Biology Lecture Notes: Cell Cycle, Mitosis, and Cancer

Flashcards covering the phases of the cell cycle, mitosis, cellular structures, regulatory checkpoints, and the biological basis and characteristics of cancer based on lecture notes.

Sexual reproduction

A process that increases biodiversity by combining genetic material from two parents, resulting in offspring with unique genetic combinations.

Interphase

A period in the cell cycle consisting of the $G_1$, $S$, and $G_2$ phases where the cell grows and performs normal functions or prepares for division.

$$G_1 \text{ phase}$$

The first stage of interphase where the cell grows, performs normal functions, and organelles are synthesized.

$$S \text{ phase}$$

The synthesis phase of interphase where DNA replication occurs and chromosomes are duplicated.

$$G_2 \text{ phase}$$

The growth phase where the cell prepares for mitosis by synthesizing proteins and checking duplicated chromosomes for errors.

M phase

The phase of the cell cycle that includes mitosis (nuclear division) and cytokinesis (division of the cytoplasm).

Mitosis

The process of nuclear division in eukaryotic cells that ensures the number of chromosomes remains constant.

Cytokinesis

The final step of cell division where the cytoplasm divides to form two separate daughter cells.

Prophase

The longest phase of mitosis where chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and the spindle apparatus begins to form.

Sister chromatids

Two identical halves of a duplicated chromosome joined together at a centromere.

Astral rays

Structures that extend from the centrioles to form the aster, helping in the positioning of the spindle fibers.

Prometaphase

The phase where the nuclear envelope fully dissolves and spindle fibers attach to the kinetochores of the chromosomes.

Kinetochore

The assembly of proteins that attaches to the centromere of a chromosome.

Metaphase

The phase where chromosomes align at the equatorial plane, known as the _______ plate.

Anaphase

The shortest phase of mitosis where sister chromatids are pulled apart toward opposite poles as the centromeres split.

Telophase

The phase where chromatids reach the poles, de-condense into chromatin, and the nuclear envelope reforms.

Cleavage furrow

An indentation that forms in animal cells during cytokinesis as the cell membrane pinches in the middle.

Contractile ring

A ring of actin filaments that tightens to split an animal cell into two during cytokinesis.

Cell plate

A structure that forms in the middle of a plant cell during cytokinesis which eventually develops into a new cell wall.

$$G_1 \text{ checkpoint}$$

A regulatory point that checks for sufficient nutrients, growth signals, and intact DNA before the cell enters the $S \text{ phase}$.

$$G_2 \text{ checkpoint}$$

A regulatory point that ensures DNA has been completely replicated and checks for DNA damage before mitosis begins.

M checkpoint

A regulatory point that verifies chromosomes are correctly aligned on the metaphase plate and spindle fibers are attached before anaphase.

$$p53$$

Known as the 'guardian of the genome,' this protein halts the cell cycle for DNA repair or initiates apoptosis if damage is irreparable.

Apoptosis

A planned or programmed cell death that occurs when there are abnormalities, such as DNA damage or viral infection.

Proto-oncogenes

Genes that promote cell division (acting as 'on switches') and can become cancer-causing oncogenes when mutated.

Cyclins

Proteins that regulate the progression of the cell cycle by activating cyclin-dependent kinases ($Cdks$).

Tumor suppressor genes

Genes that prevent uncontrolled cell division by acting as 'off switches,' such as $p53$ and $p27$.

$$p27$$

A tumor suppressor gene that regulates the cell cycle by inhibiting cyclin-dependent kinases to prevent premature entry into the $S \text{ phase}$.

Metastasis

The process by which cancer cells spread from the primary tumor to distant parts of the body to form secondary tumors.

Angiostasis

The creation of enzymes to help continue the spread and invasion of cancer cells into other tissues.

Histone

A group of proteins that form the nucleosome structure of eukaryotic chromatin.

Nucleosome

A unit made up of DNA in a eukaryotic nucleus that appears like a string of beads.

Chromatin

The network of DNA strands and proteins found in the nucleus of a cell.

Centrosome

The microtubule organizing center of the cell.

Centromere

The constricted region on a chromosome that ensures the accurate separation of chromosomes during division.

Stem cell

A cell that maintains the ability to divide and is used to repair injuries, such as red bone marrow stem cells.

Binary fission

The process of division in prokaryotic cells where the cell separates into two daughter cells using a cell wall and plasma membrane.