Presentation on theme: "RNA = RiboNucleic Acid Synthesis: to build"— Presentation transcript:
1 RNA = RiboNucleic Acid Synthesis: to build Transcription: produces an RNA copy of DNATranslation: tRNA supplies appropriate amino acidRNA = Ribonucleic Acid
2 Structure of RNA Single stranded Ribose Sugar Phosphate group Base: Adenine, Uracil, Cytosine, Guanine
3 Three Types of RNAMessenger RNA (mRNA) – transfers DNA code to ribosomes for translation.Transfer RNA (tRNA) – brings amino acids to ribosomes for protein synthesis.Ribosomal RNA (rRNA) – Ribosomes are made of rRNA and protein.
4 TranscriptionRNA molecules are produced by copying part of the nucleotide sequence of DNA into complementary sequence in RNA, a process called transcription.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 mRNA.
8 TranslationDuring translation, the cell uses information from messenger RNA to produce proteins.Transcription occurs in nucleus.mRNA moves to the cytoplasm then to the ribosomes. tRNA “read” the mRNA and obtain the amino acid coded for.Ribosomes attach amino acids together using a peptide bond, forming a polypeptide chain.Polypeptide chain keeps growing until a stop codon is reached, creating a protein.
16 Gene RegulationAll (with a few exceptions) of an organism’s cells have the same DNA. Why then are there different cells?The gene expression is different. In other words, cells ‘differentiate’ by expression of some genes and suppression of others.Cells respond to their environment by producing different types and amounts of protein. Can you think of a situation where this might happen?The different types of cells in a multicellular organism result from 'cellular differentiation', which can be defined as “the divergence in structure and function of different types of cells as they become specialized during an organism’s development”.
17 Gene Regulation: Producing Proteins Injury repair: cells can adapt to environmental changes such as an injury which requires repair by activating new genesCancer is a disease of uncontrolled and invasive cell reproduction. Cancers result when the genes responsible for coding the proteins that regulate cell division mutate and divide rapidly.
19 Questions Which base in RNA is replaced by uracil? How many mRNA codons are illustrated on the previous slide?What is the name of the enzyme that creates the mRNA copy from DNA?What is the name of the sugar in the mRNA nucleotides?What is the mRNA transcript for the DNA sequence, TTACGC
23 Gene RegulationIn simple cells (prokaryotic) lac genes which are controlled by stimuli, turn genes on and off.In complex cells (eukaryotic) this process is not as simple. Promoter sequences regulate gene operation.
24 How Does it Work?RNA Polymerase looks for a region on the DNA known as a promoter, where it binds and begins transcription.RNA strands are then edited. Some parts are removed (introns) - which are not expressed – and other that are left are called exons or expressed genes.
25 Chromosomal Mutations Deletion – Part of a chromosome is deletedDuplication – part of a chromosome is duplicatedInversion – chromosome twists and inverts the code.Translocation – Genetic information is traded between nonhomologous chromosomes.