Human Genome I

Question 1

Define known genes

Answer 1

Predicted genes that have good experimental evidence

Question 2

Define novel genes;

Answer 2

Have sequence similar to known genes, but not 100% identical

Question 3

What is special about human proteins?

Answer 3

They are longer, and have more domains , can interact with more proteins

Question 4

What do human genes undergo and why?

Answer 4

Undergo alternative slicing

So one gene can generate multiple proteins

Question 5

What does the genome encode?

Answer 5

Small portion proteins

Vast majority is elements , intergenic sequences

Question 6

What are isochores?

Answer 6

Large DNA segments that are characterised by an internal variation in GC content

Question 7

What does a CpG island consist of?

Answer 7

Cytosine base followed by a Guanine base, CpG is rare in vertebrate DNA

Question 8

What does the “retro” and “LINE” mean in line retrotransposon?

Answer 8

LINE - long interspersed elements

Retro- going through an RNA intermediate

Question 9

Describe SINE retrotransposon

Answer 9

SINE - short interspersed elements

It is a “parasites parasite” depends on LINE for its propagation

Question 10

What are LINES?

Answer 10

Active or degenerate descendants of transposable elements

Question 11

What are SINES?

Answer 11

Non-autonomous transposable elements and their degenerate descendants

Question 12

Where are Alu elements found?

Answer 12

Only found in primates

Question 13

How are alu elements sorted?

Answer 13

Can be sorted into district families according to shared patterns of variation

Question 14

What are SSTSs?

Answer 14

Simple sequence tandem repeats

Question 15

When do simple repeats occur?

Answer 15

In non-coding regions of DNA, although a few human genetic disorders are caused by microsatellite regions in coding regions

Question 16

Name 3 coding regions for simple repeats;

Answer 16

• myotonic dystrophy
• fragile X
• Huntington’s disease

Question 17

Are repeats bad for repetitive elements?

Answer 17

-> repetitive elements waste energy

-> insertion of repetitive elements can be harmful

Question 18

Why are repetitive elements still there?

Answer 18

•mammalian genomes can not get rid of them due to small population size which allows for accumulation of junk DNA
•the generation and deletion of repetitive elements have reached an equilibrium
•mammalian genomes can tolerate them bcus we developed mechanism to control them E.g siRNA

Question 19

Describe duplicated pseudogenes ;

Answer 19

Created from tandem duplication or unequal- crossover

Segment duplication is prevalent (5% of genome)

Question 20

What are multigene families?

Answer 20

Groups of genes from the same organism that encode proteins with similar sequences either over their full lengths or limited to a specific domain

Question 21

How many members in the Justine protein family and name them;

Answer 21

5
1- H1
2-H2A
3-H2B
4-H3
5-H4

Question 22

What is the job for H1 in eukaryotic genomes?

Answer 22

To hold the structure together

Question 23

What is different about eukaryotic genomes?

Answer 23

The globular proteins contain tails which are rich in amino acids which have positively charged R groups

Question 24

Are is epigenetics?

Answer 24

Phenotype changes in a cell/organism

Question 25

When does chromatin remodelling occur?

Answer 25

Modifications occur primarily within the histone amino-terminal tails protruding from the surface of the nucleosome as well as on the globular code region

Question 26

What 2 ways is the chromosome function affected by histone modifications?

Answer 26

1- electrostatic charge -> results in structural change or the binding to DNA

2- modifications are binding sites for protein recognition modules, eg. Chromaodomains recognise methlyated lysine