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GCSE Biology > Inheritance > Flashcards

Inheritance Flashcards

1
Q

What is a gene?

A

A section of DNA that codes for a specific protein (eg melanin or keratin) to produce a particular characteristic.

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2
Q

What is a chromosome?

A

A long DNA molecule that is found in a cell nucleus, and has many genes in it. It has stabilising proteins.

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3
Q

How is the structure of DNA composed?

A

Two parallel strands called backbones, which are made of sugar (deoxyribose) and phosphate. They are joined together in regular intervals by pairs of bases (A, T, C and G). The molecule is twisted, forming a double helix.

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4
Q

What are nucleotides made of?

A
  • Bases (A, T, C and G)
  • Sugar (Deoxyribose)
  • Phosphate
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5
Q

What are the four bases?

A
  • Adenine (A)
  • Thymine (T)
  • Cytosine (C)
  • Guanine (G)
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6
Q

Which bases always pair up?

A
  • Adenine and Thymine
  • Cytosine and Guanine
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7
Q

Why is DNA shaped as a double helix?

A

It is more stable

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8
Q

What do genes do?

A

Provide instructions for the cell to make proteins.

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9
Q

Which is important for controlling the proteins made, the bases, or their sequence?

A

The sequence of the bases

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10
Q

What is a mutation in DNA?

A

When something goes wrong when copying the DNA to make proteins.
OR
A change in the DNA sequence

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11
Q

What are some common mutations in DNA?

A
  • THE CAT ATE THE FAT RAT (normal)
  • THE CAT ATE THE FAT TAR
  • THE CAT ATE THE FAT BAT
  • THE CAT TET HEF ATR AT
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12
Q

How many chromosomes do human body cells contain?

A

46

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13
Q

How many pairs of chromosomes do human body cells contain?

A

23 pairs, one from your mother, one from your father.

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14
Q

How many copies of each gene do you have, and do these copies have to be the same?

A

2 copies of each gene, and no they must not be the same.

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15
Q

How many chromosomes do human gametes contain?

A

23, and are haploid

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16
Q

What are the sex chromosomes in humans called?

A

X and Y
(XX is female, XY is male)

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17
Q

What must happen to chromosomes during cell divison?

A

They must be accurately copied and passed on.

18
Q

What is cell division?

A

The process of replicating cells to make new ones.

19
Q

What are the two types of cell divison?

A

Mitosis and meiosis.

20
Q

Describe the process of mitosis.

A
21
Q

How long does mitosis take?

A

At its fastest, one hour.

22
Q

What is mitosis used for?

A
  • Growth/repair of tissues (replacement)
  • In asexual reproduction
  • Cloning
23
Q

What cell cannot duplicate?

A

Nerve cells cannot perform mitosis, and therefore can never repair. Once damaged, they cannot be fixed.

24
Q

Describe the process of meiosis.

A
25
Q

What is meiosis used for?

A

Creating Gametes

26
Q

What is crossing-over?

A

When homologous chromosome pairs exchange DNA to create genetic variation.

27
Q

How many cell divisions take place in mitosis?

A

One

28
Q

How many cell divisions take place in meiosis?

A

Two

29
Q

How many daughter cells are created in mitosis?

A

Two

30
Q

How many daughter cells are created in meiosis?

A

Four

31
Q

What is an allele?

A

A different version of the same gene.

32
Q

What does homozygous mean?

A

When both alleles are the same (eg BB or bb)

33
Q

What does heterozygous mean?

A

When both alleles are different (eg Bb)

34
Q

What is the genotype?

A

Which alleles you have (eg BB, Bb or bb)

35
Q

What is the phenotype?

A

The outward expression of the alleles you have / your appearance. (eg blue eyes)

36
Q

What is a dominant allele?

A

You only need one allele present for the characteristic to be expressed in the phenotype.

37
Q

What is a recessive allele?

A

You need two copies of the same allele for the characteristic to be expressed in the phenotype.

38
Q

What is a codominant allele?

A

When two alleles of the same gene are both expressed in the phenotype.

39
Q

What does diploid mean?

A

The full number of chromosomes are in the cell (46 in humans) and there are two of each pair of chromosomes.

40
Q

What does haploid mean?

A

Half the number of chromosomes (gametes only) and there is only one of each pair of chromosomes.

GCSE Biology (14 decks)

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