A-level生物学词汇

absorption spectrum

the spectrum obtained when radiation (light, ultraviolet radiation, etc.) from a source giving a continuous spectrum is passed through a substance.

吸收光谱

acrosome reaction

that series of observable, structural changes undergone by a sperm when in the vicinity of an ovum in the oviduct. Specifically, many openings appear in the sperm head membrane, through which the contents of the acrosome appear to be released.

顶体反应

actin

A globular contractile protein. In muscle cells, actin interacts with another protein, myosin, to bring about contraction.

肌动蛋白

adenine

a purine base that is an essential constituent of the nucleic acids and  also of such coenzymes as NAD and FAD

腺嘌呤

age structure

of a population, the number of individuals in each of several or many age categories

年龄结构

allele

alternative forms of a gene for a particular characteristic (e.g., attached earlobe genes and free earlobe genes are alternative alleles for ear shape).

等位基因

allelopathy

a chemical interaction between organisms in which one organism suppresses the germination, growth, or reproduction of the other by releasing toxins into the environment. It occurs particularly between freshwater animals, flowering plants, bacteria, and fungi.

异种化感

allopatric speciation

the development of distinct species through differentiation of populations in geographic isolation

异域物种形成

analogy

a resemblance in function, and often appearance as well, between structures which is due to convergence in evolution rather than to common ancestry. (contrast with homology)

相似，同工

anaphase

the third stage of mitosis, during which the centromeres split and the chromosomes move to the pole

后期

ascomycetes

a female reproductive structure of some ascomycetes in which plasmogamy occurs prior to ascus formation

子囊菌

ascus

the characteristic structure producing sexual spores in the ascomycetes.

子囊

basal body

A body identical in structure to a centriole, found always at the base of a cilium or eukaryote flagellum

基体

basidiocarp

a fruiting body of the higher basidiomycete fungi. Basidiocarps are the most obvious manifestations of these fungi and include mushrooms, toadstoodls, and similar bodies.

担子果

basidiomycetes

a group of mycelia funigi whose sexual reproduction results in the formation of basidia, which (except in the rusts and smuts) are borne on basidiocarps

担子菌纲

basidium

the characteristic structure producing sexual spores in the Basidiomycetes.

担子

big bang

an explosion producing a pressure oscillation of the order of a millinar or more at a distant point on the Earth. E.g., the eruption of Krakatoa in 1883. Large nuclear fusion explosions are comparable

大爆炸

binomial system of nomenclature

uses two Latin names, genus and species, for each type of organism

双名法

blastomere

one of several small cells formed form an animal zygote during cleavage.

卵裂球

blastula

The stage of the early animal embryo that succeeds cleavage and precedes gastrulation. A blastula is usually made up of a hollow ball of cell, with a wall one to several cells thick; the central cavity is the blastocoel.

囊胚

C3 plant

A plant in which the light-independent reactions of photosynthesis start with a three-carbon compound. Most plants are C3 plant

C3植物

C4 plant

a plant such as corn in which the light-independent reactions of photosynthesis start with a four-carbon compound

C4植物

Calvin-Benson cycle

cyclic reactions that are the "synthesis" part of the light-independent reactions of photo synthesis. In land plants, RuBP, or some other compound to which carbon has been affixed, undergoes rearrangements that lead to formation of sugar phosphate and to regeneration of RuBP. the cycle runs on ATP and NADPH from light-dependent reactions.

卡尔文-本森循环

carotenoid

Light-sensitive, accessory pigments that transfer absorbed energy to chlorophylls. They absorb violet and blue wave-lengths but transmit red, orange and yellow.

类萝卜素

carrying capacity

the maximum number of individuals in a population (or species) that can be sustained indefinitely by a given environment

容纳量

cell plate

a plate cell structure that begins to form in the center of the cell and proceeds to the cell membrane, resulting in cell cytokinesis

细胞板

centriole

An organelle located close to the nucleus in most animal and lower plant cells but absent from prokaryotes and higher plants.

中心粒

centromere

the small area of  a chromosome that d【北京环球教育】oes not stain with basic dyes during mitosis and meiosis; at interphase it is single while the rest of the chromosome is made up of two chromatids

着丝粒

chalone

substances found in mammalian tissue homogenates that, when applied to intact tissue cells, inhibit mitosis, particularly in the presence of adrenaline and corticosteroids

抑素

character displacement

an alternation of the traits of a species as a result of competition or other interactions with associated species.

特征替换

chemotaxis

A locomotors movement of an organism or cell in response to, and directly by, an external directional stimulus.

趋化性

chlorophyll

the green substance of plants by which photosynthesis is accomplished; it is usually localized in intracellular organelles called chloroplasts.

叶绿素

chloroplast

A plastid in which photosynthesis is carried out. Chloroplasts occur in all photosynthetic organisms except photosynthetic bacteria and blue-green algae.

叶绿体

chloroplast

a plastid in which photosynthesis is carried out. Chloroplasts occur in all photosynthetic organisms except photosynthetic bacteria and blue-green algae.

叶绿体

chromatid

a replicated chromosome physically attached to an identical chromatid at the centromere.

染色单体

chromatin

the material of which the chromosomes are composed. DNA and protein are the main constituents of chromatin, most of the protein being histone

染色质

chromosome

A DNA-histone thread residing in the nucleus of a cell. Each chromosome possesses two telomeres and a centromere, and some contain a nucleolus organizer. RNA proteins are in variably associated with the chromosome.

染色体

cilia

Numerous short, hairlike structures projecting from the cell surface that enable locomotion

纤毛

clade

in a cladistics classification, organisms are placed into taxonomic groups called clades when they share characteristics that are thought to indicate common ancestry.

进化枝

class

a group used in the classification of living organisms. A class consists of a number of similar or closely related orders or occasionally of only one order. Classes are usually large and easily recognized groups.

纲

cline

a smooth gradation of characteristics from one end of the range of a species to the other usually brought about by gradients of climate, soil, or other environmental variables.

梯度变异

coacervate

a collection of organic macromolecules surrounded by water molecules that are aligned to form a sphere

团聚层

compensatory hypertrophy

see regeneration

代偿性肥大

conidium

an asexual spore of certain fungi that is abstracted from the tip or the side of special hyphae called conidiophores. Conidia may consist of one cell or of several cells; in the latter case the septa may be longitudinal, transverse, or mixed

分生孢子子实体

continental drift

the theory that the present continents result from the break-up of a larger continent and have moved independently to their present positions

大陆漂移

convergent evolution

an evolutionary pattern in which widely different organisms show similar characteristics.

趋同进化

core

the core of the Earth is that part lying below the mantle

核心

crust

the crust of the earth is the outer shell of the Earth, defined by its composition and the properties of some seismic waves.

地壳

cyclic photophosphorylation

cyclic photophosphorylation is coupled to cyclic electron flow, in which ATP is the only product.

循环式光合磷酸化

cytokinesis

胞质分裂

cytoplasm

The living contents of a cell bounded externally by the plasmalemma, including an aqueous ground substance (hyaloplasm, cell sap, or cell matrix) containing organelles and various inclusions but excluding the nucleus and visible vacuoles.

胞质

cytosine

a single-ring nitrogenous base molecule in DNA and RNA. It is complementary to guanine.

胞嘧啶

cytoskeleton

Of eukaryotic cells, an internal “skeleton”. Its microtubules and other components structurally support the cell, organize and move its internal components. The cytoskeleton also helps free-living cells move through their environment.

细胞骨架

dedifferentiation

the loss of differentiation, as in the vertebrate limb stump during formation of a blastema

去分化

density-dependent factors

population-limiting factors that become more effective as the size of the population increases

密度制约因子

density-independent factors

population-controlling factors that are not related to the size of the population increase

非密度制约因子

dibybrid cross

a cross between individuals that differ with respect to two specified gene pairs.

双因子杂交

differentiation

the complex of changes involved in the progressive diversification of the structure and functioning of the cells of an organism. For a given line of cells, differentiation results in a continual restriction of the types of transcription that each cell can undertake

分化

diploid

any nucleus, cell or organism that possesses twice the haploid number of chromosomes

二倍体

divergent evolution

a basic evolutionary pattern in which individual speciation events cause many branches in the evolution a group  of organisms.

趋异进化

division

a unit used in the classification of plants. A division consists of a number of classes, or occasionally of only on class, with certain important characeristics in common

门

DNA-polymerase

an enzyme that bring new DNA triphosphate nucleotides into position for bonding on another DNA molecule

DNA聚合酶

dominant

the member of a pair of alleles that shows its effect in the phenotype whatever other allele is present

显性的

double helix

the three-dimensional structure of double-stranded DNA

双螺旋

dynein

A group of at least four distinct proteins found in the flagella and microtubules of eukaryotic cells and possessing ATPase activity.

动力蛋白

ectoderm

the outermost of the germ layers of metazoan embryos. It develops mainly into epidermal tissue, the nervous system, sense organs, and (in lower forms) the nephridia.

外胚层

endoderm

the innermost of the germ layers of metazoan embryos

内胚层

Endoplasmic reticulum

Folded membranes and tubes throughout the eukaryotic cell that provide a large surface upon which chemical activities taken place.

内质网

extinction

in genetics, inhibition of the experssion of differentiated properties in hybrid cells from differentiated and undifferentiated parental cells

灭绝

exponential growth curve

pattern of population growth in which greater and greater numbers of individuals are produced during the successive soubling times; the pattern that emerges when the per capita birth rate remains even slightly above the per capita death rate, putting aside the effects of immigration and emigration

指数生长曲线

family

a unit used in the classification of plants and animals. A family consists of a number of closely related or similar genera or occasionally of only one genus. Family names end in -aceae or -ae in botany and in -ideae in zoology.

科

fertilization

the joining of haploid nuclei, usually from an egg and a sperm cell, resulting in a diploid cell called the zygote.

受精

flagella

Long, hairlike structures projecting from the cell surface that enable locomotion.

鞭毛

Fungi Imperfecti

a group of fungi with septate mycelia in which sexual reprodcution is either lacking or is not known. Many of these fungi are of great importance as they cause diseases in plants, animals, and man.

半知菌亚门

gametangium

a gamete-producing structure or sex organ in plants, i.e. an antheridium, oogonium, or archegonium.

配子囊

gastrula

the stage in the development of animals embryos that follows the blastula and results from gastrulation. The cells of a gastula are differentiated into the germ layers and the central cavity opens to the exterior by the blastopore.

原肠胚

gastrulation

The process in the animal embryo by which a blastula is converted into a gastrula, with the laying down of the germ layers.

原肠胚形成

gene

a unit of heredity located on a chromosome and composed a sequence of DNA nucleotides

基因

gene amplification

a temporary dramatic increase in the numbers of a particular gene in a genome during one developmental period.

基因扩增

genotype

the catalog of genes of an organism, whether or not these genes are expressed

基因型

genus

a unit used in the classification of plants and animals. A genus consists of a number of closely related species, and members of the same genus often have a number of obvious characteristics in common by which they can clearly be seen to be related.

属

germ plasm theory

a substance thought to be transmitted in the gametes (germ cells) in an unchanged form from generation to generation. The germ plasm was believed to be unaffected by the environment and to give rise to the body cells.

种质学说

Golgi complex

A stack of flattened, smooth, membranous sacs; the site of synthesis and packaging of certain molecules in eukaryotic cells.

高尔基复合体

guanine

a double-ring nitrogenous base molecule in DNA and RNA. It is the complementary base of cytosine

鸟嘌呤

haploid

any nucleus, cell or organism that possesses a single set of unpaired chromosomes.

单倍体

haustorium

a specialized structure of some parasitic plants (e.g., dodder, mistletoe etc) which penetrates into the vascular bundles of the host plant to obtain nourishment

吸器

heterokaryon

in somatic cell genetics, the state when two cells have fused but their nuclei have not yet fused.

异核体

heterozygous

a diploid organism that has two different allelic forms of a particular gene

杂合的

histone

one of a group of simple proteins that have a high content of the basic amino acids arginine or lysine and are found associated with nucleic acids in the chromatin of eukaryotic cells.

组蛋白

homologous pair

chromosomes that pair during meiosis. Each homologue is a duplicate of one of the chromosomes contributed at syngamy by the mother or father. Homologous chromosomes contain the same linear sequence of genes and as a consequence each gene is present in duplicate.

同源染色体对

homology

a similarity between two structures that is due to inheritance from a common ancestor. The structures are said to be homologous. (contrast with analogy)

同源性

homozygous

a diploid organism that has two identical alleles for particular characteristic.

纯合的

hybrid sterility

the failure of hybrids between different species to produce viable offspring

杂种不育性

hyphae

fungal filaments that develop from the growth of germinating spores. They are the fundamental elements of a mycelium.

菌丝

incomplete dominance

the condition in which two allelic genes have a different effect when they are together as a heterozygote in a diploid cell than either of them have in the homozygous state

不完全显性

interphase

in a cell preparing to duplicate, the interphase stage can divide into a period of initial growth (G1), a period of DNA synthesis (S), and a second growth period (G2).

中期

interspecific competition

Two-species interaction in which both species can harmed due to overlapping niches.

种间竞争

intraspecific competition

interaction among individuals of the same species that are competing for the same resources

种类竞争

karyotype

the appearance of the chromosome complement of an organism or cell

核型

kingdom

in biology, a major category into which living material is classified.

界

law of independent assortment

members of one gene pair will separate from each other independently of the members of other gene pairs

自由组合定律

law of segregation

when gametes are formed by a diploid organism, the alleles that control a trait separate from one another into different gametes, retaining their indiciduality.

分离定律

lichen

thallophytic plants composed of a fungus and an algae in such close symbiosis that they form a vegetative plant body that is morphologically different from either of the constituents.

地衣

light-dependent reactions

the first stage in photosythesis, driven by light energy. Electrons that trap the sun's energy pass the energy to high-energy carriers such as ATP or NAPDH, where it is stored in chemical bonds.

光反应

light-independent reactions

the second stage of photosythesis, also called the Calvin-Benson cycle, which does not require light. During the six steps of the cycle, carbon is fixed and carbohydraes are formed.

暗反应

liposome

a vehicle formed by the homogenization (emulsification) of phospholipids in dilute salt solutions. Liposomes are the prototypes of membrane-bound biologic structure.

脂质体

logistic growth curve

pattern of population growth in which a low density population slowly increases in size, goes through a rapid growth phase, then levels off once the carrying capacity is reached.

逻辑生长曲线

lysosome

A specialized organelle that holds a mixture of hydrolytic enzymes

溶酶体

macroevolution

the large-scale patterns, trends, and rates of change among groups of species.

大进化

mantle

the part of the interior of the Earth between the crust and the core

地幔

meiosis

the process by which a nucleus divides into four daughter nuclei, each containing half the number of chromosomes of the parent nucleus.

减数分裂

mesoderm

the middle layer of the three germ layers of triploblastic animal embryos. It develops into cartilage, bone, muscle, blood, kidneys, and gonads.

中胚层

metaphase

the second stage in mitosis, during which the chromosomes align at the equatorial plane

中期

metaphase plate

the grouping of the chromosomes in a plane at the equator of the spindle during the metaphase stage of mitosis.

中期板

microevolution

changes in allele frequencies brought about by mutation, genetic drift, gene flow, and natural selection.

种内进化

Microfilament

Long, fiber-like structures made of protein and found in cells, often in close association with the microtubules; provide structural support and enable movement.

微丝

microtubule

Small, hollow tubes of protein that function throughout the cytoplasm to provide structural support and enable movement

微管

mitochondrion

A membranous organelle resembling a small bag with a larger bag inside that is folded back on itself; serves as the site of aerobic cellular respiration.

线粒体

mitosis

process that results in equal and identical distribution of replicated chromosomes into two newly formed nuclei

有丝分裂

morphogenesis

the developmental processes leading to the characteristic mature form of an organism or part of an organism.

形态发生

mortality

the number of individuals leaving the population by death per thousand individuals in the population

死亡率

mycelium

the tangled mass of hyphae that forms the  vegetative body (sometimes termed a thallus) of a fungus.

菌丝体

myosin

A protein that, with actin, constitutes the principal element of the contractile apparatus of muscle

肌球蛋白

natality

the number of individuals entering the population by reproduction per thousand individuals in the population

出生率

neurulation

developmental stage in an embryo during which the cells differentiate into the brain and spinal cord

神经胚形成

noncyclic photophosphorylation

Noncyclic photophosphorylation is coupled to noncyclic electron flow, the electrons bing used to reduce NADP+ as well as to make ATP.

非循环式光合磷酸化

nondisjunction

the failure of separation of paired chromosomes at metaphase, resulting in one daugther receieving both and the other daughter cell none of the chromosomes in question. None-disjunction can occur during a meiotic or mitotic division

不分离

Nuclear envelop

A double membrane (two lipid bilayer and associated proteins) that is the outermost portion of a cell nucleus.

核膜

Nucleoid

The DNA-containing area of a prokaryote cell, analogous to the eukaryote nucleus but not membrane bounded.

拟核

nucleoli

Nuclear structures composed of completed or partially completed ribosomes and specific parts of chromosomes that contain the information for their construction

核仁

nucleoside

a purine or pyrimidine base attached to ribose or deoxyribose. The necleosides, commonly found in DNA and RNA are: cytidine, cytosine deoxyriboside, thymidine, uridine, adenosine, adenine deoxyriboside, guanosine, and guanine deoxyriboside. Note that thymidine is a deoxyriboside and cytidine, uridine, adenosine, and guanosine are ribosides.

核苷

nucleosome

the basic unit of chromatin structure in eukaryotic cells. A nucleosome consists of eight histone molecules of four different types, together with about 140 base pairs of DNA coiled around it.

核小体

nucleus

The organelle of the eukaryote cell that contains the chromosomes and hence ultimately controls cellular activity and inheritance through the activity of the genetic materials, DNA

细胞核

Okazaki fragment

a short sequence of DNA that is the primary product of DNNA polymerase during DNA replication.

冈崎片段

one-gene-one enzyme hypothesis

the hypothesis that a large class of gene exist in which each gene controls the synthesis or activity of but a single enzyme. Since enzymes and other proteins whose syntheses are controlled by more than one gene are now known, this hypothesis has been replaced by the one-gene-one polypeptide hypothesis.

一基因一酶假说

one-gene-one -polypeptide hypothesis

the hypothesis that a large class of gene exist in which each gene controls the synthesis or activity of but a single peptide. The polypeptide may function independently or as a subunit of a more complex protein.

一基因一多肽假说

oogenesis

the specific name given to the gametogenesis process that leads to the formation of eggs

卵子发生

order

a unit used in the classification of plants and animals. An order consists of a number of similar or closely related families or only on family. Names of orders end typically in -ales in plants and in -a in animals.

目

organogenesis

the formation of organs

器官发生

ovaries

the female sex organs the produce haploid sex cells, the eggs or ova

卵巢

oviduct

the tube (fallopian tube) that carries the primary oocyte to the uterus

输卵管

ovum

an unfertilized non-motile female gamete. In many animals it is produced in the ovary

卵子

ozone layer

a layer of the atmosphere, about 20~50 km above the surface, which contains ozone produced by ultraviolet radiation.

臭氧层

pangenesis

the theory of heredity postulating that germs, humors, or essences migrate from individual body cells to the sex organs and contribute to the gametes.

泛生论

parallel evolution

the evolution of organisms that were originally very similar and have both evolved in the same direction. (contrast with convergent evolution)

平行进化

parthenogenesis

reproduction in which eggs develop normally without being fertilized by a male gamete, producing an individual usually genetically identical to the parent.

孤雌生殖

phagocytosis

The process by which the cell warps around a particle and engulfs

吞噬作用

phenotype

the physical, chemical, and psychological expression of genes possessed by an organism.

表现型

photon

a particle that has zero mass  or charge and unit spin, the quantum of the electromagnetic force.

光子

photophosphorylation

the synthesis of ATP from phosphate and ADP during photosynthesis, using light energy

光合磷酸化

photorespiration

a light-dependent type of respiration that occurs in most photosynthetic plants and differs from normal (or dark) respiration

光呼吸

photosynthesis

the synthesis of organic compounds by reduction of carbon dioxide using light energy absorbed by chlorophyll

光合作用

photosystem

one of the clusters of light-trapping pigments embedded in photosynthetic membranes. Photosystem I operates during the cyclic pathway; photosystem II operates during both the cyclic and noncyclic pathways.

光合系统

phylogeny

evolutionary relationships among species, starting with most ancestral forms and including the branches leading to their descendants.

系统发生

phylum

a unit used in the classification of animals. A phylum consists of a number of classes, or occasionally of only one class, with certain important characteristics in common, implying that all members are descended from a common ancestor.

门

pinocytosis

The process by which a cell engulfs some molecules dissolved in water

胞饮作用

plastid

An organelle present in all plants except bacteria, blue-green algea, and fungi; it is enclosed by two membranes and has various functions.

质体

polysome

Of protein system, several ribosomes all translating the same the same messenger RNA molecule, one after the other

多核糖体

population density

the number of individuals of a population that are living in a specified area or volume

种群密度

primitive streak

a longitudinal band of embryonic mesodermal cells that develops within a dorsal groove along the length of the gastrula of mammals and birds

原条

prophase

the first stage of mitosis, during which individual chromosomes become visible

前期

proteinoid

a proteinlike structure of branched amino acid chains that is the basic structure of a microsphere.

类蛋白

punctuated equilibrium

evolutionary theory that holds that morphological changes occur rapidly in time; during speciation these changes occur in small populations with the resulting new species being distinct from the ancestral form. After speciation, species retain much the same form until extinction; distinct from the phyletic gradualism theory.

间断平衡

punnett square

a method used to determine the probabilities of combination in a zygote.

旁纳特方格

purine

one of a group of nitrogenous bases whose parent compound has the formula shown. The two most abundant purines are adenine and guanine, which are constituents of nucleic acids and coenzymes

嘌呤

pyrimidine

a heterocyclic organic compound, C4N4N2, the fundamental form of pyrimidine bases. Some of these bases are constituents of nucleic acid.

嘧啶

recessive

the number of a pair of alleles that does not show its effect in the presence of any other allelic partner.

隐性的

regeneration

the replacement by an organism of tissues or organs that have been lost

再生

replication fork

a point at which the two strands of a DNA double helix are unknown and separated during replication

复制叉

rhizoid

one of many uni- and multicellular filamentous outgrowths that are produced by some algae and by the gametophytes of bryophytes and peridophytes and function as roots.

假根

ribosome

Small structures composed of two proteins and ribonucleic acid subunits involved in the assembly of proteins from amino acids.

核糖体，核蛋白体

ribulose biphosphate (RuBP)

a compound with a backbone of five carbon atoms that is required for carbon fixation in the Calvin-Benson cycle of photosynthesis.

核酮糖二磷酸

saprobe

an organism that lacks the ability of photosythesis, and lives on dead or decaying organic matter, a saprophyte.

腐生菌

semiconservative replication

the method of replication of DNA in which the molecule divides longitudinally, each half being conserved and acting as a template for the formation of a new strand

半保留复制

septate

divided by a septum

有隔膜的

species

a unit used in the classification of plants and animals. Ideally a species is defined as a group of organisms that interbreed with each other to produce fertile offspring.

物种

sperm

cells that develop from the spermatids by losing much of their cytoplasm and developing long tails; the male gamete.

精液

spermatogenesis

the specific name given to the gametogenesis process that leads to the formation of sperm

精子发生

spindle

an array of microtubules extending from pole to pole and used in the movement of chromosomes

纺锤体

sporangium

a cell within which spores or sporelike bodies are borne. Generally, it is an asexual structure of certain fungi.

孢子囊

stroma

Region within a chloroplast that has no chlorophyll

子座，基质

survivorship curve

a plot of the age-specific survival of a group of individuals in a given environment, from the time of their birth until the last one dies

存活曲线

sympatric speciation

speciation that follows after ecological, behavioral, or genetic barrier arise within the boundaries of a single population. This can happen instantaneously, as when polyploidy arises in type of flowering plant that can self-fertilize or reproduce asexually.

同域物种形成

taxon

a unit of classification of any rank in the hierarchical scale

分类单位

taxonomy

the study of the theory, procedure, and the rules of classification of organisms according to the similarities and differences between them.

分类学

telophase

the last stage in mitosis during which daughter nuclei are formed.

末期

test cross

a cross between a heterozygote of unknown genotype and an individual homozygous for the recessive genes in question.

测交

thylakoid

one of the number of flattened fluid-filled sacs that form the photosynthetic lamellar system of chloroplasts, photosynthetic bacteria, and blue-green algae.

类囊体

thymine

A single-ring nitrogenous base molecule of DNA but not RNA. It is complementary to adenine.

胸腺嘧啶

tubulin

A protein that is the major constituent of microtubules

微管蛋白

vacuole

Storage container within the cytoplasm of a cell having a surrounding membrane

液泡

X-ray diffraction

a technique for determining the arrangement of atoms in a crystalline substance by analysing the diffraction patterns produced when a narrow beam of X-rays is passed through the substance. X-ray diffraction has contributed to the elucidation of structure of many biological molecules, including some improtant macromolecules, e.g.,DNA, haemoglobin, myoglobin.

X-射线衍射

yolk

the store of food material, mostly protein and fat, that is present in the eggs of most animals.

卵黄

zygote

a diploid cell that results from the union of an egg and a sperm

合子