1 - The Cell as a Unit of Health and Disease Flashcards
When was the first human genome draft presented?
2001 (with a more complete version in 2003)
What percentage of the human genome codes for proteins?
1.5% (20,000 genes)
What percentage of the human genome is involved in protein-binding and regulation of gene expression?
80%
What are some examples of the types of genes that are involved in regulating gene expression (often through protein-binding)?
Promotors and enhancers
Chromatin binding sites
Micro-RNAs and long non-coding RNAs
Transposons
Telomeres and centromeres
What percentage of the human genome is composed of transposons?
~33%
What percentage of the human genome synthesizes RNA that will never become protein (e.g. regulatory microRNA)?
60%
Why does the non-protein-synthesizing 80% of the human genome matter in disease pathology?
Many genetic diseases and pleomorphisms stem from mutations in these sequences that regulate gene expression.
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)?
Single-nucleotide polymorphisms (i.e. A or T; C or G);
Copy number variations (different numbers of large, contiguous stretches of DNA)
What does it usually indicate about the location of two nucleotides or genes if they show linkage disequilibrium?
They are situated close to one another on a chromosome
What are some methods of epigenetic gene regulation?
Histone methylation, acetylation, phosphorylation; DNA methylation; chromatin-organizing factors
How many base pairs are in the human genome?
~3.2 billion
What letter denotes the short arm of a chromosome?
The p (petite) arm
What letter denotes the long arm of a chromosome?
The q arm
What is another way to think about single-nucleotide polymorphisms?
Allelic differences; i.e. a single nucleotide difference can switch a gene between the dominant or recessive allele type
Does histone methylation result in increased or decreased transcription and gene expression?
Either; it depends on which histone is methylated.
Does histone acetylation (specifically of lysine) cause increased or decreased transcription and gene expression?
Increased
Does histone phosphorylation result in increased or decreased transcription and gene expression?
Either; it depends on the histone phosphorylated.
What does an imperfectly fitting miRNA do to target mRNA?
Bind it and prevent translation
What does an well fitting miRNA do to target mRNA?
Cleave it
What are some task of normal cellular housekeeping?
Protection, communication, movement, nutrient acquisition, production of senescent molecules (replacement of aging molecules), molecular catabolism, energy generation
Where are normal cellular housekeeping tasks located in the cell?
They are compartmentalized within membrane-bound organelles
What are three organelles involved in cellular waste management?
Lysosomes (general degradation), proteasomes (protein grinder), peroxisomes (fatty acid oxidizer)
What are the two basic forms of ECM?
The basement membrane and interstitial matrix
What molecular class acts as an inhibitor of the cell cycle at the cell’s checkpoints?
Cyclin-dependent kinase inhibitors (CDKIs) (p53 regulates some of these)
Which type of stem cells is totipotent? Which type is pluripotent?
Embryonic stem cells; tissue-specific stem cells
