Genetic Disorders Caused by Abnormal Numbers of Sex Chromosomes and Autosomes

Trisomy X (XXX)

1/1000 women no detectable defects higher incidence of below-normal intelligence fertile bear normal children

Xyy Males

1/1000 males below-average intelligence above-average height

2/3 of XYY males are over 6 feet tall average height is 5 feet 9 inches

genetically predisposed to violence

a rather high percentage of men in prison but only a tiny percent of them commit crimes

Trisomy 21, or Down syndrome

1/900 births extra copy of the 21^st chromosome weak muscle tone

small mouth held partially open distinctively shaped eyelids

low resistance to infectious diseases heart malformation mental retardation

1/25 learns to read 1/50 learns to write

Render in English.

Признаки, сцепленные с полом

У человека Х-хромосома содержит много генов, тогда как в Y-хромосоме их очень мало – это главным образом гены, определяющие мужской пол. Признаки, контролируемые генами, локализованными в X-хромосоме, называются сцепленными с полом, так как наследование их связано с наследованием пола. Потомки мужского пола получают свою единственную X-хромосому от матери; поэтому от матери же они наследуют и все гены, определяющие признаки, сцепленные с полом. Потомки женского рода получают по одной Х-хромосоме от матери и от отца. В мужской зиготе, имеющей лишь одну Х-хромосому, содержится только по одному гену из каждой пары генов, локализованных в Х-хромосоме.

У человека гены гемофилии и цветовой слепоты находятся в Х-хромосоме и наследование этих аномалий сцеплено с полом. Гемофилия – болезнь, при которой нарушено свертывание крови, так что даже небольшой порез приводит к обильному кровотечению. Мутантный ген гемофилии обусловливает отсутствие так называемого антигемофилического глобулина – одного из веществ, участвующих в механизме свертывания крови. Этот сцепленный с полом рецессивный ген встречается сравнительно редко; гемофилия обычно проявляется у мужчин, так как у женщин для ее проявления должно быть два аномальных гена. Однако даже среди мужчин это очень редкое заболевание; у женщин оно вообще оставалось неизвестным до 1951 года, когда был описан один-единственный случай. Английская королева Виктория была гетерозиготна по гену гемофилии и передала его некоторым из своих детей и внуков.

Сцепленным с полом заболеванием, наследуемым по рецессивному типу, является также одна из форм цветовой слепоты, при которой человек неспособен отличать красный цвет от зеленого. Этим дефектом зрения страдает около 4% мужского населения, но менее 1% женского. Так же как и в случае гемофилии, для его проявления у женщины необходимы два гена, а у мужчины – только один.

Unit 9 Fungi

Introduction

How do fungi affect humans? Listen to the text and answer the question.

Reading

I. After reading the text below fill in the Table 8.1.

Table 8.1. The Major Divisions of Fungi

Common Name (Division)	Reproductive Structures	Cellular Characteristics	Economic and Health Impacts	Representative Genera
Zygote fungi (Zygomycota)	Produce sexual diploid zygospores	Cell walls contain chitin; septa are absent	Cause soft fruit rot and black bread mold	__________________________________
Sac fungi (___________)	__________________________	Cell walls contain chitin; septa are present	__________________________________	Saccharomyces (yeast); Ophiostoma (causes Dutch elm disease)
_____________ (Basidiomycota)	Sexual reproduction involves production of haploid basidiospores on club-shaped basidia	Cell walls contain chitin; septa are present	___________________________________________________	___________________________________________________
Imperfect fungi (____________)	__________________________	Cell walls contain chitin; septa are present	__________________________________	Penicillium (produces penicillin); Arthrobotrys (nematode predator)

Although nearly 100,000 species of modern fungi have been described, biologists have only begun to comprehend the diversity of these organisms – at least 1000 additional species are described each year. Like plants, fungi are grouped into divisions, which are comparable to animal phyla. The major divisions of fungi are the Zygomicota (zygote fungi), Ascomycota (sac fungi), Basidiomycota (club fungi), and Deuteromycota (imperfect fungi) (Table 1).

The zygomycetes, also called the zygote fungi, include about 600 species. Familiar – and annoying – zygomycetes are those of the genus Rhizopus, which cause soft fruit and black bread mold. The haploid hyphae of zygomycetes appear identical but are actually two different mating types. The two types “mate sexually”, fusing their nuclei to produce diploid zygospores. These resistant structures are dispersed through the air and can remain dormant until conditions are favorable for growth. Zygospores then undergo meiosis and germinate into structures that bear haploid spores. The spores then give rise to new hyphae. These hyphae may reproduce asexually, by forming haploid spores in black spore cases called sporangia, or sexually, by fusing to produce more zygospores.

The 30,000 species of ascomycetes, also called sac fungi, are named after the saclike case, or ascus (plural, asci), in which their spores form during sexual reproduction. Some ascomycetes live in decaying forest vegetation and form beautiful cup-shaped reproductive structures or corrugated, mushroomlike fruiting bodies called morels. This division also includes many of the colorful molds that attack stored food and destroy fruit and grain crops and other plants. Some ascomycetes secrete the enzymes cellulase and protease, which can cause significant damage to cotton and wool textiles, especially in warm, humid climates where molds flourish. Ascomycetes cause both Dutch elm disease and chestnut blight, but other ascomycetes are a boon to plants, forming mutually beneficial associations with plant roots. A gastronomic delicacy, the truffle, is also a member of this diverse division.

Claviceps purpurea, an ascomycete that attacks rye plants, produce structures called ergots that release several toxins, one of which is the active ingredient in the drug LSD. If infected rye is made into flour and consumed, the toxins can lead to ergot poisoning – convulsions, hallucinations, and ultimately death. This happened frequently in northern Europe in the Middle Ages, but modern agricultural techniques have essentially eliminated the disease. Another Claviceps toxin has medicinal effects if administered in low doses; that toxin is currently used in drugs that induce labor and control hemorrhaging after childbirth.

Among the ascomycetes we also find the yeasts, some of the few unicellular fungi. The yeasts include both the parasitic yeast that is a common cause of vaginal infections and the baker’s and brewer’s yeasts that make possible the proverbial loaf of bread and jug of wine. Some yeasts form hyphae when nutrients are scarce; the hyphae can elongate and reach distant food sources.

Basidiomycetes are called the club fungi because they produce club-shaped reproductive structures. The division Basidiomycetes consists of about 25,000 species, including the familiar mushrooms, puffballs, and shelf fungi, sometimes called monkey-stools. Although several mushrooms species are considered delicacies, mushrooms can be deadly. Some members of the genus Amanita contain potent toxins that are among the most deadly poisons ever found. Basidiomycetes can also be dangerous to plants; they include some devastating plant pests descriptively called rusts and smuts, which cause billions of dollars worth of damage to grain crops annually. Some members of this group, however, enter into mutually beneficial relationship with plants.

Basidiomycetes typically reproduce sexually. Mushrooms and puffballs are actually reproductive structures: dense aggregations of hyphae that emerge under proper conditions from a massive underground mycelium. On the undersides of mushrooms are leaflike gills that produce specialized club-shaped diploid cells called basidia. Basidia give rise to haploid reproductive basidiospores by meiosis. These are released by the billions from the gills of mushrooms or the inner surface of puffballs and are dispersed by wind and water.

Falling on fertile ground, a mushroom basidiospore may germinate and form haploid hyphae of two different mating types. When the two types meet, some of the cells fuse and produce an underground mycelium. These hyphae grow outward from the original spore in a roughly circular pattern as the older hyphae in the center die. The subterranean body periodically sends up numerous mushrooms, which emerge in a ringlike pattern called a fairy ring. The diameter of the fairy ring can reveal the approximate age of the fungus – the wider the ring diameter, the older the mushrooms, and their average rate of growth is known. Some fairy rings are estimated to be 700 years old.

Deuteromycetes are called the imperfect fungi because none have been observed to form sexual reproductive structures. In some species the sexual stage has been lost during evolution; in others it may exist but has not yet been observed. This large division includes about 25,000 described species of great diversity and considerable importance to humans. It was a member of this division that contaminated and killed the bacterial cultures of the microbiologist Alexander Fleming by accident. His keen observations led to the isolation of penicillin, the first antibiotic, from the fungus Penicillium. We also owe to deuteromycetes the indescribable flavor and aroma of Roquefort and Camembert cheeses. Other imperfect fungi are human parasites, causing diseases such as ringworm and athlete’s foot. Some are not content to live on dead organisms or even to parasitize live ones – they act as predators, laying deadly traps for unsuspecting roundworms.

II. What are the terms that correspond to the following definitions?

1 a structure in which spores are produced

2 a symbiotic relationship between a fungus and the roots of a land plant that facilitates mineral extraction and absorption

3 a threadlike structure that consists of elongated cells, typically with many haploid nuclei; makes up a fungus body

4 the body of a fungus, consisting of a mass of hyphae

5 a sexual spore formed by members of the fungal division Basidiomycota

6 a saclike case in which sexual spores are formed by members of the fungal division Ascomycota

Language focus 1

Must: Necessity and Obligation

1 Must is used to say what is necessary, and to give strong advice and orders to ourselves or other people.

Plants must get enough light and water if they are to grow properly.

I really must stop smoking.

2 We use must not / mustn’t to say that it is wrong to do things, or tell people not to do things.

The government mustn’t expect people to work for no money.

You mustn’t open this parcel until Christmas Day.

3 Mustn’t and needn’t / don’t have to

Mustn’t implies prohibition. This idea of the absence of necessity is expressed by needn’t, don’t need to or don’t have to.

You needn’t work tomorrow if you don’t want to. OR You don’t have to work… (NOT You mustn’t…)…if you don’t want to.

You don’t need to get a visa to go to Scotland. OR You don’t have to get a visa… (NOT You mustn’t get a visa…)

BUT: You mustn’t eat when you are lying on the sofa. (prohibition)

4 Must has no past tense. In the past, had to is used.

I had to cycle three miles to school when I was a child.

My parents had to work very had to build up their business.

I. Match sentences to the rules formulated in Language Focus 1.

1. I must lose some weight.

2. You needn’t worry – he’ll be back in a few minutes.

3. He has to call me tomorrow morning and report on the outcome of the experiment.

4. I don’t have to do all the work myself – my laboratory assistant is very good.

5. You have to be more careful. We need you alive.

6. Must I wear all these clothes? They look horrific.

7. He can’t have eaten all the chocolate on his own!

8. You mustn’t talk unless you’re asked to.

II. Translate into English.

1. Фред не любит вставать рано, но ему приходится, так как занятия в университете начинаются в девять часов.

2. Вы должны отправить посылку немедленно.

3. Он не должен идти в институт завтра.

4. Вам не надо звонить в лабораторию, все образцы уже здесь.

5. Тебе нельзя курить. У тебя слабые легкие, и вообще это вредно.

Language focus 2

Must, Need not to, Do not Have to: Degrees of Certainty

1 Must can be used to say that something is certain or highly probable.

If A is bigger than B, and B is bigger than C, then A must be bigger than C.

I’m in love. – You must be very happy. (about 100% sure)

2 We normally use cannot/can’t to say that something is certainly not the case, because it is logically or practically impossible, or extremely improbable.

She’s not answering the phone. She can’t be at home.

3 Need not / needn’t is used to say that something is not necessarily so; do not have to can also be used. Must not is not used in this sense.

Look at those tracks. That must be a dog. – It needn’t be – it could be a fox. (OR - It doesn’t have to be…) (NOT - It mustn’t be…)

4 Must have done expresses certainty about the past.

We went to Rome last month. – That must have been nice.

Tony’s lights are out. – He must have gone to sleep. (He probably went to sleep.)

If you want to say that something was improbable in the past, use can’t/couldn’t have done.

Sandra failed the test. – She can’t have studied. (She probably didn’t study.)

I. Use a number of the following phrases in dialogues of your own.

- He can’t have eaten all the samples!

- It doesn’t have to be a man, an animal is enough.

- You needn’t try, you’ll never do that.

- It must be a dreadful thing to see.

- I must have left my purse somewhere between London and Glasgow!

II. Translate into English.

1. Джон опаздывал в офис: поезда долго не было. Должно быть, водители объявили забастовку.

2. - Вы впервые летите «Аэрофлотом»? Вам не нужно волноваться, пилоты очень опытные.

3. Мы не должны были менять нашу квартиру на загородный дом. Дорога на работу стала значительно длиннее.

4. Мы сделали все покупки в прошлые выходные, так что нам не нужно было ходить в магазин в течение недели.

5. Ты читаешь книгу уже четыре часа. Должно быть, она очень интересная.

Language focus 3

Must and Have to

1 To talk about an obligation that comes from ‘outside’ (for instance a regulation, or an order from somebody else), we usually prefer have to. Compare:

- I must do some more work; I want to pass my exam.

In my job I have to work from nine to five.

- I must stop smoking. (I want to.)

I have to stop smoking. (Doctor’s order.)

- Must you wear dirty old jeans all the time? (Is it personally important for you?)

Do you have to wear a tie at work? (Is there a regulation?)

2 Talking about the past: had to and must have.

In the past, instead of must implying obligation, we use had to. Compare:

Edna isn’t in her office. She had to go home. (= It was necessary for her to go home.)

Edna isn’t in her office. She must have gone home. (= It seems certain that she has gone home.)

I. Write sentences including these Expressions (use one expression in one sentence):

… have to drink …

… must pull the cord …

… must have dropped …

… had to be brave …

… must have a good …

II. Translate into English.

1. Должно быть, я оставила зонтик в метро. Его нигде нет!

2. Майкл очень способный человек, ему необходимо продолжать образование.

3. Каждый президент США должен приносить присягу (to swear an oath) на Библии.

4. Вам когда-либо приходилось общаться с господином Х.?

5. Сегодня вы должны сделать доклад.

Language focus 4

Be to

1 We use be to in a formal style to talk about official and other plans and arrangements.

The President is to visit Spain next month.

We are to get a 10 per cent scholarship rise in June.

The past form of be to is used to say about an action which was planned in the past.

The data were to be collected for my research.

Was/were to have done can be used to show that a planned event did not happen.

I was to have started the experiment last week, but I had to postpone it.

2 If + smb. + be to: something must happen first, and only then a thing we want will happen.

If we are to get there by lunchtime we should hurry.

He knew he would have to work hard if he was to pass his exam.

3 The structure is used to give orders, often by parents speaking to children.

You are to do your homework before you watch TV.

She can go to the party, but she is not to be back late.

I. Translate into English.

1. Поезд должен прийти вовремя.

2. Вы не должны покидать школу без моего разрешения

3. Лекарство нужно принимать после еды

4. Я должен был послать ему письмо.

5. Они должны были встретить нас (но не встретили).

6. Чтобы выиграть золото на следующих Олимпийских играх, Джону нужно будет вначале улучшить технику.

7. Чтобы справедливость могла восторжествовать, нужно прежде изменить законы.

Grammar Review

I. Fill in the blanks with must or can’t.

1. You’ve been working all day. You ……….. be very tired.

2. That café ……….. be very good. It’s always full of people.

3. That cafe ……….. be very good. It’s always empty.

4. It rained every day during her vacations, so she ……….. have had a very good time.

5. Sam got here very quickly. He ……….. have walked very fast.

6. My family go away on holiday very often, so they ……….. be short of money.

II. Read the situation and use the words in brackets to write sentences with must have and can’t have.

1. The bag you bought is very good quality. (it/very expensive)

………………………………………………………………………………………

2. I haven’t seen one of my mates for ages. (he/go away)

………………………………………………………………………………………

3. I can’t find my passport. (I/leave/somewhere)

………………………………………………………………………………………

4. Mary passed the exam without studying for it. (the exam/very difficult)

………………………………………………………………………………………

5. Simon did the opposite of what I asked him to do. (he/understand/what I said)

………………………………………………………………………………………

6. I was woken up in the middle of the night by the noise next door. (the neighbours/have/a party)

………………………………………………………………………………………

III. Complete the sentences with mustn’t or don’t/doesn’t have to.

1. I ……….. eat too much. I’m supposed to be on a diet.

2. Don’t make so much noise. We ……….. wake the baby.

3. John can stay in bed tomorrow morning because he ……….. go to work.

4. You ……….. forget what I told you. It’s very important.

5. I don’t want anyone to know. You ……….. tell anyone.

6. Whatever you do, you ……….. touch that switch. It’s very dangerous.

IV. Complete the sentences with must, mustn’t or needn’t.

1. George gave me a letter to post. I ……….. remember to post it.

2. George gave me a letter to post. I ……….. forget to post it.

3. I’ve got plenty of time. I ……….. hurry.

4. I haven’t got much time. I ……….. hurry.

5. This is a valuable book. You ……….. look after it carefully and you ……….. lose it.

6. You ……….. double-check it. I’ve already done it.

V. Write two sentences for each situation. Use needn’t have in the first sentence and could have in the second.

1. Why did you keep silent? Why didn’t you say anything to prove your innocence?

………………………………………………………………………………………

2. Why did you stay in a hotel? Why didn’t you stay with us?

………………………………………………………………………………………

3. Why did he call me in the middle of the night? Why didn’t he call me in the morning?

………………………………………………………………………………………

Words, Words, Words

I. Using the words given, tell the class about lichens.

symbiotic relationship normally ascomycetes fungus

unicellular green algae cyanobacteria newly formed volcanic islands the first living things to colonize from the deserts to the Arctic slow rate of growth

attachments anchor to a surface a layered structure algal layer fungal hyphae

II. Complete the text with the correct option A-C.

Mycorrhizae are Fungi Associated with the Roots of Many Plants

Mycorrhizae (sg., mycorrhiza) are important (1) ______ associations between fungi and plant roots. Over 5000 species of mycorrhizal fungi (mostly basidiomycetes) are known to grow in intimate (2) ______ with the roots of about 80% of all plants that have (3) ______, including most trees. These associations (4) ______ both the plant and its fungal partner. The (5) ______ of mycorrhizal fungi surround the plant root and commonly invade the root cells. The fungus digests and absorbs minerals and organic nutrients from the soil, passing some of them directly into the root cells. The fungus also absorbs water and passes it to the plant – an advantage in dry, sandy soils. In return, sugar produced photosynthetically by the plant is passed from the root to the fungus. Plants that participate in this unique relationship, especially those in poor soils, tend (6) ______ and more vigorously than do those deprived of the fungus. (7) ______ new data suggest that mycorrhizae and other types of fungi may be undergoing a (8) ______ decline that could threaten the health of forests and the communities of plants and animals that rely on them.

Some scientists believe that mycorrhizal associations may have been important in the invasion of land by plants more than 400 million years ago. Such a relationship between an aquatic fungus and a green alga ((9) ______ to terrestrial plants) could have helped the alga (10) ______ the water and mineral nutrients it needed to survive out of water.

1	A symbolic	B symbiotic	C symptomatic
2	A association	B assortment	C assimilation
3	A stems	B branches	C roots
4	A benefit	B do harm	C destroy
5	A hyphal	B hyphen	C hyphae
6	A to grow larger	B to grow together	C to grow lean
7	A Exciting	B Encouraging	C Disturbing
8	A tragic	B dramatic	C bad
9	A ancestral	B predecessor	C ancestor
10	A require	B quire	C acquire

Render in English.

Лишайники

Лишайник представляет собой не один организм, а состоит из гриба и одноклеточной водоросли или цианобактерии, связанных тесными и взаимовыгодными отношениями, известными под названием мутуалистических. (Мутуализм часто рассматривают как одну из разновидностей симбиоза – буквально «совместная жизнь»; этим термином обозначают тесную взаимосвязь между двумя видами.) Фотосинтезирующий партнер образует пищу как для себя, так и для гриба; а гриб, как полагают, обеспечивает снабжение водой и минеральными веществами. Лишайники весьма живописны, напоминая мазки густой краски, небольшие кустики или изогнутые листья.

Растут лишайники очень медленно, однако они могут существовать во многих местах, где не живут никакие другие фотосинтезирующие растения: на голых скалах, на холодных горных вершинах, в тундре; здесь они подчас оказываются единственной пищей, доступной животным. Однако при загрязнении воздуха лишайники быстро погибают, поэтому состояние лишайников в данной местности может служить показателем качества ее воздуха.

Лишайникам находят и другие довольно необычные применения. Археологи определяли возраст загадочных каменных голов, обнаруженных на острове Пасхи, измеряя размеры растущих на них лишайников. А получаемые из лишайников красители используются для окраски одного из типов твида.