The Human Genome Flashcards

A guide to the human genome for clincians

You may prefer our related Brainscape-certified flashcards:
1
Q

What 2 elements lead to disease?

A

Genetics and environment

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2
Q

What is the concept of precision medicine?

A

Identify and treat people who will benefit from treatment. Those who the treatment isn’t suitable for either have to get a different treatment or for some there is no suitable alternative.

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3
Q

How is DNA organised?

A

Double stranded, antiparallel, when replicated read in 5’-3’ direction. Sugar backbone is 2-deoxyribose. Bases ATGC

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4
Q

Where is the information in DNA held?

A

The sequence of bases held on a sugar-phosphate background

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5
Q

How are DNA bases paired?

A

Adenine with thymine, cytosine with guanine

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6
Q

What does the DNA strand associate with and form?

A

Wrapped around proteins (histone) and wound into chromosomes

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7
Q

How much of your genome is genes?

A

2-3%

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8
Q

What are the 4(/5) stages of the cell cycle?

A

G1, (sometimes G0), S(ynthesis), G2 and M(itosis)

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9
Q

During what phases of the cell cycle does DNA replication occur?

A

S phase

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10
Q

What is the DNA damage and repair mechanism?

A

Damage can occur during replication of DNA, and there are repair mechanisms however if the mechanisms are defected disease can be caused.

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11
Q

What significance does only 2% of the genome being genes have in mutations?

A

When mutations occur during mitosis it has a very high chance of occurring in an area that isn’t genes so won’t affect the genotype

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12
Q

What are the key parts of meiosis?

A

One diploid parent cell = 4 haploid daughter cells. Crossing over occurs

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13
Q

When does meiosis happen?

A

During gamete formation

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14
Q

How does RNA differ in comparison to DNA?

A

Single stranded, ribose sugar in backbone not deoxyribose, and uracil instead of thymine

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15
Q

Which one is more stable, RNA or DNA?

A

DNA as if RNA was more stable it would stay making proteins for too long and it is only required for a short time to code

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16
Q

What binds to the promotors in DNA?

A

Transcription factors

17
Q

Are introns coding or non-coding?

A

Non-coding and so cut from DNA during transcription

18
Q

Are exons coding or non-coding?

A

Coding and so spliced together after introns cut during transcription

19
Q

What factors determine the amount of protein produced?

A

Rate of transcription, rate of splicing to mRNA, half life of mRNA and rate of processing of polypeptide.

20
Q

What is DNA transcribed to?

A

Pre mRNA

21
Q

What is pre mRNA spliced to?

A

mRNA

22
Q

What is mRNA translated to?

A

A protein (remember 3 bases encode an amino acid or a stop codon)

23
Q

Why do some point mutations have no affect on the protein created?

A

As sometimes a different triplet of bases code for the same amino acid

24
Q

How do sequences vary in a gene?

A

Changes in the promotor sequence and changes in the exon sequence

25
Q

What is the promotor sequence?

A

The region of the DNA sequence where transcription of a gene by RNA polymerase begins

26
Q

What causes sequence changes in the DNA between genes?

A

Single nucleotide polymorphisms (SNPs) or larger deletions/duplications

27
Q

What is polymorphism?

A

Any variation in the human genome that has a population frequency of >1% OR any variation in the human genome that doesn’t cause a disease but may be a predisposition to one.

28
Q

What is a mutation?

A

A gene change that causes a genetic disorder OR any heritable change in the human genome

29
Q

How does variation in the human genome occur?

A

Crossing over at meiosis cause variants to segregate independently of each other (unless they were close together on the chromosome)

30
Q

Why do people have genetic variants their parents don’t have?

A

As DNA replication isn’t perfect and so every cell in your body has mutations acquired during mitosis