B6: inheritance Flashcards

(20 cards)

1
Q

Describe the differences between sexual and asexual reproduction

A

SEXUAL:
- involves fusion of male and female gametes: fertilisation
- offspring receive genetic material from both parents
- variation in offspring

ASEXUAL:
- doesn’t involve gamete as there is only one parent
- no mixing of genetic material
- offspring are genetically identical (clones)
- only involves mitosis, not meiosis.

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2
Q

How does meiosis halve the number of chromosomes in gametes?

A
  1. All of the chromosome pairs are copied
  2. The cell divides in two
  3. Now both cells divide one more time to form gametes, with single chromosomes.
  • produces four different gametes from one cell, which are different. They each have different alleles.
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3
Q

How does fertilisation restore the full number of chromosomes?

A

Because the two gametes fuse together, they add up to make 23 chromosome pairs.

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4
Q

Where does meiosis take place?

A

Only in the reproductive organs

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5
Q

Describe the structure of DNA

A
  • consists of two strands, which is a polymer
  • the two strands wrap around each other to form a double helix
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6
Q

What is a genome?

A

The entire genetic material of an organism

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7
Q

Why is it important we understand what a genome is? (3)

A
  • help search for genes linked to a diseases (eg. Cancers)
  • help us understand and treat inherited disorders (eg. Cystic fibrosis)
  • can trace human migration patterns of the past
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8
Q

What is a gene?

A

A small section of DNA on a chromosome

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9
Q

What is a dominant allele?

A

An allele will show in the phenotype even if there is only one copy present.

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10
Q

What is a recessive allele?

A

An allele will only show in the phenotype if two copies are present.

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11
Q

What is an allele?

A

Versions of a gene

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12
Q

What is homozygous?

A

Two copies of the same allele

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13
Q

What is heterozygous?

A

Two different alleles

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14
Q

What is a genotype?

A

Tells us the alleles present

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15
Q

What is a phenotype?

A

Characteristics caused by the person’s alleles

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16
Q

Which allele expresses cystic fibrosis?

A

Cystic fibrosis is expressed in the recessive allele

17
Q

Describe polydactyly

A

Having extra fingers or toes.

18
Q

What is the issue around embryo screening?

A
  • expensive, money should be used elsewhere
  • often large number of embryos are created but only a small number are implanted. Some think this is unethical
  • in future, we may be able to chose desirable offspring. Some find this unethical.
19
Q

Which allele expresses polydactyly?

20
Q

Which set of sex chromosomes do males and female have?

A
  • Male: XY
  • Female: XX