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Flashcards in Biology2 Deck (24):

What is variation?

The differences between members of the same species


What is a gene?

A section of DNA that codes for a protein (or characteristic)


What is a chromosome?

A thread (long pieces) of DNA made up of a string of genes


What is DNA?

The long chemical molecule that carries the genetic code that determines the characteristics of a living thing (Deoxyribonucleic acid)


Where are chromosomes located in the body?

In the Nucleus of every cell


How many chromosomes do typical humans have?

46 (23 from Egg cell(mother) and 23 from Sperm cell(father))


What would the formula be for a female in the 23rd chromosome?

XX (X from egg and X from sperm)


What would the formula be for a male in the 23rd chromosome?

XY (X from the egg and Y from the sperm)


What are the causes of variation?



What is continuous variation?

Where there is a range of values that change gradually. This type of variation can be measured and does not have to be a whole value. Normal distribution (arc) e.g Number of people (y) to height (x)


What is discontinuous variation?

Where there is a categoric range of options. There are no values in between, it can not be measured (no scale). There is no same trend or order of categories/options are in. e.g. Number of people (y) to eye colour (x)


Describe the process of selective breeding:

1)Choose animal with desired characteristics
2) Breed them together
3) Breed the puppies when fully grown who also share desired characteristics
4) Repeat the process a number of times and you will end up with an animal with a strong set of desired characteristics


What is a clone?

A clone is an organism that is genetically identical to its parent e.g. bacteria reproducing (binary fission)- each identical half contains the same genes, plants reproducing asexually- new organisms created by cell division


Describe the cloning process scientists can undertake:

1) Animal wanting to be cloned has a body cell removed. The diploid nucleus is removed from that cell (contains full ideal chromosome set up)
2) Female animal has egg cell removed-enucleation. The nucleus is removed from this egg, leaving it empty.
3) Diploid nucleus from animal going to be cloned is put into the empty enucleated egg cell.
4) Egg is given electrical shock (stimulated) to trigger process of developing embryo in the womb (mitosis)
5) Once egg has divided into 16 unspecialised cells, they are placed in the womb of a surrogate female to develop
6) The offspring of the surrogate is a clone of the original animal!


What does genetic engineering do?

Alter an organisms genes to produce desired characteristics


Describe the process of genetic engineering:

1)Scientists take desired genes from one or more organism, these are foreign genes
2) The foreign genes are replaced into a plant or animal cell at a very early stage of development
3) The organism will develop to display the characteristics of the foreign gene


What are some examples of genetically modified animals?

-Enviropig: DNA from mouse and E.Coli to process and digest phosphorous better (less levels of phosporous in excretion- reduce water issues such as algae blooms, oxygen depletion and marine deaths. Less need to feed extra phosphorous food)
-Web-spinning goats: dragline silk gene from spiders (make silk milk to create Biosteel)
-Golden rice: two daffodil genes and one bacteria gene (produce keritol which makes Vitamin A)
-Giant salmon: gene from fish that can grow in cold water (grow quicker and all year round for food purposes)
-Sudden death mosquitos: baby mosquitos are passed a gene which makes them die before they reach sexual maturity (stop spread of malaria)


What are the advantages of cloning?

-All the new plants are genetically identical – they will all have the desired characteristics
-Organisms that are difficult or slow to breed normally can be reproduced quickly.


What are the disadvantages of cloning?

-If a clone is susceptible to disease or changes in environment, then all the clones will be susceptible.
-It will lead to less variation, and less opportunity to create new varieties in the future.
-Ethical issues


What are the problems with selective breeding?

-Future generations will share similar genes. This means some diseases could be more dangerous as all the organisms will be affected
-Higher risk of genetic disease from recessive genes
-Reduction in the size of the breeding pool


Describe the process of using bacteria for genetic engineering:

1) Plasmid (small ring of DNA) is removed from bacterium
2) The Plasmid is cut by enzymes
3) A gene is inserted into the Plasmid to complete the cut circle
4) Engineered plasmid is put back into bacterium
5) Bacterium now has desired property/ characteristic


Why is bacteria used for genetic engineering?

-Bacterium cells are less complex
-Plasmid can easily be genetically modified
-Bacteria can reproduce asexually very quickly


What is natural selection?

The way nature chooses which organisms to thrive (survival of the fittest)


Describe the process of evolution:

1) Individuals in a species show a wide range of variation
2) This variation is due to differences in genes
3) Individuals with characteristics most suited to the environment are more likely to survive and reproduce
4) The genes that allow these individuals to be successful are passed to their offspring
5) Over time, the population evolves