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Flashcards in Clinical Genetics Deck (46)
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1

T/F A significant portion of the genome codes for proteins

False, very little of the genome actually codes for proteins

2

What is the main role of heterochromatin region?

condensing DNA
gene regulation
protect integrity of DNA

3

What are some of the regulatory products coded by the genome?

tRNA, rRNA, non-coding RNAs

4

Which process complex is responsible for the splicing of RNA?

Slicesosomes, important for generating diversity

5

How does histone regulate expression?

it winds more or less tightly via acetylation and methylation, allowing or denying access of replicating machinery

6

What's euchromatin?

the open conformation of chromosome (heterochromatin is closed)

7

What is DNA methylation associated with?

Silencing genes

8

What is the CpG region also known as?

CpG islands, because they are rich around promotor regions

9

How is CpG island related to silencing of the genome

when it's hyper-methylated + low acetylation of histone, the gene is silenced

10

T/F Euchromatins have hypermethylated CpG islands

False, euchromatins are open, allowing replication. So CpGs are lacking methylation, while histones are hypermethylated

11

What are some ways of generating genome and protein diversity?

having more than one promotor on one gene

alternative splicing from the same transcript

12

What are some roles of non-coding RNAs?

act as decoy
scaffold,
guide transcription factor
enhancer

13

What are short interfering RNAs made from?

double stranded RNAs

14

What is the action of short interfering RNA

Interact with RNA-induced silencing complex to increase degradation of mRNA

15

What is the function of micro-RNAs?

interact with RISC to repress translation rather than degrade mRNAs

16

What is bi-allelic expression?

Where both maternal and paternal copy need to transcribe equal amount of proteins at a time

17

What is trisomy 21 also known as?

Down syndrome

18

What are the symptoms of down syndrome?

mental disability
congenital heart disease, GIT disease, increased risk of leukemia, early onset Alzheimer

19

What is trisomy 18 also known as?

Edwards Syndrome, with severe mental disability, limb and heart defects

20

What are some autosomal recessive conditions?

cystic fibrosis, sickle cell anaemia, thalassaemia, haemochromatosis

21

What is haplo-insufficiency?

When there is only one copy of the chromosome and not enough protein is produced.

Autosomal dominant condition

22

When does X-chromosome inactivation occur?

around 8 cell stage

23

What is the Barr body?

condensed chromosome on X-inactivation

24

How does X-inactivation occur?

due to non-coding RNA Xist expression, which creates a wave of hyperchromatin in both directions

25

What is Turner syndrome?

45X, where one X is missing. There are a few genes that must remain active

26

Which genes of the inactivated X genes must remain active?

genes that cluster at the ends of the chromosome, homologous to the Y chromosome

27

What are genomic imprinted genes?

genes that are expressed in parent-specific manner. The maternal and paternal genes come together during fertilisation

28

What is parthenogenesis and androgenesis?

parthenogenesis = all maternal origin chromosomes
androgenesis = all paternal origin chromosomes

29

T/F Maternal genes tend to conserve resource for the mother

True

30

What are the four causes of imprint disorders?

large deletion/duplication of chromosomes with imprint genes

Uniparental disomy

Epimutation

DNA mutation