DNA, Genes and chromosomes

• what do BOTH DNA and RNA do?


  carry information
• what information does DNA hold?

  genetic information
• what does RNA do with genetic information from DNA?

  Transfers this genetic information from DNA to ribosomes
• what are ribosomes made of?

  • proteins
  • rRNA
• What is a similarity between DNA and RNA?

  They are both polymers of nucleotides
• What do NUCLEOTIDES consist of ?

  • pentose (a five carbon sugar)
  • a nitrogenous organic base
  • a phosphate group
• What are the components of DNA Nucleotides?

  • deoxyribose
  • a phosphate group
  • one of the organic nitrogenous bases (adenine, thymine, cytosine, guanine)
• What do ADENINE and GUANINE have in common?

  Adenine and Guanine both have double ring structures and are classified as PURINE BASES.
• Which bases are purine bases?

  adenine and guanine
• which bases are classified as pyrimidines?


  cytosine, thymine and uracil
• What are the components of RNA nucleotides?


  • Ribose
  • phosphate group
  • one of the organic nitrogenous bases (adenine, guanine, cytosine , URACIL)
• What do thymine, cytosine and uracil have in common?

  They all have a single ring structure and are classified as pyrimidines
• how do nucleotides join together?

  by phosphodiester bonds formed in CONDENSATION REACTIONS
• what is a DNA molecule?

  a double helix composed of two polynucleotides joined together by hydrogen bonds between complementary bases

  WHEREAS RNA is a relatively short polynucleotide chain
• How many chromosomes do humans have in EVERY CELL IN THE BODY?

  46 chromosomes
• what are chromosomes in human body cells arranged into?


  homologous pairs
• What does a HOMOLOGOUS PAIR consist of?

  Two chromosomes that carry the same gene. They are not identical as they can carry different ALLELES of the same gene.
• What does the 23rd chromosome determine?


  the sex of the individual
• what chromosomes do females have?

  two X chromosomes
• what chromosomes do males have?

  an X and Y chromosome
• what is an allele described as?

  an alternative form of the same gene

  • every gene exists in two or more possible forms
• What does every individual inherit?

  two alleles of every gene from their parents