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2.1 Cell and Molecular Biology > Fergus - Introduction to the Human Genome > Flashcards

Fergus - Introduction to the Human Genome Flashcards

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1
Q

What are the three components of DNA/RNA?
(3)

A

Nucleotide made from a five carbon sugar (deoxyribose/ribose)

A phosphate

A nitrogenous base

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2
Q

How does deoxyribose differ from ribose?

A

In deoxyribose the 2nd carbon on the sugar is a hydrogen

In ribose the 2nd carbon in the sugar is an OH group

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3
Q

In what direction are new nucleotides added onto DNA?

A

From the 5’ to the 3’ end

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4
Q

What does the 5’ of DNA/RNA contain?

A

A phosphate group

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5
Q

What are the four bases of DNA?

A

Adenine
Guanine
Cytosine
Thymine

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6
Q

What are the four bases in RNA?

A

Adenine
Guanine
Cytosine
Uracil

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7
Q

How does uracil differ to thymine?

A

Uracil is closely related to thymine
Uracil has a H as its variable group while thymine has a CH3

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8
Q

How does G bind to C?

A

By three hydrogen bonds

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9
Q

How does A bind to T

A

By two hydrogen bonds

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10
Q

How many bases are needed for a complete turn of a DNA sequence?

A

10 bases

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11
Q

Classify nitrogenous bases

A

Purines

Pyrimidines

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12
Q

How many chromosomes do we have?

A

46

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13
Q

How are our chromosomes classified?

A

Autosomes

Sex chromosomes

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14
Q

How does a female karyotype occur?

A

One X chromosme from father

One X chromosome from mother

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15
Q

How does a male keryotype occur?

A

One Y chromosome from father

One X chromosome from mother

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16
Q

How does a male keryotype occur?

A

One Y chromosome from father

One X chromosome from mother

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17
Q

How does a male keryotype occur?

A

One Y chromosome from father

One X chromosome from mother

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18
Q

What is different about the karyotype in someone who has Down’s Syndrome?

A

There is an extra copy of the 21st chromosome

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19
Q

What is mosaic downs?

A

There isn’t an extra copy of chromosome 21 in every single cell

20
Q

What percentage of the human genome codes are genes (protein coding sequences)?

A

15%

21
Q

What percentage of the human genome is heterochromatin?

A

8%

22
Q

What is heterochromatin?

A

Densely packed chromatin found in the nucleus

23
Q

What percentage of the human genome is segmental duplications?

A

5%

24
Q

What are segmental duplications?

A

Duplications that may have developed due to replication errors, chromosomes that have been replicated, same sequences replicated twice

25
Q

What percentage of the human genome are single sequence repeats

A

3 % -> usually errors in replications

26
Q

What percentage of the human genome are retrovirus-like elements?

A

8%
RNA viruses that have left their genome in our genome

27
Q

What percentage of the human genome are DNA transposon ‘fossils’ and what are they?

A

7% they allow bacteria to transfer genetic material around to other cells

28
Q

What percentage of the human genome are SINEs and LINEs and what are they?

A

About 34% of the genome
Short and long interspersed retrotransposable elements
Don’t really know their function yet

29
Q

Write a note on a promoter sequence
(4)

A

No more than about 200 bp long
Determines wether a gene will be active or not
Determines wether a gene will produce RNA or not
At least one of the following is always found in a promoter:
- TATAA, CAAT, GC and Oct sequences

30
Q

Write a note on an enhancer
(2)

A

Can be thousands of bp long
Determine how much RNA can be produced

31
Q

Write a note on exons
(2)

A

They code for proteins
These end up in mRNA and are then translated into protein

32
Q

Write a note on introns

A

These do not code for proteins
They are made into RNA but are then spliced out to make mRNA

33
Q

How many exons does the biggest human gene have?

A

300

34
Q

How many bps does the dystrophin gene have?

A

It has 2.5 million base pairs but it has only 12,000 after splicing has occurred to form mRNA

35
Q

What often happens to the first exon?

A

It is often untranslated
It arrives in mRNA but does not get translated or at least not all of it does

36
Q

Give an example of a promoter

A

The methionine codon -> indicates the start point of translation

37
Q

There is part of the 5’ region (promoter) that is not translated, what happens at the 3’ region?

A

There is also a 3’ untranslated region

38
Q

Briefly describe the formation of a protein

A

Nucleus -> DNA transcription -> hnRNA -> post transcriptional processing -> mRNA -> moves out to cytoplasm through nuclear pores -> ribosome - translation -> post translational modification -> protein

39
Q

Give some examples of post transcriptional processing
(3)

A

Capping
Splicing
Polyadenylation

40
Q

How many genes do we have?

A

20,000 approximately

41
Q

What are polymorphisms?
(2)

A

Natural variations in our genome (not associated with disease)

Allows us to differentiate from each other - they are why we look different

42
Q

What does hnRNA stand for?

A

Heterogenous nuclear RNA
This is the RNA transcribed straight from DNA - there has been no modifications e.g. splicing

43
Q

Give two examples of post translational modifications

A

Phosphorylation - addition of a phosphate groups
Cleavage - chopping off a part of the protein e.g. insulin

44
Q

Is cystic fibrosis recessive or dominant?

A

Recessive

45
Q

Where is the mutation for cystic fibrosis found?
(3)

A

Found in chromosome 7
CFTR gene
Exon 10

46
Q

List the different parts of the human genome
- What makes up the human genome
(8)

A

SINEs and LINEs = 34%
Introns = 25%
Heterochromatin = 8%
retrovirus-like elements = 8%
DNA transposon ‘fossils’ = 7%
segmental duplications = 5%
single sequence repeats = 3%
Exons = 1.5%

2.1 Cell and Molecular Biology (26 decks)

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