dna and chromosomes

• What is the focus of the video series mentioned?

  DNA and chromosomes
• What should new viewers do to stay updated?

  Click to subscribe
• What should viewers have ready while watching the video?

  Paper and a pen
• What are the definitions being reviewed in the video?

  Gene and allele
• How is a gene defined in A-level biology?

  A section of DNA coding for polypeptides
• What is the difference between A-level and GCSE definitions of a gene?

  A-level is more specific about coding
• What is a polypeptide?

  A chain of amino acids
• What is the role of the Golgi apparatus in protein processing?

  It processes polypeptide chains into proteins
• What does the term locus refer to?

  The location of a gene on a chromosome
• Why are humans not genetically identical despite having the same genes?

  They have different versions of those genes
• What is an allele?

  A different form of the same gene
• How do alleles affect traits in plants?

  They result in different proteins being created
• How many pairs of chromosomes do humans have?

  23 pairs
• What is a homologous pair of chromosomes?

  Two chromosomes with the same genes
• What is a human karyotype?

  An image of all chromosomes organized in pairs
• What do the dark and light bands on chromosomes indicate?

  They show the same genes in homologous pairs
• What determines biological sex in humans?

  The 23rd pair of chromosomes
• How is DNA stored in eukaryotic cells?

  In chromosomes within the nucleus
• What is the structure of eukaryotic chromosomes?

  Linear and tightly coiled DNA
• What role do histone proteins play in DNA structure?

  They help tightly coil DNA into chromosomes
• How is prokaryotic DNA different from eukaryotic DNA?

  It is shorter and circular
• Where is prokaryotic DNA located?

  Free within the cytoplasm
• What two organelles contain their own DNA?

  Mitochondria and chloroplasts
• How is the DNA in mitochondria and chloroplasts similar to prokaryotic DNA?

  It is short, circular, and not histone-bound
• How is DNA compacted into chromosomes in eukaryotic cells?

  Wrapped around histone proteins
• If a human muscle cell has 2.3 meters of DNA, what is the mean length of DNA per chromosome?

  $0.05 \text{ m}$
• How long is the DNA in a human brain cell?

  2.3 meters
• How many base pairs does each chromosome have if the human genome contains approximately 3 billion base pairs?

  $6.5 \times 10^7$
• What are the key differences between eukaryotic and prokaryotic DNA?

  • Eukaryotic DNA is linear and longer
  • Prokaryotic DNA is circular and shorter
  • Eukaryotic DNA is histone-bound
  • Prokaryotic DNA is not histone-bound
• What are the main points about chromosomes in eukaryotic cells?

  • DNA is stored in chromosomes
  • Chromosomes are linear and tightly coiled
  • Each human somatic cell has 46 chromosomes
  • Chromosomes are organized in homologous pairs
• What are the functions of histone proteins?

  • Assist in tightly coiling DNA
  • Prevent DNA tangling
  • Help form nucleosomes
• What are the characteristics of DNA in mitochondria and chloroplasts?

  • Short and circular
  • Not histone-bound
  • Similar to prokaryotic DNA
• What is the significance of homologous pairs of chromosomes?

  • They have the same genes
  • They may have different alleles
  • They are inherited from both parents
• What is the process of DNA replication in eukaryotic cells?

  1. DNA unwinds
  2. Each strand serves as a template
  3. New nucleotides are added
  4. Two identical DNA molecules are formed
• What is the role of the Golgi apparatus in protein processing?

  • Modifies polypeptides
  • Packages proteins for secretion
  • Sorts proteins to their destinations
• What are the steps to calculate the mean length of DNA in chromosomes?

  1. Total length of DNA
  2. Number of chromosomes
  3. Divide total length by number of chromosomes
• What is the significance of the human karyotype?

  • Displays all chromosomes in pairs
  • Helps identify chromosomal abnormalities
  • Shows genetic information organization
• What are the implications of having different alleles for a gene?

  • Variation in traits
  • Potential for genetic diversity
  • Influence on phenotype expression