bio

• DNA is a basis for inheritance
• DNA is a fundamental processes occurring in all cells for copying DNA to transfer the genetic information to daughter cells. Each cell must replicate its DNA before division.
• DNA is semi conservative and parental strands are not degraded
• Base pairing allows each strand to serve as a new template for a new strand.
• DNA stands for Deoxyribonucleic acid
• DNA replication key enzymes

  • Helicase
  • DNA polymerase
  • Primase
  • Ligase
• Helicase separates the two strands which results to the formation of replication
• Primase starts the process and it creates a primer
• AUC is a RNA bases
• AUG is a DNA bases
• Polymerase binds the primer and will make the new strand of DNA.
• Exonuclease removes the primer from both strand of DNA
• DNA ligase seals the fragment of DNA from both strand to form a continuous double strand.
• RNA stands for ribonucleic acid
• Mutation is when mistakes are made in the copying of DNA and the sequences of bases is changed.
• Mutations may be a change in number of chromosomes, change in structure of chromosomes, or a change in DNA sequence.
• Mutation refers to any change in the sequence of Nucleotides in DNA, which leads to changes in the genotype and phenotype of an organism.
• Mutations can be induced or spontaneous and can either be beneficial or harmful.
• Mutations lead to variation, which is one of the driving forces of evolution.
• When a purine nucleotide is replaced by a purine nucleotide it is known as transition, and when a purine is replaced by a pyrimidine, it is known as transversion.
• Mutations occur due to deletion, insertion or substitution of one or more nucleotides.
• Mutation is one of the main factors behind genetic variations on which natural selection operates. It can also lead to various diseases, e.g. sickle cell anaemia is caused due to point mutation. They even lead to cancer.
• A mutation is a change in the sequence of bases in DNA.
• A DNA mutation changes the amino acid sequence and so a different protein may be produced
• 2 classes of mutation

  • Spontaneous mutation
  • Induced mutation
• The main causes of spontaneous mutations are:

  1. Replication errors
  2. Slipped strand mispairing
  3. Unequal crossing over
• Spontaneous mutation are mainly caused during dna replication or by incorporation of incorrect nucleotide in the growing dna chain
• Induced mutations do not occur spontaneously. They are induced through various chemical and physical agents known as mutagens. Mutagens greatly enhance the frequency of mutation.
• Mutagens are substances or conditions that increase the rate of mutations.
• Examples of mutagens

  • Chemicals
  • Ultraviolet light
  • Radiation- X-rays
  • ultraviolet rays
  • Gamma rays
• Point mutation occurs when the base sequence of a codon is changed. (ex. GCA is changed to GAA)
• Types of gene mutations are also called frameshift mutations
• 3 types of gene mutations

  • Substitution
  • Deletion
  • Insertion
• Insertion mutation is where nitrogen base is inserted/added to the sequence. It causes the triplet “frames” to shift. It always affects the amino acids and, consequently, the protein.
• Down Syndrome is where chromosome 21 does not separate correctly. They have 47 chromosomes . Children with Down Syndrome develop slower, may have heart and stomach illnesses and vary greatly in their degree of intelligence.
• Cri-du-chat means Cry of the Cat
• Edwards syndrome or Trisomy 18 was discovered by John H. Edwards
• Edwards syndrome or trisomy 18 is a genetic condition that causes physical growth delays during fetal development. Life expectancy for children diagnosed with this syndrome is short due to several life-threatening complications of the condition. Children who survive past their first year may face severe intellectual challenges.
• Patau's syndrome or trisomy 13 was discovered by Klaus Patau
• Patau syndrome or trisomy 13 is a rare genetic condition that occurs when the 13th chromosome appears three times instead of two times in a person’s DNA. it affects the development of the face, brain and heart, along with physical growth abnormalities throughout a child’s body.