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CELS 191 > Human Molecular Genetics > Flashcards

Human Molecular Genetics Flashcards

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1
Q

Why was the human genome sequenced?

A

To identify all human genes
Analyse genetic variation

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2
Q

How many different donors is the Human Reference genome made up of?

A

20

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3
Q

Describe the structure of mitochondrial DNA

A

Single, circular structure.
16,569 base pairs
All from mother
37 genes

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4
Q

Describe the structure of structure of nuclear DNA?

A

22 Autosomes, X and Y
6 billion base pairs
Half from each parent
About 20,000 genes

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5
Q

What were the findings of the human genome?

A

Less than 2% of our genome codes for proteins
Genomes are still evolving
There are no uniquely ‘human’ genes

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6
Q

How percentage of genes are intron?

A

20%

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7
Q

What is an SNP?

A

Single Nucleotide Polymorphisms which are sites in DNA that vary within populations

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8
Q

How common are SNPs?

A

1 in every 300 nucleotides

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9
Q

Where are SNPs mainly from?

A

Your parents

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10
Q

Are SNPs harmful?

A

Not often

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11
Q

What can SNPs tell us?

A

Who we are related to.
Ancestors
Response to drugs

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12
Q

True or false, a linked SNP is less likely to be inherited?

A

False

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13
Q

What are STRs?

A

Short tandem repeats, repeats of 2-5 nucleotides, found in specific regions of the genome

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14
Q

What are InDels?

A

Small insertions or deletions, second most common variant type in the human genome

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15
Q

What does it mean for a person to be 3,8 at STR 1?

A

They have inherited 8 repeats of CAG from their mother and 3 from their father

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16
Q

What are the structural variants in the human genome?

A

CNVs

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17
Q

What is a CNV?

A

Copy number variation are chunks of DNA that are present in different amounts relative to the reference genome.

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17
Q

How many CNVs do humans have?

A

10,000

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18
Q

How do you compare sequences?

A

By aligning them, lining them up and marking the points where the sequences are the same

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18
Q

Why can we not accurate sequence DNA as it degrades?

A

DNA changes its sequence as it degrades

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19
Q

What are CNV genes commonly associated with?

A

Sensory perception and immunity

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20
Q

What can we achieve from comparing genomes within a species?

A

Differences may show disease or characteristics of an individual

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20
Q

What did we discover from sequencing Neanderthal nucleotides?

A

Modern humans in Europe and Asia carried Neanderthal DNA.
Our DNA holds variants that arose in Neanderthals

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21
Q

How much of the non-African genome is Neanderthal DNA?

A

2-4%

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22
Are mutations inherited or aquired?
Both
23
What is a mutation?
Permanent changes to the DNA sequence
24
What are germline mutations?
Mutations that are passed on via the gametes
25
What are somatic mutations?
Mutations in somatic cells, they are not passed to the next generation
26
What kind of mutation is cancer caused by?
Somatic
27
What is the driving force of evolution?
Mutations
28
What does being diploid mean for humans?
They have two copies of each of their genes
29
What does a mutation require to have a phenotype?
Affect the function of a gene
30
Is loss or gain of function alleles dominant?
Gain of function
31
Why are loss of function alleles typically recessive?
because a normal copy of the gene exists on another chromosome which can replace the lost function
32
Why is a gain of function mutation dominant?
Because having an allele that does something well or novel, will not be replaced with a normal copy of the gene
33
What is a Monogenic Disease?
A disease caused by the inheritance of 1 gene.
34
What is a characteristic of an autosomal recessive mutation?
Not seen in every generation Passed on by 2 asymptomatic carriers Inherited by females and males equally
35
What are the characteristics of an autosomal dominant inheritance
Occurs commonly Affect individuals have an affect parent Inherited equally by both males and females
36
What are the characteristics of an X-linked recessive inheritance pattern?
Fathers cannot pass to their son Mostly affects males
37
What is a polygenic disorder?
Involve several genes acting together with environmental factors.
38
What is genetic determinism?
With most disease, disease related variation may not mean that you get the disease. Diseases are probabilistic, not deterministic.
39
What percentage of human genes have an unknown function?
20% (4,000)
40
How can we find out what a gene does?
Find the equivalent gene in another organism and increase the rate of random mutation. Deliberately break a particular gene and see what happens
41
What is a model organism?
Ones that can be raised in a controlled environment and are easy to genetically manipulate.
42
What are 3 model organism?
Mouse, zebrafish, drosophila.
43
What is transgenesis?
Engineering a multicellular organism by adding 'foreign' DNA
44
What is the purpose of transgenesi?
Understand how genes work, in gene therapy, or engineer recombinant proteins
45
How does transgenesis occur in mice?
DNA is reimplanted into eggs
46
How do we know whether a gene variant is pathogenic?
Genes can be damaged or modified, and by examining the model organism, we can identify what a gene normally does
47
What is CRISPR?
Clustered regularly interspaced short palindromic repeats. A gene editing program.
48
Describe targeted mutation using CRISPR-Cas9
First decide what gene you wish to mutate and then design a guide RNA and bind it to your gene of interest.
49
What happens when CRISPR-Cas9 enters the nucleus?
It finds the target sequence and matches it using guide RNA, it then makes a double stranded break in the DNA. In the absence of the the template, DNA enzymes try to repair the cut, and because of this, it is possible to edit the DNA sequence at the cut site
50
Can we fix genetic disease?
Yes! But only if we know what causes it and have a way to correct the defect.
51
Describe gene therapy in terms of cystic fibrosis
By taking fake plasmid DNA and inserting it into the lungs via a nebulizer. This makes proteins which restore the functions of some cells.
52
What is the purpose of gene therapy/
To fix genetic disease in somatic cells
53
How can genetic disease be fixed in the germline? (3)
Test embryos before implantation 3 parent babies Edited babies
54
Describe the specialisation of cells during embryotic development
An embryo begins as totipotent cells which can give rise to all cell types, it then becomes terminally differentiated and eventually can only give rise to one type of cell.
54
How is the fate of an embryonic cell determined?
By proteins turning genes on and off. Certain control genes which code for transcription become activated.
54
What is a totipotent cell>
A naive embryo cell
54
What is genomic equivalence?
Differentiated cells can change phenotypically but also genotypically
54
What is a pluripotent cell?
They can develop into any cell type, given the right conditions.
54
Where are embryonic stem cells harvested from?
Inner cell mass of Mammalian blastoclast embryos
55
What are iPS?
Induced pluripotent stem cells
56
What is the purpose of iPS?
They are made by reprogramming adult stem cells and can be made from anyone.
57
What features does a stem cell have?
They are undifferentiated, multipotent cells
57
True or false, there is a limit to how much a stem cell can divide?
False
57
What is the purpose of a stem cell?
To replace the cells that need to be replaced
57
What type of stem cells can be used for transplants?
hematopoietic stem cells
57
What is the purpose of umbilical cord banking?
Can be used to treat blood diseases such as leukaemia and are less restricted than other blood stem cells
58
What are hematopoietic stem cells and where are they found?
Blood stem cells and are found in the bone marrow
58
What kind of cell is totipotent?
Fertilised egg cells
59
What is totipotent?
Able produce any cell of an adult individual
60
What types of cells are pluripotent?
Embryonic stem cells
61
What is multipotent?
Cells that can only give rise to one or a few cell types
62
What cells are multipotent?
Adult stem cells
63
What is the basis of regenerative medicine?
Pluripotent stem cells can be used to replace or repair damaged organs
64
How does regenerative medicine work?
Stem cells can be encouraged to differentiate into specific cell types and can be transplanted into patients

CELS 191 (4 decks)

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