RNA các vấn đề xoay quanh

Types of RNA Three main types  Messenger RNA mRNA – transfers DNA code to ribosomes for translation..  Transfer RNA tRNA – brings amino acids to ribosomes for protein synthesis..  Ri

Ribonucleic Acid

Structure of RNA

 Single stranded

 Ribose Sugar

 5 carbon sugar

 Phosphate group

 Adenine, Uracil, Cytosine, Guanine

Types of RNA

 Three main types

 Messenger 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

of the nucleotide sequence of DNA into

complementary sequence in RNA, a process called transcription.

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.

mRNA

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

The Genetic Code

 This is the language of mRNA

 Based on the 4 bases of mRNA

 “Words” are 3 RNA sequences called

codons

 The strand aaacguucgccc would be

separated as aaa-cgu-ucg-ccc the amino acids would then be Lysine – Arginine – Serine - Proline

Genetic Codes

from messenger RNA to produce proteins.

ribosomes tRNA “read” the mRNA and obtain the amino acid coded for.

forming a polypeptide chain.

stop codon is reached.

Translation to Protein

Translation

 Gene mutations result from changes in a single gene Chromosomal mutations

involve changes whole chromosomes

Gene Mutation

 Point Mutation – Affect one nucleotide

thus occurring at a single point on the

gene Usually one nucleotide is

 Frameshift Mutation – Inserting an extra nucleotide or deleting a nucleotide

causes the entire code to “shift”

Gene Mutation

Chromosomal

Mutations

duplicated

code.

between nonhomologous chromosomes.

Chromosomal Mutations

Mutations

More Mutations

Gene Regulation

 In 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

Review