人教版生物必修二知识点总结

1、人教版生物必修二知识点总结 （human teaching edition biological compulsory two knowledge points summary）zhengzhou class 1106 singing i. the basic law of heredity (1) the law of segregation of genes the advantages of pea as a material: (1) pea can be strictly self pollinated, and it is closed pollinated and can mai

2、ntain pure breed under natural conditions. (2) varieties have distinguishable characters. the artificial hybridization test process: (left pistils), emasculation bagging (anti interference), artificial pollination the genetic phenomenon of a pair of relative characters: a pair of homozygous parents

3、with a pair of relative characters crossed, and the offspring showed a kind of expression the characters of f1 and f2 generations were separated, and the separation ratio was 3:1. the essence of the law of gene segregation: in heterozygous cells, alleles located on a pair of homologous chromosomes h

4、ave certain independence, when the organism is in meiosis, alleles are separated by homologous chromosomes, respectively in two gametes, independently transmitted to the offspring as gametes. (2) the law of free combination of genes the genetic phenomenon of two pairs of relative characters controll

5、ed by two alleles: hybridization of homozygous parents with two pairs of relative characters after generation of f1 selfing, offspring appeared in four phenotypes, with a ratio of 9:3:3:1. each of the four phenotypes is pure zygote accounted for 1/16 in the two generations, accounting for 4/16; the

6、proportion of dominant individuals accounted for 9/16; the proportion of double recessive individuals accounted for 1/16; the single heterozygote accounted for 2/16 * 4=8/16; the double heterozygote accounted for 4/16; the parent type proportion accounted for 9/16 and 1/16; the proportion of recombi

7、nant types each accounted for 3/16, 3/16 the essence of the law of free combination of genes: the separation or combination of non allelic genes located on non homologous chromosomes is not mutually exclusive interfering. in meiosis, gametes are formed on the homologous chromosomes and separated fro

8、m each other at the same time a free combination of non allelic alleles on the source chromosome. using the principle of free combination of genes to cultivate new varieties: good characters are in different varieties, the best varieties were obtained by crossbreeding first, selecting the ones that

9、met the requirements, and then carrying out continuous self - pollination. memory point: 1. gene segregation law: a pair of relative characters of two biological pure hybrids, the offspring only show dominant characters; trait segregation appeared in the two offspring, and the ratio of dominant char

10、acters to recessive characters was close to 3:1. the essence of the 2. gene segregation law is that in a heterozygous cell, a pair of homologous chromosomes is found to be independent, in meiosis, gametes are separated and separated into two gametes, independently transmitted to offspring by gametes

11、. 3. genotype is the memory factor of trait expression, while phenotype is the form of genotype. phenotype = genotype + environment condition. the substance of the 4. gene combination law is that the separation or combination of non allelic genes located on non homologous chromosomes is not mutually

12、 exclusive disturbed. in meiosis, gametes are formed on the homologous chromosomes and separated from each other at the same time a combination of non allelic alleles on chromosomes. within the range of the laws of the free combination of genes, individuals with the n allele the gametes produced may

13、 have at most 2n species. two, cell proliferation (1) cell cycle: a continuous division of cells, starting from the completion of a division, until the next division is complete. (2) mitosis: the biggest feature of interphase is the replication of dna molecules and the synthesis of proteins the main

14、 changes of chromosomes in prophase are prophase, metaphase, division and anaphase. especially note the doubling of chromosome numbers at anaphase due to mitotic division. the difference of mitosis between animals and plants: the formation of spindle in a. is different; the mode of cytokinesis is di

15、fferent at the end of b. (3) meiosis: object: sexually transmitted organisms period: primordial germ cells form mature germ cells features: chromosomes are duplicated only once, and cells divide two times continuously results: the number of chromosomes in the newly created germ cells was reduced by

16、half than that of the original germ cells. major changes in chromosomes during sperm and egg formation: meiosis, first interphase, chromosome replication, prophase homologous chromosomes form four bodies (often cross crossing between non sister chromosomes), and metaphase chromosomes are homologous

17、on the equatorial plate, the latter chromosomes are separated at the same time, while the non homologous chromosomes are free; the second prophase of meiosis is stained the body is randomly distributed in the cell, the centromere of the metaphase chromosome is arranged on the equatorial plate, and t

18、he centromere of the later chromosome is divided and dyed separation of monomeric bodies. identification of the patterns of mitosis and meiosis: (in the case of diploid organisms) there are no homologous chromosomes in 1. cells. meiosis second division 2. having homologous chromosomes, forming four

19、bodies, arranged on an equatorial plate, or separating from each other. meiotic first division 3. homologous chromosomes do not have these particular behaviors. mitosis memory point: the result of 1. meiotic division is that the number of chromosomes in the newly created germ cells is less than half

20、 that of the original reproductive cell. during meiosis 2., homologous chromosomes in the association are separated from each other, indicating that chromosomes are independent of each other; two homologous when the chromosome moves toward which pole is random, different pairs of chromosomes (non ho

21、mologous chromosomes) can be freely combined. 3. the halving of the number of chromosomes in meiosis occurs in the first division of meiosis. 4. a spermatogonia undergoes meiosis to form four sperm cells, and sperm cells undergo complex changes to form sperm. 5. an egg cell undergoes meiosis, formin

22、g only one egg cell. 6. for sexually transmitted organisms, meiosis and fertilization are necessary for the maintenance of each organisms precursor cells the constancy of the number of chromosomes is important for biological inheritance and variation three 、 sex determination and sex linked inherita

23、nce (1) xy type of sex determination: the female has a pair of identical sex chromosomes (xx), and the male has a pair a heteromorphic sex chromosome (xy). meiosis produces spermatozoa that produce sperm containing the x chromosome and contain y staining somatic sperm. the female produced only one e

24、gg cell containing the x chromosome. fertilization occurs when x spermatozoa and y spermatozoa are associated with the chances of egg cell binding are equal, so the chances of male and female births are equal, with a ratio of 1:1. (2) recessive inheritance of x (such as color blindness, hemophilia,

25、drosophila wink, female, leaf shape, etc.) male patients are more than female patients it belongs to the cross (i.e. grandpa genetic atavism), daughter and grandson female patients whose fathers and sons are patients; males suffer from illness, and their mothers and females are at least carriers (3)

26、 recessive inheritance on the x chromosome (e.g., resistance to vd rickets, pendulum nystagmus) female patients are more than male patients. continuous generation. a male patient whose mother and daughter must be a patient. (4) genetic inheritance on the y chromosome (e.g., external auditory canal h

27、irsutism) father to son, pathogenic genes to children and grandchildren, with successive generations, also known as holandric. (5) the relationship between sexual inheritance and the law of segregation of genes: genes associated with sex, sex chromosomes, and sex chromosomes a pair of homologous chr

28、omosomes, the sex linked inheritance, in essence, conforms to the law of gene segregation. memory point: 1. chromosomes in living cells can be divided into two groups: chromosomes and sex chromosomes. there are two main ways of determining sex: one is xy, the other is zw. 2. characteristics of sexua

29、l inheritance: (1) the characteristics of x with autosomal recessive male patients than female patients; with atavism (due to the disease gene is on the x chromosome, which is usually passed through the daughter to the grandchild); the father and the son of the female patient must be suffering conve

30、rsely, the male patient must have been transmitted to the causative gene by his mother. (2) x chromosome dominant inheritance features: female patients are more than male patients, most of whom have continuous generation, that is, from generation to generation there are patients, male patients, moth

31、ers and daughters must be patients. (3) genetic characteristics associated with y chromosome: all patients are male; the causative gene, father, son, and offspring (xian xiong genetic). four. the nature of genes (1) dna is the major genetic material biological genetic material: in the whole biologic

32、al world, the vast majority of organisms are using dna as genetic material. dna biological (cellular structures of biological and dna viruses), dna is genetic material; only a small number of viruses (such as aids) there is no dna, only rna, and rna is genetic material, such as viruses, sars viruses

33、, avian influenza viruses, etc. prove the experimental design idea that dna is a genetic substance: try to separate dna from protein, individually and directly to observe the role of dna. (2) the structure and replication of dna molecules structure of dna molecule the basic unit of a.: deoxy nucleot

34、ides (consisting of phosphoric acid, deoxy ribose, and bases). b. long chain of nucleotides: polymerized by a certain order of deoxy nucleotides c. plane structure: d. spatial structure: regular double helix structure. e. structure features: diversity, specificity and stability. replication of dna a

35、. time: mitotic interval or the first division of meiosis b. features: edge resolution, edge replication, half preserving replication. c. conditions: templates (two strands of dna molecules), raw materials (four free deoxy nucleotides), enzymes (helicase), dna polymerase, dna ligase, etc., energy (a

36、tp) d. result: the dna molecule, like template dna, was generated by replication. e. meaning: the inheritance of genetic information to the offspring by replication keeps the continuity of genetic information. (3) the structure and expression of genes the concept of genes: genes are dna molecular fr

37、agments with genetic effects, and genes are arranged linearly in chromosomes. the process of protein synthesis by gene control: transcription: the formation of messenger rna by the pairing of bases with the template of one strand of dna. in the ribosome, messenger rna is used as a template to transp

38、ort rna as a vehicle for the synthesis of certain amino acids ordered protein molecules memory point: 1.dna is a substance that produces stable genetic changes in type r bacteria, and the various traits of bacteriophages are transmitted through dna the two experiments showed that dna is a genetic ma

39、terial. 2. the genetic material of all living things is nucleic acid. the cell contains both dna and rna and contains only dna biological inheritance the quality is dna, and the genetic material of a small number of viruses is rna. since the vast majority of biological genetic material is dna, so dn

40、a is the major genetic material. the variation of the order of 3. base pairs constitutes the diversity of dna molecules, and the particular alignment of base pairs, the specificity of each dna molecule is also formed. this explains the diversity and specificity of organisms from the molecular level

41、because. 4. the transmission of genetic information is accomplished by the replication of dna molecules. gene expression is controlled by dna proteins achieved by synthesis. the unique double helix structure of 5.dna provides a precise template for replication, and ensures replication by complementa

42、tion of base pairs capable of proceeding accurately. the reciprocal ratio between the two complementary chains is reciprocal. in the entire dna molecule, the purine sum of bases = sum of pyrimidine bases. in the entire dna molecule, the ratio is the same as for each chain in the molecule. the 6. off

43、spring are similar in character to their parents, because the offspring acquire a copy of parental reproduction of dna. seven genes are dna fragments with genetic effects, genetically arranged on chromosomes, and chromosomes are vectors of genes. 8. because different genes have different sequence of

44、 nucleotide (base order), so different genes are different genetic information. (i.e., the dna of the gene, the nucleotide order, represents the genetic information). the arrangement of the deoxyribonucleic acid of the 9.dna molecule determines the sequence of nucleotides in the messenger rna, messe

45、nger rna the arrangement of nucleotides determines the order of amino acids, and the arrangement of amino acids determines the protein the specificity of the structure and function, thus enabling organisms to exhibit a variety of genetic characteristics. genes control the synthesis of proteins: base

46、s base number due to: base number on mrna: amino acid number =6:3:1. the amino acid codon is the messenger rna on the three adjacent bases are not bases on the transport rna. transcription and translation strictly follow the principle of base complement matching. be careful：when paired, the a corres

47、ponds to u on the rna. 10. all genetic traits are controlled by genes. some genes control the metabolic process by controlling the synthesis of enzymes; another way in which genes control traits is by controlling the structure of protein molecules to directly affect traits. five, biological variatio

48、n (1) gene mutation the concept of a gene mutation: a gene caused by the addition, deletion, or alteration of base pairs in dna molecules structural change. the characteristics of gene mutation: a. gene mutation is widespread in the biological world, b. gene mutation is random occurrence of c. the f

49、requency of gene mutations is very low, d., most mutations are harmful to organisms, and e. mutations are non directional the significance of gene mutation: the basic source of biological variation, which provides the initial raw material for biological evolution. types of gene mutation: natural mut

50、ation and induced mutation application of artificial mutation in breeding: the frequency of variation can be improved by artificial mutation, and the breeding can be improved greatly matter character. (2) chromosomal variation variation of chromosome structure: deletion, addition, inversion, translo

51、cation. such as: criduchat syndrome. variation in the number of chromosomes: including the increase or decrease of individual chromosomes in cells and the multiplication of chromosomes in groups land increase decrease. chromosome group characteristics: a, a chromosome group does not contain homologo

52、us chromosome b, a chromosome contained in the group of dyeing the body shape, size, and function vary. c, a genome, contains a whole set of genes that control biological traits diploid or polyploid: an individual that develops from fertilized eggs and contains several chromosomes in a somatic cell

53、an unfertilized germ cell (sperm or egg cell) that develops into haploid (possibly 1 or more genomes). methods to induce polyploid: germination seeds and seedlings were treated with colchicine. principle: when akimizu sensuku used in dividing cells to inhibit cell division, prophase spindle formatio

54、n, resulting in non separation of chromosomes, thereby causing doubling the number of chromosomes in cells. the characteristics of polyploid plants: stout stem, leaves, fruits and seeds are relatively large, nutrients, carbohydrates and protein etc. the quality has increased. the haploid plant chara

55、cteristics: plants grow small and highly sterile. methods: anther haploid plants were obtained from xiupei keep. the significance of haploid breeding: significantly shorten the breeding years (only two years). memory point: the 1. chromosome group is a group of non homologous chromosomes in cells, w

56、hich differ in shape and function, but the carrier controls a complete set of information about biological growth, heredity, and variation. such a group of chromosomes is called a genome. 2. heritable variation is a change in genetic material, including gene mutation, gene recombination, and chromos

57、omal variation. gene mutation the biggest feature is the creation of new genes. it is a change in genes at one locus of a chromosome. genetic mutations are common, it also occurs randomly and has a low mutation rate, most of which are harmful to organisms, and the mutations are not directional. a ge

58、netic mutation is the root of a biological variation this source provides initial material for biological evolution. gene recombination is a combination of the original genes of the organism and is not productive genes that are newly created, but are genetically inserted into an individual by crossi

59、ng the genes that are not in the same body. sexual reproduction the process of gene recombination provides a very rich source of biological variation. this is an important reason for the formation of biodiversity one of them is of great significance to biological evolution. these two variants are no

60、t visible under the microscope, but the chromosomes change the difference is that the structure and number of chromosomes change, and the microscope can clearly see. this is the most important difference between the former and the two. the change involves chromosome changes. such as structural chang