Study Guide 5 (exam2) Flashcards
What is binary fission?
Asexual reproduction; cell divides into two identical cells
What happens during the S phase of the cell cycle?
DNA replication occurs; two identical copies of each chromosome.
What occurs during the G2 phase?
makes organelles, condenses chromosomes, and builds microtubules
What is the M phase?
Nucleus divides and chromosomes are split into two daughter cells
What happens during cytokinesis (C phase)?
Division of the cytoplasm into two daughter cells
What is a diploid cell?
Two sets of chromosomes (one from each parent)
What are homologous chromosomes?
Same size, shape, and genes—one from mom, one from dad
What is the centromere?
Joins sister chromatids and attaches to kinetochore.
What are sister chromatids?
Identical chromosome copies (S phase) joined at the centromere.
What is a karyotype?
Ordered display of chromosomes to pair homologous ones
What is monosomy?
One chromosome missing from a pair
What is trisomy?
Three copies of a chromosome instead of two
What is chromatin?
DNA + proteins that form chromosomes when not dividing
How many nucleotides are in a typical human chromosome?
140 million nucleotides (1.4 x 10^8).
What is a nucleosome?
Basic unit of DNA packaging, (DNA wraps around histone proteins)
What is programmed cell death (apoptosis)?
Controlled process of cell death (develop/maintain healthy tissues)
What happens at the G1 checkpoint?
Checks size, energy, and DNA to decide to divide, rest (G0), or delay
What does the G2 checkpoint do?
Checks for DNA errors before mitosis
What does the M checkpoint monitor?
Ensures proper chromosome alignment before anaphase
What is the G0 phase?
Resting, non-dividing state
What role does telomerase play in cells?
Prevents telomere shortening, allowing unlimited cell division
What is cancer?
Uncontrolled cell division due to gene mutations
What are the deadliest cancers in the U.S.?
Lung cancer, colon/rectal cancer, and breast cancer.
What is mitosis?
Cell division (nonreproductive cells) —> two identical daughter cells
What is meiosis?
Halves chromosome number, produces 4 (non-identical) gametes
What is a eukaryotic chromosome?
DNA coiled around histones, separable during division
What are histones?
Proteins that package DNA into nucleosomes
What is interphase?
Cell prepares for division (G1, S, G2)
What happens during the G1 phase?
Cell grows, performs functions, checks readiness for DNA replication
