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AQA A level Biology > Genetic information, variation and relationships between organisms > Flashcards

Genetic information, variation and relationships between organisms Flashcards

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1
Q

Definition of a gene?

A

A gene is a base sequence of DNA that codes for
- the amino acid sequence of a polypeptide
-a functional RNA (including ribosomal RNA and tRNAs)

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2
Q

What is the locus?

A

The fixed position a gene occupies on a DNA molecule

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3
Q

What is a triplet?

A

A sequence of three DNA bases coding for a specific amino acid.

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4
Q

The genetic code

A
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5
Q

Degenerate

A

More than one triplet can be coded for one amino acid

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6
Q

Universal

A

Triplet code is the same code for all living organisms in one amino acid

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7
Q

Non- overlapping

A

Each base is only part of one triplet codon

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8
Q

What are introns?

A

Non coding regions of a gene

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9
Q

What are exons?

A

Coding regions of a gene

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10
Q

DNA in prokaryotes

A

Short, circular and not associated with proteins.

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11
Q

DNA in eukaryotes

A

Long, linear and associated with proteins called histones. Together a DNA molecule and its associated proteins form a chromosome.

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12
Q

DNA of mitochondria and chloroplasts

A

Short, circular and not associated with proteins.

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13
Q

Genome

A

The complete set of genes in a cell

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14
Q

Proteome

A

The full range of proteins that a cell is able to produce.

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15
Q

Structure of chromosome

A

At start of cell division, they appear as two threads joint by a single thread (each thread known as chromatid). These are conjoined by a centromere.
DNA is held together by histones.

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16
Q

Chromosomes in humans

A

46
23 pairs

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17
Q

Chromosomes in gametes

A

23

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18
Q

Homologous chromosomes

A

A pair of chromosomes, one maternal and one paternal which have the same gene loci

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19
Q

What is an allele?

A

Different versions of the same gene

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20
Q

Gene mutation

A

A change in the base/ nucleotide sequence of DNA resulting in the formation of a new allele

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21
Q

Sources of DNA from organisms

A

Bone/ skin/ preserved remains

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22
Q

Reasons for low levels of genetic diversity

A
  • Inbreeding
  • Population started with small number of individuals
  • Population may have been very small
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23
Q

RNA structure

A

A polymer forming a single strand.
- Pentose sugar ribose
- Nitrogen containing organic bases (adenine,guanine,cytosine, uracil)
- Phosphate group

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24
Q

The two types of RNA in protein synthesis

A

messenger RNA (mRNA)
transfer RNA (tRNA)

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25
Q

Structure of mRNA

A

Linear
Exons
Codon

26
Q

Structure of tRNA

A

Clover leaf shape
Has specific amino acid binding site

27
Q

Function of transcription

A

The process of making mRNA from DNA

28
Q

Results of transcription
- prokaryotic cell

A

Transcription results directly in the production of mRNA from DNA.

29
Q

Results of transcription
- eukaryotic cell

A

Transcription results in the production of pre-mRNA which is then spliced to form mRNA.

30
Q

Function of translation

A

Translation as the production of polypeptides from the sequence of codons carried by mRNA.

31
Q

RNA polymerase role

A
32
Q

Ribosome role

A
33
Q

Role of tRNA

A
34
Q

Role of ATP

A
35
Q

What is the process of splicing?

A

Introns are removed from the pre-mRNA by the spliceosome and exons are spliced back together.

36
Q

What is a spliceosome?

A

Huge, multimegadalton ribonucleoprotein (RNP) complexes found in eukaryotic nuclei.

37
Q

Meiosis stages

A

Prophase, metaphase, anaphase, telophase
- two stages process each stage occurring twice yet DNA only replicates once

38
Q

Crossing over

A

Process by which non sister chromatids exchange alleles and DNA

39
Q

Ways in which meiosis increases genetic variation?

A
  • Exchange of genetic material between chromatids of maternal and paternal origin. (prophase)
  • Orientation of each paire of chromosomes one spindle is a random event. (metaphase)
  • Independant segregation
40
Q

What is meiosis?

A

Meiosis is a type of cell division which results in four genetically varied daughter cells

41
Q

Independant segregation

A

Separation of chromosomes, halving them resulting in four daughter cells with completely different combinations of maternal and paternal chromosomes.
- Completely random event
- Increases genetic variation

42
Q

Mutations

A
43
Q

Mutagenic agents

A
44
Q

Base deletion

A
45
Q

Base substitution

A
46
Q

Genetic diversity

A

The number of different alleles of genes in a population.

47
Q

Principles of natural selection

A

Random mutation can result in new alleles of a gene.
Many mutations are harmful but, in certain environments, the new allele of a gene might benefit its possessor, leading to increased reproductive success.
The advantageous allele is inherited by members of the next generation and over many generations, the new allele increases in frequency in the population.

48
Q

Anatomical adaptations

A
49
Q

Physiological adaptations

A
50
Q

Behavioural adaptations

A
51
Q

Courtship behaviour

A
52
Q

What are groups called in phylogenetic classification?

A

Each group is called a taxon (plural is taxa).

52
Q

Phylogenetic classification

A

Arrange species into groups based on their evolutionary origins and relationships. Using a hierarchy in which smaller groups are placed within larger groups with no overlap between groups.

53
Q

What is the order of the heirarchy comprising the taxa?

A

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

54
Q

Acronym for heirarchy of taxa

A

Do Keep Ponds Clean Or Frogs Get Sick

55
Q

Binomial classification

A

A formal system of naming species of living things by giving each a name composed of two parts, their Genus and Species

56
Q

Definition of species

A

Groups of organisms which are able to produce fertile offspring

57
Q

Definition of species richness

A

A measure of the number of different species in a community.

58
Q

Index of diversity

A

The relationship between the number of species in a community and the number of individuals in each species.

59
Q

Farming techniques which reduce biodiversity

A
60
Q

Conservation

A

AQA A level Biology (6 decks)

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