Genetic Information Storage and Transfer Flashcards

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1
Q

How is genetic information stored

A

In units called genes

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2
Q

What is the genotype

A

the sets of genes inherited

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3
Q

What is the phenotype

A

Individual characteristics and appearance

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4
Q

What mostly determines the phenotype
Why is this not always so simple

A

Genotype determines phenotype
There are other influences which can alter the observed effect

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5
Q

What phrase could one use to describe the genotype in eukaryotes

A

Fuzzy instructions

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6
Q

What are the key factors affecting phenotype, other than genotype

A

Epigenetics
Environment
Randomness

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7
Q

How does Epigenetics affect phenotype

A

Chemical modification to genes that turn them on/off
Heritable and passes on as cells divide

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8
Q

How does the environment affect phenotype

A

Classic example height: malnutrition stunts growth and lowers final height
In plants: day length and temperature cycles can affect flowering time
Complex examples in human health: heart disease, Crohns disease

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9
Q

How does randomness affect the phenotype

A

During cell development some processes do not repeat exactly
Cell-cell interactions may be subtly different

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10
Q

How would you study the effect of genetics

A
  • Take organisms from very similar genetic backgrounds
  • Use very similar environments
  • Doing both at once is common to reduce the effect of phenotypic variation in animal studies
    Inbred mice (highly similar genetics)
    Kept in identical environments, fed identical food etc
  • Use knockout or gene-edited animals to examine the role of genetic change
    Animals are very similar apart from a known change (congenic)
    Common to use siblings/littermates
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11
Q

How could u study the influence of the environment on phenotype

A

If you had clones (genetically identical individuals) you could study influence of environment
This is done widely with bacteria, yeast and human cell lines

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12
Q

What is the problem with using animal clones to study the effect of the environment with

A

Many animal clones have been created but not always identical

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13
Q

How would you create a cat clone (or other mammals)

A
  • Take an egg cell and remove the genetic material
  • Fuse the enucleated egg with a cell from the animal to be cloned, or transfer the nucleus from the donor cell
  • Zap with an electrical pulse to activate the new hybrid cell
  • Implant into surrogate mother and wait for delivery
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14
Q

How do the genetics of coat colour work in cats

A
  • Orange or black depends on a gene on the X chromosome, allele O=orange, o=black

In female mammals, one random copy of X is inactivated in each cell - known as X inactivation

So a female with a mixed genotype will have some cells expressing orange allele and some expressing black - which results in mixed colours of orange and black fur - tortoiseshell

White patches of a calico are random and a result from the action of another gene on one of the autosomes

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15
Q

Is human cloning allowed

A

Human cloning is considered unethical and is explicitly banned in most countries
Similarly, human gene editing is also prohibited in most countries
However in the UK, nuclear transfer can be used to avoid mitochondrial diseases (3 parent babies)

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16
Q

‘natural clone’ known as an identical twin
How do they oocur

A

Identical twins occur when a fertilised egg splits during early development
Genetically identical, usually share a very similar environment

17
Q

What are the rates of non-identical and identical twins per thousand

A

Non-identical - about 23 per thousand
Identical - about 4 per thousand

18
Q

Why are we all not clones of our parents or siblings

A

Each individual has a unique genotype - a complete set of inherited
This is because their genome is a randomised mixture of their parents
Sexual reproduction results in individuals, with unique genotypes

19
Q

Briefly, how do genes influence phenotypes

A
  • Genes code for proteins
  • Proteins act inside cells
  • Cell interact with other cells
  • Organs and tissues are established
  • Organism is assembled and grows
20
Q

What is the genome?

A

Is the complete set of genetic material within one chromosomes set
Varies hugely in size between different species, as does gene number