lecture 3 - genetic factors of genetic disease

Question 1

What are the 3 types of mutations, based on scale?

Answer 1

chromosomal, sub-chromosomal, DNA

Question 2

What are chromosomal mutations?

Answer 2

When the number of whole chromosomes changes due to missegregation during meiosis

Question 3

What are sub-chromosomal mutations?

Answer 3

When a chunk of chromosome changes in position or is deleted/inserted.

Question 4

What are the 5 types of subchromosomal mutation?

Answer 4

deletion, duplication, inversion, insertion, translocation

Question 5

What are point mutations?

Answer 5

Single nucleotide substitutions in DNA.

Question 6

What are indel mutations?

Answer 6

Insertions or deletions of a small number of bases in DNA

Question 7

What is a frameshift mutation?

Answer 7

An indel that is not in a multiple of 3 meaning that the down stream amino acid sequence generated during translation will be different.

Question 8

What are dynamic mutations?

Answer 8

Expansion of polymorphic DNA repeats - where 2-4 nucelotides are repeated - leading to abnormal gene products

Question 9

What is epigenetics?

Answer 9

Chemical covalent modification of DNA that result in changes to the regulation of genes without altering the DNA sequence

Question 10

What is epigenomics?

Answer 10

the study of the complete set of epigenetic modifications on the genetic material of a cell, known as the epigenome

Question 11

What is DNA packaged and organised into?

Answer 11

chromatin

Question 12

What are the components of chromatin?

Answer 12

DNA & histones

Question 13

What are histones?

Answer 13

Proteins that package DNA into chromatin

Question 14

What are the 2 forms of chromatin, which is dynamic?

Answer 14

Euchromatin, heterochromatin

Question 15

What is the loosely packed form of chromatin?

Answer 15

Euchromatin

Question 16

What is the densely packed form of chromatin?

Answer 16

heterochromatin

Question 17

What are the 2 types of mutation, in terms of what type of cell they occur in?

Answer 17

Somatic, germline

Question 18

What is the diameter of euchromatin?

Answer 18

10nm

Question 19

What is the diameter of heterochromatin?

Answer 19

30nm

Question 20

What feature of histone proteins aid in binding to DNA?

Answer 20

positively charged tails - bind to negatively charged DNA

Question 21

What form of chromatin allows for gene expression?

Answer 21

Euchromatin - it is loosely packed

Question 22

Why does euchromatin allow for gene expression?

Answer 22

Loosely packed form of chromatin, so transcription factors have access to the gene and its promotor.

Question 23

Why does heterochromatin prevent transcription?

Answer 23

DNA is condensed so the promotor of genes within that region is inaccessible to RNA polymerase, preventing transcription from occuring.

Question 24

What are the 2 key postranslational covalent modification of histone tails that can lead to changes in transcriptional activity?

Answer 24

Acetylation, methylation

Question 25

What is histone acetylation?

Answer 25

The addition of an acetyl group (CH3CO) to the lysine groups of histone tail

Question 26

What is the result of histone acetylation?

Answer 26

Acetyl group neutralises positive charge of lysine side chain, decreased their interaction with negatively charge DNA, and uncondensing the DNA to make it transcriptionally active

Question 27

What is histone demethylation?

Answer 27

The removal of methyl groups (CH3), from lysine (K) and arginine (R) amino acids in histone tails.

Question 28

What is the result of demethylation of histones?

Answer 28

Chromatin decondenses into transcriptionally active euchromatin.