Basic Concepts Flashcards
How many cells are in the body?
30-40 trillion cells that have a great amount of coordination and specialization
What is the cell cycle?
It is the cell division process
G1, S, G1, M, G0
What is G1 in the cell cycle?
G1 (Gap 1): Longest phase
Cell growth and preparation for DNA replication
What is the S phase in the cell cycle?
Synthesis: DNA replication
What is the G2 phase in the cell cycle?
G2 (Gap 2): The cell continues to grow and prepares for mitosis
What is the M phase in the cell cycle?
M (Mitosis): Cell growth stops and starts cell division
What is the G0 phase in the cell cycle?
G0 (Gap 0): Cell leaves cell cycle and stops dividing
What are the two checkpoints in the cell cycle?
G1 and G2 checkpoints
What is the purpose of the G1 checkpoint?
Checks for errors in DNA synthesis
What is the purpose of the G2 checkpoint?
The cell ensures it is ready for mitosis
What is the restriction point (R)?
After this point in the cell cycle, the cell commits to the cyles for division, no additional growth factor required
How many base pairs are found in a DNA molecule?
50-250 million base pairs
Are genes evenly dispersed in the chromosome?
No, there are regions with 60-120 genes in close proximity called microbands
An average microband has 3-5 million base pairs
What percentage of the human chromosome code for genes?
Only 10%, the rest may have important regulatory roles
What are histones?
They are a complex of proteins that DNA will wrap around to facilitate super condensation of the chromosomes into a small size that can fit inside the nucleus
What is a gene?
A portion of chromosomal DNA sequence required for the production of a polypeptide (protein) or a functional RNA molecules
What are some components of a gene?
Coding sequence
Promoters and other regulatory sequences
What are the four types of nucleotides in DNA?
Adenosine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
What are the nucleotide pairs?
A - T
G - C
Which of the three nucleotides in a codon poses the most significant risk for protein product modification due to a point mutation?
If the first and second bases are different, it will result in a completely different amino acid, potentially causing significant changes to structure and function
Do gene mutations always cause disease?
No, the impact is either not significant, increased risk, or even reduced risk for disease
What are promoters?
DNA sequences that promote gene expression
They are required for DNA transcription (contain RNA polymerase binding site)
How many genes are in the human body?
19,000 individual genes in the nuclear DNA genome is a conservative estimate
38 confirmed genes in the mitochondria