欧阳建强 男科主任 副主任医师
余守华 副主任医师 男科主任
邓贻芳 妇科主任 副主任医师
胡秀丽 妇科主任 主治医师
赵莹 妇科主任 主治医师
碱性氨基酸basic acidic/ the kind of amino acids with R groups receiving H+ easily, including the Lys Arg His/ the kind of amino acids with R groups giving off H+ easily, including Asp Glu/ nonpolar polar
中心法则 a dogma shows the general pathway of information flow via RNA DNA replication,transcription,translation and reverse transcription.
Tm:melting temperature,the temperature at which half of the DNA molecule undergoes denaturation.
Km: the substrate concentration when enzyme operations at one half of the maximum velocity.
turnover number: is a measure of catalytic activity, is the number of molecules of substrate transferred into product per molecule of enzyme in a defined period of time.
primary RNA transcript: (hnRNA)the RNA molecule transcribed from eukaryotes DNA, is the precursor of the mature mRNA.
反式作用因子trans-acting factors: the protein outside DNA control expression of a gene and binds to the cis-acting elements of the DNA.
分子伴侣chaperon: a protein required in protein folding into 3D rapidly and precisely, binds continuously and reversibly to unfolded hydrophobic segments so as to prevent aggregation.
半保留复制semiconservative replication: each DNA strand serves as a template for the synthesis of a new strand, producing two new DNA molecules, each with one new strand and one old strand.
Enzymes can be inhibited by specific substances called inhibitor. Inhibitor has specificity for enzyme and binds to an enzyme and interferes with its activity without causing the denaturation of enzyme.
Domain: discrete parts of the tertiary structure, either globular or fibrous in shapes, but tightly packed together. They have a particular function. Domains are much larger regions and may consist of motifs.
Motif: a functional supersecondary structure, is particularly stable arrangements of several elements of secondary structure and the connection between them. Motifs are much smaller and nearby segments and may be units of the domain.
DNA consists of four kinds of bases-A,G,C,T and a deoxyribose and a phosphate. RNA consists of four kinds of bases-A,G,C,U and a ribose and a phosphate.
DNA has secondary structures like DNA doubt helix, triplex and tetraplex and tertiary structure called superhelix and can form the nucleosome with the histone further form the chromosome.
DNA is the storage form of genetic information can replicate itself passing genetic
information from generation to generation and control the gene expression by transcription.
The main function of RNA is transfer genetic information from DNA to protein. DNA synthesis is through semi-conservative and semi-discontinuous replication. RNA synthesis is through asymmetric transcription.
’In prokaryotes, RNA pol has a core enzyme with α2ββ and a ζsubunit. The RNA
pol initiates the synthesis of RNA, elongates the RNA strand and stops at termination sequence. Promoters typically consist of two consensus sequence elements: the -35region with consensus TTGACA whereζsubunit recognizes and binds; the -10 Pribnow box with consensus TATAAT where is ideal for unwinding. In initiation, ζsubunit recognizes the -35 sequence; RNA-pol holoenzyme and promoter form “closed promoter complex”;polymerase unwinds about 16-18 pairs to form “open promoter complex”; Theζsubunit separates from the polymerase complex; prokaryotic polymerase has the helicase activity and the DNA unwinds at the -10 Pribnow box (A/T rich region) and this unwound region is known as a transcription bubble.
In eukaryotes, RNA-pol I transcribes 45S-rRNA; RNA-pol II transcribes hnRNA; RNA-pol III transcribes tRNA,5S-rRNA and snRNA. The promoter contains TATA box(Hogness Box),CAAT box and GC box. To begin transcription, RNA-pol requires many transcription factors: TFIIA,B?(specially, TFIID binds to the TATA box and TFIIF has the helicase activity and unwind the eukaryotic DNA.)In initiation, three steps in formation of the pre-initiation complex(PIC): step1, formation of the DAB complex, TFIIA+TFIIB+TFIID; step2, binding of the RNA-pol II/TFIIF complex; step3, binding of TFIIE.
Prokaryotic polymerases can recognize the promoter and bind to it directly.
Eukaryotic polymerases have to rely on transcription factors to recognize and initiate transcription at specific promoter sequences.
In prokaryotes, initiation requires the large and small ribosome subunits, the mRNA, the initiator codon and three initiator factors(IF1,2,3). At the beginning, three steps in formation of translational initiation complex: the SD sequence aligns mRNA on ribosome for translation; the leading codon(AUG)of the mRNA molecule associates with the small ribosomal subunit; the AUG codon associates with the UAC anticodon
fmetof fmet-tRNA ,the first AA is N-formylmethionine; the small ribosomal subunit
fmetassociates with large subunit, fmet-tRNA is positioned at the P site.
In eukaryotes, initiation requires the large and small ribosome subunits, the mRNA, the initiator codon and many initiator factors. The initiation complex forms with CBP, eIFs and small ribosomal subunit. CAP binding protein II(CBP) binds to mRNA
75’CAP structure and ribosome recognizes mRNA by binding to mG cap at 5’ end of
mRNA. The complex scans the mRNA for the first AUG closest to the 5’end of mRNA.
metThe first AA is not formylated and met-tRNA is positioned at the P site with help
Chain elongation has three steps: entrance, an activated tRNA-AA containing an anticodon complementary to the next codon; peptide bond formation, catalyzed by
transpeptidase; translocation, polypeptide-tRNA in the A site is translated to P site and deactivated tRNA in the P site is released.
Termination: if one termination codon appears in the A site, release factor is active; transpeptidase is converted to esterase and stops the peptide bond formation; release of the polypeptide chain from the tRNA and the ribosome.
1.isoenzyme: are enzymes that differ in amino acid sequence but catalyze the same biochemical reaction.
2.primer:is a short segment of RNA strand ,complementary to template, binding to the lagging strand of DNA provides free 3’-OH end from which the new polynucleotide chain can grow.(The primer is RNA rather than DNA because DNA polymerases cannot start chains de novo.)
3.central dogma: shows the general pathways of information flow via DNA and RNA replication, transcription, translation and reverse transcription.
4.alternative splicing: In splicing, the introns are excised alternatively and then the exons are sewn together to form different mature mRNAs thus translating different proteins.
5.SD sequence: a sequence upstream the AUG initiation codon in the mRNA, is complementary to a sequence in the 16S-rRNA of the ribosomal small subunit. Its core sequence is AGGA. It’s necessary to indicate the ribosome where to bind.
6.gene expression: the processes of the genetic information in DNA converted into functional proteins. The information flow includes transcription and translation. The biosynthesis of rRNA and tRNA also belongs to the process of gene expression.
7.proteome: the entire collection of expressed proteins in an individual cell or organism at a particular time, or the complement of proteins expressed by a genomes. 问答题 （6选4）（4*10）
2.简述raising the concentration of substrate对解除competitive inhibitor抑制作
The shape and structure of competitive inhibitor are very similar to substrate and can mimic substrate or transition state and fits into the active site, physically blocking substrate’s access into the active site. So the inhibitor and substrate effectively compete with each other for the active site of enzyme. Regardless of the concentration of a competitive inhibitor, a sufficiently high substrate concentration will displace the inhibitor from the active site.
Example: malonate and succinate compete with succinate dehydrogenase.
3.DNA synthesis在leading strand和lagging strand的不同
The continuous strand or the leading strand is the one in which 5’to 3’synthesis proceeds in the same direction as the replication fork movement.
The discontinuous strand or the lagging strand is the one in which 5’to 3’synthesis proceeds in the direction opposite to that of the fork movement. This strand replicates in pieces called Okazaki fragment.
4.Describe the process of initiation、elongation and termination at the stage of eukaryotic translation.
5.阐述两个实验以证明蛋白质空间构象conformation由primary structure-AAs sequence决定
6.阐述 transcription of prokaryotes的两个终止机制 Rho-dependent and Rho-independent
When the RNA pol comes to the end of a gene, it stops synthesizing RNA and drops off the DNA and it has two mechanisms: Rho dependent termination and Rho independent termination. Rho is the termination factor protein with 6 subunits. It’s a ATP-dependent helicase and can bind to the newly synthesized mRNA. It moves along RNA transcript, finds the “bubble”, unwinds it, displaces the polymerase and releases the RNA chain. The Rho independent termination requires specific sequences—the termination sites in DNA: (1)the ends of genes sometimes consists of a GC rich region (transcription terminator) which causes growing mRNA to form hairpin structure; (2) the signal followed by a run of As(or Ts)in the template strand;(3) the GC hairpin disrupts the binding of the mRNA to the DNA template;(4) the A rich stretch makes only weak bonds to the Us in the mRNA. The affinity of RNA pol for DNA is already fairly low so termination is easily achieved.
6.Oxidative respiratory chain
7.Glutamate pyruvate transaminase
1.State the reason why covalent modification causes the function change of protein. Give an example in your answer sheet.
Many enzymes can be regulated by chemical modification through adding or removing a functional group. Covalent modification is reversible and require one enzyme for activation and one enzyme for inactivation.
Example: phosphorylation and dephosphorylation are the most common covalent modification. It requires the protein kinase and phosphatase.
Pyruvate dehydrogenase+ATP——pyruvate dehydrogenase-Pi+ADP(pyruvate dehydrogenase kinase/pyruvate dehydrogenase phosphatase)
2. State the mechanism of megaloblastic anaemia at the time of Vitamin B12 deficiency.
3. Compare the difference and respective electron transfer chain between phosphate-3-glycerol shuttle and malate-asparate shuttle. State the mechanism of the difference between their ATP productions.
4. List all the enzymes, participating in the glycogenesis and glycogenolysis in the liver, and their functions.
5. State all the procedures of gene cloning at the time of using plasmid as vectors. 05八年生化期中考题
增色效应(hyperchromacity): Denaturation of DNA leads to increase of OD260 血管新生
small nonmessageRNA: snmRNAs consist of small nuclear RNA or snRNA, small nucleolar RNA or snoRNA, small cytoplasmic RNA or scRNA, small catalytic RNA, small interfering RNA or siRNA and so on. These snmRNAs play important roles in post-transcriptional process and transportation of hnRNA and rRNA and the regulation of gene expression. 胆固醇逆转运
酶的变构调节: allosteric enzymes are multi-subunit proteins with multiple active sites. They have a second ligand-binding site away from their catalytic centers(also called the regulatory site or allosteric site). An allosteric inhibitor or activator binds to the regulatory site and cause the conformational change in the allosteric enzymes.
1 用米氏方程说明a)when s >>km,v is independent
b}v is first order when s << km
c)explain km=s when v =1/2Vmax
2 一个18c的脂肪酸倍塔氧化后生成多少atp 详细说明
Secondary structure refers to particularly stable arrangements of amino acid residues giving rise to recurring structural patterns.(mainly the αhelix, βsheet,βturn and random coil)
5）HB和MB的binging curve 说出不同点
Myoglobin is a single polypeptide(153 amino acid residues)with one heme group. Hemoglobin has four chains and two subunits(two αchains with 141 amino acid residues and two βchains with 146 amino acid residues). It’s a tetrameric protein with four heme groups.
The binging curve of myoglobin is “ rectangular hyperbola” shaped. The binging curve of hemoglobin is “S” shaped.
Myoglobin functions as an oxygen-storage protein.
Oxygen binding to hemoglobin is both allosteric and cooperative. As O2 binds to one binding site, the hemoglobin undergoes conformational changes that affect the other binding sites. Conformational changes mediated by subunit-subunit interactions
result in cooperative binding. So hemoglobin functions as an oxygen-transport protein.
1.hnRNA :also the primary transcript, is premature form of mRNA transcribed from DNA in the nucleus. By processing and modifying, on the way from nucleus to cytoplasm the hnRNA convert into mature mRNA.
2.reverse transcription: retroviruses which are enveloped single stranded RNA can replicate through a DNA-RNA intermediate using reverse transcriptase, this way of replication is called reverse transcription.
Reverse transcriptase is an RNA-dependant DNA polymerase and catalyzes three different reactions: RNA-dependent DNA synthesis; RNA degradation; DNA-dependent DNA synthesis.
4.nucleic acid probes
5.proto-oncogen and oncogen
1. describe the mechenism of transcription termination of prokaryotics
2. what is cis-acting elements? Give 2-3 examples
Cis-acting elements are specific control sequences in the DNA, which activators and repressors of eukaryotic gene transcription recognize and bind to.
3. list three features of DNA replication
Semi-conservative replication, each strand of template DNA is being copied; semi-discontinuous replication, the leading strand copies continuously which the lagging strand copies in Okazaki fragments and joined by ligase; bidirectional chromosomal DNA replication, bidirectional replication involves two replication forks which move in opposite direction; require of primer, high fidelity of replication.
In prokaryotes, DNA polymerase I performs many clean-up functions during replication, recombination and repair. DNA pol II is an enzyme in the type of SOS DNA repair. DNA pol III is the principal replication enzyme. All polymerases have the 3’-5’exonuclease activity and DNA pol I has the 5’-3’exonuclease activity. DNA replication requires helicase (using chemical energy from ATP to separate two parent strands); DNA primase (an RNA polymerase that generates an oligoribonucleotide that is extended by DNA polymerase III); SSB (single binding protein binds to single stranded DNA, preventing the DNA from reannealing with the complementary strand); topoisomerases (consist of type I and II, enzymes that
catalyze changes in DNA supercoiling); DNA ligase (sealing the nicks between newly synthesized Okazaki fragments into a single continuous strand).
DNA replication in prokaryotes has three steps: initiation, elongation and termination. In initiation, gyrase(a type of topoisomerase) relaxes supercoils in replication origin(OriC); initiator proteins(DnaA and DnaC) attach to the region; DNA helicase(DnaB) binds initiator proteins on the DNA and denatures the region using ATP as an energy source; DNA primase binds helicase to form a primosome, which synthesizes a primer; SSB binds to single-stranded DNA, stabilizing the separated strands and preventing renaturation while gyrase relieves the topological stress produced by the DnaB helicase. In elongation, the elongation phase of replication includes two operations: leading strand synthesis and lagging strand synthesis. Leading strand synthesis begins with the primer at the replication origin. Deoxyribonucleotides are added to this primer by DNA polymerase III. Leading strand then proceeds in the same direction with the fork movement. Lagging strand synthesis is accomplished in short Okazaki fragments. When an Okazaki fragment is completed, replication halts and the core subunits of DNA polymerase III dissociate from the completed Okazaki fragment and associate with the new Okazaki fragment. The entire complex responsible for coordinated DNA synthesis at a replication fork is called replisome. In termination, the gaps between fragments of lagging strand are filled by DNA polymerase I and uses its 5’-3’exonuclease activity to remove the RNA primer lying ahead of the polymerase site. Finally, DNA ligase connects the fragments. DNA replication in eukaryotes is similar to that in prokaryotes. Differences: chromosomes are linear with multiple origins of replication; replication fork moves more slowly; eukaryotes have at least 5 DNA polymerases:DNA polymerase α has the primase and polymerase activities, initiating the replication fork; DNA polymerase β is responsible for the SOS DNA repair; DNA polymerase δ has the helicase activity and responsible for DNA elongation; DNA polymerase ε performs many clean-up functions during replication, recombination and repair. DNA polymerase γ is responsible for the DNA replication in mitochondrial. In initiation, the DNA sequence of origins of replication is referred to as replicators.The origin recognition complex(ORC, a multisubunit protein)binds to the sequences within the replicator. DNA polymerase δ separates the parental DNA strands and replication protein A(a single-stranded DNA-binding protein)binds to and stabilizes the single strand. Replication begins with the binding of DNA polymerase α which forms the primer. In elongation, RFC(protein replication factor C) displaces DNA polymerase α and attracts PCNA(proliferating cell nuclear antigen). Then PCNA binds to DNA and strengthens polymerase δ to elongate the polynucleotide strand. Replication continues in both directions from the origin until adjacent replicons meet and fuse. RNA primers are removed and the DNA fragments are joined by DNA ligase. The termination of replication on linear eukaryotic chromosomes involves the synthesis of telomeres at the ends of each chromosome which’s catalyzed by telomerase.
chemical modification,(covalent modification)
okazaki fragment: a small proportion of newly synthesized DNA and are joined by DNA ligase to form one of the daughter DNA strands.
大题： use examples to illustrate gene regulate at and after transcription initiation.
activation of oncogene
3 features of gene replication.
1 肿瘤 2 传染病
SNP of genome
5.人类基因组计划中，public 基因测序与 privat 基因测序的相同与不同
Inhibitor: substance that binds to an enzyme and interferes with its activity without causing the denaturation of enzyme.
Inhibitor has specificity for enzyme and do not denature the enzyme, which is the difference between the inhibition caused by inhibitor and denatureation.
Secondary structure: refers to the particularly stable arrangements of amino acid residues giving rise to recurring structural patterns, mainly the α-helix,β-sheet,β-turn and random coil.
Gene: A certain DNA region, the basic unit which include genetic information. Genome : DNA include whole genetic information .
Spilt gene: a eukaryotic gene in which the coding sequence is divided into two or more axons that are interrupted by a number of introns.
Some regions of DNA, which get transcribed into RNA but not translated into protein, are called introns.
Those regions of DNA that do code for amino acids in the protein are called exons.
Spliceosome: a complex of several snRNA molecules (U1, U2, U5, and U4/U6, named according to the snRNA they contain) and some different proteins.
Splicing :In "splicing", the introns are excised and the exons are sewn together to form mature RNA .Splicing occurs in the nucleus.
cDNA: a synthetic DNA catalyzed by reverse transcriptase and is complementary to an mRNA template.
Asymmetric transcription: the characteristic of transcription, means that in a limited region of DNA duplex only one DNA strand is used as template.
Reverse transcriptase has three kinds of activities: RNA-dependent DNA synthesis; RNA degradation; DNA-dependent DNA synthesis.
DNA denaturation : separation of the double stranded DNA into single stranded caused by breaking of H-bonds between base pairs under high temperature, changing of PH or ion strength.
Hybridization：hybrid duplex(heteroduplex) formed between DNA/DNA or DNA/RNA derived from different species (sources) after mixing, denaturation and annealing. Function of the subunits of RNA pol in prokaryotes:
(i)? subunit : recognizes and binds to the initiation site of gene.
(ⅱ)a : (2) bind to other proteins ; sometimes contact the DNA;
(ⅲ)b' : keeps the RNA pol on the DNA track;
(iv)b: forms the phosphodiester bonds.
Promoter : conserved sequence necessary to start to transcribe specific sequence of DNA (40bp).
cis-acting elements :DNA sequence that control the activity of a gene in the DNA molecule itself (promoters, enhancers, silencers) TATA box, CAAT box .
denaturation: a loss of three-dimensional structure sufficient to cause loss of function is called denaturation. Proteins can be denatured not only by heat but by extremes of pH, by certain organic solvents such as alcohol or acetone, by certain solutes such as urea and guanidine hydrochloride, or by detergents.
Renaturation: Certain denatured proteins regaining their native structure and their biological activity is called renaturation.
DNA replication: DNA replication is an enzymatic polymerization of deoxyribonucleotides.
Proofreading: If the polymerase has added the wrong nucleotide, translocation of the enzyme to the position where the next nucleotide is to be added is inhibited.The 3’- 5’exonuclease activity removes the mispaired nucleotide, and the polymerase begins again. This is known as proofreading. Replication proceeds with an extraordinary degree of fidelity. The fidelity of DNA is maintained by the following three mechanisms: (1)base selection by the DNA polymerase, polymerization relies on the hydrogen bonds of correct pairing complementary bases and the common geometry of the standard A=T and G≡C base pairs, an incorrect nucleotide may be able to hydrogenbond with a base in the template, but it can be rejected before the phosphodiester bond is formed;(2)a 3’-5’proofreading exonuclease activity that is part of most DNA polymerases, this nuclease activity permits the enzyme to remove a newly added nucleotide and is highly specific for mismatched base pairs;(3) specific repair systems for mismatches left behind after replication, the 5’-3’ exonuclease activity of intact DNA polymerase I can replace a segment of DNA (or RNA) paired to the template strand, in a process known as nick translation. These activities have a role in both DNA repair and the removal of RNA primers during replication .
Replicon: the DNA replicated from a single origin is called a replicon or replication unit.
Telomeres: telomeres are the physical ends of linear eukaryotic chromosomes consisting of a repeated G or C rich strand.
DNA repair: mismatch repair, base excision repair, nucleotide excision repair, direct repair, recombinational repair and SOS response.
Replication fork: the site of DNA synthesis is called the replication fork because the complex formed by the newly synthesized daughter strands arising from the parental duplex resembles a two-pronged fork.＋ 更多类似范文