semester 2 unit 1 Flashcards
Cell cycle
Interphase, mitosis, cytokinesis
Interphase stages
G1, S phase, G2
How many stages of mitosis? What are they?
- Prophase, metaphase, anaphase, telophase (cytokinesis follows mitosis).
How do you calculate mitotic index?
Mitotic index = number of cells in mitosis / total number of cells
What happens during G1 phase?
Gene expression and cellular respiration (producing ATP)
What happens during S phase?
DNA replicates creating two identical DNA strands
What happens during G2 phase?
Cell prepares to divide by replenishing energy, synthesizing proteins, and growing in size
What happens during prophase?
Chromosomes condense, forming two chromatids. Nuclear membrane disintegrates causing spindle to form.
What happens during metaphase?
Spindle organizes chromosomes on equator of the cell. Some spindle fibres attach to the centromeres and some span the cell. M-checkpoint occurs.
What happens during anaphase?
Some spindle shorten which pull the chromatids apart. Other spindle lengthen which cause cell to elongate.
What happens during telophase?
Two new nuclei form.
What happens during CYTOKINESIS?
The cell cytoplasm divides creating two new daughter cells.
What happens during INTERPHASE?
Cell spends most of their life in interphase. It grows and replicates its DNA/centrosomes in order to prepare for cell division.
What happens during MITOSIS?
The cell replicates and separates its chromosomes. The cell nucleus that holds the DNA divides into 2 equal parts.
How do plant cells divide?
Plant cells construct a new cell plate. The materials needed to do so are delivered by vesicles from Golgi.
How do animal cells divide?
A ring assembles in the middle of cell creating a cleavage furrow that moves inward (energy using process) to separate the two cells.
When do plant cells begin cytokinesis?
Prophase
When do animal cells begin cytokinesis?
Anaphase
Cyclins
Cyclins control cell cycle progression by determining whether it will be fast or slow. Mutations in cyclin genes can lead to cancer. Cells cannot progress in cell cycle unless specific cyclins (D, E, A, B) reach a certain concentration.
Cyclin D
Synthesized during G1. Triggers transition from G1 to S phase.
Cyclin E
Synthesized during G1. Triggers transition from G1 to S phase.
Cyclin A
Initiates DNA replication. Prepares centrioles for mitosis.
Cyclin B
Progresses cell in & out of mitosis.
What is mitotic spindle made of?
Microtubules and proteins
Which cells have centrioles?
Animals have centrioles, plants have no centrioles.
What’s chromatin?
Substance in cell’s nucleus that’s composed of primarily DNA and proteins
What’s a chromatid?
One of the two identical halves of a chromosome that’s been replicated during cell division
What’s a chromosome?
DNA molecule that holds genetic material
Malignant tumor vs benign tumor
Malignant tumors grow rapidly and spread throughout the body destroying nearby tissues. Benign tumors grow slowly and don’t spread.
Mutagen
An agent (radiation, chemical substance) that causes a genetic mutation
Oncogene
A gene that can transform into a tumor cell
Kinetochore
Protein complex that attaches to spindle & centromere
