Stem Cells and Cell Specialization in Multicellular Organisms

Stem Cells

Cells with the ability to divide endlessly and differentiate into various cell types.

Cell Specialization

Process where cells develop specific traits and functions for survival.

Differentiation

Process where unspecialized cells transform into specialized cells.

Meristematic Tissue

Plant tissue with rapidly reproducing cells that can become various tissue types.

Zygote

Single cell formed from the fusion of two gametes during fertilization.

Embryo

Early stage of development from zygote until body structures begin to appear.

Fetus

Stage of development from the ninth week of gestation until birth.

Gametes

Cells that fuse during sexual reproduction to form a zygote, each with half the genetic material.

Bicoid Protein

Morphogen determining the end in fruit fly embryos.

Tumor

Mass of cells, like cancer cells, reproducing rapidly with improper differentiation.

Cell Signaling

Process transferring information from cell surface to nucleus, crucial in controlling gene expression.

Morphogens

Signal molecules controlling cell differentiation, occurring in concentration gradients.

Self-Renewal

Process where stem cells divide to produce daughter cells that remain as stem cells.

Differentiated Cells

Cells with specialized functions and traits adapted for specific roles.

Gene Expression

Process where genes become active or inactive based on cell signals.

Mitochondria

Organelles in cells responsible for energy production through cellular respiration.

Gradients

Areas of concentration differences, like those of signal molecules in cell differentiation.

Nerve Cells

Cells with diminished ability to reproduce once specialized, like neurons.

Muscle Cells

Cells with limited ability to reproduce once specialized, like muscle fibers.

Epithelial Cells

Cells like skin cells that retain the ability to reproduce rapidly throughout life.

Stem Cell Niches

Locations in organisms where stem cells are present in high numbers and can differentiate.

Stem cell niche

Environment providing support for normal stem cell function

Malignancies

Cancer resulting from changes in a specific niche

Tumour growth

Associated with increased blood vessel development

Anticancer therapy

Involves limiting blood vessel support to cancer regions

Totipotent cells

Cells that specialize into pluripotent stem cells at 4-6 days

Multipotent stem cells

Present in adult tissues like bone marrow, more specialized than pluripotent cells

Unipotent stem cells

Form only a single cell type but can self-renew

Stem cell research

Data sharing common, but research restricted due to cultural reasons

Blood cell production

Stem cells in bone marrow produce blood cells alongside self-renewing stem cells

Epithelial stem cells

Multipotent cells in hair follicles involved in hair growth and skin regeneration

Stem cell niches

Areas in the body with signaling factors for self-renewal and differentiation

Types of stem cell

Totipotent, pluripotent, multipotent, unipotent with distinct characteristics

Embryonic stem cells

Discovered in mice, used for therapeutic cloning and cell replacement

Stem cell therapy

Potential treatment for diseases like Parkinson's, Alzheimer's, and diabetes

Cell-based therapies

Utilizing stem cells for treating diseases and traumas like spinal cord injuries

Ethical issues

Controversy around pluripotent stem cells sourced from embryos

Cell specialization debate

Discussion on the nature of stem cell research and ethical constraints

Cell size importance

Varied sizes in human cells based on function, essential for specialization

Zygote formation

Occurs when male and female gametes combine during fertilization

Embryonic development

Process from zygote to embryo, fetus, and infant involving cell differentiation

Sperm cell function

Transport genetic material for zygote formation

Red blood cells

Carry oxygen, contain haemoglobin, lack mitochondria and nucleus

White blood cells

Defend against infections, retain nucleus, possess enzymes

Blood smear

Microscopic view showing white and red blood cells

Neurons

Specialized nerve cells transmitting impulses

Motor neurons

Carry brain signals to muscles, have long axons

Striated muscle fibers

Specialized cells in skeletal muscle for movement

Surface area-to-volume ratio

Ratio affecting cell size and material exchange

Mitotic spindle

Critical for proper cell division

Cell differentiation

Process determining cell type and size within an organism

Cell physiology

Basic processes like material movement in/out of cells

Cell size constraints

Limits based on surface area-to-volume ratio

Models in science

Simplified versions to understand complex systems

Stem cells

Reproduce, differentiate, form specific cells

Totipotent stem cells

Rare, can differentiate into any cell type

Cell signaling

Controls gene expression in embryo and organism development