Pharmacogenomics Flashcards
how many cells in the human body
30-40 trillion
how many different types of cells
200
how many cells die each day and are replaced?
100 billion
what are the cell cycle phases
G1, S, G2, M, G0
what is G1
cell grows and prepares for DNA synthesis
Cell is getting bigger, enzymes, and molecules required for synthesis are prepared
what is the S phase
DNA replication
One copy into 2 copies (doubling of DNA material)
what is the G2 phase
cell continues to grow and prepare for mitosis
Has to accumulate the molecules for mitosis, cell continues to get bigger in order to divide into 2 cells (don’t want small daughter cells)
what is the M phase
mitosis: cell stops growth and starts division
Further divided into 4 phases: prophase, pro-metaphase, metaphase, telophase, cytokinesis
what is G0 phase
cell has left the cell cycle and stopped dividing
Daughter cells can keep dividing or leave the cell cycle
Cell is stable and doing biological functions
Some cells leave and become permanent: neurons
where are the checkpoints in the cell cycle?
G1 and G2
what happens at the G1 checkpoint?
DNA synthesis
Checks if the cell is ready for DNA synthesis (problem with unwinding, etc)
what happens at the G2 checkpoint
preparation for mitosis
Checks whether the cell is ready for mitosis (does it have all the molecules)
what is the R point
cell commits to the cycle for division
Before the R: cell is growing and is preparing for DNA synthesis (requires growth factors)
After R: no longer needs growth factors, it is now an AUTOMATIC process
Happens 2-3 hours before the S phase
G1 checkpoint and R point happen very closely together
how many pairs of chromosomes
23 pairs
22 autosomes
1 pair of sex chromosomes
what is a chromosome
Complex of DNA molecules and proteins
how many base pairs in a DNA molecule
50-250 million base pairs
how many base pairs and genes in an average chromosome
130 million base pairs
2500-5000 genes
what do the non-coding regions do?
regulate gene functions
Only 10% of human chromosomes code for genes
what is a microband
3-5 million base pairs and 60-120 genes
what is the chromosome structure?
Chromosome–>chromatin fiber–>nucleosome–>histone–>gene–>nucleotide
what are the nucleotide base pairs
A-T: 2 H bonds
C-G: 3 H bonds
what is a histone
DNA wraps around a histone polymer
2 linker regions of DNA: H1 anchors the 2 DNA linkers to the histone atomer
H2A and H2B are paired; H3 and H4 are paired
Also called DNA beads
what is a gene
A portion of chromosomal DNA sequence required for the production of a polypeptide (protein) or a functional RNA molecule
what is the size of a small gene vs a large gene?
small-1.5 kb
large-2000kb
which is the biggest gene?
DMD gene
what is the size of mature mRNA compared to the gene?
1/10th
Small genes encode for proteins but bigger genes have introns that will be spliced out
what are the 4 nucleotides in mRNA
A, U, G, C
how many nucleotides in a codon
3
what does the first/second letter in a codon dictate?
tells you the amino acids made
what happens if the 3rd nucleotide is changed?
can end up with the same amino acid or a different one
what is transcription
gene–>mRNA
what is translation
mRNA–>protein
how many genes expressed in a typical human cell
15,000 genes expressed
Pattern of expression is different from one cell to another (brain vs. cardiac)
Genes may be different and expression may be different
how do eukaryotic genes differ from prokaryotic
have introns and exons