DNA and Proteins

• DNA replication is essential for cell division and the transmission of genetic information from one generation to the next.
• Complementary base pairing: Adenine and Thymine (A and T)

  Guanine and cytosine (G and C)
• Each nucleotide has three components: a sugar molecule, a phosphate group, and a nitrogenous base
• Complementary base paring reasons:

  1. Structure of DNA remains exact and orderly.
  2. The DNA molecule can store large quantities of generic information as the molecule is very large.
• Semi-conservative in DNA replication means each double strand of DNA consists of one old strand and one new synthesised strand.
• The two enzymes in the process of DNA replication is the Helicase enzyme and the DNA polymerase enzyme
• Step 1: The helicase enzyme breaks the hydrogen bonds between the bases in the original DNA strand and unzips the double helix structure.

  
  

  Step 2: Each strand serves as as a template for making a new complementary strand.

  
  

  Step 3: DNA polymerase enzymes add free DNA nucleotides to the exposed corresponding base of the separate strands forming hydrogen bonding.

  
  

  Step 4: The new DNA is synthesised in the 5' to 3' direction.

  
  

  Step 5: Each new double stranded DNA rewinds into a double helix and are joined at the centromere.
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  Long strands of DNA is coiled around histones
• DNA wrapped around histones forms a structure called nucleosome
• The structure of nucleosome helps to tightly condense the DNA in the chromosome structure.
• Is it eukaryotes or prokaryotes that have no nucleus
• Genetic material found free in cytoplasm in a region called nucleoid.
• Singular chromosome that is circular and continous.
• Intro is non-coding
• Exon- coding for the protein
• Eukaryotic chromosomes are linear in shape
• Eukaryotic chromosomes have condensed structures
• Attached by proteins at the centromere to the spindle apparatus during cell divison.
• Binary fission

  1. Circular chromsome is replicated
  2. Attaches to the cell membrane
  3. Membrane pinches off
  4. 2 new daughter cells are formed
• Bacteria are always prokaryotes
• Prokaryote - no nucleus, organelles or membranes
• Eukaryote - has a nucleus, organelles and membranes
• The 2 DNA molecules that each consist of one new and old strand of DNA this is called semi-conservative.
• Ribosomes are made up of RNA and protein.
• During transcription mRNA is produced from DNA.
• mRNA leaves the nucleus through nuclear pores.
• mRNA carries the genetic code to ribosomes where it is translated into proteins.
• Transcription happens in the nucleus.
• Protein synthesis occurs at ribosomes.
• Translation is when mRNA makes a polypeptide chain.
• Gene- Sequence pf DNA nucleotides that code for assembly of protein/RNA
• Protein- Macromolecule essential to cell structure and function
• Amino acids are fundamental units
• Transcription is the process of converting DNA nucleotides sequence to messenger RNA (mRNA)
• Splicing is the removal of non-coding regions called introns
• The introns are removed from the mRNA by a protein-RNA complex called spliceosome. The exons are joined back together by the spliceosome and this is called mature mRNA
• Exon - Coding region that codes for amino acids
• 1 codon is 1 amino acid
• 1 codon contains three bases (AUG)
• degenerate is one amino acid can be coded for many codons