Cell Cycle, Growth, Death and Differentiation

Flashcards covering key vocabulary and concepts from the lecture notes on cell cycle, growth, death, and differentiation.

Binary Fission

The method of cell replication used by prokaryotes.

Prokaryotic Cell Replication Purpose

Growth and development, maintenance and repair, and reproduction.

Binary Fission Result

Daughter cells are genetically identical to the parent cell in bacteria.

Binary Fission

An exponential process where the population doubles after every cycle of division.

Clones in Bacterial Colonies

All organisms in a colony of bacteria are clones and therefore are genetically identical due to binary fission.

Eukaryotic Cell Cycle Main Phases

Interphase, Mitosis, Cytokinesis

Interphase

cellular growth and duplication of chromosomes

Mitosis

separation of sister chromatids and the formation of two new nuclei

Cytokinesis

division of the cytoplasm and formation of two daughter cells.

G1 Phase

The cell grows by increasing cytosol volume, synthesizing proteins for DNA replication, and replicating organelles.

G0 Phase

Cells that are not required to replicate rest in this phase. Cells are either quiescent or terminally differentiated.

S Phase

The cell replicates its DNA turning one chromosome into two genetically identical sister chromatids.

Diploid

Somatic (body) cells containing two sets of paired chromosomes

G2 Phase

The cell continues to grow and prepare itself for mitosis, similar to the G1 phase.

Mitosis Stages

Prophase, Metaphase, Anaphase, Telophase (PMAT)

Prophase

Chromosomes coil and condense, nuclear envelope disappears, and nucleolus disappears.

Metaphase

Spindle fibers fully form and attach to the centromere of each chromosome, guiding them to the equator of the cell.

Anaphase

Spindle fibers contract, splitting the centromere and pulling each sister chromatid to opposite ends of the cell.

Telophase

Chromosomes densely pack together at either end of the cell, new nuclear membranes form, spindle fibers disintegrate, and chromosomes decondense.

Cytokinesis

The cytoplasm divides and the organelles evenly distribute themselves before separating into two daughter cells.

Cell Cycle Checkpoints Purpose

To verify that the cell has grown to the correct size, has synthesised enough protein for DNA replication, checks if the DNA has been damaged during mitosis and cell growth, and checks if there are enough nutrients and oxygen.

Apoptosis

The controlled death of cells in the body

Apoptosis Function

Regulates the total number of cells in our body, is important for our development, and is an essential method of removing malfunctioning or diseased cells.

Apoptosis Pathways

Mitochondrial (intrinsic) pathway and Death receptor (extrinsic) pathway

Mitochondrial (intrinsic) Pathway

Internal components of the cell (such as DNA) are damaged, mitochondria detect this damage and release cytochrome c into the cytosol, activates caspase enzymes, initiating apoptosis.

Death Receptor (extrinsic) Pathway

Death signalling molecules can be recognised by death receptor proteins. When these molecules bind to a death receptor surface protein, caspase enzymes are activated, initiating apoptosis.

Apoptosis Stages

Activation of caspases, Digestion of cell contents, Cell shrinks, Membrane blebbing and breakage

Tumors

When the rate of apoptosis decreases too much, cell growth can increase exponentially, resulting in the formation of tumors

Benign Tumors

Relatively slow-growing masses of cells that are generally enclosed within a capsule which prevents the abnormal cells from separating and invading other parts of the body

Malignant Tumors

Cells of some benign tumors can mutate further and become malignant when they gain the ability to invade nearby tissues and/or enter the bloodstream or lymphatic system and travel to other parts of the body.

Self-sufficiency

Tumor cells can replicate without external chemical growth signals, either producing their own signals or permanently activating cell growth pathways.

Antigrowth deactivation

Mechanisms that prevent cell replication when not needed are disabled in tumor cells, allowing replication to initiate.

Increased survival

Apoptosis no longer functions correctly in tumor cells.

Blood supply formation

Tumor cells can form new blood vessels to maintain an adequate nutrient and oxygen supply.

Tissue invasion and metastasis

Malignant tumor cells can invade nearby tissues and migrate to other parts of the body via the bloodstream or lymphatic system.

Stem Cells

Undifferentiated cells with the capability of differentiating into specialised cells.

Stem Cell Properties

Self-renewal and Potency

Self-renewal

Stem cells can replicate without disrupting their ability to differentiate, producing both a differentiated cell and a copy of themselves when they replicate.

Potency

Stem cells are undifferentiated cells which can give rise to differentiated cells with a specialised function.

Totipotent Stem Cells

Can differentiate into any cell type.

Pluripotent Stem Cells

Can differentiate into multiple cell types.

Multipotent Stem Cells

Can differentiate into a limited number of specialised cell types belonging to a specific tissue or organ

Unipotent Stem Cells

Only differentiate into one cell type found in a specific tissue but can divide repeatedly.