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Flashcards in Human Genome Deck (24)
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1
Q

What is Chromatin, and its function

A

Chromatin is a substance found within a chromosome consisting of DNA and proteins.

It’s function is to tightly package DNA in compact and dense structure.

2
Q

Draw and label a nucleus (5)

A

Allocate

  1. Eurochromatin
  2. Heterochromatin
  3. Nucleolus
  4. Nuclear Envelope
  5. Nuclear Pores
3
Q

What are the functions DNA has to fufil? (3)

A
  1. Encodes all the information required to make an organism (DNA to RNA to Protein)
  2. It must replicate itself accurately
  3. It must allow beneficial mutations to be selected.
4
Q

What are the central dogma of Molecular biology? (3)

A
  1. DNA Synthesis (replication)
  2. RNA synthesis (transcription)
  3. Protein synthesis (translation)
5
Q

What is Genetics? (1)

A

A study of the process by which characteristics are passed from parent to offspring (hereditary)

6
Q

What is a Gene?

A

A single unit of biological information that encodes for a specific protein or regulatory molecule

7
Q

What is the human genome?

A

A complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria.

8
Q

Give a brief history of the human genome discovery (4)

A

1990-2003 - 20 countries in 6 countries work together, first analysis in 2001, then published further sequence in 2003.

2001 - Celera (Craig Venter) also published sequence in 2001. Also published first diploid genome of an individual in 2007.

2008: 1000 Genomes Project; 2010: 10,000 Genomes Project; 2013: 100,000 Genomes Project and NHS: linking clinical data to sequence
2016: 1m+ US ‘All of us’ program

Now: Private and public enterprises

9
Q

What are the cost and timeline changes associated with human genome sequencing, future?

A

First Genome - 13 years, $13 billion
Now - Few days, $5000
Next Few Years - 15 mins, $500

10
Q

Important stats.
How many bases of DNA?
How many Genes?
What is the proportion of repeating elements?
What is the proportion of Genome that actually codes for proteins?

A
  1. 3.2 x 10^9
  2. 20,000 Genes
  3. 50% repeating
  4. 1.5% codes for proteins
11
Q

What is the extent of human genetic variation? (3)

A
  1. All genes are 99.99% identical.
  2. Each have around 3 million single nucleotide polymorphisms (SNP)
  3. Each have around 50-100 SNPs associated with an inherited disease. Two copies of gene means we’re healthy.
12
Q

Rank from what is caused by genetic factors alone to Multifactorial to environment:

  1. Diabetes
  2. Sickle Cell Anaemia
  3. Tuberculosis
  4. Scurvy
  5. Heart Disease
A
  1. Sickle Cell Anaemia

Multifactorial:

  1. Tuberculosis
  2. Diabetes
  3. Heart Disease

Environment alone:

  1. Scurvy
13
Q

What is the impact of genomics on Medicine (what we can learn/research) Part 1. (3)

A
Functional Genomics (what we learn):
1. Mechanisms of disease (rare diseases)
  1. Targeted theraperutics and gene therapy (cancer biology)
  2. Human Evolution
14
Q

What is the impact of genomics on Medicine (how we apply to treatment) Part 2. (3)

A

Personalised Medicine:
1. Prediction of disease (Huntington’s)

  1. Pharmacogenetics (40% of drugs prescribed have no effect due to genetics)
  2. Ethics (Foetal DNA from maternal blood)
15
Q

What is the structure of DNA? (3)

A
  1. Double helix of nucleic Acid
  2. Complementary strands of nucleotides. A-T, C-G
  3. Sequence of bases code for different proteins
16
Q

Describe the molecules involved in DNA and the bonds they make. (4)

A
  1. Phosphate-sugar and nitrogenous base make up a nucleotide.
  2. The DNA strand has 5 prime end and 3 prime end.
  3. Hydrogen bond between base pairs in double strand
  4. Strong ‘phosphodiester’ Covalent bonds within each linear strand
17
Q

How is DNA arranged in chromosome? (4)

A
  1. DNA is tightly wound around a ‘bead’ of histones.
  2. Chromatin fibre is tightly packed into nucleosome
  3. Chromatin fiber folds into loops.
  4. This makes up mitotic chromosome.
18
Q

What is Nucelosome made of? (2)

A

Core Particles

  1. 8 histones (octomer) (2x H2A, H2B, H3, and H4)
  2. Histones +ve, DNA -ve charged.
19
Q

How is DNA condensation Regulated? (2)

A
  1. Chromatin-remodelling complexes using ATP.

2. Histone modifying enzyme (using ATP). (Adds/removes, acetyle, phosphate or methyl groups)

20
Q

How can supercoiling affect gene expression? (2)

A

Supercoiling can affect gene expression by causing it to be switch off.

(B-globin: Severe Anaemia
Tumour suppressor genes: Cancer)

  • Histone pattern can be inherited
21
Q

What is Epigenetics? (2)

A

Heritable changes in gene function that cannot be explained by changes in DNA sequence (e.g methylation).

22
Q

One example of Chromatin Diseases?

A

Rubinstein-Taybu Syndrome (RSTS). Mutation in histone acetyl-transferases.

1/100,000.

Non-specific symptoms, Intellectual disability, Facial abnormalities, big thumbs and toes.

23
Q

How many pairs of chromosomes do we have? (2)

A
  1. Normal Cells (Diploid) - 22 homologous autosomal chromosomes and a pair of sex chromosomes (XX/XY)
  2. Except Haploid gametes (22 single chromosomes + X or Y = 23)
24
Q

What is Cytogenetics?

A

The study of inheritance in relation to the structure and function of chromosomes.