B1 - You And Your Genes Flashcards

1
Q

How many chromosomes are there in a gamete?

A

23 chromosomes

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2
Q

What is an allele?

A

A variation of the same type of gene.

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3
Q

Where are chromosomes found within a cell?

A

In the nucleus

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4
Q

True or false - in humans, chromosomes are usually found in groups of four?

A

False - they are found in pairs

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5
Q

How do genes control the different characteristics we develop?

A

They code for the proteins which structure our features and therefore the characteristics we display

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6
Q

What do the words ‘genotype’ and ‘phenotype’ mean?

A
Genotype = All of the genes in an organism
Phenotype = The genes the organism displays
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7
Q

Is a person’s weight determined by genes, the environment or a combination of both?

A

Both

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8
Q

Name the two types of sex cell.

A

Egg cells and sperm cells

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9
Q

How many chromosomes are found in sex cells? And what are these cels called?

A

23 chromosomes

Gametes

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10
Q

Why do most children look a bit like both of their parents but not identical to either?

A

Because you receive half of your genes from both parents

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11
Q

What is the difference between homozygous and heterozygous?

A
Homozygous = both your alleles for that particular gene are the same e.g. AA
Heterozygous = your alleles for that particular gene are different e.g. Aa
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12
Q

What sex chromosomes do human males have?

A

X and Y

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13
Q

How does a gene on one of the human sex chromosomes cause embryos to develop into males?

A

Because it codes for the protein which develops the testes and the rest of the male reproductive system.

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14
Q

Is the allele for cystic fibrosis dominant or recessive?

A

Recessive

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15
Q

What are the symptoms of cystic fibrosis?

A
  • thick, sticky mucus
  • difficulty breathing
  • difficulty digesting food = often small and skinny
  • chest infections =painful coughing
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16
Q

What are the symptoms of Huntington’s disease?

A
  • Clumsiness
  • Memory loss
  • Poor concentration
  • Mood changes
  • Tremors (shaking)
17
Q

What is the chance of a child inheriting Huntington’s disease if one of their parents has one copy of the faulty allele?

A

50%

18
Q

During IVF treatment, what is the process of testing embryos to see if they have a genetic disorder called?

A

Pre-implantation genetic diagnosis

19
Q

Other than testing embryos during IVF, give other uses of genetic testing.

A
  • To check if you have a condition before antibiotics are prescribed to you and prevent adverse reactions
  • Children and adults can be checked to see if they carry alleles for genetic disorders.
20
Q

What happens to an embryo in IVF treatment of it carries a genetic disorder?

A

It is discarded.

21
Q

Describe three issues surrounding genetic testing.

A

1- That all of the embryos have equal rights to life and should not be discarded
2- If someone in the family has a genetic disorder should all their relatives be tested?
3- If someone has a genetic disorder is it right for them to have children?

22
Q

Write a definition of the word ‘clone’.

A

A clone is an organism with identical DNA to another.

They have the same genes and the same alleles of those genes.

23
Q

How can bacteria reproduce asexually?

A

Their cells duplicate, doubling the population each time.

24
Q

How can plants reproduce asexually?

A

Some plants produce horizontal stems called runners that move out from the base of the plant and form new clones at their tips e.g strawberry plants
Other plants produce underground fleshy structures called bulbs. These can then grow to form a new identical plant e.g garlic

25
Q

How can animals reproduce asexually?

A

Some animals can lay eggs that are already fertilised and then become identically organisms e.g female greenfly
Female greenfly’s can also reproduce sexually when they feel like it

26
Q

How are identical twins formed?

A

Identical twins are also clones. One egg is fertilised by sperm and starts to develop. The embryo then splits in 2 and they begin to develop separately. These 2 embryos are still genetically identical.

27
Q

What are stem cells?

A

Unspecialised cells - they can develop into different types of cells depending on what ‘instructions’ they are given

28
Q

What are the two main types of stem cells and what are their differences?

A

Embryonic Stem Cells - found in early embryos, the stem cells are removed and then the embryo is destroyed. They can turn into ANY cell.
Adult Stem Cells - found in adult animals and can maintain and repair old and damaged tissues. CANNOT turn into any cell type. No embryos have to be destroyed as they can be removed from the bone marrow of the animal

29
Q

Describe ways in which stem cells could be used to treat an illness.

A

Embryonic Stem Cells - replace faulty cells such as creating a new heart muscle for those with heart disease, insulin-producing cells for those with diabetes and nerve cells for those paralysed by spinal injuries.
Adult Stem Cells - cure diseases such as those with blood diseases can have bone marrow transplants as the stem cells can turn into new blood cells and replace the faulty ones.