7-Genetic Variation & Its Control Flashcards Preview

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Flashcards in 7-Genetic Variation & Its Control Deck (37)
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0
Q

What does the nucleus of a cell contain?

A

Chromosomes.

1
Q

Where is the information that results in plants and animals having similar characteristics carried?

A

By genes in the sex cells from which they develop.

2
Q

What are chromosomes made up of?

A

DNA.

3
Q

What is a gene?

A

A section of a chromosome.

4
Q

What genes do?

A

Carry information that control the characteristics of an organism.
Different genes control different characteristics.

5
Q

What do chromosomes come in?

A

Pairs, but different species have different numbers of pairs, e.g. Humans have 23.

6
Q

What is variation?

A

Differences between individuals of the same species.

7
Q

What might variation be due to?

A
Genetic causes (i.e. different genes that've been inherited).
Environmental causes (i.e. conditions in which the organism has developed).
It's usually a combination of both.
8
Q

Why might identical twins grow up to look slightly different?

A

Environment has altered the way they look. E.g. if one has a diet high in fat & does little exercise then he can become fatter than his brother.

9
Q

What is an example of genetic variation?

A

Different colours of dogs’ coats.

10
Q

What happens during sexual reproduction?

A

The sperm from the male fuses with an egg from the female. The genes are mixed to form a completely new individual.

11
Q

Why does sexual reproduction produce a lot of variation?

A

The mixing of genes is completely random.

12
Q

What is asexual reproduction?

A

One parent produces individuals that are genetically identical to the parent (clones).

13
Q

Does asexual reproduction cause variation?

A

No, the individuals have exactly the same genetic information.

14
Q

Can plants reproduce asexually?

A

Yes, many do so naturally and the offspring are clones of the parent.

15
Q

Why would a gardener choose to take cuttings?

A

When they have a plant with the desired characteristics, they may want more.
It’s a quick and cheap way of producing new plants.

16
Q

How should you take cuttings?

A

By taking stem, leaf or root cuttings.

These should be grown in a damp atmosphere until roots develop.

17
Q

What are clones?

A

Genetically identical individuals.

18
Q

How do you prepare a tissue culture?

A
  1. Parent plant with desired characteristics selected.
  2. A few cells scraped off into several beakers with nutrients and hormones.
  3. Week or 2 later lots of genetically identical plantlets growing. The same can be done to these.
  4. Whole process must be aseptic (carried out in absence of harmful bacteria) or new plants will rot.
19
Q

How are embryo transplants carried out?

A
  1. Parents with desired characteristics mated.
  2. Embryo removed before cells become specialised.
  3. Embryo split into several clumps.
  4. These embryos implanted into uteruses of sheep who’ll eventually give birth to sheep.
20
Q

What are the genetics of the offspring from embryo transplants?

A

Genetically identical to one another but not to the parents.

21
Q

Why do farmers use embryo transplants?

A

Don’t have to wait for normal breeding cycles.
Can produce many more offspring.
Can use only the best animals with desired characteristics.

22
Q

How is adult cell cloning/fusion cell cloning carried out?

A
  • DNA from donor animal inserted into empty egg (nucleus removed).
  • Electric shock causes egg to begin to divide to form embryo cells which contain the same genetic info as the donor.
  • When embryo is ball of cells it’s implanted into the womb of an adult female.
23
Q

What are GM (genetically modified) crops?

A

Crops that have had their genes modified by the addition of new DNA.

24
Q

Why might crops be genetically modified?

A
  • To improve crop yield, eg larger tomatoes etc.
  • To improve resistance to pests or herbicides, eg soy plants have been made resistant to herbicides so farmers can eliminate weeds without killing the crop.
  • To extend the shelf-life of fast ripening products, eg tomatoes.
25
Q

What are some concerns about GM crops?

A
  • Genes from GM crops could be transferred via pollen to non-GM crops or to other plants. Eg resistance to herbicides to weeds creating ‘superweeds’.
  • Nectar from GM crops can harm insects that feed on it.
  • Uncertainty about the effects of eating GM crops on human health.
26
Q

Why are genes transferred to the cells if animals and microorganisms at an early stage?

A

So they develop the desired characteristics which can be passed on asexually or if the organism is cloned.

27
Q

Where is insulin normally produced?

A

In the pancreas.

28
Q

What does insulin do?

A

Helps to control blood glucose levels.

29
Q

Why do diabetics need to inject insulin?

A

They don’t produce enough themselves.

30
Q

How can large quantities of insulin be produced?

A
  1. Scientists use enzymes to cut a chromosome at specific places so they can remove the piece of DNA they want. In this case insulin.
  2. Another enzyme used to cut open a plasmid. Other enzymes are used to insert the human DNA into the plasmid.
  3. Plasmid is inserted into the bacterium which divides rapidly. Soon there are millions if bacteria with instructions to make insulin.
  4. Bacteria cultured on large scale and commercial quantities of insulin are produced.
31
Q

What is recombinant DNA cloning?

A

DNA fragment transferred from one organism to another. Could be used to produce bacteria that will make insulin or GM crops with desired characteristics.

32
Q

What is reproductive cloning?

A

Used to generate an animal that has the same nuclear DNA as another currently/previously existing animal (a twin). This can be used to produce farm animals with desired qualities.

33
Q

What are the pros of cloning plants, animals and humans?

A

Traditional breeding methods are slow.
Can predict characteristics of offspring.
Quick response to crop/livestock shortages.
Organ donation: clone has matching tissue so no risk of rejecting the organ.
Used to repopulate endangered species.

34
Q

What are the cons of cloning plants, animals and humans?

A

Loss of livelihood of traditional farmers.
Cloning companies may have monopoly on patent for clones.
Cloning is unnatural.
Fear of creating ‘perfect race’.
Human clones wouldn’t have ‘parents’.
Doesn’t allow natural evolution.

35
Q

What are the pros of GM crops?

A

More cost-effective.
Reduce pesticide use.
Can benefit human health.
Safe for human consumption.
Could provide more food for developing world.
Preserve habitats as less land needed for agriculture.

36
Q

What are the cons of GM crops?

A

Increase pesticide use as farmers spray freely.
Cross-contamination of GM crips could destroy non-GM trade.
Mainly benefit big GM companies.
Increasing yields won’t help developing world as distribution is the problem not the amount.
Could affect wildlife as there are no weeds as a food source.