Chapter 8: The Cell Cycle, Mitosis, and Cancer

Why does the cell cycle matter?

Can learn how growth and development works to repair tissue and organ damage, grow new organs and limbs, create new cancer treatments, and slow down or even reverse aging

Binary Fission

A form of asexual reproduction used in prokaryotes where two identical offspring are made

Vertical Gene Transfer

The transfer of genes from parent to offspring, how humans get their genes

What does asexual reproduction help with?

Allows for rapid division and evolution

Horizontal Gene Transfer

Bacteria obtain genes and DNA fragments from their environment, this is how bacteria become antibiotic resistant

Pangenome

All the genes in a population, bacteria have a large pangenome unlike humans 

Eukaryotic Cell Cycle

Multicellular organisms use the cell cycle to regulate growth and development throughout their lives

Somatic Cells

Cells of our body such as skin cells, lung cells, muscle cells, and nerve cells

Homologous Chromosomes

They carry the same genes, but may have different versions of those genes that are expressed differently

Parts of the cell cycle

Interphase and Mitotic Phase

Interphase

Most of the cells time is spent in interphase, it consists of 3 phases: G1 which is the first gap, S-phase, and G2 which is the second gap

G1(first gap)

The daughter cells grow, in some cases doubling their size

S-phase

The chromosomes are duplicated

G2(second gap)

Cell grows more, prepares for cell division, and the centrioles begin to form and organize the mitotic spindle

Mitotic Phase

How eukaryotic cells divide asexually, divided into 2 phases: mitosis and cytokinesis

Mitosis

Division of nuclear material, has 5 stages: prophase, prometaphase, metaphase, anaphase, telophase

Prophase

microtubules begin to emerge from the centrosomes which forms the spindle, chromosomes coil, nucleoli disappears

Prometaphase

The spindles attach to the centrosomes at the kinetochores which starts moving the chromosomes to the center of the cell, nuclear envelope disappears

Metaphase

Spindle is fully formed, chromosomes align at the center of the cell

Anaphase

Sister chromatids separate at the centromeres, daughter chromosomes are moved to opposite sides of the cell, cell elongates

Telophase

Nuclear envelope forms around daughter chromosomes creating daughter nuclei, nucleoli reappears, spindles disappear

Cytokinesis

Division of the cytoplasm into separate cells

Apoptosis

Programmed cell death, some cells are programmed to die as part of growth and development, different than necrosis

When does apoptosis occur?

When a cell is overly stressed and initiates a signal from within the cell or when the cell is no longer required and receives a death signal from other cells

How does apoptosis occur?

Proteins called caspases are released, they create blebs which are irregular bulges in the cells membrane, then the blebs form apoptotic bodies that are phagocytized by white blood cells

Cancer

An abnormal growth of cells, they have escaped the checks of the cell cycle therefor avoiding apoptosis

Tumors

Benign tumors are not spreading throughout the body, malignant tumors are cancerous and spreading, and metastasized is where the cancer is spreading throughout the body

Bodies defense against cancer

Telomeres are repeating segments of DNA at the end of our chromosomes that limit the number of cell divisions our somatic cells can go through

Oncogenes

Genes that are linked to cancer

Proto-oncogenes

Normal genes involved with cell growth and development, a mutation turns them into an oncogene which is a step closer to cancer

Mutagens

Things in the environment that cause mutations in cells

Carcinogens

Substances that cause cancer

Cancer Treatments

Chemotherapy prevents cancer cells from completing mitosis causing them to die, radiation kills cancer cells that can’t repair their damaged DNA, and immune therapy programs the immune system to target the cancerous cells