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Biology GCSE > Topic 3: DNA and Inheritance > Flashcards

Topic 3: DNA and Inheritance Flashcards

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1
Q

What is an allele?

A

A variety of a gene

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2
Q

What is the genotype?

A

The genes present for a trait.

Example: BB, Bb, bb

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3
Q

What is a phenotype?

A

The visible characteristic.

Example: blue eyes, curly hair, red flowers.

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4
Q

What is a dominant allele?

A

An allele that shows in the phenotype whenever it is present.
(shown as capital)

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5
Q

What is a recessive allele?

A

An allele that is hidden when a dominant allele is present.

Shown as lower case

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6
Q

What is a homozygous allele?

A

A genotype in which the two alleles for the characteristic are identical. (AA or aa)

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7
Q

What is a heterozygous allele?

A

A genotype in which the two allele for a particular characteristic are different. (Aa)

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8
Q

What is DNA?

A

DNA molecules carry the genetic code that determines the characteristics of a living organism.

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9
Q

What is a gene?

A

A gene is a section of DNA that codes for a specific protein.

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10
Q

What is a chromosome?

A

Long threads of DNA, each made up of many genes.

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11
Q

Where is a chromosome located?

A

In the nucleus of a cell.

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12
Q

What is the structure of the DNA molecule?

A

Double helix. (Two strands twisted together in a spiral.

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13
Q

What is the backbone of each DNA strand made of?

A

Sugar and phosphate molecules.

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14
Q

What are the 4 bases that occur in DNA molecules?

A

Thymine T
Adenine A
Guanine G
Cytosine C

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15
Q

What are the complementary base pairings?

A

Thymine - adenine (T-A)

Guanine - cytosine (G-C)

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16
Q

What is the triplet code?

A

A code of three bases. Amino acids are then joined in this order to make the protein.

17
Q

What is selfing?

A

When gametes from the same parent fuse. (example: where pollen from one plant lands on the stigma of the same plant)

18
Q

How do you construct a Punnett square?

A

Determine the parental genotypes
Split the alleles for each parental type and add them into your Punnett square around the edges.
Work out the new possible genetic combinations inside the Punnett square.
Use this to answer the question. You may be asked to comment on the proportion of different allele combinations in the offspring, calculate a probability ratio, or just determine the phenotypes of the offspring.

19
Q

How is homozygous recessive written?

A

aa

20
Q

Hoe is homozygous dominant written?

A

AA

21
Q

How is heterozygous written?

A

Aa

22
Q

Which chromosome determines the sex?

A

23rd

23
Q

What is the Punnett square for sex determination?

A

X X
X XX XX
Y XY XY Always 50/50

24
Q

What is genetic profiling?

A

A method of comparing DNA.

25
Q

What is the process of genetic profiling?

A

By cutting DNA into fragments and comparing the fragments with each other.

26
Q

What are 3 examples of genetic profiling?

A
  • Paternity testing (see who is biologically a child’s parent)
  • Forensic identification (matching a criminal with the DNA left on a crime scene)
  • Matching an organism’s DNA to classify it
27
Q

What are 2 benefits of genetic profiling?

A
  • It can help catch criminals

- It can be used to identify the presence of disease-causing genes

28
Q

What is an ethical issues surrounding genetic profiling?

A

It can be used against people by insurance companies based on a person’s predisposition to certain diseases.

29
Q

What is the structure of DNA and what is it made out of?

A

It is a polymer made of many nucleotide monomers

It is made of 2 strands in the shape of a double helix

30
Q

What is the genome?

A

The entire genetic material of an organism.

The human genome being the entire genetic material that makes a human.

31
Q

How does the sequence of DNA affect the protein made in protein synthesis?

A

DNA is a triplet code where 3 bases code for one amino acid and the order of amino acids determine the protein produced.

32
Q

What is the F1 generation?

A

The offspring produced when 2 organisms are bred together.

33
Q

What is the F2 generation?

A

The offspring produced from the F1 generation.

34
Q

What is genetic engineering?

A

Altering the genome of an organism.

35
Q

What is a transgenic organism?

A

An organism that contains foreign DNA.

36
Q

What is genetic modification?

A

Something that allows genetic material from one organism to be transferred into the DNA of another.

37
Q

What is an advantage of genetic modification? (within plants)

A

genes for disease resistance can be transferred to crop plants to increase yield.

38
Q

What is a disadvantage of genetic modification? (within plants)

A

Creation of super weeds if the herbicide resistance genes are taken up by weed species.

39
Q

What is a herbicide?

A

a substance that is toxic to plants.

Biology GCSE (9 decks)

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