Shape of the DNA Molecule although DNA looks like thin long strings under a microscope it turns out that DNA has a very specific shape. this shape is called a double helix. On the outside of the double helix is the backbone which holds the DNA together. Between the backbones are the nucleotides represented by the letters A, T, C, and G. A different nucleotide connects to each backbone and then connects to another nucleotide in the center

Only certain sets of nucleotides can fit together this is called a base pairing. You can think of them like puzzle pieces: A only connects with T; And G only connects with C

About 99.9% of the DNA of every person on the planet is exactly the same it’s that 0.1% that makes us all unique—– The helix structure  of DNA molecules in your body was discovered  by Dr. James Watson and Francis Crick  in 1953—– if you unraveled all the DNA molecules in your body and placed them end to end it would stretch to the sun and back several times—– DNA is organised into structures called chromosomes within the cell—– DNA was first isolated and identified by Swiss biologist Friedrich Miescher in 1869

DNA REPLICATION: before a cell divides it duplicates it’s DNA to ensure that each resulting cell will have a complete set of DNA molecules

During this process the DNA molecule separates into two strands and then produces TWO new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template, or model, for the new strand

-MOST PROKARYOTES: DNA replication begins at a single point in the chromosome and proceeds, often in two directions until the entire chromosome is replicated

-EUKARYOTIC CHROMOSOMES: DNA replication occurs at hundreds of places. Replication proceeds in both directions until each chromosome is completely copied
-RNA pairs with DNA

RNA:-Ribose sugar -Uracil(U)-can  travel In and out Of nucleus Through nuclear Pores-

DNA: -Thymine (T)-Double stranded- in eukaryotes inside nucleus
DNA-

A pairs with U
T pairs with A
G pairs with C     
C pairs with G.
-RNA consists of long chain nucleotides-

Messenger RNA (mRNA): instructions for assembling amino acids into proteins. These molecules carry copies. Serves as messengers from DNA to the rest of the cell

Ribosomal RNA (rRNA): Proteins are assembled on ribosomes. Ribosomes are made up of several dozen proteins.

Transfer RNA (tRNA):During the construction of a protein, a third type of RNA molecule transfers each amino acid to the ribosome as it is specified by coded messages in mRNA

Transcription: RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complimentary sequence in RNA.

-requires an enzyme known as RNA polymerase-

-During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA

MUTATIONS: are changes in the genetic material

Gene mutations: change in a single gene

Point mutations: gene mutations involving changes in one or a few nucleotides because they occur at a single point in the DNA sequence

Chromosomal mutations: changes in whole chromosomes

The DNA sequence of a gene can be altered in a number of ways. Gene mutations have varying effects on health, depending on where they occur and whether they alter the function of essential proteins. The types of mutations include:

sickle cell disease: suckling effect on red blood cells, usually turns to clots, anemia, and bouts of pain

Nonsensical mutation: A nonsensical  mutation is also a change in one DNA pair.

Frameshift mutation: occurs when the additional or loss of DNA bases change  a gene’s reading frame.