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science yr 9 end of years > Biology - Genetics > Flashcards

Biology - Genetics Flashcards

1
Q

What is DNA? Describe it’s structure.

A

Deoxyribonucleic acid is the chemical molecule in the nucleus that carries our genetic code. It codes for our characteristics. It is arranged into long, coiled molecules called chromosomes.

Normal human body cells (e.g skin cells) have 46 chromosomes (23 pairs)

Human sex cells (sperm and egg) have half this number (23)

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2
Q

Where is DNA found in the cell?

A

In the nucleus

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3
Q

What is a gene?

A

A gene is a section of a chromosome that codes for a particular characteristic.

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4
Q

What is an allele?

A

For each gene we inherit two forms of the gene (one from our mother and one from our father). Each form of the gene is called an allele. A different form of a gene.

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5
Q

What is variation?

A

The difference between individuals of the same species. Their are two types of variation:
genetic (inherited) variation
Environmental variation

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6
Q

What is the difference between dominant and recessive alleles?

A

• Dominant alleles are always expressed even if only one of the alleles is dominant. e.g. BB or Bb
• Recessive alleles are only expressed if there are 2 recessive alleles. e.g. bb

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7
Q

What are homozygous alleles?

A

Two identical alleles for a characteristic. (e.g. BB, tt)

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8
Q

What are heterozygous alleles?

A

Different alleles for a characteristic. (e.g. Bb, Tt)

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9
Q

What is genetic variation?

A

The variation has been inherited genetically.

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10
Q

What is environmental variation?

A

The variation hasn’t been passed down through genetics and it is based on your lifestyle.

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11
Q

Cat fur:
Parents phenotype: Black, Black
Parents genotype: Bb, Bb

Work out what the possible phenotype and genotypes are for the child.

A

BB, Bb, Bb, bb
Black, Black, Black, White
75% Black 25% White

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12
Q

Eye Colour:

Parents phenotype: Brown, Brown
Parents genotype: Bb, Bb

Work out what the possible phenotype and genotypes are for the child.

A

BB, Bb, Bb, bb
Brown, Brown, Brown, Blue
75% Brown, 25% Blue

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13
Q

Hair Colour:

Parents phenotype: Black, Blonde
Parents genotype: Bb, bb

Work out what the possible phenotype and genotypes are for the child.

A

Bb, Bb, bb, bb
Black, Black, Blonde, Blonde
50% Black, 50% Blonde

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14
Q

What is a genetically inherited disorder?

A

A genetic disorder is a disease caused by a faulty gene or chromosome.

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15
Q

What is a recessive genetic disorder?

A

This is a genetic disorder where the individual has inherited 2 faulty alleles, one from Mum and one from Dad.

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16
Q

What is a dominant generic disorder?

A

This is a genetic disorder where the individual has inherited one ONE faulty alleles. Either from Mum or Dad.

17
Q

How are genetic disorders inherited?

A

A condition passed from parents to their offspring in their genes.

18
Q

Cystic Fibrosis:

Parents genotypes: Cc, Cc

Work out the probability that the child will suffer from this condition too.

A

CC, Cc, Cc, cc
50% carrier, 25% healthy, 25% cystic fibrosis sufferer

19
Q

Polydactyly:

Parents genotypes: Pp, pp

Work out the probability that the child will suffer from this condition too.

A

Pp, Pp, pp, pp
50% healthy, 50% polydactyly sufferer

20
Q

What is selectivd breeding?

A

Breeding organisms to produce offspring with the desired characteristics.

21
Q

What are the stages of selective breeding?

A

Step 1: Decide which characteristics you want to encourage. For example, a dog breeder wishes to have dogs with a gentle nature.
Step 2: Select parents that show high levels of this characteristic. For example, the dog breeder would choose parent dogs that show a gentle nature.
Step 3: Breed these individuals together.
Step 4: Select the offspring that show high levels of this characteristic, and breed them.
Step 5: Repeat for many generations until the offspring all show high levels of the desired charácteristic.

22
Q

What are some advantages of selectively breeding animals and plants?

A

• Higher economic gains
• Create new varieties of crops
• Eliminating disease
• Does not involve Genetic Modification
• Produce fitter stronger animals

23
Q

What are some disadvantages of selectively breeding animals and plants?

A

• Animal discomfort
• Loss of variety and variation (inbreeding)
• No control of genetic mutations
• Can lead to loss of traits
• It can change the evolution of a species

24
Q

What is genetic engineering?

A

A technique where scientists insert foreign genes into organisms to change their characteristics.

25
Q

What does GMO stand for?

A

Genetically Modified Organism

26
Q

What is the process of genetically engineering an organism to produce insulin?

A
  1. DNA taken from a human cell
  2. Use an enzyme to cut/isolate the required gene (for insulin) from the DNA
  3. Use a different enzyme to cut the Plasmid out of a bacterial cell
  4. Use an enzyme to cut a section of DNA
    from the plasmid
    The plasmid is called a vector
  5. Insert the gene for insulin into the plasmid
  6. Use another enzyme to join the ends of the DNA
  7. Put the plasmid with the insulin gene back into a bacterial cell
  8. Leave the bacteria to divide to make multiple copies of the bacteria which produces insulin.
  9. Insulin is removed and purified.
  10. Ready for use in humans.
27
Q

What are the advantages of genetic engineering?

A
  1. Single genes can be added from one organism and added to a different species.
  2. It only takes one generation so it is a quick process.
  3. Engineered organisms have a specific desired characteristic.
28
Q

What are the disadvantages of genetic engineering?

A
  1. Genetically engineered crops may breed with wild plants which cold introduce foreign genes into the ecosystem.
  2. Some people worry that we don’t know the long term affects of eating genetically engineered foods as itis a new science.
  3. Some people see it as unethical and that scientist should not interfere with nature.
29
Q

What is meant by a clone?

A

An organism that is genetically identical to its parent.

30
Q

What are natural clones?

A

Organisms made during asexual rerpoduction.

31
Q

What are artificial clones?

A

An identical copy of an organism made by humans. Usually in a laboratory.

32
Q

What is the process of nucleur transfer cloning?

A
  1. TAKE A NORMAL BODY CELL (CONTAINS FULL AMOUNT OF CHROMOSOMES) FROM THE ORGANISM TO BE CLONED AND REMOVE THE NUCLEUS.
  2. TAKE AN EGG CELL FROM ANOTHER ORGANISM AND REMOVE THE NUCLEUS (AND DISCARD IT).
  3. INSERT THE NUCLEUS OF THE NORMAL BODY CELL
    INTO THE EMPTY EGG CELL.
  4. ELECTRIC SHOCK IS GIVEN TO STIMULATE CELL DIVISION.
  5. IMPLANT THIS EMBRYO INTO UTERUS OF A SURROGATE ORGANISM TO DEVELOP INTO A CLONE.
33
Q

What are the advantages of cloning?

A

Save animals from extinction.
Bring back animals that have died out.

34
Q

What are the disadvantages of cloning?

A

Cloning plants reduces the variety of genes available (the gene pool). This can increase the risk of disease, or a change in the plant’s environment, destroying a species.
The power to clone could be misused in the futre with cloning humans.

35
Q

What is cystic fibrosis?

A

Produce lots of sticky mucus which can block their air passages and make it difficult to breathe and can lead to chest infections and makes it difficult for food to be absorbed. It is caused by a recessive allele.

36
Q

What is polydactyly?

A

Extra digits on their hands or feet. These can be small stumps of soft tissue or extra fingers or toes. It is caused by a dominant allele.

37
Q

List three characteristics that are genetically controlled?

A

Your eye colour
Having ears with lobers or without
Your blood group

38
Q

List three characteristics that are environmentally controlled?

A

Your religion
Your language
Having long or short hair

39
Q

List three charctersitics that are controlled by both?

A

Height
Weight
Human hair colour

science yr 9 end of years (4 decks)

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