?

  • Parental genotypes: Dd x Dd
  • Probability of healthy offspring: 75% (or 3/4)
  • Probability of offspring having the disease: 25% (or 1/4)
• What are the probabilities in monohybrid inheritance when the dominant allele causes disease?

  • Parental genotypes: Dd x Dd
  • Probability of healthy offspring: 25% (or 1/4)
  • Probability of offspring having the disease: 75% (or 3/4)
• How many chromosomes do human beings have?

  Human beings have 46 chromosomes grouped in 23 pairs.
• What are the sex chromosomes in humans?

  The sex chromosomes can be XX for females and XY for males.
• What gametes do females produce?

  Females produce gametes (egg cells) that contain the chromosome X.
• What gametes do males produce?

  Males produce gametes that can contain either the X or Y chromosome.
• What is the probability of offspring being female or male?

  The probability of offspring being female is 50% and male is 50%.
• What occurs during mitosis?

  • One round of division.
  • Produces two diploid cells.
  • Cells are genetically identical (clones).
  • Occurs during growth, repair, cloning, and asexual reproduction.
• What occurs during meiosis?

  • Two rounds of division.
  • Produces four haploid cells.
  • Cells contain half the chromosome number.
  • Cells are genetically different (genetic variation).
  • Used for the production of gametes.
• What is the haploid number of chromosomes in humans?

  The haploid number of chromosomes in humans is 23.
• What is the diploid number of chromosomes in humans?

  The diploid number of chromosomes in humans is 46.
• What are truly genetic characteristics and environmental influences?

  • Truly genetic characteristics: Eye color, blood type, gender, genetic disorders.
  • Environmental influences: Amount of exercise, smoking, etc.
  • Genetic and environmental influences: Height, weight, etc.
• What is a mutation?

  A mutation is a rare, random change to the sequence of bases in DNA.
• What does a mutation change in DNA?

  A mutation changes the bases in the DNA sequence.
• What are examples of changes caused by mutations?

  • Changes in the order of bases.
  • Substitution of a base.
  • Deletion of a base or more.
  • These changes can lead to different codons in mRNA.
  • This can result in different amino acids in proteins.
• What can changes in the DNA sequence lead to?

  Changes in the DNA sequence can lead to a different codon in the mRNA and a different amino acid in the protein.
• What are some potential effects of mutations on proteins?

  Mutations can lead to different-shaped enzymes, changes to the active site, or enzymes not being made.