dna

• What is a gene?

  • A short section of DNA
  • Codes for a polypeptide and functional RNA
• What is a polypeptide chain?

  A polypeptide chain is the primary structure of a protein.
• What role does the Golgi apparatus play in relation to polypeptides?

  The Golgi apparatus processes polypeptide chains into functional proteins.
• What is the definition of locus?


  • Locus refers to the location of a gene on a chromosome.
• Why are humans not genetically identical despite having the same genes?

  Humans have different versions of the same genes, known as alleles.
• What is an allele?

  • An allele is a different form of the same gene.
  • It represents an alternative version of a gene.
• How do alleles affect traits in plants?

  Different alleles can result in different traits, such as flower color or height.
• How is DNA stored in eukaryotic cells?

  • DNA is stored in chromosomes.
  • Chromosomes are tightly coiled structures located in the nucleus.
• How many pairs of chromosomes do humans have in somatic cells?

  Humans have 23 pairs of chromosomes in somatic cells.
• What is the appearance of chromosomes when a cell is not undergoing division?

  Chromosomes appear as single thread-like or stick-like structures.
• What happens to chromosomes after DNA replication during interphase?

  Chromosomes become double structures held together by a centromere.
• What are homologous pairs of chromosomes?

  • Homologous pairs are pairs of matching chromosomes.
  • They have the same genes but may have different alleles.
• What is a human karyotype?

  A human karyotype is an image of all chromosomes organized in pairs.
• What do the dark and light bands in a karyotype indicate?

  They indicate the same genes are present in homologous chromosomes.
• What determines biological sex in humans?

  The 23rd pair of chromosomes, which are the sex chromosomes.
• How is DNA stored in prokaryotic cells?

  • DNA is stored as shorter, circular chromosomes.
  • It is not associated with histone proteins and is free in the cytoplasm.
• What is the role of histone proteins in eukaryotic cells?

  Histone proteins help tightly coil DNA to fit into the nucleus.
• What similarities exist between the DNA in mitochondria and chloroplasts compared to prokaryotic DNA?

  • DNA in mitochondria and chloroplasts is shorter.
  • It is circular and not histone-bound, similar to prokaryotic DNA.
• How is the length of DNA in a human muscle cell related to that in a brain cell?

  Both have the same length of DNA, which is 2.3 meters.
• How do you convert the length of DNA from meters to millimeters?

  You multiply the length in meters by 1,000.
• How do you calculate the mean length of DNA in each chromosome from the total length of DNA?

  You divide the total length of DNA by the number of chromosomes.
• How do you calculate the number of base pairs in each chromosome from the total number of base pairs?

  You divide the total number of base pairs by the number of chromosomes and express it in standard form.
• What are the key points about DNA and chromosomes covered in the video?

  • Genes are sections of DNA coding for polypeptides and functional RNA.
  • Alleles are alternative forms of a gene.
  • Humans have 23 pairs of homologous chromosomes.
  • Eukaryotic DNA is stored in linear chromosomes associated with histone proteins.
  • Prokaryotic DNA is shorter, circular, and not associated with proteins.
  • Mitochondria and chloroplasts contain DNA similar to prokaryotic DNA.