基因和如何运行(英文版).ppt

1、GENES AND HOW THEY WORK,General Biology CIE HKBU 2012,Watson and Crick discovers DNA / Feb 28th 1953,First Document on DNA published in Nature 25th April 1953,Watson and Crick - Awarded Nobel Prize in 1962,DNA,DNA is often called the blueprint of life. In simple terms, DNA contains the instructions

2、for making proteins within the cell.,Why do we study DNA?,We study DNA for many reasons: Its central importance to all life on Earth medical benefits such as cures for diseases better food crops.,Chromosomes and DNA,Chromosomes are made up of genes. Genes are made up of a chemical called DNA. DNA is

3、 mainly located in nucleus.,Deoxyribonucleic acid (DNA),Cytosine C Thymine T Adenine A Guanine G,DNA has four different bases:,DNA - Structure,The nucleotide is the fundamental unit of the nucleic acid polymer. There are four nucleotides: cytosine (C), guanine (G), adenine (A) and thymine (T). The D

4、NA consists of a long combination of four different nucleotide bases. DNA are lined up as a double helix. These chemicals can form many possible combinations. Different combinations of the letter ATCG will give people different characteristics. The DNA patterns are the codes for manufacturing protei

5、ns.,What are the bases in DNA,A adenine T thymine C cytosine G guanine Base pair rules,Complementary strands,Example First strand GGGTTTAAACCC Second strand CCCAAATTTGGG,DNA by the numbers,Each cell has about 2 m of DNA. The average human has 75 trillion cells. The average human has enough DNA to go

6、 from the earth to the sun more than 400 times. DNA has a diameter of only 0.000000002 m.,The earth is 93 million miles from the sun.,Lets Go to the Video!DNA structure,DNA structure,How can DNA function?,Part 1 Replication,DNA makes a Copy of Self,Replication is the process where DNA makes a copy o

7、f itself. Why does DNA need to copy? Simple: Cells divide for an organism to grow or reproduce, every new cell needs a copy of the DNA or instructions to know how to be a cell. DNA replicates right before a cell divides.,Copying DNA,Step 1- DNA unwinds and unzips Step 2- Once the molecule is separat

8、ed it copies itself. The new strand of DNA has bases identical to the original,Semi-conservative,DNA replication is semi-conservative. That means when it makes a copy, one half of the old strand is always kept in the new strand. This helps reduce the number of copy errors.,Lets Go to the Video!DNA r

9、eplication,DNA replication,Part 2 Transcription,What is Gene,The basic units of inheritance; it is a segment within a very long strand of DNA with specific instruction for the production of one specific protein. Genes located on chromosome on its place or locus.,Transcription DNA to RNA,When a secre

10、tary transcribes a speech, the language remains the same. However, the form of the message changes from spoken to written,Transcription is the reading of the DNA and changing the code to messengerRNA.,Transcription DNA to RNA,Transcription tools- video,RNA polymerase RNA nucleotides Transcription,Pr

11、omoter,RNA splicing,Exons- coding region Introns- noncoding region Splicing- remove introns and exons are joined to produce an mRNA molecule with a continuous coding sequence.,DNA to RNA,DNA remains in the nucleus, but in order for it to get its instructions translated into proteins, it must send it

12、s message to the cytoplasm, where proteins are made. The chemical used to carry this message is messenger RNA.,Lets Go to the Video!DNA to RNA,Transcription,Lets Go the the VideoRNA processing,RNA processing 1 RNA processing 2,Question,Q1) Whats the main difference between DNA and mRNA? Q2) IF the D

13、NA strand is GTACCAGATTAGC What would the RNA strand be? Q3) Explain why our genes are longer than mRNA that leaves the nucleus.,Part 3 Translation,Translation,To translate English into Chinese requires an interpreter. Some person must recognize the worlds of one language and covert them into the ot

14、her.,Codon,The flow of information from gene to protein is based on codons. A codon is a three-base word that codes for one amino acid What can be the interpreter to translate codon the amino acid?,tRNA Transfer RNA,The cells interpreter tRNA translated the three-letter codons of mRNA to the amino a

15、cids that make up protein.,Codon recognition,Genetic translation converts nucleic acid language into amino acid language.,Ribosome- carry tRNA to elongate the polypeptide,Peptide bond formation,Start and Stop codons,Proteins build our body,Proteins are the building blocks for everything in your body

16、. Proteins made up bones, teeth, hair, earlobes, muscles and blood. Those proteins help our bodies grow, work properly, and stay healthy. Scientists today estimate that each gene in the body may make as many as 10 different proteins. Thats over 300,000 proteins!,Lets Go to the Video! DNA TRANSLATION

17、,translation,Question,What is the peptide sequence can be translated by the following DNA? mRNA-AAUAUGAAGUUUGGCGCAUGAAAG Polypeptide-,Short Summary,Part 4 Mutation,What would happen if a genetic mutation changed a start codon to some other codon?,Mutations change the meaning of genes,IF error occur

18、in DNA replication,Mutated/ non functional protein,Causes of mutations,Germ-line mutation affects all cells in the resulting offspring,Genetics mutation,Genetic mutation: Sickle Cell Anaemia 鐮刀型紅血球疾病,ATG GTG CAT CTG ACT CCT GAG GAG AAG TCT GCC GTT ACT GCC CTG TGG GGC AAG GTG AAC GTG GAT GAA GTT GGT

19、GGT GAG GCC CTG GGC AGG CTG CTG GTG GTC TAC CCT TGG ACC CAG AGG TTC TTT GAG TCC TTT GGG GAT CTG TCC ACT CCT GAT GCT GTT ATG GGC AAC CCT AAG GTG AAG GCT CAT GGC AAG AAA GTG CTC GGT GCC TTT AGT GAT GGC CTG GCT CAC CTG GAC AAC CTC AAG GGC ACC TTT GCC ACA CTG AGT GAG CTG CAC TGT GAC AAG CTG CAC GTG GAT

20、CCT GAG AAC TTC AGG CTC CTG GGC AAC GTG CTG GTC TGT GTG CTG GCC CAT CAC TTT GGC AAA GAA TTC ACC CCA CCA GTG CAG GCT GCC TAT CAG AAA GTG GTG GCT GGT GTG GCT AAT GCC CTG GCC CAC AAG TAT CAC TAA, 2010 Paul Billiet ODWS,Hemoglobin mRNA sequence, 2010 Paul Billiet ODWS,Mutation in the hemoglobin gene,Lets Go to the Video! DNA mutation,DNA mutation,Question,Q1) What is the type of genetic mutation in Sickle Cell Anaemia? Q2) How could a single base substitution result in a shortened protein pr