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Flashcards in Evolution & Origins of Life Deck (75)
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1
Q

What is the RNA world hypothesis?

A

Early life thought to be based on self-replicating, self catalytic, RNA molecules

2
Q

What are opsins?

A

G protein coupled receptors that convert light to nerve impulses

3
Q

What are hCONDELs?

A

Regions of deletions in human genomes that are highly conserved in closely related relatives

4
Q

How did eukaryotes arise?

A

Through endosymbiosis

5
Q

How can phylogenetic relationships be represented?

A

Using phylogenetic tree diagrams

6
Q

What is radiometric dating?

A

Measuring the ratio of parent daughter nuclides

7
Q

Outline the order of appearance of cells in the fossil record

A

Prokaryotes -> Eukaryotes -> Multicellular organisms -> Animals

8
Q

Define classification

A

Arranging taxa into an ordered, heirarchal system

9
Q

What is the start codon present in bacteria?

A

A modified version called Formyl-methionine

10
Q

Give examples of analogical structures

A

Insect wings and Bird wings

  • different developmental mechanisms
  • but have overlapping molecular components
11
Q

Name the PAX6 homologs

A

Mouse - small eye
Drosophilia fly - eyeless
Humans - PAX6 aniridia

12
Q

Why is the rate of radioactive decay constant?

A

It is not affected by the following factors

  • temperature
  • pressure
  • chemicals
  • electrical fields
  • magnetic field
13
Q

What can be determined using the fossil record?

A

The order and age of organisms

14
Q

Give an example of analogical molecules

A

Crystallins (lens proteins)
many different transparent proteins in different species
all have different functions as well
provide stability, transparency and refraction

15
Q

How has the diversity of cells increased so much?

A

The rate of diversification increases with multicellularity

16
Q

What is molecular analogy?

A

Molecular evolution convergence

- proteins can have similar functions with no common molecular structure

17
Q

How has the plastid genome evolved?

A

Has a loss of genes compared to its earlier form

The ‘lost’ genes are present in the nuclear genome

18
Q

What are the 4 basic processes of multicellularity?

A
  • spatial organisation
  • change in form/ specialisation
  • growth
  • differentiation
19
Q

How can mutations increase survival?

A

If mutation results in beneficial characteristics, the organism will survive better than its competition

20
Q

What is the fossil record?

A

Rock and organic material dated by measuring decay of natural occurring radioactive isotopes

21
Q

Approximately how many times has the cellular structure of eyes evolved?

A

Over 40 times - origin of eye components varies

22
Q

What is a homeodomain?

A

Transcription Factors found in genes regulating morphogenesis in plants, animals and fungi

23
Q

Give an example of a mutation tolerated by DNA

A

Sickle Cell Anemia (ScA)

  • mutation in both β globin gene Glu6Val
  • mutant Hb molecules aggregate and form crystals when deoxygenated
  • results in cells with sickle shape
  • cells get trapped in capillaries -> can cause tissue death
24
Q

What do all bacteria, archae and eukaryotes have in common?

A

They all carry genetic material DNA

25
Q

What is the function of the Drosophilia eyeless / PAX6 gene

A

Pax6/eyeless is involved in development of eyes & brain of both invertebrates & vertebrates

26
Q

How do eukaryotes detect light?

A

Via Opsins

27
Q

What are the consequences of gene duplication in evolution?

A
  • Complementary functions (original and duplicated genes carry out same function)
  • non overlapping functions
  • Regulatory mutations partition the activity of ancestral genes
28
Q

What are orthologs?

A

two genes from different organisms that have arisen from a common ancestor

29
Q

What is the start codon used in archae & eukaryotes?

A

Methionine AUG

30
Q

Why is radiometric dating an accurate way to determine age?

A

Parent and daughter nuclides cannot leave or enter materials once they have formed
There is no intrusion of other, later rock
No contamination

31
Q

Describe and explain the presence of HOX genes in vertebrates today

A

Vertebrates have 4 HOX gene clusters
- 2 duplications of ancestral chromosome
Gene order along chromosome corresponds to position of expression within the embryo
determined by homeodomains

32
Q

What allows for diversification?

A

Gene duplication

33
Q

Where are catalytic enzymes found?

A

Ribozymes are present in organisms from bacteria to humans

34
Q

How do different flu strains evolve?

A

Flu strains infecting the same cell can swap parts of their genetic material

35
Q

Why do bacteria normally not grow in citrate?

A

Under normal conditions With oxygen
Promoter for citrate is OFF
bacteria don’t produce enzyme
so don’t grow in citrate

36
Q

What is the function of the plastid genome?

A

Encode the proteins necessary for plastid function

37
Q

What is meant by homology?

A

Two structures that are from a common ancestral version

38
Q

How can phylogenetic relationships be studied?

A

The fossil record

Molecular analysis

39
Q

What is The Cambrian Explosion?

A

The sudden appearance of complex organisms in the fossil records

40
Q

What is the major difference in modern eukaryotes compared to their earlier form?

A

Modern eukaryotes contain plastids - mitochondria and chloroplasts

41
Q

Why are some mutations in DNA tolerated?

A

mutations are tolerated based on their effect - can sometimes have an advantage

42
Q

How are morphological differences established in cells?

A

During development even though reproductive, selective pressure acts on the adult form

43
Q

What is the advantage of the gene mutation causing sickle cell anemia?

A

Mutation of 1 β globin gene can give protection against malaria due to lower parasitaemia
-fewer complications -> improved malaria survival rates

44
Q

Describe the genome of present day eukaryotic opsins

A

Eukaryotic opsins share sequence homology

Diverged to detect different wavelengths of light

45
Q

What is catalytic RNA?

A

Ribozymes

46
Q

Which animals is the HOX gene present in?

A

In vertebrates (chromosomal organisation and function is conserved)

47
Q

How are animals so different despite evolving from the same genome?

A

Animals share the vast majority of their genes.

Their gene sequencing is the same but the gene expression differs

48
Q

Give an example of homological structures in organisms

A

Tetrapod limbs

- have similar developmental mechanisms

49
Q

What is meant by the term phylogenetics ?

A

New species arise from earlier species sharing relationships

50
Q

What are the 2 types of molecular homology?

A
  • Paralogs

- Orthologs

51
Q

How did bacteria and archae come about?

A

Overtime DNA and proteins became surrounded by phospholipids

52
Q

Outline an experiment that can be used to observe the process of evolution

A
  1. Grow 12 colonies of E. coli on petri dishes
  2. Every day take each culture and place in a clean flask
  3. Every 500 generations (75 days) freeze samples
    4 Test for ability to grow in citrate in the presence of oxygen
53
Q

Explain the function of N-neuraminidase gene in flu strains

A

An enzyme which allows viral particles to be released from the cell
- the better the cell is at releasing, the further the virus can spread

54
Q

How can mutations act as molecular clocks?

A

Species that share a recent common ancestor will have fewer differences/mutations than species
more distantly related

55
Q

Describe the evolutionary structure of HOX genes

A
  • Paralogs (duplicated from ancestral animals)

- Present in clusters along chromosome

56
Q

Approximately how many hCONDELs have been identified in the human genome?

A

583 regions identified across all chromosomes

57
Q

Which parent are mitochondria inherited from?

A

Mitochondria are maternally inherited

58
Q

Define evolution

A

New species arise from earlier species via an ongoing process driven by accumulated, heritable
changes

59
Q

What is the consequence of mutations in the PAX6 homologs?

A

Lead to retinal defects and ectopic eyes

60
Q

Define what is meant by analogy?

A

Similar structures with no common ancestors but have similar functions due to convergent evolution
(through selection ended up with similar functions)

61
Q

How are living organisms classified?

A

Based on morphological or molecular criteria

62
Q

Define the term taxonomy

A

The naming of groups of organisms

63
Q

What are paralogs?

A

two genes from the same organism arisen by duplication

64
Q

What happens if duplicated genes mutate?

A

Function differs slightly to original gene

organism still survives as original genes till present

65
Q

What evidence is there to support the theory of endosymbiosis?

A
  • Mitochondria have their own circular genome
  • MtDNA replicates independently of nuclear DNA
  • Mitochondria formed by fission of existing mt
  • mt genome share similarities with typhus bacterium ricketta prowazeki
66
Q

How do changes in genotype arise?

A
  • mutation
  • recombination of genetic material
  • natural selection
  • genetic drift
  • gene flow
  • applied selection
67
Q

What is meant by the term morphogenesis?

A

Anatomical development

68
Q

Explain what the term Phylogeny means

A

The determination of ancestral relationships of organisms and their evolutionary history

69
Q

Which genes are swapped amongst flu strains?

A

H-haemagglutinin (binds)

N-neuraminidase (release)

70
Q

How do bacteria evolve to grow in citrate in presence of oxygen?

A

The citrate gene is adjacent to Rnk promoter
RNK Promoter is always ON in presence of oxygen
some bacteria are able to grow in citrate
they duplicate DNA segement containing citrate, RNK promoter and RNK
Duplication results in the citrate gene to be turned on in oxygen presence

71
Q

What is the earliest cell type?

A

Prokaryotes

72
Q

How does H-haemagglutinin work?

A

Binds host cells by recongising specific receptor sites on their cell surface and infects

73
Q

What is the function of homeodomains?

A

Homeodomains share a characteristic protein fold structure that binds DNA

74
Q

What are HOX genes?

A

Homeotic genes that control the body plan of an embryo along the head-tail axis

75
Q

Why did the RNA world evolve into DNA genomes?

A

DNA is more stable than RNA

- greater range of protein enzymes