1 - The Cell as a Unit of Health and Disease

Question 1

When was the first human genome draft presented?

Answer 1

2001 (with a more complete version in 2003)

Question 2

What percentage of the human genome codes for proteins?

Answer 2

1.5% (20,000 genes)

Question 3

What percentage of the human genome is involved in protein-binding and regulation of gene expression?

Answer 3

80%

Question 4

What are some examples of the types of genes that are involved in regulating gene expression (often through protein-binding)?

Answer 4

Promotors and enhancers

Chromatin binding sites

Micro-RNAs and long non-coding RNAs

Transposons

Telomeres and centromeres

Question 5

What percentage of the human genome is composed of transposons?

Answer 5

~33%

Question 6

What percentage of the human genome synthesizes RNA that will never become protein (e.g. regulatory microRNA)?

Answer 6

60%

Question 7

Why does the non-protein-synthesizing 80% of the human genome matter in disease pathology?

Answer 7

Many genetic diseases and pleomorphisms stem from mutations in these sequences that regulate gene expression.

Question 8

Two random human beings will share an average of 99.5% of their genome. What are the two main forms of variance in the 0.5% (~15 million base pairs)?

Answer 8

Single-nucleotide polymorphisms (i.e. A or T; C or G);

Copy number variations (different numbers of large, contiguous stretches of DNA)

Question 9

What does it usually indicate about the location of two nucleotides or genes if they show linkage disequilibrium?

Answer 9

They are situated close to one another on a chromosome

Question 10

What are some methods of epigenetic gene regulation?

Answer 10

Histone methylation, acetylation, phosphorylation; DNA methylation; chromatin-organizing factors

Question 11

How many base pairs are in the human genome?

Answer 11

~3.2 billion

Question 12

What letter denotes the short arm of a chromosome?

Answer 12

The p (petite) arm

Question 13

What letter denotes the long arm of a chromosome?

Answer 13

The q arm

Question 14

What is another way to think about single-nucleotide polymorphisms?

Answer 14

Allelic differences; i.e. a single nucleotide difference can switch a gene between the dominant or recessive allele type

Question 15

Does histone methylation result in increased or decreased transcription and gene expression?

Answer 15

Either; it depends on which histone is methylated.

Question 16

Does histone acetylation (specifically of lysine) cause increased or decreased transcription and gene expression?

Answer 16

Increased

Question 17

Does histone phosphorylation result in increased or decreased transcription and gene expression?

Answer 17

Either; it depends on the histone phosphorylated.

Question 18

What does an imperfectly fitting miRNA do to target mRNA?

Answer 18

Bind it and prevent translation

Question 19

What does an well fitting miRNA do to target mRNA?

Answer 19

Cleave it

Question 20

What are some task of normal cellular housekeeping?

Answer 20

Protection, communication, movement, nutrient acquisition, production of senescent molecules (replacement of aging molecules), molecular catabolism, energy generation

Question 21

Where are normal cellular housekeeping tasks located in the cell?

Answer 21

They are compartmentalized within membrane-bound organelles

Question 22

What are three organelles involved in cellular waste management?

Answer 22

Lysosomes (general degradation), proteasomes (protein grinder), peroxisomes (fatty acid oxidizer)

Question 23

What are the two basic forms of ECM?

Answer 23

The basement membrane and interstitial matrix

Question 24

What molecular class acts as an inhibitor of the cell cycle at the cell’s checkpoints?

Answer 24

Cyclin-dependent kinase inhibitors (CDKIs) (p53 regulates some of these)

Question 25

Which type of stem cells is totipotent? Which type is pluripotent?

Answer 25

Embryonic stem cells; tissue-specific stem cells