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Left RSFC Year 13 2022-24 > 4: Genetic information, variation and relationships between organisms > Flashcards

4: Genetic information, variation and relationships between organisms Flashcards

1
Q

Define the term exon.

A

Base/nucleotide/triplet sequence coding for polypeptide/sequence of amino acids/primary structure;

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2
Q

Describe Transcription in Eukaryotes [5]

A
  1. Hydrogen bonds (between DNA bases) break;
  2. (Only) one DNA strand acts as a template;
  3. (Free) RNA nucleotides align by complementary base pairing;
  4. (In RNA) Uracil base pairs with adenine (on DNA) OR (In RNA) Uracil is used in place of thymine;
  5. RNA polymerase joins (adjacent RNA) nucleotides;
  6. (By) phosphodiester bonds (between adjacent nucleotides);
  7. Pre-mRNA is spliced (to form mRNA) OR Introns are removed (to form mRNA);
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3
Q

Describe Translation [5]

A
  1. (mRNA attaches) to ribosomes OR (mRNA attaches) to rough endoplasmic reticulum;
  2. (tRNA) anticodons (bind to) complementary (mRNA) codons;
  3. tRNA brings a specific amino acid;
  4. Amino acids join by peptide bonds via condensation reaction;
  5. (Amino acids join together) with the use of ATP;
  6. tRNA released (after amino acid joined to polypeptide);
  7. The ribosome moves along the mRNA to form the polypeptide;
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4
Q

Describe the role of ATP in the process of translation in protein synthesis.

A
  1. Releases energy;
  2. (So) peptide bonds form between amino acids OR (So) amino acid joins to tRNA;
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5
Q

Give two structural differences between a molecule of messenger RNA (mRNA) and a molecule of transfer RNA (tRNA).

A
  1. mRNA does not have hydrogen bonds / base pairing, tRNA does; OR mRNA is linear / straight chain, tRNA is cloverleaf;
  2. mRNA does not have an amino acid binding site, tRNA does;
  3. mRNA has more nucleotides;
  4. (Different) mRNAs have different lengths, all tRNAs are similar / same length;
  5. mRNA has codons, tRNA has an anticodon;
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6
Q

What is an allele?

A

(Different) form/type/version of a gene / different base sequence of a gene;

Formed via mutation.

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7
Q

What is a gene?

A
  • A sequence of DNA (nucleotide) bases that codes for a polypeptide;
  • ‘codes for a functional RNA’
  • ‘codes for rRNA/tRNAs’
  • ‘codes for a sequence of amino acids/primary structure’
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8
Q

Define degenerate code

A

More than one codon for one amino acid

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9
Q

Explain what the term non-overlapping DNA means.

A

A base from one triplet cannot be used in an adjacent triplet

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10
Q

Explain how selection occurs in living organisms [5]

A
  1. Variation due to mutation;
  2. Different
    selection pressures     environmental/abiotic/biotic conditions / Different
    selection pressures    ;
  3. Selection for different/advantageous, features/characteristics/mutation/allele;
  4. Differential reproductive success / (selected) organisms survive and reproduce;
  5. Leads to change in allele frequency;
  6. Occurs over a long period of time;
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11
Q

A mutation in a gene coding for an enzyme
could lead to the production of a non-functional enzyme. Explain how [5]

A
  1. Change in base sequence (of DNA/gene);
  2. Change in amino acid sequence / primary structure (of enzyme);
  3. Change in hydrogen/ionic/ disulphide bonds;
  4. Change in the tertiary structure/active site (of enzyme);
  5. Substrate not complementary/cannot bind (to enzyme / active site) / no enzyme-substrate complexes form;
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12
Q

Not all mutations in the nucleotide sequence of a gene cause a change in the structure of a polypeptide. Give two reasons why

A
  1. Triplets code for same amino acid
  2. Occurs in introns /non-coding sequence;
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13
Q

Define genome

A

(All) the DNA in a cell/organism;
(all) the ‘genes’/alleles’ ‘genetic material/code’ in a cell/organism/ person’

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14
Q

Define proteome

A

(The proteome is the full) range of / number of different proteins that a cell is able to produce (at a given time);

OR

(The proteome is the full) range of / number of different proteins the genome / DNA is able to code for;

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15
Q

Define ‘gene mutation’ and explain how a gene mutation can have:
* no effect on an individual
* a positive effect on an individual.

[6]

A

(Definition of gene mutation)
1. Change in the base/nucleotide (sequence of chromosomes/DNA);
2. Results in the formation of new allele;
(Has no effect because)
3. Genetic code is degenerate (so amino acid sequence may not change); OR
Mutation is in an intron (so amino acid sequence may not change);
Accept description of ‘degenerate’, eg some amino acids have more than one triplet/codon.
4. Does change amino acid but no effect on tertiary structure;
5. (New allele) is recessive so does not influence phenotype;
(Has positive effect because)
6. Results in change in polypeptide that positively changes the properties (of the protein) OR Results in change in polypeptide that positively changes a named protein; For ‘polypeptide’ accept ‘amino acid sequence’ or ‘protein’.
7. May result in increased reproductive success OR May result in increased survival (chances);

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16
Q

Describe two aseptic techniques she would have used when transferring a sample of broth culture on to an agar plate.
Explain why each was important.

A
  1. Keep lid on Petri dish OR Open lid of Petri dish as little as possible.
  2. To prevent unwanted bacteria contaminating the dish.
    OR
  3. Wear gloves / Wear mask / Wash hands;
  4. To prevent contamination from bacteria on hands / mouth / Prevent spread of bacteria outside the lab;
    OR
  5. Use sterile pipette / Flame the loop / Flame the neck of the container of the culture;
  6. To maintain a pure culture of bacteria
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17
Q

Bacteria are able to synthesis human proteins. Suggest why.

A

Mechanisms of Transcription and Translation are UNIVERSAL.

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18
Q

The genome is…….

A

(The) complete set of genes in a cell/organism

OR

(All) the DNA in a cell/organism;

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19
Q

The proteome is…….

A

Range of proteins that a cell/organism can produce

OR

Range of proteins the genome/DNA can code for;

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20
Q

Suggest and explain one reason why bacteria might not be able to produce every human protein.

A

Cannot splice (pre-mRNA), so cannot remove introns

OR

Do not have Golgi (apparatus), so cannot process/modify (proteins);

OR

Do not have transcriptional factors (required), so cannot carry out transcription/produce mRNA;

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21
Q

What is a substitution mutation?

A
  1. Replacement of a base by a different base (in DNA);
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22
Q

Name 3 types of single point gene mutations.

A

Addition
Deletion
Substitution

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23
Q

Which mutation can be refered to as a silent mutation and explain why. [4]

A
  • Substitution;
  • The genetic/DNA code is degenerate;
  • More than one triplet can code for the same amino acid;
  • Mutation may not lead to a change in the primary structure / number and seguence of amino acids;
24
Q

What type of mutation leads to a change in chromosome number?

A

Non-disjunction of chromatids, during meiosis (II).

25
Q

How would you calculate the number of cells present after a number of divisions?

1 cell divides 5 times

A

2^n

= 2^5

= 32

2 to the power n (N=number of divisions)

26
Q

Define genetic diversity.

A

The number of different alleles of genes in a
population.

27
Q

State one example of directional selection.

A

Antibiotic resistance in bacteria

28
Q

State one example of stabilising selection.

A

Human birth weight

29
Q

State two major factors in evolution and diversity within living organisms.

A

Adaptation & Selection

30
Q

State two examples of Natural selection

A

Stabilising & Directional
Disruptive (leads to speciation, covered in year 13)

31
Q

How can evolution be measured?

A

Through changes in allelic frequencies (within a population over time)

32
Q

What is a species?

A
  1. Group of similar organisms / organisms with similar features / organisms with same genes / chromosomes;
  2. (that can)Reproduce to produce fertile offspring;
33
Q

Explain what is meant by a heirarchy? [2]

A
  1. Groups within groups;
  2. No overlap (between groups);
34
Q

Explain what is meant by a phylogenetic group?

A

(Grouped according to) evolutionary links/history/relationships / common ancestry;

35
Q

Describe how organisms are grouped in a phylogenetic classification system. [2]

A
  1. Hierarchy (of groups) with no overlaps
    OR (smaller) groups within (larger) groups with no overlaps;
  2. (Grouped) according to evolutionary origins/relationships/history;
36
Q

Explain what is meant by genetic
diversity.

A

Difference in DNA/base sequence/alleles/genes;

37
Q

The number of species present is one way to measure biodiversity.

Explain why an index of diversity may be a more useful measure of biodiversity. [2]

A

Also measures number of individuals in a species / different proportions of species;
Some species may be present in low/high numbers;

38
Q

What is meant by species richness?

A

The number of different species in a community.

39
Q

Define community.

A

All the individuals of all the species living in the same area at the same time.

40
Q

Explain how natural selection produces changes within a species. [6]

A
  1. Variation [caused by mutation] between members of population / species;
  2. Predation / disease / competition results in differential survival;
  3. Some have adaptations that favour survival;
  4. Differential reproductive success / survive to reproduce/ have more offspring/
  5. Pass on their advantageous alleles /
  6. Changes allelic frequencies
41
Q

Describe how comparisons of biological molecules in two species could be used to find out if they are closely related. [3]

A

Compare:

  • DNA base sequence;
  • RNA base sequence;
  • sequence of amino acids /primary structure (of named / same protein)
42
Q

In classification, comparing the base sequence of a gene provides more information than comparing the amino acid sequence for which the gene codes. Explain why [3]

A
  • Reference to base triplet/triplet code / more bases than amino acids / longer base sequence than amino acid sequence;
  • Introns/non-coding DNA;
  • Same amino acid may be coded for / DNA code is degenerate;
43
Q

Scientists can use protein structure to investigate the evolutionary relationships
between different species.

Explain why. [3]

A
  1. Amino acid sequences / primary structure;
  2. Closer the (amino acid) sequence the closer the relationship;
  3. (Protein structure) related to (DNA) base/triplet sequence;
44
Q

A forest was cleared to make more land available for agriculture.
After the forest was cleared the species diversity of insects in the area decreased.
Explain why. (4)

A
  1. Decrease in variety of plants / fewer plant species;
  2. Fewer habitats/niches;
  3. Decrease in variety of food / fewer food sources;
  4. Aspect of clearing forest (killing insects) eg machinery, pesticides;
45
Q

Suggest one ethical argument for maintaining biodiversity.

A
  • Prevent extinction
  • loss of populations
  • reduction in populations
  • loss of habitats
  • save organisms for future generations (idea of);
46
Q

Suggest one economic argument for maintaining biodiversity.

A

A suitable example of how some species may be important financially e.g.
1. medical / pharmaceutical uses;
2. commercial products / example given;
3. tourism;
4. agriculture;
5. saving local forest communities;

47
Q

Farmers clear tropical forest and grow crops instead. Explain how this causes the diversity of insects in the area to decrease. [4]

A
  1. Lower diversity of plants/ few species of plants/less variety of plants/few plant layers;
  2. Few sources/types of food/feeding sites;
  3. Few habitats/ niches;
  4. Fewer (species of) herbivore so few (species of) carnivores;
  5. Aspect of agriculture (killing insects);
48
Q

Describe how courtship behaviour increases the probability of successful mating. [5]

A
  1. Attracts/recognises same species;
  2. Attracts/recognises mate/opposite sex;
  3. Indication of sexual maturity/ fertility / synchronises mating;
  4. Stimulates release of gametes;
  5. Form pair bond;
49
Q

What system is used to scientifically name organisms?

A

Binomial system consisting of the name of its genus and species

E.g., Homo sapien

In italics; Genus first - species second; only the first letter of the genus is a capital.

50
Q

What are the different taxa in classification?

A

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Delicious-King-Prawn-Curry-Or-Fat-Greasy-Sausages

51
Q

What are the three domains?

A

Eukarya
Archaea (Bacteria)
(Eu)bacteria

52
Q

Name the 4 Eukarya Kingdoms

A

Animals (Animalia)
Plants (Plantae)
Fungi
Protists (Protoctista)

53
Q

Quantitative investigations of variation within a species must include……

A
  • Collecting Random samples (removes bias)
  • Calculating a mean (of recorded values) and standard deviation (reduces the effect of anomolous data)
  • Interpretation of mean values using Student T test (STATS TEST) to detemine if differences are significant.
54
Q

There are different types of gene mutation.

Which describes incorrectly the effect of the mutation in an exon of a gene.

A) A substitution may not result in a change to the encoded amino acid.

B) An inversion will result in a change in the number of DNA bases.

C) A deletion will result in a frame shift.

D) An addition will result in a frame shift.

A

B) An inversion will result in a change in the number of DNA bases.

55
Q

Give one reason why antibiotics are not effective against viruses.

A

Do not have bacterial structures/enzymes
OR
Do not have metabolic processes/synthesise proteins
OR
Do not have a cell wall/murein/peptidoglycan/glycoprotein;
OR
Do not have ribosomes

Left RSFC Year 13 2022-24 (10 decks)

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