遗传学期末考试复习资料

遗传学期末考试复习资料

遗传复习资料————（⽩痴粗略版，参考要慎重，呵呵！另外没按⽼师讲课的顺序）Lecture Contents

1. Introduction.

2. Three laws of genetics.

3. The chromosome theory of inheritance.

4. The mapping and analysis of genomes.

5. Genetics of genomes.

6. Quantitative genetics.

7. Population genetics.

8. Gene functions in molecular level.

9. Extranuclear inheritance.

10. Gene mutation and epigenetic variation.

11. Genetic recombination and transposon.

12. Developmental genetics（待定）.

2.Three laws of genetics.

基因的分离定律，⾃由组合定律，连锁与互换定律Segregation

An individual inherits a unit of information (allele) about a trait from each parent During gamete formation, the allelessegregate from each other

Independent assortment

Traits are not inherited together

In forming the gametes, the “Factors” for any two traits assort independently from one another

Mendel concluded that the two “units”for the first trait were to be assorted into gametes independently of the two “units”forthe other trait

Members of each pair of homologous chromosomes are sorted into gametes at random during meiosis

连锁与互换定律：处在同⼀染⾊体上的两个或两个以上基因遗传时，联合在⼀起的频率⼤于重新组合的频率；在配⼦形成的过程中，同源染⾊体的⾮姊妹染⾊单体间发⽣局部交换的结果导致重组类型的产⽣。What are the advantages of peas?

Large # of pea varieties

Peas are small, easy to grow, short generation time

Peas can self-fertilize; bisexual

Dominance显性=the ability of one allele to express its phenotype at the expense of an alternate allele; the major form ofinteraction between alleles; generally the dominant allele will make a gene product that the recessive can not; therefore thedominant allele will express itself whenever it is present

Recessive隐性= an allele whose expression is suppressed in the presence of a dominant allele; the phenotype thatdisappears in the F1 generation from the cross of two pure lines and reappears in the F2 generation Genotype = the genes of an organism; for one specific trait we use two letters to

represent the genotype. A capital letter represents the dominant form of a gene (allele), and a lowercase letter is theabbreviation for the recessive form of the gene (allele).

Phenotype = the physical appearance of a trait in an organism

Allele --one alternative form of a given gene pair; tall and dwarf are the alleles for the

height of a pea plant; more than two alleles can exist for any specific gene, but only two of them will be found within anyindividual

Allelic pair 等位基因对 = a combination of two alleles

Homozygote = an individual which contains only one allele at the allelic pair; for

example DD is homozygous dominant and dd is homozygous recessive; pure lines are homozygous for the gene of interest

Heterozygote = an individual that contains two different alleles at the allelic pair; for

example the Dd heterozygote

Backcross = the cross of an F1 hybrid to one of the homozygous parents; for pea

plant height the cross would be Dd x DD or Dd x dd; most often, though a backcross is a cross to a fully recessive parent

Testcross = the cross of any individual to a homozygous recessive parent; used to

determine if the individual is homozygous dominant or heterozygous

Monohybrid 单因⼦杂种= the offspring of two parents that are homozygous for

alternate alleles of a gene

Monohybrid cross = cross between parents that differ at a single allelic pair (usually

AA x aa)

sex-linked inheritance 伴性遗传Exceptions to Mendelian Genetics

Phenotype = Genotype + EnvironmentCrop Yield = Genotype+ Minerals+ Water+ Light- Pests

etc.

Human Skin Color = Genotype+ Sun (UV) Exposure- Aging Factors

All of the characters studied by Mendel had traits that were dominant or recessive

* For many characters the 2 alleles give a blended result

* Example: flower color in snapdragons(⾦鱼草)

* Blending of this sort is called incomplete dominance（不完全显性）

* In another type of blending both alleles seem to assert their whole effect; example- blood group antigens(see multiplealleles section below); this is called codominance （共显性）

* Dominance may depend upon which function of the gene is monitored: Example sickle cell anemia(镰⼑型贫⾎症) gene

* Sickle cell gene acts like a recessive in producing anemia

* Hemoglobin（⾎⾊素）mutation, causes hemoglobin to form crystals, damaging red blood cells

* AA = normal (A is normal hemoglobin allele)

* AS = heterozygous, relatively normal (no anemia)

* SS = homozygous for sickle gene, causes severe anemia

* If you look at the amount of hemoglobin produced the alleles look like they are codominant

* AS person produces 50% hemoglobin A, 50% hemoglobin S

Multiple Alleles

Example: ABO blood groups in humans

* 3 alleles: A, B, O

* A & B dominant over O

* A & B codominant to each other

* Type O produces no sugar antigens

* 6 genotypes and 4 phenotypes

* Phenotype can be determined by treating drops of blood with antisera which react with the A or B sugar groups