Bald bears

Following on from a discussion in my A2 class this week, my attention has been drawn here. She looks so sad!

The Cell

What’s that? You’re bored of the summer holidays? You need some good science TV to keep your biology appetite satisfied? Well that’s lucky, because BBC have a fantastic series on the cell. It’s called, appropriately, The Cell and is on Wendesday 10pm BBC4. If you haven’t seen it yet you’ve missed the first two episodes, but thankfully the iPlayer has the whole series, so you can catch up.

Proper science telly.

http://www.bbc.co.uk/programmes/b00m5w92

Royal Society Prize for Science Books

It was about this time last year that I began putting together a ‘further reading’ list for A level biologists. It was to be included in the ‘welcome booklet’ that we gave the year 12’s at the start of the year. The task was harder than you might expect. It’s easy to find good books about genetics and evolution, but other aspects of biology just don’t get written about that much. Surveying the biology teachers at school found that we had, more or less, all read the same books (these were therefore included in the list), but finding a range of books to list that we knew were good was worryingly difficult.

It’s a shame that I did not know about the Royal Society Prize for Science Books. I do now. ‘The world’s most prestigious award for science writing’ (their words, not mine) have published their longlist for this year’s award, and it makes for interesting reading.

I have to admit, I have only read one of the books on the list, the rather fabulous ‘Bad Science’ by Ben Goldacre. It’s good enough to make it onto next years further reading list. But I’m ashamed to say I haven’t even heard of any of the other books, yet alone read any of them! So, as a committed scientist, I plan to read at least one of the books on the list. I’ll be reading ‘The drunkard’s walk: How randomness rules our lives’, by Leonard Mlodinow. I’ll let you know how it goes!

The shortlist will be announced on 25th June 2009, and the winner on 15th September 2009, so you may prefer to wait until then to pick one. But do pick one! I’d love to hear from anyone who has read any of these books and could give me a review of it. If it’s good enough I’ll let everyone know.

Instructions in Question Papers

Good luck to all of the Biologists sitting exams over the next few days. Remember that staff are available for any last minute clarifications you may need. All you need to do is ask. We don’t mind!!!

As a last minute piece of advice I would encourage all students to make sure they read the questions carefully and answer the question as it is asked. Explain when it asks you to and describe when it says ‘describe’. Its very easy to drop marks by confusing the ‘trigger’ words. Click here for a pdf from AQA that explains all of the instructions that could appear in the questions.

Monoclonal Antibodies

So we understand how antibodies are made in the body. Plasma cells are generated through the cloning of B lymphocytes when they recognise the correct antigen and are stimulated to divide by activated helper T cells. Lots of plasma cells are cloned and these plasma cells make lots and lots of antibodies. These antibodies bind to the non-self antigen. Easy! (Click here for a clearer explanation, and here for an animation)

Antibodies are very useful to scientist because they are antigen specific, meaning they will only bind to one antigen or cells containing that antigen. So antibodies can be adapted to act as markers. For example, an antibody that attaches to antigens on cancer cells can be manufactured in the lab and labeled with a radioactive marker. When this antibody is introduced into the body it attaches to the antigens on the cancer cells. A radioisotope scan will then locate all of the cancer cells in the body with that particular antigen. This makes it easy for doctors to track the spread of a cancer and check success rates after surgery, for example.

So the question is how can we manufacture antibodies outside of the body? Plasma cells only live for a short time and cannot clone themselves. So we need to find a way of extracting the correct plasma cells from the body and giving them a way of reproducing so that they can produce enough antibodies to be of medical use.

Antibodies produced in large quantities outside of the body are called monoclonal antibodies. This is how they are produced:

1. The target antigen is injected into a mouse.
2. The antigen is recognised by a few B lymphocytes in the mouse spleen and these lymphocytes multiply to form a clone of plasma cells.
3. A sample of the mouse spleen is extracted which should contain these plasma cells.
4. The plasma cells are mixed with mouse myeloma (cancer) cells. These two types of cells fuse to produce a cell called a ‘hybridoma’.
5. Non-hybridised plasma cells soon die, and unhybridised myeloma cells are killed by removing a metabolite from the culture medium which is vital to their survival. The hybridoma cells can produce this metabolite, therefore they survive.
6. The surviving cells are subcultured. This means putting each hybridoma cell into a separate culture.
7. Lots of different plasma cells (for lots of different antigens) will have be collected from the spleen (step 3) so there will be lots of different hybridomas each producing a different antibody. The antibodies from each culture are tested against the target antigen. If the culture is producing the correct antibodies they will cause agglutination when exposed to the antigen.
8. Hybridoma cells which cause agglutination of the specific antigen are identified and then mass cultured in large fermenters. These fermenters will produce large quantities of the specific antibody.

There is an excellent animation of monoclonal antibody production from the good people at Sumanas Inc here.

So we can produce large quantities of antibodies outside the body for scientific use. These can be used in a number of different ways, such as;

• As markers to identify specific cells in the body (such as cancer cells).
• As markers for cell surface proteins (such as carrier proteins)
• To carry drugs to specific cells in the body. This allows targeted medication, particularly useful in the treatment of cancers.
• As diagnostic tools for diseases, used in blood or urine analyses.
• To identify hormones (such as in pregnancy tests).

Monoclonal antibodies have a huge range of uses in medicine and in research labs. They are often referred to as ‘magic bullets‘ as they can be made to target specific antigens.

Of course, the use of mice to produce the initial plasma cells is controversal. It would be unethical to induce disease in humans to extract plasma cell, and some people think it is unethical to do this mice. On the other hand, many human lives have been saved by the use of monoclonal antibody technology. What do you think?

Data Analysis Skills

So, you should all be aware that we’ve been trying hard to bring your data analysis skills up to scratch.  Some of you are finding it easier than others so here is the ultimate quick guide for describing a line graph!

1. Read each axis carefully - What does the graph actually tell you?

2. Look at the general trends and correlations - Describe the general correlations of each line that is on the graph.  Are they positive or negative correlations? 

3. Compare different categories – If there is more than one line on the graph describe the similarities and differences between the categories (each category is represented by a line).  Do they all do the same thing?  If not, say how they differ, and when these differences occur.

4. Make quantitative comparisons – A step-up from GCSE!  Now you should look at the line(s) and make comments with a quantitative element.  For example, if you are comparing relative risk of lung cancer from smoking, and you have two different groups (<10 cigarettes a day and >20 cigarettes a day), you can work out how many times greater the risk is in the >20 group compared to the <10 group, when they’ve both smoked for 50 years.  If the relative risk for the >20 group is 40 and the relative risk for the <10 group is 10, then you can say that the risk is 4 times greater for the >20 group compared to the <10 group. 

 

If you get into a routine of how to approach a graph, you should find it a lot easier!

To see graphical analysis in action in the real world, have a look at this from

http://www.statistics.gov.uk/cci/nugget.asp?id=866

Cigarette Smoking Slight fall in smoking prevalence

 

Percentage of adults who smoke cigarettes by sex: Great Britain 1974 to 2005

In 2005, 24 per cent of adults aged 16 or over in Great Britain smoked cigarettes, indicating a slight fall in the prevalence of smoking among both men and women since the late 1990s.

The proportion of adults who smoked cigarettes fell substantially in the 1970s and the early 1980s – from 45 per cent in 1974 to 35 per cent in 1982. After 1982 it declined gradually until the early 1990s, levelling out during the 1990s. It then fell smoothly from 28 per cent in 1998/99 to 24 per cent in 2005.

In July 2004 the Government set a new target to reduce the overall proportion of cigarette smokers in England from 28 per cent in 1996 to 21 per cent or fewer by 2010 – with a reduction from 32 to 26 per cent or less among manual occupation groups. In England in 2005, 29 per cent of those in manual occupational groups were cigarette smokers, compared with 33 per cent in 1998. Together with the fall in overall prevalence, this indicates some progress towards targets.

While men are still more likely than women to smoke cigarettes, the gap has narrowed. In 1974, 51 per cent of men and 41 per cent of women smoked. In 2005, 25 per cent of men and 23 per cent of women were cigarette smokers.

Cigarette smoking continues to be more common among adults aged 20 to 34 than among other age groups. In 2005, 32 per cent of adults aged 20 to 24 and 31 per cent of adults aged 25 to 34 were smokers compared with 14 per cent of those aged 60 and over.

The proportion of men who were heavy smokers (on average 20 or more cigarettes a day) fell from 14 per cent in 1990 to 10 per cent in 1998. Among women, the proportion fell from 9 per cent to 7 per cent over the same period. Since then the proportions have remained virtually unchanged, although there is a suggestion of a slight downturn in the last couple of years. The proportion of adults smoking fewer than 20 cigarettes a day has been around 17 to 19 per cent of both men and women since 1998.

In 2005 just over two thirds (68 per cent) of cigarette smokers in Great Britain said that they wanted to give up, but 56 per cent said it would be difficult to go without smoking for a whole day. Overall, 16 per cent of smokers said they had their first cigarette of the day within five minutes of waking up: this varied according to how much respondents smoked, ranging from only 2 per cent of those who smoked fewer than 10 a day to 33 per cent of those who smoked 20 or more cigarettes a day.

Source:
General Household Survey, 2005

Order of the taxons

The favorite youtube video clip of the moment must be the BBC’s April 1st Flying Penguins clip.  It was obviously designed to help A2 Biologists remember the order of the taxons. Thank you BBC.

King Penguins Can Only Fly Going South

Kingdom, Phylum, Class, Order, Family, Genus, Species.

A2 Level Biology Field Course

It’s that time of year!!!

The A2 Biology Field Course for the current year 12’s will take place on the following dates:

• Monday 7th July 09.00-17.15 going to Robin Hood’s Bay
• Wednesday 9th July 09.00-17.00 going to Teesmouth Sand Dunes
• Thursday 10th July 09.00-17.45 going to Grinton Moor, Muker Meadows and Hazel Brow Farm.

The course allows us to deliver the practical ecology work within Unit 5. Three days allows us to cover a large part of the unit so it’s really important that you make sure you can come.

Put the dates in your diary and make sure you return the permission slip.

You will receive a letter about the course from your teacher soon.