S C I O N S

The DNA

\-Deoxyribonucleic Acid

\-is a polymer of  nucleotides

\-Discovered by Watson and Crick

Four kinds of nitrogenous bases

•Purine bases(**Adenine,guanine**)

•Pyrimidine bases(**Cytosine,thymine**)

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DNA replication

occurs before **a cell divides, ensuring that the cells in a multicellular organism all carry the same genetic information**.It is also the mechanism for producing the DNA copies that offspring inherit from parents during reproduction. 

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RNA

RIBONUCLEIC ACID

\-A  pairs with  U;   G  pairs with  C

\-single stranded and shorter

Genetic Code

\-consists of  64 codons,

\-but only **61** code amino acids.

\-Three codons act as a signal to stop the process.

\-One codon, **AUG, codes for methionine**, and is also the Start signal for translation.

Mutations

Changes in the DNA sequence, that may be **passed along** to future generations.

Point mutations

A Single base substitution.

\-THE CAT SAW THE RAT

\-THE CAT SAW THE HAT

Deletion

a small DNA segment is lost.

Insertion

a segment of DNA is added.

Frame-shift mutation

Modification of the reading frame **after a deletion or insertion, resulting in all codons downstreams being different.**

Messenger RNA (mRNA)

Is a type of molecule of RNA that **travels from the nucleus to the ribosomes,** where the information in the copy is used for a protein product

Ribosomal RNA (rRNA)

Is the RNA component of the ribosome and a **cell’s protein factory in all living cells.** It provides a mechanism for **decoding mRNA into amino acid** and i**nteracts with tRNA**

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Transfer RNA (tRNA)

\-Is an **adaptor molecule** composed of RNA, typically **73 to 93 nucleotides** in length that brings amino acids from the cytoplasm to a ribosome to help the make the growing protein .

\-Transport molecule that carry specific amino acid to a ribosome.

\-Each tRNA recognizes the correct codon,on the mRNA molecule.

Genetic code

Is shared by all organisms.

Codon CAU

It can be fined by the **amino acid histidine** as encoded by

Prokaryote or a eukaryote

The **copy of the DNA** happens where the cell is either

DNA polymerase**.**

Is responsible in **bonding the new nucleotide together.** 

Enzymes and other proteins

Are responsible for the **process of replication**

Enzyme 

Begins the process by **unzipping the double helix** to separate the strands of DNA

Floating free nucleotides

Will be paired with the n**ucleotide of the existing** DNA strand

DNA

Is found i**nside the nucleus of the cells** which are embedded in the chromosomes.

The transcription process

Occurs when the nucleotide sequence along the **DNA is copied** into a strand of mRNA

DNA Strand

Will be exposed once the DNA molecule **uncoils**

RNA polymerase

Is responsible for **the alignment and binding together of the ribonucleotides** that will create the single strand of RNA molecule

Translation

Is the **final step in the synthesis** of a small protein through the help of the mRNA.

Nucleic acid

Large molecules composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus.

Nucleic acid

Large molecules composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus.

Double helix

DNa has two strands of nucleotides joined together to form a twisted molecule which looks like a ______